Weight Of Cotyledons Research Articles

Seedling Growth of Cicer Milkvetch as Affected by Seed Weight and Temperature Regime1

Seedling vigor of cicer milkvetch (Astragalus cicer L.) has been improved by breeding for high seed weight, but it is not known how growth characteristics differ among seedlings derived from seed of different weight classes. Therefore, the objective of this study was to determine the effect of seed weight (3.2, 3.6, 4.0, 4.4, 4.8, 5.2, and 5.6 g/1,000 seeds) and temperature regime (20 C day/15 C night and 25 C day/20 C night) various seedling growth traits. When averaged over all sampling dates, temperature regime significantly affected area of upper leaves; dry weight of cotyledons, primary leaf, upper leaves, stems, and roots; height of seedlings; total dry weight of shoots; and total dry weight of seedlings. Values for all traits except weight of cotyledons and primary leaf were higher at 25/20 C than at 20/15 C. Cotyledon area and primary leaf area were not influenced by temperature. Within a temperature regime, seed weight also significantly affected all characters. For most seedling traits an increase in dry weight or area was associated with increased seed weight.In a growth analysis study, temperature treatments significantly affected initial seedling weight, initial leaf area, relative growth rate, relative leaf area expansion rate, relative leaf weight expansion rate, leaf area partitioning coefficient, leaf weight partitioning coefficient, and final seedling weight. Temperature regime did not affect initial leaf weight and net assimilation rate. Seed weight was positively and linearly associated with initial seedling weight, initial leaf area, and initial leaf weight at both temperatures and with final seedling weight at 20/15 C. The lack of association of seed weight with some important growth analysis traits suggests that certain seedling vigor characters are entirely independent of seed weight. The initial advantage of high seed weight progenies, however, tended to be maintained in the early phases of seedling development, as indicated by final seedling weight. Thus, with populations selected for high seed weight, additional progress in improving seedling vigor might be achieved through selection for relative leaf area expansion rate, net assimilation rate, or other traits.

Studies on reproduction in prolific ewes:7. Variability in the growth of individual foetuses in relation to intra-uterine factors

SUMMARYThe weights of 44 twin foetuses, 99 triplets and 44 quadruplets, varying in gestational age from 55 to 145 days, were studied in relation to age, sex, litter size, uterine position, placental structure and weight, and ovulation rate. Triplet and quadruplet foetuses were more variable in weight, within litters, than were twins. The difference increased with foetal age and was attributed to increased competition between foetuses which were located within the same horn of the uterus. The effect was largely associated with differences in placental development, i.e. numbers of cotyledons and weight, but those differences did not entirely account for the reduction in foetal weight with increasing litter size. Differences in placental development, arising from embryo mortality, also accounted for the reduction in foetal weight when ovulation rate exceeded litter size. In contrast, differences in foetal weight associated with the sex of the foetuses were only partly mediated by differences in cotyledon weight. Foetuses in the larger litters are thus not only lighter in weight but are more variable in weight, the increased variability being controlled by events in early pregnancy.

Onset of synthesis of progesterone by ovine placenta.

The extra-ovarian contribution to progesterone levels in the circulation has been measured in ovariectomized ewes in which pregnancy was maintained by treatment with medroxyprogesterone acetate. Since adrenal production of progesterone is low this procedure allows the determination of placental secretion. Placental production of progesterone has been shown to rise initially between 50 and 70 days of gestation, with a second phase of increase between 90 and 120 days of gestation. Both periods of increased secretion of progesterone were reflected in rises in progesterone production by placental explants in organ culture and in the activity of 3 beta-hydroxysteroid dehydrogenase in the tissue. The activity of 3 beta-hydroxysteroid dehydrogenase exceeded the rate of progesterone production by approximately 30-fold, and it appears unlikely, therefore, that this enzyme is rate-limiting in the synthesis of progesterone. Surgical reduction of the number of cotyledons led to compensation by an increase in weight of individual cotyledons with no significant increase in specific 3 beta-hydroxysteroid dehydrogenase activity or rate of production of progesterone in organ culture. It was concluded that the rise in placental production of progesterone in the middle period of gestation is unlikely to result either from an increase in 3 beta-hydroxysteroid dehydrogenase activity or from exposure to factors stimulating placental growth.

