PHYLOGENY OF VENOMOUS SNAKES 49 



ciple as echidnin. Jourdain (1894) found that Tropidonotus viperinus, 

 Elaphis (Bsculapii, Coronella lavis and Rinachis scalaris enjoy the same 

 immunity against the viper's venom as Tropidonotus torquatus. He held it 

 certain that these snakes have the venom-producing apparatus and contain 

 its product in the blood. Jourdain ventured a still more far-reaching gen- 

 eralization, that every snake is provided with the venogenous gland. 



While the experimental data concerning the toxic property of the posterior 

 yellowish portion, alleged to be homologous with the real poison gland by 

 Leydig, are strikingly meager, a mere anatomical investigation into the extent 

 in which that particular portion of the supralabial gland comes into existence 

 among the non-poisonous species seems to warrant enough interest to be 

 briefly dwelt upon in this place. Several species of the Aglyphous snakes 

 have been studied by some investigators. Of the subfamily of Natricinae (or 

 Colubrinae) some species of the genus Natrix (or Tropidonotus), of the sub- 

 family Coronellinae, some species of the genus Elaphe (s. Coluber), Ptyas (s. 

 Coryphodori) and Herpetodryas, 1 and of the subfamily Rhachiodontinae, the 

 genus Daspeltis have been studied. 



Tropidonotus natrix s. Natrix torquatus Fleming: the glandula labialis 

 superior consists of a grayish and a yellowish portion. The glandular grains 

 are made of aggregates of tubules. The cellular elements of the yellowish 

 portion are filled up with granules, and appear like the rennet cells. The 

 epithelium of the excretory duct is a high, clear cylinder cell. The entire 

 yellowish part is provided with one single duct, while the anterior parts 

 have many small ducts opening near the teeth. Leydig (1873) drew an 

 analogy between the yellow portion and the parotid of the mammalia. The 

 posterior part of the yellowish portion is described by Leydig as having 

 the dark, granulated epithelium. Reichel described a similar character of 

 the cell and added that the nucleus is situated basally. The examination 

 of the grayish part reveals many tubules with clear cylindrical cells, which 

 show transverse striation when treated with osmic acid. The reddish- 

 grayish portion contains transparent, non-granulated cells, which are cylin- 

 drical and have basal nuclei. Sometimes there are smaller, highly granulated 

 cells with nuclei dislodged. These are usually met with in the edge of the 

 acini. Some alveoli may consist entirely of this type, others chiefly of the 

 first-named kind, and still others of a mixture of the two types. Reichel con- 

 sidered these varying types of the epithelia as the representatives of different 

 stages of cellular activity, the first type being the resting state. 



Tropidonotus subminiatus Reinwardt: Niemann (1892) has described the 

 supralabial and the yellowish gland separately. He found four smaller 

 excretory ducts in the former and one larger for the latter. The yellowish 

 gland is surrounded by a strongly developed connective tissue capsule, which 

 has a circular cleft to allow the entrance of the blood-vessels. The long-oval 

 tubules of the gland are surrounded by a thin, delicate connective tissue mem- 

 brane. The glandula labialis superior is wrapped up in a layer of strongly 

 developed connective tissue, within which a lymphatic space is also present. 



1 Probably synonymous with Liopeltis Fitzinger. 



