12 DIPTERA [CH. 



Cyclops. When an infected specimen of the latter is taken into 

 the stomach, the filariae are set free and penetrate into the tissues 

 of the vertebrate host. The transmission of the Leucocytozoon 

 of the rat by Lcelaps is of the same nature, for the rats can only 

 become infected by swallowing Lcelaps containing the parasites. 

 As mentioned above the transmission of Trypanosoma lewisi 

 by the rat-flea is also of this nature, and Strickland has shewn 

 that the surest way of infecting rats with this trypanosome 

 is to feed them with fleas containing the parasite. 



REFERENCES. 



Brumpt, E. (1910). Precis de Parasitologic. Paris : Masson et Cie. 

 Castellani and Chalmers (1912). Manual of Tropical Medicine, 2nd 



edition. London : Bailliere, Tindall and Cox. 

 Hindle, E. (191 1). The Transmission of Spirochceta duttoni. Para- 

 sitology, vol. IV. pp. 133-149. 

 Manson, P. (1908). Tropical Diseases, 5th edition. London : Cassell 



and Co. Ltd. 

 Mesnil, F. (1912). Modes de propagation des Trypanosomiases. Les 



Trypanosomes chez I'hote invert6br^. Bxdl. Inst. Pasteur, vol. x. 



pp. 1-17 and 49-63. 

 Minchin, E. A. (1912). An Introduction to the Study of the Protozoa. 



London : Edward Arnold. 

 Strickland, C. (191 1). Mechanism of Transmission of T. lewisi by the 



Rat-fiea. Brit. Med. Journ. 191 1, p. 1049. 



CHAPTER II 



DIPTERA. — GENERAL DESCRIPTION AND CLASSIFICATION 



Definition. The large Order of Diptera includes all those 

 insects provided with two well-developed wings and, in addi- 

 tion, a hinder pair of rudimentary wings known as halteres, or 

 balancers. The mouth-parts are usually adapted for piercing 

 and sucking, and are more or less modified according to the 

 habits of the insect. The various stages of development, larva, 

 pupa, and adult, or imago, are quite distinct, metamorphosis 

 being complete. In addition, all the members of the Order 



