Slit-like Opening Research Articles

Formation of the pits with taste buds at the lingual root in the striped dolphin, Stenella coeruleoalba.

The tongue of the striped dolphin, Stenella coeruleoalba, shows a V-shaped row of pits on its posterior dorsum. Their development is described on the basis of macroscopic and light microscopic observations on fetal, young, and adult stages. Four to eight pits occur, most often five in the adult. Anlagen of the pits first protrude as round epithelial thickenings which later increase in diameter and become thin. The circular primordia then sink, and grooves oriented both circularly and radially develop in the walls of the shallow pits thus formed. Pits and grooves deepen with development so that older pits become lined with conical projections. As pits grow further, they become elongated anterolaterally, retaining slit-like openings. Each pit in the adult is 2-8 mm long and about 1 mm wide. The pits are not derived from lingual gland ducts but develop independently. Taste buds resembling those of other mammalian tongues can be found in young dolphins but are few in number and limited to the thin epithelium of the pit projections and to that of the side wall of the pits. They first appear in the late prenatal period but degenerate in the adult. A rich nerve supply is observable in the lamina propria below taste buds in the calf. The pits and their projections in the dolphin correspond to the vallate papillae of other mammals, but whether each projection or a whole pit corresponds to a single vallate papilla is undecided.

STEWARTIOTHECA GEN. N. AND THE NATURE AND ORIGIN OF COMPLEX PERMINERALIZED MEDULLOSAN POLLEN ORGANS

Stewartiotheca gen. n. is a bell‐shaped, unisynangiate pollen organ with eccentric radial symmetry and a single series of about 80 pollen sacs. Infoldings that vary in depth occur circumferentially and extend from the periphery to a point off center. This position also marks the location of a sclerenchyma column (proximally) and a sclerenchyma‐lined, conical hollow (distally) that opens onto the distal face of the organ. Plates of ground parenchyma extend inward from the outer covering of the organ at locations of infoldings, while similar plates with sclerenchyma strands occur between these locations. Pre‐pollen of Monoletes type was released through distal longitudinal slitlike openings of the pollen sac faces toward the sclerenchymatous ground tissue plates. Vascular bundles entering the organ undergo repeated dichotomies, and lead to numerous bundles both in the cover (one per sac for those sacs that abut directly on cover tissue) and internally (one per pair of pollen sacs that lie opposite one another across the location of an infolding). The most complex permineralized medullosan pollen organs Sullitheca, Stewartiotheca, and Dolerotheca are considered to have evolved from a similar type of cup‐shaped organ with a single ring of pollen sacs, broadly open distally, and with a central hollow. Circumferential infoldings of one organ of this type were involved in the origin of both Stewartiotheca and Sullitheca, while four similar organs, each showing infoldings non‐circumferentially, fused to produce the Dolerotheca type organ (exemplified by D. formosa), a compound synangium.

Description of a gland associated with the foveae dorsales in 2 species of Dermacentor ticks, and its possible role in sex pheromone activity (Metastigmata: Ixodidae).

Histological evidence concerning the existence of a pair of small glands associated with the foveae dorsales in females of Dermacentor variabilis (Say) and Dermacentor andersoni Stiles is described. Each gland comprises several lobes linked to the ducts and pores of the fovea by filamentous protoplasmic connections. In the unfed females, the gland appears to be very small, flattened and compressed in the cuticular recess below each fovea. In partially fed females, however, the gland appears to grow until it has increased to approximately 3 times in depth and 2.5 times in breadth at the end of the 5th day of attachment. Masses of intensely staining granular material were visible in the gland cells and colloid-like substance accumulated in the foveal ducts in hematoxylin-eosin stained sections of partially fed females. Scanning electron microscopy of the foveae dorsales of unfed D. andersoni females revealed the presence of narrow, slit-like openings, oriented approximately in the direction of the anterior-posterior axis. No evidence of foveae dorsales could be found in males of either D. variabilis or D. andersoni . The Possible role of the glands in relation to sex pheromone activity in ticks is reviewed.

A Stereoscan electron microscope study of the male form ofHemiarthrus abdominalis(Kröyer) (Isopoda, Epicaridea, Bopyridae)

Summary Observations have been made on the male form of Hemiarthrus abdominalis (Kröyer) (Isopoda, Epicaridea, Bopyridae) with the Stereoscan electron microscope. The male lacks eyes but has two slit-like openings in the dorsal cuticle of the head. The peraeon is clearly divisible into seven somites, each with a pair of robust, sub-chelate peraeopods. The somites of the pleon are fused to form a pleotelson which lacks pleopods and uropods, but has several ‘pores’ in the ventral cuticle.

