Warm Moist Conditions Research Articles

Seed Cryopreservation, Germination, and Micropropagation of Eastern Turkeybeard, Xerophyllum asphodeloides (L.) Nutt.: A Threatened Species from the Southeastern United States.

Xerophyllum asphodeloides (Xerophyllaceae), known as eastern turkeybeard, is an herbaceous perennial found in eastern North America. Due to decline and destruction of its habitat, several states rank X. asphodeloides as “Imperiled” to “Critically Imperiled”. Protocols for seed cryopreservation, in vitro germination, sustainable shoot micropropagation, shoot establishment in soil, and seed germination are presented. Seeds from two tested sources were viable after 20 months of cryopreservation. Germination of isolated embryos in vitro was necessary to overcome strong seed dormancy. Shoot multiplication and elongation occurred on ½ MS medium without PGRs. Shoots rooted in vitro without PGRs or with 0.5 mg/L NAA or after NAA rooting powder treatment and placement in potting mix. When planted in wet, peaty soil mixes, shoots grew for two months and then declined. When planted in a drier planting mix containing aged bark, most plants continued growth. In the field, plant survival was 73% after three growing seasons. Safeguarding this species both ex situ and in situ is possible and offers a successful approach to conservation. Whole seeds germinated after double dormancy was overcome by incubation under warm moist conditions for 12 weeks followed by 12 weeks cold at 4 °C and then warm.

Mineralisation of soil organic carbon in two Andisols under oil palm: an incubation study into controlling factors

Understanding the factors controlling stability against mineralisation of soil organic matter is important for predicting changes in carbon stocks under changed environment or management. Soil carbon dynamics in oil palm plantations are little studied and have some characteristics that are unusual compared with other agricultural soils, such as high management-induced spatial variability and warm moist conditions. The aim of this work was to determine the factors controlling the mineralisability of the intermediate-stability carbon fraction of volcanic ash surface soils (0–5 and 15–20 cm depth) from oil palm plantations in Papua New Guinea. Soils with carbon contents of 2.2–35.2%, from areas with low and high organic matter inputs, were incubated for up to 812 days and soil respiration was measured periodically. Mean carbon turnover rates were 0.18–1.58, 0.07–0.23 and 0.03–0.07 a–1 on Days 54, 379 and 812 respectively. Turnover rate was initially (Day 54) correlated with pre-incubation total carbon content (r = 0.88), the ratio of permanganate-oxidisable carbon to total carbon (r = 0.62) and the ratio of oxalate-extractable Al and Fe to total carbon (r = –0.51 and –0.54 respectively), but the correlations decreased with time, being insignificant on Day 812. In the soils that had changed from C4 grassland 25 years previously, turnover rate was negatively correlated with δ13C, which increased with depth, but δ13C did not change significantly over the course of the incubation. Temperature sensitivity of mineralisation varied little, despite large differences in soil properties and changes in mineralisation rate. This suggested that turnover rates were affected to similar extents by biochemical recalcitrance and physical protection, as these two factors influence temperature sensitivity in opposing directions. Physico-chemical protection of organic matter appeared largely related to interaction with poorly crystalline Al and Fe oxides.

Physiological epicotyl dormancy and its alleviation in seeds of Yunnanopilia longistaminea: the first report of physiological epicotyl dormancy in China.

Yunnanopilia longistaminea is an endangered monotypic species belonging to Opiliaceae. This edible plant is an important germplasm source with a high economic value in China if propagation were less difficult. Seed dormancy and germination of this species were investigated to improve propagation. Considering seeds have a fully developed embryo and mature and are dispersed in summer, and radicles and epicotyls emerge the following autumn and next spring, respectively, we hypothesized that Y. longistaminea seeds may undergo physiological epicotyl dormancy. Seed moisture content and viability decreased as dehydration occurred. Thus, the seeds may be recalcitrant. The seed germination of this species involves two stages: radicle emergence and epicotyl (shoot) emergence. The optimum temperature was 28 °C and 28 °C/20 °C to radicle emergence. The optimum GA3 solution for the seeds undergoing shoot emergence was 100 mg L−1. The percentages of shoot emergence in seven and 14 days stratification at 5 °C were slightly higher than those in other groups. This study is the first to describe physiological epicotyl dormancy in Y. longistaminea seeds. Under natural conditions, seeds are subjected to Y. longistaminea a autumn → winter → spring temperature. Warm moist conditions and cold stratification can improve radicle emergence and alleviate epicotyl dormancy, respectively. The duration of cold stratification also significantly affects the epicotyl dormancy release of Y. longistaminea. Optimal dormancy breakage methods are warm (28 °C/20 °C) → cold (5 °C) → GA3(100 mg L−1) → warm (28 °C/20 °C).

