rubicunda, Cehis albifrons), Cercopithecidse (Macacus assamiensis, M. cyno- molgus, M. rhesus, M. ocreatus, Cercopithecus campbetti, C. patas, C. diana, C. lalandi, C. melogenys, C. calUtricha, Semnopithecus entellus), Simiidse (the chimpanzee, Anthropopithecus troglodytes, and Ourang-outang, Simia, satyrus),
All of these bloods reacted to the anti-serum for human blood, the New World monkey bloods less, and least of these the bloods of the Hapalidse. I am at present attempting to estimate quantitatively the differences in the amount of reaction obtained.
When the experiment was tried with the anti-serum for dog's blood, the only bloods besides those of the domesticated dog which were found to react were those of other Canidse (C. aureus, C. mesomelas, C. procyonides, C. cerdo). Similarly, the anti-serum for horse blood only gave a reaction with the blood of the horse and donkey. The anti- serums for ox and sheep blood have given reactions, which indicate the existence of a " blood relationship " between certain of the true ruminants. Whereas the anti-serum for ox blood acted powerfully on the blood of the ox and other members of the bovine section, it also produced reactions, but to a lesser degree, with the bloods of several species of the ovine section (Sheep and Goat), with the blood of several species of deer, the antelope and gnu. The anti-serum for sheep's blood gave almost as powerful a reaction with the 1)1 ood of the closely related goat as it did with that of the different species of sheep, and also produced lesser reactions with the bloods of the other rumi- nants above mentioned.
The above experiments, which are being prosecuted on a large scale, the attempt being made to obtain a variety of anti-sera, indicate with certainty that we possess in this test a most valuable aid in the study of classification of animals. I am at present engaged in producing anti-sera for monkey blood, one of the objects being eminently practical. Just as in the case of the anti-serum for ox blood, which acts power- fully on ox blood and feebly on sheep's blood, and vice versit, we shall by means of both the anti-serum for human blood and the anti-serurn for monkey blood be able to differentiate the blood of man and monkey conclusively. This would scarcely have any practical application in this country, but it might very well be a matter of great medico-legal importance in countries where there are monkeys. Thus, I recently received a letter from Mr. E. H. Hankin, of Agra, stating that a case had come before him where it appeared essential to make a test to determine if certain blood-stains were caused by human or monkey blood. In such cases it would be necessary to prepare anti-sera for the most prevalent genera or species of monkey.
The more powerful the anti-serum obtained the greater is its sphere of action upon the bloods of related species. For instance, a weak anti-serum for human blood produced no reaction with the blood of the
