457 
was still possible that they might eventually simply disappear 
altogether, the nuclear constituents of the trypanosome body being 
perhaps more resistant than the rest of the protoplasmic structure of 
the celL 
In order to throw some light upon this matter, we examined a 
number of infected animals which had been treated with atoxyl, this 
substance having the effect of destroying the parasites in the blood 
in the course of a very few hours at the most. When the blood of 
such animals was treated by injection of atoxyl and examined during 
the time when the parasites were still increasing in number, it was 
found that a large percentage of the trypanosomes could be observed 
dead among the corpuscles of the blood, but during the rapid 
disintegration which follows nothing comparable to the formation of 
the latent bodies is encountered. On the contrary, the nuclei in these 
instances are among the first of the organs to be affected by a general 
disintegration, which rapidly produces masses of debris, wherein it is 
only just possible to recognise from their shapes the remains of 
trypanosome cells (see fig. 41). 
The same appearance is produced through the disintegration and 
death of the trypanosomes in the blood of an animal which has been 
killed by the disease. 
From all this, it would appear that the latent bodies are not 
produced during the ordinary course of cell disintegration, and must 
be considered from some other point of view. 
At this point it is, however, necessary to explain that when animals 
are injected with atoxyl at a time when the trypanosomes are 
decreasing in numbers in the blood, the disintegration does not 
necessarily overtake all the trypanosomes present. It is found, in 
fact, that a certain number of trypanosomes under such conditions do 
not succumb to the effects of the drug, but round themselves up and 
become encysted (see figs. 37, 40). These cysts are, however, very 
much larger than the latent bodies. They appear to be true resistant 
forms produced directly in response to the drug, and are not in any 
way comparable to the latent bodies we have just described. 
With regard to the latent bodies which are produced at the 
maxima of an oscillating infection (structures which at first sight 
might, and probably would, be taken for disintegration products), 
these are, as we have seen, eventually collected m the spleen and 
