474 Col. Sir D. Bruce and others. Trypanosome [May 13, 



Table II — continued. 



No. of 

 experiment. 



Source of 

 Tirus. 



Period of 

 incubation, 

 in days. 



Duration of 

 disease, 

 in days.* 



Remarks. 







White rat. 





397 

 551 

 684 

 699 



1646 

 626 



1001 

 455 

 729 



1708 



Or 



Monkey 

 Eat 



J) 



17 

 16 

 16 



12 

 12 

 13 



9 

 11 



8 



39 

 18 

 32 



16 

 22 

 23 

 12 

 21 

 12 



Died of Trypanosoma pecorum. 

 Killed for cultivation experiments. 

 Died of Trypanosoma pecorum. 

 Experiment stopped after 57 days. 

 Died of Trypanosoma pecorum. 

 Killed for cultivation experiments. 

 Died of Trypanosoma pecorum. 

 )? j> 



n )» 

 )> » 







12 -6 



21 



Mouse. 





686 

 398 

 627 

 454 



Ox 

 Monkey 

 )> 



Mouse 



26 

 12 

 6 



41 

 26 

 12 



Experiment stopped after 59 days. 

 Died of Trypanosoma pecorum. 

 J) )j 





Average 



14-7 



26 





Duration includes the days of incubation, it dates from the day of infection. 



Theiler describes a trypanosome from Chai-Chai, near the mouth of the 

 Limpopo, in Portuguese East Africa ; from the mouth of the Zambesi ; and 

 also from Zululand, which resembles the one under discussion, in not 

 infecting guinea-pigs ; and considers that this one fact is sufficient for tlie 

 creation of a new species. We cannot agree with him in this, as there is no 

 practical importance, except in the laboratory, in the fact that the guinea- 

 pig is insusceptible ; and, moreover, until more experiments liave been made, 

 we cannot be sure that under certain conditions of dosage or passage through 

 the smaller animals the guinea-])ig will remain refractory. 



The important facts in regard to this species are, that man is not 

 susceptible, ljut that tlie valuable domestic animals are, and that in these 

 animals the disease is, as a rule, a fatal one. 



As long as our knowledge of trypanosomes is limited it seems better to 

 group them under as few names as po8sil)le. As knowledge grows, and 

 as fundamental differences emerge, then it will be tiiiie to define them more 

 strictly. As far as our ])re.S('nt knowledge goes, the morphology of 