Relationships among uterine and placental factors in prolific ewes and their relevance to variations in foetal weight

ABSTRACTObservations were made on the distribution of ovulations between the two ovaries, the distribution of foetuses between the two uterine horns, the total numbers of cotyledonary burrs, and the weights and numbers of foetal cotyledons for each foetus in 80 Finnish Landrace × Dorset Horn ewes killed between 50 and 145 days of gestation. While ovulations were randomly distributed between right and left ovaries, viable foetuses were more evenly distributed between right and left uterine horns. Migration of embryos between the horns contributed to this relative balance but early foetal mortality, which increased with ovulation rate, tended to upset it. The mean number of foetal cotyledons per foetus depended on litter size and distribution, and at any fixed litter size was substantially reduced in those ewes with six or more ovulations. Foetal weights were also relatively low in these ewes. The total weight of cotyledons per foetus decreased by about 12% for each increase of one in number of foetuses, as compared with a 20% decrease in number of cotyledons but only a 7 to 11 % decrease in the weight of the individual foetuses. Comparisons between foetuses within the same litter led to similar trends in the ratios of cotyledon numbers, cotyledon weights and foetal weights. It is suggested that the presence of some very small lambs in large litters should not be attributed to maternal under-nutrition in late pregnancy.

Effect of Cytokinins on the Expansion and Metabolism of Excised Cucumber Cotyledons

Expansion of excised cucumber (Cucumis sativus L.) cotyledons was stimulated by treatment with cytokinin, and commenced after a lag period of about 4 h. Expansion induced by benzyladenine (BA) was due mainly to increase of fresh weight, but cell number increased slightly. Hydrolysis of protein and lipid was stimulated by BA, and soluble sugars increased simultaneously. However, there was no significant change in the dry weight of cotyledons during the period of expansion. It is assumed that the transformation of lipid to sugar in the cotyledon is stimulated by BA. The respiration of cotyledons was evidently stimulated by BA and was entirely inhibited by respiratory inhibitors, e.g. NaN,, malonate and dinitrophenol. Inhibitors of protein and nucleic acid synthesis, such as chloramphenicol and actinomycin D, inhibited only the BA-induced expansion. They had no effect on the expansion of controls. These results suggest that different biochemical processes are involved in the expansion of cotyledons induced by BA and in controls. The former is related not only to respiration but also to the synthesis of protein and nucleic acid. BA increased DNA and RNA content per cotyledon. The increase of total RNA is due mainly to the increase of 25 S and 18 S rRNA.

Effect of maternal anaemia on the placenta and the newborn infant.

Foetal birthweight, placental morphometry and maternal, cord blood and placental haemoglobin and iron levels were studied in 69 anaemic mothers (haemoglobin less than 110 g/l) and 16 mothers without anaemia (haemoglobin greater than or equal to 110 g/l). The birthweight, placental weight and number of placental cotyledons were significantly reduced in the severely anaemic mothers (haemoglobin less than or equal to 60 g/l) and had direct relationships with the maternal haemoglobin levels. However, placental volume and surface area showed no constant relation to maternal haemoglobin. The haemoglobin and iron levels in the cord blood and placental tissue were found to have linear correlations with the maternal haemoglobin levels. The low levels of placental and cord serum iron in the severely anaemic mothers suggest that iron supply to the placenta and the foetus is affected in maternal anaemia and the foetus takes iron in direct proportion to the levels available in the mother.

ダイコンの生長と光合成における子葉の役割

When cotyledons of radish plants were excised at an early stage of growth, decrease in plant growth was observed. To understand this phenomenon, the role of cotyledons in radish growth was examined.Dry weight of cotyledons decreased and that of the other organs increased in the dark, whereas dry weight of every organ increased in the light. Furthermore, dry weight of hypocotyls and that of roots decreased in decotylized plants grown in the light, but decrease in dry weight of foliage leaves was not observed. From these results, it was concluded that cotyledons were the source and the other organs were the sink. Especially, the foliage leaves could be regarded as the strongest sink.In Rapid Red cultivar, the growth phase could be divided into two periods (Phase 1 and Phase 2). In Phase 1, the growth of foliage leaves was enhanced by the supply of reserve materials and photosynthetic products from cotyledons. In Phase 2, activet hickening growth of hypocotyls was caused by a sufficient supply of photosynthetic products from foliage leaves. Therefore, it is concluded that the decrease in radish growth by decotylization is due to the resulting decrease in the growth of foliage leaves.