Clay mineralogical characteristics and the palaeoclimatic significance of a Holocene to Late Middle Pleistocene loess–palaeosol sequence from Chaoyang, China

ABSTRACTChanges in soil chemistry in response to varying climatic regimes can alter the equilibria of soil systems and result in different clay minerals. Variations in phyllosilicate clay composition can reflect temporal and spatial climatic changes, such as summer/winter monsoon cycles. The objective of this research was to investigate the mineralogy of the clay fractions as a proxy for determining variations in the East Asian monsoon climate, based on a section at Chaoyang in China spanning the last 0.423 Ma BP. The clay mineralogy record in the Chaoyang section was compared with other proxies as recorded in this section and with other palaeoclimatic indicators, including oxygen isotopes from oceanic sediments and loess–palaeosol sections on the Chinese Loess Plateau (CLP). The results from clay mineralogy and related climatic studies show that the summer monsoon has a trend of four increased stages and four decreased stages; whereas the winter monsoon displays the opposite trend. During the last 0.423 Ma BP, the strongest winter monsoon occurred around 0.243–0.311 Ma BP. During this period, which included an intense winter monsoon, the soil in the section had the least illite, one of the smallest kaolinite and illite/Chlorite (I/C) indices and an overall decreasing clay content. The period 0.225–0.243 Ma BP had the strongest summer monsoon over the last 0.423 Ma BP. This period had the greatest amount of illite, the highest I/C index, greater overall clay content and the strongest magnetic susceptibility signal. Additionally, this section contained the smallest mean grain size. The multi-monsoon climate cycles of alternating cold-dry and warm-moist conditions as recorded in the Chaoyang section corresponded well with multiple glaciation cycles based on deep sea sediments. This indicates that the Chaoyang section provides a record of palaeoclimate changes in northeast China that can be linked to mineralogical suites to assist in reconstructing the palaeoclimate over the Late Middle Pleistocene, and complements the global palaeoclimate records in the CLP.

Germination patterns of a suite of semiarid grassland forbs from central New Mexico

We examined the germination response of 21 forb species collected from semiarid grasslands of central New Mexico. After-ripened seeds were subjected to 1 of 3 treatments: 1) no treatment; 2) a 3-wk stratification at 5 °C (cold-moist treatment); or 3) a 3-wk warm-moist treatment at 30 °C. All seeds were incubated under an alternating 10/20 °C temperature regime for 6 wk following treatment. Temperature regime had a significant effect on 13 of the 21 species. Twelve species responded positively to the warm-moist treatment, germinating during or following 3 wk at 30 °C. Six species were largely nondormant, germinating under all 3 treatment regimes, and 5 species did not germinate to an appreciable degree under any of the 3 treatment regimes. Ten species responded negatively to the 3-wk stratification, and in only one case was germination slightly improved by the 3-wk stratification. A subsequent 12-wk stratification treatment did, however, increase germination for 3 of the 5 dormant species. These results indicate that, while some species may require stratification, many southwestern grassland forbs are adapted to the combination of moisture and temperature associated with a monsoonal regime, that is, a warm-moist period. Summer, rather than fall, sowing is recommended as it will provide the benefit of dormancy-breaking dry heat followed by warm-moist conditions of the July to September monsoon. Pendleton RL, Pendleton BK. 2014. Germination patterns of a suite of semiarid grassland forbs from central New Mexico. Native Plants Journal 15(1):17–28.

Rethinking stratigraphy and site formation of the Pleistocene deposit at Cueva Negra del Estrecho del Río Quípar (Caravaca de la Cruz, Spain)

Cueva Negra del Estrecho del Río Quípar (Caravaca de la Cruz, Murcia, Spain), hereinafter Cueva Negra, is a key-site for understanding the early peopling of Europe. Since 1990, systematic excavation has revealed an intriguing assemblage of lithic and faunal remains, and hominin teeth. It was deposited 0.99–0.78 Ma according to palaeomagnetic and biostratigraphical data; pollen data indicate warm moist conditions. Recently, possible evidence of thermal alteration was detected in a deep part of the deposit. We report here on our revision of the Cueva Negra stratigraphy, and offer information on site formation processes, based on new field observations and preliminary data from soil micromorphology. The Cueva Negra succession comprises three main stratigraphical complexes. Complex 1 is late Holocene. Complexes 2 and 3 are Pleistocene and are formed mainly of alluvial sediment, with subordinate inputs from the cave walls. Complexes 2 and 3 were accumulated almost without interruption, being separated by an erosive surface truncating a thin alluvial soil developed at the top of Complex 3. Our initial micromorphological findings indicate that anthropic inputs are mostly in derived positions, very likely having undergone inward displacement from the mouth of the rock-shelter.