The organization of the malleolar sensory system in the solpugid, Chanbria sp.

Five malleoli extend ventrally from the proximal segments of each hind leg of mature and immature solpugids. Each malleolus contains the dendrites of 72,000 bipolar sensory neurons with somata in a ganglion in the leg just dorsal to the malleolus. The dendrites terminate in a sensory groove which extends along the ventral edge of the sense organ. The sensory groove has a slit-like opening to the outside, suggesting that these sense organs are chemoreceptors. The malleoli also contain long processes from microvillar cells with somata in the sensory ganglion. The microvillar cell processes extend into the malleolus to the ciliary ending of the dendrites where each process has an enlarged microvillar ending which surrounds the outer segments of 15 to 22 dendrites and releases a sense secretion.

A ring chromosome No. 16 in an infant with primary hypoparathyroidism

A male infant whose clinical features included hypertelorism epicanthic folds, beak-shaped nose, high-arched palate, micrognathia, low-set ears with slit-like openings of the external auditory canal, and bilateral cryptorchidism was found to have a ring chromosome No. 16. Hypoparathyroidism was diagnosed at 4 1/2 months of age. The proband had four different cell populations associated with the instability of the ring chromosome. The haptoglobin, Kell, Duffy, and Rh loci were not in the deleted portions of chromosome No. 16. The possible relationship of the chromosomal abnormality to hypoparathyroidism is discussed.

Spiracles of Adult Scarabaeoidea (Coleoptera) and Their Phylogenetic Significance. I. the Abdominal Spiracles1

A comparative study was made of the number, location, and morphology of abdominal spiracles of adult Passalidae, Lucanidae, and Scarabaeidae, using material of more than 150 genera. Major evolutionary trends are a reduction from 8 to 7 or fewer pairs of functional spiracles, a reduction in size of the posterior spiracles or of their openings, migration of 1 or more posterior pairs of abdominal spiracles into the tergites or sternites, and changes in the filter apparatus from simple atrial spines to a solid wall with imbedded trabeculae surrounding a slitlike subatrial opening. These characters are useful for assessing relationships between genera, tribes, and subfamilies, but division of the Scarabaeoidea into 2 great series, the Laparosticti and Pleurosticti, should be abandoned, since repeated evolutionary changes in location and size of the spiracles and in their number and morphology as well have occurred in different phyletic lines.

Descriptions of Three New Species of Mites Phoretic upon Native Bees

Three sarcoptiform mites, Caloglyphus boharti, Glyphanoetus nomiensis, and Histiostoma inquilinus, are described herein. The first is known to associate only with the alkali bee, Nomia melanderi Ckll., in central Wyoming, the second with N. melanderi in Wyoming and with N. nortoni Cress, in southern Louisiana, and the third with Xenoglossa strenua (Cress.) in Maryland. The small enclosed environment of the earthen, wooden, waxy, or leafy cells of native bees provides interesting opportunity for the study of coenetics in a microecosystem. Many, perhaps most, animal species in such an ecosystem are mites, these distributed into various trophic levels. Various species of bacteria and fungi constitute the flora. The actual food of acarine consumers is difficult to determine, but some clearly seem fungivorous, others saprophagous. Most of these mites are distributed by the bees whose nests they inhabit, and nearly all possess a specialized developmental stage in which they are relatively well-equipped to survive those periods of exposure to elevated temperatures and comparative drought en- countered during dispersal. All described here are phoretic in a greatly modified third nymphal instar termed the hypopus. This paper is the first of a series dealing with the systematics, ethology, and interrelationships of certain species inhabiting the cells of the alkali bee. The terminology utilized in the descriptions of G. nomiensis, H. inquilinus, and in the hypopus of C. boharti follows that of Hughes and Jackson (1958) except that the median slitlike opening between coxae IV is called the genital opening. Setal designations for the adults of C. boharti are those of Tiirk and Tiirk (1957). All measurements are in microns. Descriptions are based on type specimens, the range of variation within the type series following in parentheses.

