222 
V. IN ANOPHELINES ! 
A large series of Anophelines (Pyretophorus cost alts) was dissected 
at periods ranging from twelve hours to eleven days after 
feeding on experimental animals heavily infected with Trypanosoma 
gambiense. In the interval between feeding and being dissected, the 
mosquitoes were fed every two days on uninfected animals. Alimentary 
canal, malpighian tubules, ovaries, and salivary glands were carefully 
examined, and forms recognisable as connected with the trypanosomes 
were seen only in the alimentary canal; at first some confusion was 
caused by the presence of the sporozoites of a coccidium-like 
protozoon. 14 After 42 hours no trypanosomes were seen. From 12 
up to 42 hours after feeding the changes similar to those described in 
the gut of other arthropods were observed. Nothing peculiar was 
seen. 
V. DISCUSSION 
When malarial parasites are ingested by a receptive anopheles, 
only those parasites survive which are prepared for development in 
the environment provided by their new host. The remainder die. 
If the blood is heavily infected there is therefore necessarily a large 
number of degenerating parasites present in the insect’s alimentary 
canal. The same may be true of trypanosomes ingested by tsetse flies, 
he mass of degenerating parasites confuses one’s perception and 
ia <es it extremely difficult to pick out the forms capable of further 
development. 
It is by examining in fresh coverslips and, later, stained prepara- 
«ons, the parasites in trypanosome-infected blood taken from the gut of 
cts, that the changes invariably taking place under such conditions 
-■^ki ^ ^ eterm * ne d- ft seems reasonable to deduce that forms 
ana y appearing are those best suited for the new environment, 
f ti ^ thCymay P° ssihl y concerned with the further development 
parasite. Such forms should therefore be most carefully 
communication was in the n^int ( !i!,’ t »! lis J Connection was received while the presen 
survives ingestion bv mosnnit,»« c hancJ s. Its authors show that Trypanosoma bru:‘ 
only 14 hours. The^pS * * ours = * remains viruYent to mice to 
e si the ingested parasites is not reported on. 