Large-Scale Influences on the Evolution of Winter Subtropical Maritime Cyclones Affecting Australia’s East Coast

Abstract Subtropical maritime low pressure systems frequently impact Australia’s eastern seaboard. Closed circulation lows in the Tasman Sea region are termed East Coast Cyclones (ECC); they can evolve in a range of climatic environments and have proven most destructive during the late autumn–winter period. Using criteria based on pressure gradients, inferred wind field, and duration, an objectively determined database of ECC occurrences is established to explore large-scale influences on ECC evolution. Subclassification based on evolutionary trajectory reveals two dominant storm types during late autumn–winter: easterly trough lows (ETL) and southern secondary lows (SSL). Synoptic composites are used to investigate the climatological evolution of each storm type. ETL cyclogenesis occurs along the eastern seaboard at the confluence of warm moist subtropical easterlies and cool air over the continent that is advected from higher latitudes. SSL develop when a cold extratropical cyclone moves equatorward and interacts with warm moist conditions in the Tasman Sea. At seasonal time scales, a complex interplay of tropical and extratropical influences contributes to high-frequency storm seasons. ETL are more frequent during neutral or positive phases of the El Niño–Southern Oscillation, cool sea surface temperature anomalies (SSTAs) in the tropical Indian Ocean, and neutral to positive southern annular mode phases. SSL are more frequent during years with warm SSTAs in the eastern Indian Ocean, warm SSTAs in the western Pacific, and high-latitude blocking.

Multiple small monthly doses of dicyandiamide (DCD) did not reduce denitrification in Waikato dairy pasture

The effectiveness of multiple small doses of the nitrification inhibitor dicyandiamide (DCD) to decrease denitrification under warm moist conditions was tested in a 1-year field trial on a grazed dairy pasture. DCD was applied approximately every 4 weeks as an aqueous spray onto ten replicate plots 3 days after rotational grazing by dairy cows. Each application was at the rate of 3 kg DCD ha−1, with a total annual application of 33 kg ha−1. Denitrification was assessed 5 days after each DCD application using the acetylene block method. At the end of the trial, the rate of degradation of DCD under summer conditions was measured. DCD significantly decreased the mean annual nitrate concentration by about 17%. Denitrification and denitrification enzyme activity were highly variable and no significant effect of DCD in decreasing denitrification was detected. In the summer month of December, DCD degraded rapidly with an estimated half-life of 5±3 days (mean and standard deviation).

A history of facial eczema (pithomycotoxicosis) research

Facial eczema (pithomycotoxicosis), a photosensitisation of ruminants grazing pasture, has been known in New Zealand for over 100 years, but its cause, a toxin produced by a largely saprophytic fungus, Pithomyces chartarum, growing on litter at the base of pasture and sporing profusely under warm moist conditions in late summer and autumn, was found only 50 years ago. As the fungus spores it produces the toxin sporidesmin which, when eaten by sheep, cattle, goats or deer, causes liver injury with inflammation and blockage of bile ducts. Phylloerythrin, a photodynamic breakdown product of chlorophyll, is no longer excreted but circulates in the blood, causing lesions of unpigmented skin when the affected animal is exposed to sunlight. Lesions do not appear until at least a week after sporidesmin has been ingested, and this lag period delayed discovery of the causative agent, first thought to have been an abnormal metabolite of rapidly growing ryegrass. However, before the role of P. chartarum was discovered, the pathology of the disease had been described, toxic extracts had been made from herbage mown from pastures associated with facial eczema outbreaks, and the weather conditions preceding outbreaks had been defined. When the causative agent was identified, cultures of P. chartarum on artificial media produced sporidesmin for chemical characterisation and animal dosing trials. Control of facial eczema in the field was first by avoiding toxic pasture, detected by P. chartarum spore counts on herbage, later by reducing P. chartarum pasture populations by spray application of substituted thiabendazole fungicides, and later still by protecting animals with oral doses of zinc at close to toxic levels. Sheep vary widely in their sensitivity to sporidesmin, either under field conditions in facial eczema outbreaks or when dosed orally with sporidesmin, and breeding resistant animals by selection after sporidesmin challenge is the best long‐term control method at present. Whilst facial eczema outbreaks have been most severe in New Zealand, the disease has been reported from an increasing number of countries with warm temperate climates in which ruminants are intensively grazed on pasture. The great majority of New Zealand isolates of P. chartarum produce sporidesmin, but varying proportions of those in other countries do not.