Some Observations on the Plaster Bagworm, Tineola walsinghami Busck (Lepidoptera: Tineidae)

Although there is some doubt about the validity of the specific name for the plaster bagworm, the name given in the title has been in common usage for more than twenty years. The very short description of the insect by Busck (1933) is accompanied by a statement that the larvae are not cloth feeders but eat remains of insects caught in spider webs. In the same year Kea (1933) stated that larvae of Tineola uterelia Walsingham [wwalsinghami Busck(?)] refused insect remains but were in reality feeders on woolens and furs like other familiar members of the family. Watson (1939, 1946) has repeated the observations of Busck so far as feeding on dead insects is concerned but recognizes the species as an important household pest. Mallis (1954) repeats Watson's statements about the larvae feeding on insect remains in spider webs and adds that this is a precarious way for an insect to make a living. Within infested buildings the cases of the plaster bagworm are quite noticeable on light-colored plastered walls. Grains of sand are commonly attached to the exterior of the silken cases and it is only logical for the layman to assume that the little creatures within the cases are feeding on the plaster. If such infested buildings are carefully examined, additional cases will be found under furniture and attached to woodwork where they are much less obvious than on the walls. Over a period of more than 20 years the writer has observed the plaster bagworm in the Gulf Coast region. In addition to the infestations within buildings, the insect occurs under buildings where the cases hang from subflooring, joists, sills, and foundations. Cases may be found attached to the exterior of buildings in shaded locations, under farm sheds, under lawn furniture, attached to stored farm machinery, and even on tree trunks. The question of the food of these larvae in these unusual situations has been of interest to the writer for many years. It was not until recently that some detailed studies of the insect were made to determine its food habits under out-of-doors conditions. Busek (1933) was on the right track but did not carry his observations far enough. Although fragments of dead insects are occasionally attached to the exterior of the cases (as are sand, bits of paint, shreds of paper, etc.), the most common and abundant food of the species is old spider webs which are consumed in large quantities. Under caged conditions the larvae are also fond of webs of Corrodentia and Embiidina from the trunks of trees. Larvae do not hesitate to chew holes in old abandoned cases of their species and it is assumed that this silk is utilized as food. Perhaps other types of webs also serve as food under conditions in nature. The structure of the case of the plaster bagworm is interesting. It has been described as having the shape, size, and flatness of a cantaloupe seed. Unlike the cases of most case-bearing Lepidoptera, the case of the plaster bagworm is the same on both ends. Slit-like openings occur at each end

STUDIES OF THE DEVELOPMENT OF ZOSTERA MARINA L.: II. GERMINATION AND SEEDLING DEVELOPMENT

Seeds of Zostera marina L. are shed in Prince Edward Island waters during mid to late summer and germinate the following spring. Occasionally seeds germinate in nature before winter; they can be germinated during autumn and winter in the laboratory. Elongation of cells of the cotyledon and doubled-back axial hypocotyl pushes the embryo out of the seed coat. Cell increase plays no part in this or subsequent elongation of cotyledon and hypocotyl. Leaves emerge through the slit-like opening at the top of the cotyledonary sheath. Hairs develop from cells of the convex surface of the basal swollen hypocotyl; two adventitious roots grow from the cotyledonary node, develop root hairs, and anchor the seedling. Stelar tissues of the hypocotyl and cotyledon differentiate at germination. No characteristically thickened tracheary elements differentiate in hypocotyl or cotyledon. In the hypocotyl, phloem differentiates around the central xylem parenchyma and abuts externally on endodermis which develops Casparian strips. Xylem parenchyma differentiates adaxially against the phloem in the single cotyledonary strand. Differentiation of procambium and vascular tissues in the leaf primordia follows as these expand. Vascularization of the stem nodes is complicated by differentiation of strands to the roots and leaves. All internodes except the first have one pair of cortical bundles. The pair of lateral veins of the first true leaf differentiate in connection with the stele at that node; the lateral bundles from each later-formed leaf pass through one internode as cortical bundles and unite with the stele in the node below.

A device for obtaining better detail in roentgenograms of crying infants; slit shutter radiography.

A device is described for taking sharp x-ray images of the lungs of crying and restless infants under 3 years of age. Directly before the tube opening of a condenser discharge x-ray machine a lead shutter with a transverse slit-like opening 5mm. wide is mounted to operate like a focal plane shutter. When released electrically from the control panel it falls downward 7cm. after first closing the filament and high voltage primary circuits. The exposure in any given point on the film from the resulting x-ray emission is limited by the lead shutter to between 1/200 and 1/400 of a second determined both theoretically from standard formulas and experimentally. Test films of infants' chests were made with a full wave rectified unit (0.1 sec. exposure), a condenser discharge unit (0.05 sec. exposure) and a condenser discharge unit with a slit shutter. Details in the former films were often too indistinct for clinical evaluation whereas the details in the latter were considerably better than that obtained by conventional techniques. Improved detail in chest studies and simplicity of operation of the slit shutter should be of value in clinical and experimental medicine.

Exostosis of the external auditory canal.

