147 
BAR be 
CHARTER IN 
SHCRETION AND COLLECTION OF VENOM IN 
SNAKES. 
Non-poisonous as well as poisonous snakes possess parotid and 
upper labial glands capable of secreting venom. In the former the 
organs of inoculation are wanting, but we shall see later on that 
the toxic secretion of their glands is just as indispensable to them 
as to the snakes of the second category for the purpose of enabling 
them to digest their prey. 
For the morphological, histological, and physiological demon- 
stration of the existence of these glands in harmless reptiles we 
are indebted to Leydig (1873), whose discovery has since been 
confirmed and extended by the researches of Phisalix and Ber- 
trand, Alcock, L. Rogers, and L. Lannoy. 
The parotids of Grass Snakes are mixed glands of the sero- 
mucous type. The serous tubes are situate almost exclusively in 
the posterior portion of the gland. As we proceed towards the 
anterior portion, we find that these serous tubes are interspersed 
with others which are exclusively mucous or sero-mucous, and they 
become entangled with those of the upper labial gland, properly 
so-called. The substance of the gland is divided into several lobes 
by bands of connective tissue ;. the tubes are separated by septa of 
the same tissue, in extremely delicate layers (Lannoy). 
In poisonous snakes these glands are much more developed, 
especially in their binder portions, which sometimes assume 