Managing soils to enhance the potential for bioremediation of water repellency

Water repellency can significantly reduce crop and pasture establishment and production in sandy soils. Management practices that increase the rate of water infiltration into dry soils following the first rains at the end of the dry season were investigated. In the laboratory, addition of water to water repellent soil and maintenance of warm moist conditions produced a gradual decline in water repellency. This was supported by results in the field which showed that under daily irrigation there was a gradual decline in water repellency over time. However, under dryland conditions, other mechanisms to increase water infiltration had to be found. In the laboratory, after the addition of lime and kaolinite clay, there was an initial rapid decline in repellency, indicative of a physical mechanism, followed by a more gradual decline suggesting a biological response. In the field, under dryland conditions, the addition of lime and kaolinite clay resulted in a reduction in water repellency, and in the case of lime, this effect increased with the size of application. Estimates of the numbers of wax-degrading bacteria in the treated soils, using a most-probable-number assay, showed at least a 10-fold increase in lime-treated sands, but not in the clay-treated sands. The results suggest that lime may provide a viable alternative for increasing the wettability of soils by physical mechanisms and by promoting microbial activity by bacteria responsible for wax degradation, resulting in more consistent plant germination and establishment, and increased crop yields.

Leafy spurge (Euphorbia esula) seed dormancy

Leafy spurge is a herbaceous perennial weed that reproduces asexually through adventitious vegetative buds and sexually by seeds. Seeds can remain viable in the soil for up to 8 yr. The objectives of this research were to determine whether the seed coat and endosperm restrict germination and to assess whether afterripening treatments affect germinability. Germination of nonafterripened intact seeds was 30% after 28 d of incubation. Afterripening seeds for 12 wk under warm moist conditions provided a twofold stimulation to 58% germination after 21 d compared with the control and three other afterripening treatments. Afterripening under warm moist conditions for an additional 12 wk provided nearly complete germination within 7 to 21 d, but seeds harvested in year 2000 also responded in the same way to cool moist conditions. The removal of seed coat (dehulled) and removal of endosperm surrounding the embryonic axis in dehulled seeds led to rapid germination, approaching 80 to 90% in 5 d. Fructose did not enhance germination of dehulled seeds or embryonic axes. Thus, leafy spurge displays coat-imposed seed dormancy that can be overcome by afterripening under moist conditions.

Dormancy termination of western white pine ( Pinus monticola Dougl. Ex D. Don) seeds is associated with changes in abscisic acid metabolism

Western white pine (Pinus monticola) seeds exhibit deep dormancy at maturity and seed populations require several months of moist chilling to reach their uppermost germination capacities. Abscisic acid (ABA) and its metabolites, phaseic acid (PA), dihydrophaseic acid (DPA), 7'-hydroxy ABA (7'OH ABA) and ABA-glucose ester (ABA-GE), were quantified in western white pine seeds during dormancy breakage (moist chilling) and germination using an HPLC-tandem mass spectrometry method with multiple reaction monitoring and internal standards incorporating deuterium-labeled analogs. In the seed coat, ABA and metabolite levels were high in dry seeds, but declined precipitously during the pre-moist-chilling water soak to relatively low levels thereafter. In the embryo and megagametophyte, ABA levels decreased significantly during moist chilling, coincident with an increase in the germination capacity of seeds. ABA catabolism occurred via several routes, depending on the stage and the seed tissue. Moist chilling of seeds led to increases in PA and DPA levels in both the embryo and megagametophyte. Within the embryo, 7'OH ABA and ABA-GE also accumulated during moist chilling; however, 7'OH ABA peaked early in germination. Changes in ABA flux, i.e. shifts in the ratio between biosynthesis and catabolism, occurred at three distinct stages during the transition from dormant seed to seedling. During moist chilling, the relative rate of ABA catabolism exceeded ABA biosynthesis. This trend became even more pronounced during germination, and germination was also accompanied by a decrease in the ABA catabolites DPA and PA, presumably as a result of their further metabolism and/or leaching/transport. The transition from germination to post-germinative growth was accompanied by a shift toward ABA biosynthesis. Dormant imbibed seeds, kept in warm moist conditions for 30 days (after an initial 13 days of soaking), maintained high ABA levels, while the amounts of PA, 7'OH ABA, and DPA decreased or remained at steady-state levels. Thus, in the absence of conditions required to break dormancy there were no net changes in ABA biosynthesis and catabolism.