Cotyledonary Senescence of Xanthium strumarium Linn

Cotyledonary senescence of Xanthium strumarium was delayed by removal of the supracotyledonary shoot, and this delay was accompanied by an increase in dry weight and surface area of cotyledons. Gibberellic acid (GA3) was found to enhance cotyledonary senescence and benzyladenine to retard it. Growth and senescence of cotyledons was completed in three successive stages-an initial phase when both dry weight and surface area increased, a second phase of dry weight decrease and surface area increase, and a third phase when dry weight decreased and cotyledons ceased to expand. Removal of the supracotyledonary shoot delayed the commencement of the second and third phases by at least 10 days. Relative amounts of chlorophyll, nucleic acid, and protein differed in cotyledons of normal seedlings and cotyledons of those seedlings in which supracotyledonary shoots had been removed.

Effects of Germination on Cotyledon Nitrogen, Starch, Reducing Sugar, and Growth of Lima Seedlings

AbstractPoor seedling establishment which frequently reduces stands and causes uneven seedling growth in lima bean (Phaseolus lunatus L.) plantings points up the need for research to identify those changes occuring during the seedling establishment phase. This research is needed to show how these changes are associated with early seedling growth. Accordingly, cotyledons from seedlings of two lima bean cultivars, ‘Nemagreen and Jackson Wonder,’ were compared during pre‐ and postemergence for changes in total N, protein N, nonprotein N, starch, reducing sugars, and seedling growth.Cotyledons of Jackson Wonder were significantly higher in total N than Nemagreen because of the protein N fraction. The nonprotein N fraction did not differ between cultivars.The protein:nonprotein N in Nemagreen approached 1 on the sixth, seventh, eighth, and ninth day after planting. Maximum decrease of protein N and a corresponding maximum increase of nonprotein N occurred on the fourth, fifth, sixth, and seventh day for each cultivar. A net decrease in total N in cotyledons occurred during postemergence.Reducing sugars were present in cotyledons of resting seed and developing seedlings but did not differ in amount between cultivars.The period of most rapid starch depletion and cotyledon weight loss occurred during postemergence and was accompanied by rapid increases in top dry weight.

Changes in Carbohydrate Contents of Germinating Soybean Seeds1

Changes in dry weights, total soluble carbohydrates, and individual sugars in the cotyledons and embryo axes of soybean (Glycine max (L.) Merrill) seeds from a relatively high oil variety, ‘Hawkeye’ (22%), and a low oil line, P.I. 86002 (16%), were determined over a 13‐day germination period. Total dry weights of cotyledons decreased while those of embryo axes increased as the seed germinated. Total soluble carbohydrates accounted for 15% of the total dry weights in cotyledons of ungerminated seeds and decreased more rapidly throughout the germination period than did cotyledon weights. Total soluble carbohydrates of the embryo axes increased steadily during the first 5 days and declined thereafter. Similar patterns of utilization of soluble carbohydrates were observed for Hawkeye and P.I. 86002 even though their cotyledons differed 6% in oil content.Stachyose, raffinose, and particularly sucrose were the dominant sugars found in ungerminated soybean seeds. Stachyose and raffinose declined rapidly in the cotyledons by day 3 and disappeared by day 9 of germination. Sucrose increased slightly during the first 3 days but decreased steadily after the third day. Fructose and glucose appeared in day‐1 cotyledons, with the former reaching a maximum value on the fifth day and the latter on the ninth. Stachyose, raffinose, and sucrose were also the major sugars found in the 0‐day embryo axes. Stachyose and raffinose were depleted completely by day 3 in the embryo axes of P.I. 86002 and by day 5 in Hawkeye. Sucrose decreased between day 5 and day 13 for P.I. 86002 but showed irregular change in Hawkeye during this period. Fructose and glucose appeared in day‐1 embryo axes, continued to increase through day‐5 of germination, and decreased thereafter.

