ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01608.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01609.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01610.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

Summary.This paper describes the morphological changes of the gut ofVespaduring metamorphosis, and also the histological changes which occur in the mid‐gut epithelium.The first histological changes are observed in the late larval stage (pre‐pupa), when phenomena of disputed significance occur—the formation of globules and their apparent liberation into the gut‐lumenThis is followed by rapid multiplication of the replacement‐cells.The bases of the histolyzing epithelial cells contain large vacuoles, and it is probable that these exert a mechanical force, pushing the epithelium away from the basement‐membrane. This process of casting is probably aided also by chemical disintegration of the cell‐bases and basement‐membrane, by the force exerted by the rapidly growing replacement‐cells, and by severe muscular peristalsis of the intestinal muscle‐layers.The rapid proliferation of the replacement‐cells leads to the formation of the new epithelium. This is at first irregularly disposed and thrown into folds which disappear as the diameter of the gut increases.The cast epithelium lies in the gut‐lumen, and is removed by an undetermined method, probably a combination of “auto‐digestion” and by enzymes liberated from the new cell‐layer. Phagocytosis plays no part in the process.The early epithelium shows certain characteristic features, particularly a refringent edge, which splits away by delamination and gives rise in this manner to the peritrophic membrane which thus arises during the pupal period. There is only one pupal epithelium.The adult morphology is attained before the imago emerges, but the cells of the epithelium are small and “cuboid.” The final histological characters (such as greater size, perinuclear space, etc.), are not at first present, and probably do not appear until after the first meal.A discussion of the time‐relations of these various processes and consideration of the results of other investigations leads to the theory that metamorphosis is started by a single original stimulus, and though some amount of progress may follow from this, its completion appears to depend upon the serial development of other succeeding stimuli each

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01611.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

Summary.1The dental peculiarities of the walrus,Odobenus obesus, may be ascribed in their entirety to the structural modifications induced by the huge size of the canine tusks and to the diet which the animal has adopted.2The dental succession is best represented by the formulæ: Deciduous i. 3/3, c. 1/1, m. 3/3 = 28; Successional I. 2/0, C. 1/1, P. 4/3, M. 1/1 = 26; Functional I. 1/0, C. 1/1, P. 3/3 = 18. The last of these is well known. The first differs from previous interpretations in recognizing but three milk‐molars, and the second is devised to acknowledge definitely the existence of a successional upper second incisor and fourth premolar and to designate as true molars the upper and lower posterior rudimentary teeth.3The enlargement of the upper canines has caused the loss of the medial incisors, the alignment of the outer upper incisor and lower canine with the cheek‐teeth, and an antero‐lateral shift in the angle of implantation of the upper teeth.4The diet, composed chiefly of hard‐shelled molluscs, has required a concentration of force in the anterior portion of the mouth. This has been accomplished by the production of massive jaw‐bones and heavy solid dental columns.5The necessity for an adequate dental armament at an early age has been met (a) by a long period of suckling, while the face and teeth were growing; (b) by the nearly simultaneous eruption of the entire dental battery; and (c) by the expanding cones of the growing roots, which made it possible for dental equipment to keep pace with facial development without additional teeth, a mechanism not noted in any other mammal.6The details of the processes of structural modification, growth, wear, and senescence related to the dentition have been recited according to the evidence available.7By the application of the principles set forth in this discussion miscellaneous specimens of teeth may be identified with reasonabl

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01612.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

Summary.1The structure of the immature stages shows clearly that the genusPlatyaucheniashould be removed from the Cassidinæ and put in the Hispinæ.2The head, though of a true miner, does not show any of the types of structure previously recorded as belonging to a miner.3The mouth‐parts have become greatly simplified.4The last segment of the abdomen belongs to one of the types described as occurring among the Hispinæ, and they do not show any of the typical abdominal modifications of the Cassidine larvæ.5The last pair of spiracles open laterally, a modification which has not been previously recorded in the Hi

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01613.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

Summary.1Architeuthis clarkei, a new species of Giant Squid, is described from a specimen stranded in January 1933 at Scarborough, Yorks. Its relation to the other species of the genus is discussed.2The distribution of the Giant Squids stranded or observed in the North Atlantic is described and discussed.3In order to account for the curious distribution of the records it is suggested that in the North AtlanticArchiteuthisfinds its optimum conditions in temperate waters and that it occurs in moderately deep water off the United States coasts. The frequency of strandings on the coast of Newfoundland might be due to the fact that the animals come near the surface as the deeper layers of the north east‐going current are chilled, and get into difficulties owing to the rapid gradient from warm to cold water off the Grand Banks. The wider distribution off the north‐west coasts etc. of Europe fits in with this suggestion.4It is suggested, on the strength of the structure of the fins, arms, adhesive apparatus etc., thatArchiteuthisis a sluggish animal, comparing unfavourably withSthenoteuthisand the smaller squids in point of activ

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01614.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01615.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

摘要:

Summary.Only the points in which the cranial morphology ofRana grayidiffers from that of the common European species ofRanawill be given here.1The anterior process of the crista subnasalis is comparatively long and projects forwards beyond the superior prenasal cartilage.2A ventromedian process of the crista subnasalis appears in the palate, in this way separating the partes palatinæ of the premaxilla and the maxilla from each other.3In the one specimen both the foramina frontalia are absent; in the other the normal condition obtains.4The plica obliqua, which is poorly developed, is suspended from the cartilago obliqua and not from the tectum nasi.5The posterior niche‐like portion of the vestibulum is practically absent.6The two Gauppian “Wülste” are both present, but they are not demarcated sharply from each other.7The recessus alaris and the infundibulum are smaller than in the EuropeanRana.8The cavum principale has a small ventromedian recess.9An infundibular vestige of the recessus sacciformis is present.10The musculus lateralis narium is slightly different from that of the EuropeanRana.11A small prechoanal pouch is present.12The septomaxillary consists of an anterior unpaired portion which has three posteriorly directed processes.13The nasals are much smaller than in the common European species ofRana.14A peculiar cartilaginous plate, which is connected synchondrotically to the solum nasi, occurs on the ventral surface of the os en ceinture.15A little further backwards a small cartilaginous cyst appears on either side of the os en ceinture.16Both the parasphenoid and the fronto‐parietals are indented anteriorly.17The exoccipital and the prootic do not fuse with each other.18Rana grayipossesses a so‐called “Mundwinkeldrüse” situated between the palatal and the facial portions of the maxilla. The gland consists of adenoid tissue and has a lumen which opens into the buccal cavity.19The pterygoid fuses with the processus oticus and with the processus basalis.20In the one specimen the quadratomaxillary acquires a bony connection with the paraquadrate.21A delicate rod‐like cartilage, which is connected synchondrotically to the symphysial cartilage, occurs on the ventral surface of the pars menta

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01616.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1933.tb01617.x

出版商:Blackwell Publishing Ltd    

年代:1933

数据来源: WILEY