Propagation of Pawpaw—A Review

Pawpaw (Asimina triloba) is an under-exploited small tree with commercial potential as a fruit crop, ornamental tree, and source of secondary products with insecticidal and medicinal properties. It is most often propagated from seeds that are recalcitrant and must be stored moist at a chilling temperature. Seeds display combinational (morphophysiological) dormancy. Endogenous, physiological dormancy is broken by about 100 days of chilling stratification followed by a period of warm moist conditions where the small embryo develops prior to seedling emergence about 45 days after the warm period begins. Pawpaw cultivars with superior fruit characteristics are propagated by grafting onto seedling understocks. The most common practice is chip budding. Other methods of clonal propagation have proven problematic. Pawpaw can be propagated from cuttings, but only in very young seedling stock plants. Micropropagation from mature sources is not yet possible, but shoot proliferation has been accomplished from seedling explants and explants rejuvenated by induction of shoots from root cuttings of mature plants. However, rooting of microcuttings and subsequent acclimatization has not been successful.

Use of Zinc Alloy Coatings on Steel Cord Reinforcement in Vehicle Tyres

SUBJECTTyres which are radially reinforced with high tensile steel cords need to develop a bond between the rubber and the steel. Brass coatings on the cord are currently used to promote the bond but deterioration takes place with time and corrosion of the underlying steel occurs eventually. Zinc-cobalt coatings have been used as a replacement for brass. These coatings are capable of being drawn in the cord making operation provided that the cobalt content is 1.5wt%. Pull-out tests after vulcanising show that zinc-cobalt promotes similar adhesive strengths to that achieved with brass coatings. After ageing in warm moist conditions for up to 16 days the zinc-cobalt coating maintained higher levels of adhesion than brass. In tyre tests the zinc-cobalt coatings were superior in preventing red rust formation on the steel

Alternaria dianthi . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Alternaria dianthi . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Dianthus spp., and other members of the Caryophyllaceae including Gypsophila and Saponaria spp. It is occasionally reported from other plants (e.g. Hibiscus esculentus (51, 1025; 42, 655)). DISEASE: Carnation blight. The fungus causes yellowing and necrosis of the host tissue, initially killing the leaves but in severe infections, also the stem and eventually the whole plant. The fungus can persist in the soil, from where it can attack seedlings, usually destroying them rapidly. It also infects the host's flowers, seed capsules and seeds. GEOGRAPHICAL DISTRIBUTION: Africa: Egypt, Malawi, Morocco, Mozambique, South Africa, Tanzania, Zambia, Zimbabwe. Asia: Cyprus, India, Japan, Malaysia, Taiwan, Thailand, Turkey, USSR (Armenia, Republic of Georgia). Australasia & Oceania: Australia (New South Wales, Queensland, South Australia), New Zealand, USA (Hawaii). Europe: Austria, Bulgaria, Czechoslovakia, Denmark, France, Germany, Hungary, Italy, The Netherlands, Norway, Poland, Romania, Spain Sweden, UK, Yugoslavia. North America: Bermuda, Canada, Jamaica, Panama, Puerto Rico, USA. South America: Brazil, Uruguay. TRANSMISSION: Successful growth and sporulation of the fungus requires warm moist conditions (optimal mycelial growth is at ca 20°C), although mycelium can survive at 0°C. Transmission of conidia is usually via wind, seeds or soil. A damp leaf surface is essential for infection.