Development of Enzymes in the Cotyledons of Watermelon Seedlings

Changes in hypocotyl length, cotyledon weight, lipid content, chlorophyll content, and capacity for photosynthesis have been described in seedlings of Citrullus vulgaris, Schrad. (watermelon) growing at 30 C under various light treatments. Corresponding changes in the levels of 19 enzymes in the cotyledons are described, with particular emphasis on enzymes of microbodies, since during normal greening, enzymes of the glyoxysomes are lost and those of leaf peroxisomes appear. In complete darkness enzymes of the glyoxysomes reach a peak at 4 days and decline as the fat is depleted. Enzymes of mitochondria and of glycolytic pathways also peak at 4 to 5 days and either remain unchanged or decline to a lesser extent. Exposure to light at 4 days, when the cotyledons emerge, results in a selectively greater destruction of enzymes of the glyoxylate cycle; chlorophyll synthesis and capacity for photosynthesis increase in parallel, and there is a striking increase in the activities of chloroplast enzymes and in those of the leaf peroxisomes, hydroxypyruvate reductase and glycolate oxidase. The reciprocal changes in enzymes of the glyoxysomes and of leaf peroxisomes can be temporally dissociated, since even after 10 days in darkness, when malate synthetase and isocitrate lyase have reached very low levels, hydroxypyruvate reductase and glycolate oxidase increase strikingly on exposure to light and the cotyledons become photosynthetic. Furthermore, the parallel development of enzymes of leaf peroxisomes and functional chloroplasts is not immutable, since hydroxypyruvate reductase and glycolate oxidase activity can be elicited in darkness following a 5-minute exposure to light at day 4 while chlorophyll does not develop under these conditions.

Changes in nucleic acids, protein and ribonuclease activity during maturation of peanut seeds<xref ref-type="fn" rid="fn1"><sup>1</sup></xref>

Changes in weight, protein, RNA, DNA and ribonuclease activity during maturation of the peanut seed have been studied. The investigation period began with fruits harvested four weeks after the pegs turned at right angles in the soil and continued through the fourteenth week. Fresh weights of both cotyledons and embryonic axes increased rapidly during early maturation (8 weeks) and continued in the cotyledons through 12 weeks. The water content at maturity was still adequate for enzymatic processes at 45% and 39%, respectively, for embryonic axes and cotyledons. The levels of DNA and RNA also increased rapidly during early maturation of both cotyledons and embryonic axes. DNA content decreased during the remainder of maturation while RNA decreased from 8 to 11 weeks in the cotyledons and then increased during the after-ripening period to a value near its previous maximum at 8 weeks. RNA levels in the embryonic axes underwent a gradual increase throughout maturation. The large decrease in cotyledonary RNA during weeks 8 through 11 could be related to increased RNase activity during the period.

Changes in the cotyledons of Cucurbita maxima during germination. I. General characteristics

Various structural and physiological changes in squash cotyledons were followed as a function of germination time. Temperature, to which squash plants are very sensitive, was kept constant at 31 °C but light conditions were varied.In light-germinated plants (16 h light/day) the cotyledons changed from storage organs to greatly enlarged photosynthetic leaves, within 5 days. Incorporation of major amounts of thymidine-2-14C throughout the cotyledons occurred only during the enlargement phase.Dark-germinated plants, in which the cotyledons enlarged very little, produced a long, stout hypocotyl. No major incorporation of thymidine-2-14C into the cotyledons occurred, suggesting that little cell division occurs in the cotyledons of dark-germinated squash plants.Fresh- and dry-weight changes in the cotyledons were consistent with the changes in morphology of light- and dark-germinated plants. The cotyledons of plants which were dark-germinated for 6 days and then placed in 16 h light per day did not reach the fresh weight per cotyledon or dry weight per cotyledon level attained by cotyledons from plants germinated, from the beginning in 16 h light per day.

The Effect Soaking Pea Seeds With or Without Seedcoats Has on Seedling Growth

Pea seeds (Pisum sativum L. ;Alaska') with intact seedcoats (WC) and with seedcoats removed (WOC) were soaked in distilled water for 24 hours at 20 degrees . The water, containing the pea diffusate, was decanted after the second, fourth, sixth, eighth, twelfth, and twenty-fourth hour and analyzed for total nitrogen, alpha-amino nitrogen, carbohydrate, and total solute dry weight. The seeds were germinated at 20 degrees in a 16 hour photoperiod of 300 foot candles. Stem lengths and dry weights of roots, shoots and cotyledons were determined after 4, 11, and 18 days of growth. WOC seeds imbibed more water than WC seeds during the 24 hour imbibition period. Diffusates from WOC seeds always contained more solute than diffusates from WC seeds. Maltose, glucose, and fructose were not detected in the early diffusates from WOC seeds but were found in WC seed diffusates at all times. Seedlings from WC seeds had longer stems than those from WOC seeds. The dry weight of stems and roots of WC seedlings was greater than those from WOC seedlings. The dry weight of cotyledons from 18 day-old WC seedlings was less than from WOC seedlings. Water absorption by WC seeds was slower than by WOC seeds. Removal of the seedcoat allowed rapid imbibition resulting in seed injury presumably because of the loss of solutes which included monosaccharides, disaccharides, amino acids, and other nitrogen containing compounds. These results are consistent with the hypothesis that rapid imbibition disrupts membrane organization leading to reduction of seedling growth.