EXOSTOSES of the external auditory canal vary in size and may be single or multiple. They are relatively frequent, occurring chiefly in late adolescence or early adult life. Men are more subject to these growths than women. Growths large enough to obstruct the canal will cause partial deafness and constitute a serious hazard when middle ear suppuration is present.1Secondary inflammation of the cutaneous canal may be caused by pressure of the growths against the opposing wall. Cerumen tends to collect in the narrow slitlike openings.2 The cause of this pathological change is unknown in the majority of cases, and the reader is referred to the standard textbooks on otolaryngology for a discussion of the theories of etiology. The case presented here is secondary to trauma. It may have been the result of a local periostitis alone or in conjunction with a fracture.

Congenital transposition of the great arterial trunks

In this study, five cases of transposition of the arterial trunks are presented (Table I). There are four cases of complete transposition according to the older classification of Rokitansky, and one case of partial transposition of the arterial trunks. Thus, according to Spitzer's more recent classification there are four cases of group III, representing a lack of torsion of the arterial trunks, and one case of group II, representing partial torsion. The youngest patient was eighteen days of age and the oldest lived for seven months. In four of the five cases, the ductus arteriosus was patent but in one case it was represented by a mere fibrous cord and there was dimpling of the intimal surface of the pulmonary artery and aorta over the respective points of junction with the ductus arteriosus. In one case the foramen ovale was closed by a thin membrane, and it was but a slitlike opening in another case. The interventricular septum was intact in three of the five cases and patent in two of them. The patency was attributable to an absence of the membranous portion of the septum. Systolic murmurs were audible in four of the five cases, but the patency of the fetal passages might well account for these murmurs. In two cases there was associated situs inversus. In four of the five cases the diagnosis of congenital heart disease was made without qualification before the patient died. The electrocardiogram indicated the presence of auriculoventricular dissociation in one case in which an interventricular septal defect existed.

III.—Fossil Representatives of the Lithodomous Worm Polydora

The borings of the Polychæt Annelid Polydora ciliata (Johnston) are familiar in limestone pebbles and the stouter mollusc-shells on our coasts, but shales and occasionally other rocks are not free from their attacks. They may be recognized by the double aperture, often loosely described as keyhole-shaped, leading to a U-shaped cylindrical tube. The union of the two apertures in a single depression, by the loss of the organically formed septum between them, produces a more slit-like opening, whereas if the surface of the pebble be further worn the two round holes are more clearly distinguished. The differences between the burrows of Polydora and those of other lithodomous Annelids, especially the associated Dodecaceria, were clearly stated by Dr. W. C. M'Intosh in a very full paper “On the Boring of certain Annelids” (1868, Ann. Mag. Nat. Hist. [4], ii, pp. 276–95, pls. xviii–xx).

Potato Black Scab

THE discovery this autumn of black scab in the potalo crop in two localities in co. Down was the means, through the Irish Department of Agriculture, of supplying me with excellent material of diseased tubers for examination. I have kept the resting “spores” of the chytridian fungus Chrysophlyctis endobiotica, Schilb., causing the disease, under varied conditions of temperature, nourishment, moisture, and light, and have succeeded in causing the “spores” to germinate, especially by cultivation in potato juice. Each “spore” proves to be a zoosporangium, full of zoospores or zoogonidia, seen in active swarming motion before rupture of the sporangium. The zoospores, 1.5–2 in diameter, escape through a slit-like opening in the wall of the sporangium 30–60 μ in diameter, and have the usual characters of a chytridian zoospore.

THE PLUM-TWIG GALL-MITE: Phytoptus phlœocoptes, Nalepa

In January, 1895, I received from a fruit grower at Industry, Pa., several plum-twigs which were badly infested with what was to me a new pest. Two of these twigs are shown, natural size, on the accompanying plate. It will be seen that a ring of small, sub-spherical excrescences encircles the base of each bud and also the bases of two short shoots. The correspondent wrote that he had 400 trees badly infested, and a majority of the plum trees in his neighborhood were affected. The Damsons seem especially subject to attack, but all varieties suffer more or less.The excrescences were then of a dark brown colour, with a slight reddish tinge. Usually a slit-like opening could be distinguished on the surface. Upon carefully cutting through one of the excrescences, I was surprised to find a cavity in the interior that was packed nearly full of very minute whitish creatures, which proved to be four-legged mites or Phytoptids. Thus, these excrescences were the galls formed by the mites, and in which they were then hibernating. There were hundreds of the mites in each gall and all of them in a dormant condition. Thus, each twig was harbouring thousands of the little creatures. The fleshy portion of the galls, between the cavity and the onter skin, is of a dark magenta colour. The galls vary in size, some of the larger ones containing two or three cavities.