Germination, Host Preference, and Phenolic Content of Witchweed (Striga hermonthica) Seed Populations

Phenolic content, germination percentage, and host preference were compared among 11 seed populations of witchweed (Striga hermonthica(Del.) Benth. # STRHE). Significant differences in germination percentage occurred among the seed populations after preconditioning by their exposure to different durations of warm-moist conditions. Greatest percentage of seed germinated after 8 days of preconditioning. Preconditioning for more than 16 days reduced percentage germination. The host specificity range of witchweed seed populations that parasitized pearl millet [Pennisetum americanum(L.) K. Schum] was broader than were those seed populations that attacked sorghum [Sorghum bicolor(L.) Moench.]. Results of thin-layer chromatography indicated large variations in phenolic content among the witchweed seed populations.

Genital warts-recent advances.

It was formerly axiomatic that all clinical types of wart were caused by the same virus, the morphology of a wart being conditioned only by the type of epidermis which this virus infected. This was the ‘unitary’ theory, which was formulated after a series of experimental transfers of warts from one part of the body to another had been performed in the early years of this century. According to the ‘unitary’ theory, genital warts were a special kind of skin wart, modified in appearance by the thinness of the genital epithelium and by the warm moist conditions prevailing in the area. Sexual contact was regarded as only one of many ways in which the wart virus could reach the genitals. Feelings ran high on the natural history of genital warts, and after Barrett, Silbar & McGinley (1954) suggested that they should be regarded as a venereal disease, one outraged physician went so far as to circularise 336 dermato-venereologists in various countries to ask whether this view was correct, and 94% answered‘no'. Recent advances have necessitated a revision of these opinions.

Lower timberline in central Colorado during the past 15,000 yr

A 15,000 yr paleoenvironmental record at the elevation of lower timberline in central Colorado suggests two major paleoclimatic changes during that interval: (1) at 10,000 yr B.P., from cool-moist conditions to warm-moist conditions and (2) at 4,000 yr B.P., to warm-dry conditions. This sequence can be interpreted as a shift from precipitation predominantly originating from Pacific winter storms (before 10,000 yr B.P.) to a predominantly monsoonal-type regime (lasting until 4,000 yr B.P.) to the present pattern. Contemporaneity of higher upper timberline and lower lower timberline during the 10,000 to 4,000 yr B.P. interval is not contradictory but a result of changes in those circulation patterns.

Factors influencing the growth ofPithomyces chartarumin pasture

Abstract An examination of factors which could influence the growth of Pithomyces chartarum and the development of facial eczema toxicity in pasture indicated that: 1. 1. Growth and sporulation on dead grass leaves and stems is most rapid under warm (70°F to 80°F) moist conditions. It is retarded by prolonged exposure to high levels of moisture around the dead herbage, and considerably accelerated on tissues with a high content of soluble organic material, e.g., freshly dead, well-nourished leaves.2. 2. The ability of spores to adhere to live leaves is directly related to the wettability of the leaf surfaces.3. 3. The wettability of the lower epidermis of ryegrass leaves is high. The upper epidermis of ryegrass leaves and both surfaces of the leaves of paspalum and cocksfoot are difficult to wet. The lower epidermis of white clover leaves is moderately wettable.4. 4. Spore germination is greatly stimulated by cell exudates from damaged areas on live leaves of ryegrass or paspalum provided the leaves are moist. Dilute juice pressed out from ryegrass leaves has a similar effect on spore germination.5. 5. As judged by nitrogen analyses, considerable quantities of soluble organic material are readily available at the surface of immature leaves of ryegrass if they are wetted after being grown under warm moist conditions. This is not the case with mature leaves.6. 6. Germination of spores followed immediately by a period of rapid mycelial growth in dilute ryegrass juice can lead to a significant rise in facial eczema toxicity within 15 hours.

PALYNOLOGY IN SOUTHERN NORTH AMERICA

Pollen analysis of two deep lacustrine cores under Mexico City indicates a series of moist-dry oscillations with longer trends of changing temperature—a climatic record which appears to extend as far back as early Wisconsin. The individual moist pulsations, although marked by warmth, were evidently times of glacial nourishment; the dry phases, some of which were cool, were evidently times of abatement. The upper 50 m of the profiles indicate two episodes of maximum glaciation; the details that follow the more recent agree with present knowledge of the Cary-Mankato-Latest sequence of the Wisconsin. Under milder conditions between the postulated Taze-well and Cary glacial maxima, soil might have formed on exposed till. The base of the profiles indicates warm-moist conditions with falling temperature to about 50 m. Because of tectonic and volcanic disturbance, it is not clear whether this cooling represents a separate advance or merely an early phase of the first maximum above the 50-m level. For the tropical Mexico City area, it is shown that the moist periods of glacial nourishment were also relatively warm.