XI 



THE SKIN AND SENSE ORGANS 



THE SKIN 



1. General. 



The outer skin of the Salamander is moist and devoid of scales. It 

 is highly glandular, however, and the glands are of two kinds — the 

 mucus glands^ whose function is to keep the skin moist, and the venom 

 glands. In this respect the skin of Salamandra is less slimy than that 

 of the Frog, a feature probably correlated with the diminished respi- 

 ratory function of the skin in the former animal. The mucus glands are 

 distributed over the whole surface, and do not disclose their presence 

 by any external excrescence or other sign visible to the naked eye. 



2. Venom Glands. 



The second kind of gland is the poison or venom gland. These are 

 much larger than the mucus variety, and usually reveal their location 

 by a slight mammilliform protuberance, while the central pore is quite 

 visible to the naked eye, and where the glands occur beneath the 

 yellow pigment — as is frequently the case — the opening is often 

 marked by a black dot. Although the venom glands may occur 

 almost anywhere on the body, they are more numerous over the dorsal 

 surface, and are more highly developed in certain definite areas 

 as in the paratoid glands and along the mid-dorsal line from the 

 nape to the tip of the tail. There are also, strangely enough, several 

 medium-sized glands on the feet between the toes. The paratoid 

 glands consist of some twenty-five to thirty flask-shaped glands, 

 the bases of which may readily be seen on removing the skin. A 

 double alternating row of such glands extends right along the back for 

 the whole length of the vertebral column. The remaining scattered 

 venom glands are definitely smaller and less conspicuous. The 

 venom glands are distinguishable from the mucus variety, particu- 

 larly in preserved specimens, by their more granular contents and 

 opaque appearance, the mucus glands being translucent or pearly. 



With regard to the histology and development of the glands much 

 has been published which is outside the scope of the present work. 

 For these details the papers of Leydig (1876), Pfitzner (1880), 

 Drasch (1894), Ancel (1900-2), Schuberg (1908), Nierenstein 