Development of Cotyledon Cell Structure in RipeningPhaseolus vulgarisSeeds

Changes in weight, nitrogen content, and cell fine structure were followed in ripening cotyledons of greenhouse-grown beans. The seeds mature within 53–56 days from flowering, cotyledon weight and nitrogen content increasing most rapidly between days 22 and 34. The cotyledon parenchyma cells first become very highly vacuolate, but soon the large vacuoles are divided up and converted to reserve protein bodies, while cell expansion continues. Vacuole subdivision is accompanied by synthesis of cytoplasm containing masses of rough-surfaced ER (endoplasmic reticulum), which persists till the cotyledons dry out, and presumably synthesizes the reserve protein. Starch grains grow within plastids to reach diameters of 50 μ. Young cotyledons are green but chlorophyll disappears when the seed dries. Most organelles are recognizable in dry cotyledon cells; the ER is, however, replaced by small vesicles. Ribosomes are dispersed free in the cytoplasm during dehydration; this could indicate a destruction of mRNA (messenger ribonucleic acid) in preparation for a switch to a different metabolic activity during germination. Some comparisons are drawn between cell fine structure in the cotyledons during ripening and germination.

Progesterone and placental development in the sheep.

SUMMARY Pregnant ewes were ovariectomized 3 weeks after mating, and were injected daily with graded doses of progesterone (0·05–1·35 mg./kg.) for the next 6 weeks. A minimum daily dose of 0·15 mg./kg. was found necessary for the regular maintenance of pregnancy. On the 60th day of pregnancy, when the ewes were killed, there was little or no effect of dose of progesterone on foetal weight, weight and number of cotyledons, weight of uterus and membranes or volume of amniotic fluid. However, at the low doses of progesterone the volume of allantoic fluid was about ten times higher than normal, suggesting that progesterone plays some part in the water balance of the conceptus. In treated ewes, the cotyledons tended to be of the bovine type with foetal tissue enveloping the maternal, which suggests that growth of maternal cotyledons may be limited by the absence of ovaries. It is suggested that the large variations usually observed in the placental size of sheep, are not due to variations in output of ovarian progesterone, and that the normal daily output of the ovine corpus luteum during the first 2 months of pregnancy is equivalent to at least 15 mg. of subcutaneously injected progesterone.

STUDIES ON THE PLACENTA OF THE SHEEP (OVIS ARIES L.). PLACENTAL SIZE.

Summary. A positive correlation is reported between birth weight and the weight of intact cotyledons and of foetal cotyledons. At equal cotyledon weight, single foetuses are heavier than twins, male foetuses are heavier than females and those of older ewes tend to be heavier than those of younger ones. There is great variability in the total weight of cotyledons per ewe, even within groups of similar ewes. The relationship between foetal weight and cotyledon weight appears to be curvilinear near parturition, increases in foetal weight being associated with increasingly large increments in cotyledon weight. Foetal weights of about 1 \m=.\5kg are achieved at very low cotyledon weight. There is only slight correlation between foetal weight and number of cotyledons, because of a compensatory increase in the weight of individual cotyledons when they are few in number. This involves both foetal and maternal tissue. The number of cotyledons per foetus varies with breed and strain of sheep, litter size, age (or parity) of ewe, sex of lamb and with environmental conditions and the number of caruncles in the uterus. There is a marked tendency for a constant proportion of the caruncles (70 to 80%) to develop into cotyledons. Fine and medium wooled Australian Merinos have fewer cotyledons than any other breed for which data are available. In the sheep, as in man, a number of very small foetuses, with very small placentae, reach full term.

STUDIES ON THE PLACENTA OF THE SHEEP (OVIS ARIES L.). EFFECT OF SURGICAL REDUCTION IN THE NUMBER OF CARUNCLES.

