u8 



THE ANIMAL PARASITES OF MAN 



Leish man's methods and results may be summarized thus : 

 Saline emulsions of the organs of infected ticks were made, after 

 the organs had been most carefully dissected out. The ticks were 

 first kept for several days at certain constant temperatures, such as 

 24 to 25 C. or blood heat, 37 C. The saline emulsions of the 

 organs were inoculated, separately, into experimental animals, and the 

 results recorded : 



At 24 C. At 37 C. 



Salivary glands Negative ... Positive 



Mai pighian tubules Positive ... Positive 



Gut and contents Positive ... Positive 



Excrement Positive ... Positive 



Genital organs Positive ... Positive 



Coxal fluid is usually negative ; thick, white excrement from 



Malpighian tubes is posi- 

 tive. 



When the ticks were 

 incubated at 21 to 24 C. 

 no spirochaetes, as such, 

 were seen in the organs, 

 except perhaps in the gut, 

 where they often dis- 

 appeared in a few days. 

 a When the ticks were pre- 



FIG. $$Spiroch(zta duttoni and its coccoid bodies vioiisly incubated at 35 to 

 in the tick (0. moubata}. Mononuclear cells of the tick o p. r__ f f fV, r ^A Have 

 (O. moubata} containing (a) Spirochoete breaking up into 37 C ' tor tw ? S > 

 coccoid bodies; () Similar tick-cell containing coccoid spirochaetes, as Such, re- 

 bodies or granules. Such mononuclear cells occur in Qr . f _ p _ r : n t u p a ,rf organs 

 various organs of ticks and in developing Malpighian appear in the gut, Ol gall 

 tubules. (Original. From preparations by Fantham.) and haemOCCelic fluid. 



The infection proceeds, 



not from the salivary gland, but from the infective excrement, 

 that is, from the thick, white material voided by the tick while 

 feeding, usually towards the end of the meal. This Malpighian 

 excrement passes into the wound caused by the bite, being greatly 

 aided by the clear and more limpid coxa fluid, which bathes the under 

 surface of the tick's body, and mixes with and carries the infective 

 excrement into the wound. Ticks remain infective for a long time. 



The spirochaetes in the gut of infected ticks divide by a process 

 of multiple transverse fission into granules, which are composed of 

 chromatin (fig. 54). These granules sometimes known as coccoid 

 bodies are capable of multiplication. Leishman first found them in 

 clumps inside the cells of the Malpighian tubules (cf. fig. 55). 



To summarize, when spirochaetes are ingested by a tick, some of 

 them pass through the gut-wall into the haemoccelic (body) fluid. 

 They then bore their way into the cells of various organs (fig. 55*7) 



