81 
sed sponges and partly through subjecting freshly and carefully dis- 
sected glands to pressure. In both cases the secretion showed itself 
exceedingly poisonous, very small quantities being sufficient to cause 
the death of frogs, rabbits and other animals. I abstain from further 
discussion on the poisonous qualities of the secretion, as they will be 
specially treated in a separate publication by Professor Dr. C. G. San- 
TESON. The doubt as to the poisonous action of the secretion being 
now settled in the affirmative, it was of interest to me to investigate 
the finer structure and discover if any similarity could be found in 
the microscopical anatomy of these poison glands to those of the 
Ophidiae, which had already been investigated by a good many ana- 
tomists, as can be seen by the list of literature by HorrMann (2) in 
Bronn’s Manual of Zoology. However, very little has been done by 
modern investigators as to the finer structure of poisonous glands and 
of all the literature I have been able to obtain, the best information 
was got from Lrypie (3), Emery (1), NIEMANN (4) and West (6). 
The Helodermidae may claim the honor of being the only family 
amongst the Reptiles who have their poison apparatus situated in the 
submaxillary region, the Ophidiae generally having their poison fangs 
in the maxillary regions and the glands situated quite close, extending, 
however, very far back in some instances. 
Any phylogenetical relation between the poison apparatus of this 
Saurian reptile and that of the Ophidiae is naturally out of the que- 
stion and the acquirement of the properties of the submandibular 
glands in Heloderma can only be regarded as a matter of converg- 
ence. 
The general opinion of those authors who have investigated the 
venomous glands in the Ophidiae is, that they belong to the tubular 
glands; West (6), who has lately published on the subject, finds that 
the poison glands belong to the tubulo-racemose type, and consist of 
small polygonal lobules arranged round the branches of a duct. 
Emery (3) has found the glands in Naja haje to be histologically dif- 
ferent regions, one consisting of long tubes converging to the efferent 
duct and the other consisting of small lobes arranged round this duct. 
He supposes the first-mentioned region to be the one that secretes the 
poison and the other to be only a mucous gland. The two animals 
I have used in this investigation were killed by chloroform and the 
glands carefully dissected from the body, parts of them being fixed in 
different fluids. I have tried ZEnker’s and FLemmina’s fluids as well 
as the picro-nitric mixture and the best result was obtained with 
ZENKER’S fluid, in which the gland was fixed without any contraction 
Anat. Anz. XIII. Aufsätze. 6 
