﻿172 STRONG. 



Statements in the literature in regard to the lethal dose of pest bacilli 

 for monkeys of different species vary somewhat and are not entirely 

 definite. 



Albreelit and Gohn 31 (Report of the Austrian Plague Commission) in their expe- 

 riments with monkeys used the small, long-tailed, brown Indian species. Inocula- 

 tions of living cultures in amounts of from 0.5 to 4 oesen were made. With some 

 strains 0.5 oese killed animals after forty-eight hours and with others 2 oesen failed 

 to kill. It is not possible from their experiments to arrive at a general deter- 

 mination of a lethal dose for these animals, since strains of different virulence 

 and in different amounts and with different .methods of inoculation were employed 

 and no series of animals by any one method of experimentation is given. 



Wyssokowitz and Zabolotny 32 (Russian Plague Commission) in their experi- 

 ments used three Indian species, described as the Macacus with the long tail, 

 the Macacus with the short tail and the black ape with a long tail. The two 

 latter were found to be more susceptible to pest infection, dying in from two 

 and one-half to three days, while the former usually succumbed in from four to 

 five days after inoculation. These monkeys proved to be very sensitive to small 

 amounts of plague bacilli. A prick on the palm of the hand or sole of the 

 foot of the animal with a needle which had been moistened with a plague culture, 

 invariably produced death in from three to ten days. 



In 1001 Zabolotny, 33 in further experiments, confirmed the fact that in the 

 animals of both the species Macacus radiatus and Semnopithccus cntcllus a 

 small amount of pest bacilli gave rise to fatal infection, but that the latter 

 species was more susceptible and succumbed in a shorter time. 



The German Plague Commission used two varieties of monkeys in their 

 experiments, Macacus radiatus and Semnopithecus entellus. The later species 

 was extraordinarily sensitive to pest infection, succumbing in six days to the 

 subcutaneous injection of 0.01 or 0.001 oese of the virulent plague bacillus and 

 dying of larger inoculations after two days. These monkeys also succumbed to 

 pest infection if small amounts of pest bouillon cultures were rubbed into 

 superficial wounds of the skin. The species Macacus radiatus was much less 

 susceptible. When the skin was scarified and a fresh agar culture rubbed over 

 the wounded area, or 0.01 of an oese of an agar culture injected subcutaneously, 

 the animals acquired a moderate pest infection, with fever, glandular swellings, 

 etc., but usually survived. However, 1 oese of a two-day agar culture suspended 

 in 1 cubic centimeter of bouillon and injected subcutaneously, always caused 

 the death of this species in three or four days, and * or I of an oese always 

 brought about the same result, although in a slightly longer time. 



In the report of the Indian Plague Commission mention is merely made of 

 the fact that the gray Indian monkey is more susceptible to plague than the 

 brown. 



Only the common Philippine species (Cynomolgus philippinensis 

 Geoff.) was employed in my experiments with monkeys. The similarity 

 of pest infection in these monkeys to that observed in human beings is very 

 marked, and in the experimental work with them all forms of infection 

 with plague have been encountered. This species of monkey appears to 

 stand between Macacus radiatus Geoff. (Macacus sinicus Linn) and 



3l Loc. cit., 713. 



32 Ann. d. Vinst. Pasteur (1897), 11, 663. 



23 Arch. Sci. Biologiques (1901), 8, 390. 



