NATURAL PARASITES OF GLOSSINA 403 



partially drawn out and the top jar tapped, when the flies will pass into 

 the lower one. The netting is now replaced and tied round the mouth 

 of the fresh jar, and the old one removed. This little manoeuvre is soon 

 learned, and if care is taken the flies do not escape. The jars must be 

 carefully labelled and always returned to the same place. Kleine kept 

 his jars on a table divided up into compartments, each of which \vas 

 covered with a cloth ; the jars were all laid on their sides. The puparia 

 can be readily recovered from the jars by opening the netting opposite 

 the place where they are lying, tilting the jar, and gently rolling them on 

 to the palm of the hand ; if any of the larvae escape out of the jars 

 they will be found on the cloth on the floor of the compartment. 



The puparia are transferred to larger jars, on the bottom of which there 

 are layers of sand, and are buried just beneath the surface, the mouth 

 of each jar being covered with mosquito netting. Puparia can be carried 

 long distances by packing them in a small box with some sand, taking 

 care not to have too much sand over them, otherwise they are apt 

 to be suffocated. 



From the twentieth day onwards the puparia should be examined daily. 

 The recently hatched flies are removed from the pupal jar by the same 

 method as that employed in changing the flies from one jar to another. 

 If all the above precautions are observed, and the feeding and keeping 

 of the flies carefully supervised, they can be kept alive for months. 



When experimenting with caught tsetse flies the worker should bear 

 in mind that they may be naturally infected with protozoal parasites 

 (gregarines and flagellates). Novy w^as the first to recognize the import- 

 ance of the natural flagellate (Crithidla grayi) of Glossina palpalis. 

 Since he pointed out the possibility of confusing this parasite with the 

 developmental stages of any trypanosome the fly may ingest, several 

 observers have attempted, but without success, to shew that grayi is a 

 vertebrate trypanosome. Minchin for instance believed grayi was a bird 

 trypanosome, while Koch and Kleine were of the opinion that it came 

 from the blood of the crocodile. In discussing this subject one of the 

 writers pointed out that there is no proof that grayi is a vertebrate 

 trypanosome, and that it is in all probability a natural flagellate of 

 Glossina palpalis. Roubaud has recently attacked this problem. After 

 examining a large number of flies, and finding that grayi cannot be 

 inoculated into animals in any of its invertebrate forms, he comes to the 

 conclusion that there can be no doubt that it is a natural flagellate of the 

 fly. It has yet to be shewn how palpalis becomes infected and whether 

 grayi represents one or two distinct species. 



