C. Strickland and N. H. Swellengrebel 451 
of the parasite in tlieir bodies after being ingested, but we have not 
yet been able to obtain infection with arthropods in which subsequent 
dissection has shewn the persistence of T. leivisi. 
IV. Description of a peculiar form of T. lfavisi. 
We would like to make bi'ief mention here of a curious form of try¬ 
panosome found in the rat’s blood by one of ns. It is characterised by 
an enormous elongation of the posterior end of the body, the total length 
of the protozoon being 45 ya. The flagellum is short, and stains deeply 
red with Giemsa’s stain, and though it does not end in the blepharoplast 
which is very large and spherical, yet no basal granule is evident at its 
proximal end. The nucleus is situated in the anterior part of the cell 
and shews the achromatic substance perfectly with disseminated chro¬ 
matic granules in it. The protoplasm possesses a distinctive band of 
dense cytoplasm in its middle third, and also a riband of dense protoplasm 
at the anterior end along the flagellar side. Posterior to the nucleus 
is a very distinct band of very loose spongioplasm. Disseminated all 
through the protoplasm are a number of prominent chromidia. 
Wendelstadt and Fellmer have recently found such forms in rats 
inoculated with T. leioisi which have been passed through reptiles and 
other cold-blooded animals. Its presence in a spontaneously infected rat 
is therefore suggestive. Thomson (cited by Woodcock) has also previously 
seen these forms, and other organisms with a considerable prolongation, 
bnt not so filiform, have been encountered by one of us (N. H. S.). 
Summary and Conclusions. 
1. Trypanosoma lewisi was found in 25 “/o of caught in and 
about Cambridge. Of these rats 12®/o were young, 33 "/o adult, and 
29 Vo old. In this region the endemicity was localised to certain 
areas. 
