276 Mr. K G. Plimmer and Prof. J. Eose Bradford. 



son lake, the micronucleus a deep red, and the protoplasm a delicate 

 blue; these reactions are constant throughout all the stages of its 

 life-history. 



The protoplasm of the adult Trypanosoma does not stain uniformly, 

 as does that of some of the other forms, but there are parts faintly 

 stained and parts unstained which is again in favour of the alveolar 

 structure mentioned above. The vacuole is quite distinct as a clear 

 round space, when the organism is stained by this method. 



The macronucleus is generally of an oval or elongated shape, and it 

 may be either unform in colour, or in the form of fine threads ; this 

 latter is seen especially in those forms which show other signs of division. 

 The micronucleus is seen as an intensely stained round dot, or as a short 

 rod, this latter form again being seen in those' forms which show other 

 signs of approaching division. With the highest powers (1*5 apochro- 

 matic objective and 18 compensating eyepiece of Zeiss) we have not been 

 able to make out any special structural characters in this body. The 

 flagellum is not stained by this method, but if the preparation has 

 been well fixed, it is easily visible; the vibratile membrane also is 

 unstained, and can be generally better studied in specimens stained by 

 simple stains, preferably thionin. 



As regards the movements of the organism, in preparations where no 

 pressure is exercised, they can be seen moving either with the flagellum 

 or with the blunt end in front ; but we think that the commoner mode 

 of progression is with the flagellum forward. 



The size and length of the body varies very much with the period of 

 the disease at which the blood is examined, and with the kind of animal. 

 The largest forms we have seen have been in rat's blood, just after death, 

 and the smallest in rabbit's blood, early in the disease. 



B. Distribution of the Trypanosoma. 

 1. In the body of Normal Animals. 



(a) In the Blood. — We have found the flagellate form in the greatest 

 numbers in the blood of the mouse, towards the end of the disease. 

 In the rat also they occur in great numbers, and in both these animals 

 they can be found in the blood on the fourth or fifth day. In the dog 

 large numbers can be seen in the 1 blood from the sixth day. In the 

 cat they are fewer in number in the same lapse of time than in any of 

 the animals before mentioned. 



The rabbit seems to be the most refractory animal of any we have as 

 yet used, and the Trypanosoma are found in the blood in small num- 

 bers only, and at very uncertain intervals. 



(b) In the Lymphatic Glands. — In the superficial glands nearest to the 

 point of inoculation the flagellate organism can be found earliest. In 

 the rat the Trypanosoma can be found in the nearest superficial gland 