Summary. Various numbers of caruncles, up to eighty-four, were removed surgically from forty-two Merino ewes before mating. Fertility was not apparently related to the number of caruncles removed except that pregnancy terminated some weeks prematurely in some of the ewes in which sixty or more caruncles were removed. Birth weight was reduced by removal of caruncles, but was more closely correlated with the weight of functional cotyledons than with their number. Reduction in the number of caruncles was partly compensated for by an increase in weight of individual cotyledons. This compensation was proportionately greater in foetal than in maternal tissues. There was no clear evidence of the formation of new caruncles but there was evidence that the number of caruncles may decline spontaneously. It is concluded that, while very little placental tissue is necessary to allow gestation to reach the 100th day, when foetal weight begins to increase rapidly, subsequent foetal growth is limited by the size of the placenta. The results also show that estimation of foetal age from physical dimensions of the foetus may be grossly misleading.

The influence of seed size and depth of sowing on pre-emergence and early vegetative growth of subterranean clover (Trifolium subterraneum L.)

Changes in the pre-emergence distribution of dry matter in subterranean clover (Trifolium subterraneum L.) variety Bacchus Marsh were followed at 21°C, using three sizes of seed and three depths of sowing, ½, 1¼, and 2 in. Decreasing seed size and increasing depth of sowing both reduce the weight of the cotyledons a t emergence. Seed of the three sizes were sown a t three depths in pot culture a t staggered intervals so that emergence was simultaneous. Dry weight in the early vegetative stage was proportional to seed size, and total leaf area and leaf numbers showed similar trends. Plants of each seed size grew at the same relative rate. No effect of depth of sowing could be detected, and this was shown to be due to the cotyledon area a t emergence being constant for any given seed size, regardless of varying depth of sowing and hence of cotyledon weight. It was concluded that seed size in a plant having epigeal germination and without endosperm is of importance: firstly, in limiting the maximum hypocotyl elongation and hence depth of sowing, and secondly, in determining cotyledon area. Cotyledon area in turn influences seedling growth, which is not affected by cotyledon weight. Once emergence has taken place, cotyledonary reserves are of no further significance in the growth of the plants.

The Effect of Level of Feeding on the Reproductive Capacity of the Ewe

A study was made, in 1953 and 1954, of the effect of feed level on the reproductive capacity of yearling ewes. Ewes (short-yearlings) were divided at random into two groups; one group was fed on roughage-plus-grain, and the other was fed on roughage-only beginning in January of both years. The feeding regimen was continued until the time of slaughter in the fall. Half of the ewes on each feed level was slaughtered 3 days post-coitum, and the other half at 40 days post-coitum (except some ewes that showed a second heat after breeding and were rebred and killed 3 days later). The study includes observations on ovulation rate, fertilization rate, normality of the ova as well as measurements and weights of structures and organs of the reproductive tract, and weights of embryos, embryonic membranes and fluids. The results were as follows: Ewes on the high level of feeding had significantly higher ovulation rate, larger follicles, and higher number of follicles 2 mm. or more in diameter. Fertilization rate was higher, though not significantly so, for the ewes on the higher level of feeding. The embryonic survival rate was lower in the ewes on the higher level of feeding. The difference in embryonic survival rate between the two groups of ewes was highly significant in 1954. Also there was a significant interaction between year and level of feeding on embryo survival. Ewes on the higher level of feeding had significantly larger uteri (slaughtered 3 days post-coitum). The weight of the 40-day pregnant horn of ewes (cotyledons trimmed off) was significantly affected by feed level. Also the non-pregnant horns of ewes fed on grain-plus-roughage were significantly larger than for ewes fed on roughage-only. Level of feeding did not have a significant effect on weight of cotyledons in the pregnant uterine horn, but a significant interaction between feed level and size of litter on the weight of cotyledons was shown in 1953. Feed level had no significant effect on crown-rump length of 40-day embryos, weight of embryos, amnion weight, amnionic fluid weight, chorionic fluid weight, and size of amnionic vesicle. There was a significant effect for feed level on weight of chorion. Comparing the pregnant horns only, it was shown that ewes which had twin embryos (each in separate horn) had significantly larger and heavier horns (cotyledons removed) than pregnant horns of ewes having single embryos. Crown-rump length of embryos, weight of embryos, weight of amnions, weight of chorions, weight of amnionic fluid, and size of amnionic vesicle were greater for singles than for twins under both levels of feeding, but differences only in chorion weight and in size of amnionic vesicle were statistically significant. Migration from one uterine horn to the other occurred for at least 12 percent of the embryos. One case of suspected identical twins was observed.