RKPOR-r ON Dot I: 



Mercuric Perchloride and Potassium Iodide and have improved 

 generally and later a complete cure has been anticipated, for the 

 animals showed no symptoms of ill-health and gained considerably Jr. 

 body weight. This favourable condition was maintained for ten 

 months or a year ; but when the same animals were exposed to certain 

 depressing conditions calculated to test to the utmost whether a per. 

 raanent cure had been effected or whether the plasmoidal or resting 

 form of the trypanosoma had only been lying dormant in small 

 numbers, ready to become active and again increase and multiply 

 when favourable circumstances intervened, or the inhibitory in- 

 fluences which held the further development of the trypanosoma in 

 check were removed, It was then found that within a period of 

 eighteen days, not only were immature forms of the trypanosoma to 

 be found in the blood of the general circulation, but there was a 

 further eruption of plaques, and a fatal termination ensued after a 

 few months' interval. Time has only allowed of my proving 

 experimentally that the trypanosomata of Dourine and Surra respec- 

 tively may and can be cultivated 'in vitro' by the methods introduced 

 by Novy and McNeal, but sufficient time has not elapsed to allow of 

 experimental inoculations being made with cultivations far removed 

 from the initial virus. Shortly it may be possible, and probably 

 will be, to bring about mitigated forms of the two diseases, and thus 

 confer protection with large or repeated small doees of attenuated 

 cultures of trypanosornata, including the bio-chemical products of 

 the protozoon, elaborated during its development ' in vitro.' 

 Until, however, this further branch of investigation is entered upon 

 and careful experiments are conducted and worked out, positive 

 results being obtained, the prospects in the near future of curing or 

 controlling the vagaries of the Dourine or that of the Surra Try- 

 panosoma are but small. 



Section XI, -NOTES ON THE LIFE HISTORY OF THE TRYPANOSOMA. 



I. The trypanosoma, the 'materies morli* of Dourine. The 

 trypanosoma of Dourine differs in size, according to the age of the 

 parasite. It is i'or the most part smaller in size than the Surra 

 hsBmatozoon and considerably smaller than the organism of 



