TRYPANOSOMES, TRYPANOSOMIASIS, AND SLEEPING SICKNESS 43 
inoculated into the animals. These animals became infected, though the incubation 
period was lengthened. Alter the appearance of the parasites the disease ran its 
natural course, and the animal succumbed to the infection in almost the same time as 
others which had been inoculated with blood in which the organisms were seen. 
Monkeys ot 1*5 to 2*5 kilo, weight inoculated intraperitoneally with 
5-0 to 8-o c.c. of apparently negative blood always became infected. Kittens can 
receive two c.c, pups, two to four c.c. of blood intraperitoneally without untoward 
symptoms developing, and show parasites usually in nine to fourteen days. The 
kitten and pup are especially useful for studying the disease as they quickly show the 
parasites in large numbers, and periodicity, particularly in kittens, is not a marked 
feature. Dogs are also useful, but the number of parasites observed may for a 
considerable period be small, and the possibility of the unskilled observer passing 
them by is enhanced. 
The Cultivation of Trvpanosomes 
Novy and McNeal in a series of papers emanating from Professor Novy's 
laboratory, have shewn that it is possible to cultivate some of the trypanosomes 
infecting animals, T. lewisi, T. brucei, T. evansi, and a numerous series in birds. We 
have been able to cultivate T. lewisi and T. brucei on the media proposed by these 
investigators. Our attention has, however, been directed more to the artificial 
cultivation of T. giimbieuse, T. dimorphon, and the other pathogenic trypanosomes. If 
the results must conform to Koch's postulates, then we must admit we have failed. 
Various strains of T. gambiense are capable of being cultivated in a modified blood 
agar medium and kept alive for sixty-eight days by transference from tube to tube or 
through flasks ; after the seventeenth day of cultivation we found it no longer 
capable of infecting a susceptible animal, no matter what amount of culture was used. 
The trypanosome loses its form to a great extent, its staining reaction is altered 
and it finally dies. Numerous trials have been made with various changes in the 
composition of the media but without success. Guided however by the history of 
the numerous failures of Novy and McNeal before their efforts were rewarded, we 
believe that our successors will be able to cultivate these parasites with greater 
success than we have had. That the task is a difficult one is evidenced by the 
fact that of the many trypanosome investigators only one 111 addition to those working 
in Nova's laboratory has been been able to publish a successful result, and this 
only a repetition of a former investigator's work. 
A synopsis of our attempts is included here in the hopes that they will act as 
a spur to the investigation of this most important subject. As the result of our 
experience, we feel that the undivided attention of the research worker is necessary 
to secure success. 
