448 Profs. A. Alcock and L. Bogers. On the Toxic [Apr. 28, 



glycerine extract — both diluted and undiluted — of the gland. But as 

 in a series of control experiments with the secretion of the Harderian 

 gland, with the fresh serum, and with pure glycerine, we found that 

 the subcutaneous injection of pure glycerine is sometimes fatal to rats 

 and mice, we have altogether eliminated the results of experiments in 

 which glycerine extract, diluted or undiluted, was used. Our recorded 

 experiments, therefore, refer exclusively to the effects of the liquid 

 extracted by water or normal salt solution from the parotid gland 

 quickly removed from the still-quivering head of the decapitated 

 snakes. 



The only specimen of Chrysopelea ornata that we could obtain was a. 

 very young one, from which, as we expected, we got no results. But 

 in the case of Cerberus rhynchops, Dipsas Forstenii, and Dryopliis mycte- 

 rizans we confirmed the statements and opinions of other authors as 

 to the venomous character — so far as small mammals are concerned — 

 of these Opisthoglyphous Colubridce. 



We next tried the effect of the parotid secretion of Tropidonotus 

 piscator and Zamenis mucosus, both of which belong to Boulenger's section 

 of Aglyplia, or harmless Colubrines, none of whose teeth are grooved. 



As before, we used white mice and white rats, and controlled our 

 experiments so as to eliminate the influence of blood-serum and of 

 glycerine ; and we found that, so far as these small mammals are con- 

 cerned, the parotid secretion of these two " harmless " Colubrines is 

 decidedly toxic. 



Nor, even in our small series of experiments, did we fail to find 

 some evidence of that graduated variability which any one who ap- 

 proaches this question from the evolution side looks for. AYhen all 

 allowances are made, the parotid extract of Zamenis appears to be con- 

 siderably more potent than that of the other Aglyphous Colubrine 

 Tropidonotus ; and, among the Opisthoglyphous snakes, Dipsas seems to 

 be decidedly more virulent than Cerberus, and Cerberus slightly more 

 venomous than Dryopliis. It is further worthy of notice that the 

 poison of the two Aglyphous snakes [Zamenis and Tropidonotus) ap- 

 pears to act more on the nervous system, causing general convulsions, 

 while that of the Opisthoglyphous snakes seems rather to affect the 

 respiratory centre and to occasion respiratory convulsions. 



We have made no experiments with the parotid secretion of other 

 orders of reptiles or other classes of vertebrata, to ascertain whether 

 or no the normal parotid saliva of animals other than snakes has any 

 toxic properties when subcutaneously injected. Such experiments 

 would be a natural continuation of the present inquiry. Especially 

 would it be interesting, in view of its curious snake-like tongue and 

 its persistently evil reputation, not only among the natives of India 

 but also among educated Europeans, to test the saliva of the great 

 " water-lizards " of the genus Varanus. 



