214 SOME EXPERIMENTS WITH THE 
In Heloderma suspectum, there are two large glands, one on each side of the anterior 
part of the lower jaw between the skin and the bone. When one of these glands has 
been freed from its outer sheath it is found to be not a single gland but a series of three 
or four glands, each perfectly distinct from the others and emptied by a separate duct. 
These glands increase in size posteriorly, so that the last is very much larger than the 
first. They vary in number because of the occasional union of the first and second 
glands, or the presence, posteriorly, of a small, isolated, ductless portion. Their ducts 
open between the lower lip and gum, as described by Stewart. It is shown later on that 
these are the yenom-producing glands. 
No glands have yet been described as existing in the upper jaw; indeed there seems 
to be no room there for a well-developed gland. Nevertheless, paper which comes in 
contact with the upper jaw during the bite collects almost as much fluid as is obtained 
from the lower jaw. This, however, is true only when the paper is bitten a very few 
times. The saliva of the upper jaw is exhausted much more quickly than that of the 
lower. This fact, taken in connection with the absence of known glands, might lead one 
to suspect that the upper jaw receives its saliva from the lower and holds it in the compli- 
cated folds of its gums. This might perhaps be true if one or more segments of the sub- 
labial glands secreted a harmless fluid, but the following experiments show that all are 
specialized for the production of venom. I believe that the harmless saliva is secreted 
by minute glands which lack of material has prevented me from finding—that it is in 
fact the ordinary buccal liquid of lizards. That it is present in the lower jaw as well as 
in the upper would seem to be shown by the fact that the fluids of both jaws are decidedly 
alkaline, while a solution of the poison gland itself is quite neutral. 
The following experiments were performed to show that each part of the sublabial 
glands is deyoted to the production of yenom: 
EXPERIMENT XX VIII.—January 5, 1897. Soaked the first portion of the right sublabial gland in 
water and injected the resulting solution (three minims) into the breast muscles of a small finch, at 
12.26 P.M. 
12.28. Respiration forced; eyes closed. 
12.29. Respiration greatly forced. 
12.31. Flutters. 
12.314. Convulsions and death. 
12.35. Heart beating weakly; blood dark but lightens quickly. 
EXPERIMENT X XIX.—January 5, 1897. Soaked the second portion of the right sublabial gland in 
water and injected solution (four minims) into breast muscles of a small finch, at 12.00 M. 
12.04. Eye nearly closed; respiration normal. 
12.05. Respiration slightly forced. 
