REPORT ON DOUETNB. 



trypanosoma and any developmental forms present probably 

 return, as such, to the blood of the general circulation. 



VIII, Reappearance of a plaque after an interval of a few days 

 on the original site. A certain percentage of plaques disappear 

 completely, and after an interval of one to"several days reappear at 

 the original site. This is to be accounted for by the fact that 

 after the majority of the developmental forms have been carried 

 away into the general circulation at the time of the absorption of 

 fluid from the first plaque some few failed to escape and were 

 retained in situ. As long as the toxin is present in the plaque, 

 the developmental forms of the try panosomata are unable to reach 

 maturity, but as soon as a certain percentage or may be all the 

 toxin has been eliminated, the inhibitory influence exercised over 

 the growth of the amoeboid and plasmodial forms is removed and 

 their development into mature protozoa proceeds unchecked. As 

 they in turn mature, the toxin re-accumulates and the previous 

 changes again occur. 



IX. What changes take place to the trypanosoma in the vaginal 

 mucus ? As previously recorded, the protozoon is generally intro- 

 duced in the genital passage of the mare during covering. It 

 may accommodate itself to its new surroundings, and be found in 

 the mucus located in the lower portion of the vagina as early as 

 the 17th or 18th day after intercourse. Whether the trypano- 

 soma is present in the anterior portion of the vagina, or in the 

 uterus, at an earlier date and gradually moves towards the external 

 orifice, has not been definitely decided, but it would appear probable. 

 If successive examinations are made during the course of the 

 disease, the parasite either in relatively large or small numbers 

 may be found in the vaginal mucus for periods varying in length.* 

 Sometimes the maximum number are present shortly after the 

 commencement of the paroxysm and then gradually diminish and 

 they may appear later during that period. The result appears to 

 be the same, vie., periods occur during which the mature parasite 

 is absent from the vaginal mucus. Thus, as in the blood, so in 

 vaginal mucus, paroxysms and intermissions are marked. The 



* Since the above was written, in one case the trypanosoma in small numbers has been 

 noted in the vaginal mucus during a period of 45 days without an; iutormission. 



