456 Proceedings of Royal Society of Edinburgh. [sess. 
of appetite, which usually, though not invariably occurred, and was 
probably the cause of a temporary slight fall in weight during the 
day or two days succeeding each injection. On the other hand, 
during the process of successful immunization, the animals increased 
in weight, they fed well, and appeared to acquire increased vigour 
and liveliness. This has been frequently exemplified in the smaller 
animals, such as rabbits ; and also, very conspicuously, in an aged 
and previously sedate horse, which, in the process of immunization, 
has now received eleven times the estimated minimum-lethal dose. 
It is marvellous to observe these evidences of the absence of 
injurious effects, and even of the production of benefit in an animal 
which, for instance, has received in one single dose a quantity of 
venom sufficient to kill, in less than six hours, fifty animals of the 
same weight, and, in the course of five or six months, a total 
quantity of venom sufficient to destroy the lives of 370 animals of 
the same species and weight. There are few facts in the whole 
range of biology more calculated to arrest the attention or produce 
astonishment in the mind of the observer ! 
With the cobra venom, I have also immunized cats, both by 
subcutaneous and by stomach administration j but the significance 
of the latter method of administration must be reserved for a future 
communication. As I have stated, a horse is also being immunized ; 
and I have to express my obligations to Principal Williams and 
Professor W. Owen Williams, for granting me the accommodation 
of their establishment, and to Mr Davis, M.E.C.V.S., also of the 
New Veterinary College, for much valuable assistance. 
Following the same plan of research with the three other 
venoms, it was found that the minimum-lethal dose per kilogramme 
for rabbits of the Diamantina venom is *0015 grm. ; of the venom 
of Sejjedon lixmachates, ’0025 grm.; and of the venom of Crotalus 
*004 grm.* The Crotalus venom is, in its purity, altogether com- 
parable with the cobra venom ; and the determinations, therefore, 
show that cobra venom is sixteen times more powerful than Crotalus 
or rattlesnake venom. This venom, as well as the two others, how- 
ever, much exceed cobra venom in the intensity of their local 
* Diamantina venom, milligramme. ’ 
Sepedoii Immachates, 2\ ,, 
Crotalus horridusy 4 „ 
