42 JOURNAL OF THE [April, 



THE COMPARATIVE ANATOMY OF THE 

 VERTEBRATE SKIN. 



BY GEORGE WILLIAM KOSMAK. 



(^Read January igtA, 1894.) 



I. Introduction. 



- The subject to which I ask your attention this evening presents 

 to both biologist and microscopist a varied and fascinating line 

 of work in original research and invesiigation. In its morphology 

 and physiology many points are still doubtful and obscure, await- 

 ing the biologist's explanation and elucidation ; while to the 

 working microscopist there is held forth an equal opportunity in 

 a field where little satisfactory work has yet been dowe — e.g., in 

 the technique and new methods of sectioning and staining. 



The study of the skin, anatomically and physiologically, is a 

 subject vast and extensive, with an accompanying literature 

 equally so. The latter, however, consists of a mass of detail, 

 much of which is unimportant. The beginner must wade through 



Explanation of Plate 41. 



Fig. 1.— Diagram of Fish Skiu. Transverse section, illustrating general structure. 

 (After Wiedersheim.) S C. striated cuticular border of epidermis; A. slime cells; E, 

 epidermis; D, derma; K, goblet cell; L, granular cells of Petromyzon; B, blood vessels; 

 V, vertical connective-tissue bundles; H, horizontal connective-tissue bundles. 



Explanntion of Plate 42. 



Fig. 2.— (a) Diagrammatic cross-section of skiu of larval Salamander; (6) ditto, of 

 adult form. (After Wiedersheim.) E. epidermis; D, dermis; S C, striated cuticular 

 border of E; C. stratum corneum; M, stratum Malpighii; P, pigment; O, subcutane- 

 ous layers of muscle; B, blood vessels; N, epithelium of glands; X, Y, integumentary- 

 glands; T, muscles of glands. 



Explanation of Plate 4 3. 



Fig. 3.— Feather Development. Diagrammatic. (After Studer.} a, 6, c, d, e,/ de- 

 note successive stages. C, stratum corneum; M, stratum Malpighii; D, derma; F, F', 

 feather germ; P, pulp; Q, quill; B, bai-bs: B', barbules. c is a cross-section of the 

 feather germ in b, showing the ridges of Malpighiau cells covered by the horny layer of 

 epidermis. 



Fig. 4.— Hair Development. Diagrammatic, a, ?>, c, d, e,/ denote successive stages. 

 C, stratum corneum; M, stratum Malpighii; D, derma; F, hair follicle; B, blood vessels; 

 K, hair knob: G, sebaceous gland; P, hair papilla— in e and / are indicated two stages 

 in its formation; in / it has become vascular. 



