THE NON-PATHOGENIC MAMMALIAN TRYPANOSOMES 403 



Series (a). — The non-pathogenic mammalian trypanosomes. 

 Series (b). — -The pathogenic mammalian trypanosomes. 

 This classification is, in our opinion, in accord with evolutionary 

 knowledge. 



SERIES A: THE NON-PATHOGENIC MAMMALIAN 

 TRYPANOSOMES. 



It is quite beyond the limits of this book to give detailed accounts 

 of these trypanosomes, and all that we can do is to attach a list of 

 the more common with an account of a few. 



Classifiable. 

 Two genera are known — viz.: — 



A. Endoglobular forms known — Endotrypanum, 



B. Endoglobular forms unknown — Lewisonella. 



Unclassifiable. 



C. Little known forms — Trypanosoma sensu lato. 



Genus Lewisonella Chalmers, 1918. 



Definition. — ^Trypocastellanellese, found in mammals, non-patho- 

 genic, without endoglobular forms. 



Type Species. — Lewisonella lewisi Saville Kent, 1880. 



We will describe the type species L. lewisi Saville Kent, 1880, in 

 greater detail. 



Lewisonella lewisi (Saville Kent, 1880). 



Synonyms. — Herpetomonas lewisi Kent, 1 880 ; Trichomonas lewisiCrookshank, 

 1886; Trypanomonas lewisi Labbe, 1891; Trypanosoma sanguinis Kanthack, 

 Durham, and Blandford, 1898; T. rattorum Borner, 1901; Trypanomonas 

 muriumDanil, 1899; Try panozoon lewisi L.uhe, 1906; Trypanosoma lewisi Kent, 

 1880. 



Remarks. — L. lewisi was the first mammalian trypanosome to be discovered, 

 for it was seen by Chussat in 1850 in Epimys rattus (probably not by Gros in 

 1845), who thought it was a young nematode, while Lewis, in Calcutta, in 

 1877, rediscovered it, and recognized that it was a protozoon. It is a typical 

 Lewisonella, and is found in Epimys rattus L., E. norvegicus Pall, and E. 

 rufescens Gray all over the world — in Asia (India, Ceylon, Java, Philippines, 

 Japan), in Europe (England, Ireland, France, Holland, Germany, Russia), 

 in Africa (Uganda, Abyssinia, Gambia, and Cameroons), and in America 

 '(United States and Brazil). It is non-pathogenic and restricted to rats, 

 among which it is spread by Ceratophyllus fasciatus, the rat-flea. 



Morphology. — It is a very active, worm-like little parasite darting about 

 among the corpuscles. It is 24 to 25 jj, in length and i'5 in breadth. The 

 anterior end is very pointed, and the whole parasite is thin. The tropho- 

 nucleus is situated near the junction of the middle and posterior thirds of the 

 body, and the kinetonucleus, which is rod-shaped, is situated anteriorly. 

 There are eight myonemes in the ectoplasm (periplast) . Prowazek distinguishes 

 small male forms with a nucleus rich in chromatin, large female forms with 

 clear cytoplasm, and indifferent forms with many granules and poorly defined 

 nucleus. 



Life-History — In the Vertebrate. — The life-history in the rat has been 

 worked out by Breinl and Hindle (Fig. 89, p. 384). The filament they 



