360 
THE DEVELOPMENT OF TRYPANOSOMA LEWISI 
OUTSIDE THE VERTEBRATE HOST 1 . 
By N. H. SWELLENGREBEL, Ph.D. 
(.Hygienic Institute, University of Amsterdam), 
and C. STRICKLAND, B.A. 
{Assistant in Protozoology, Quick Laboratory, Cambridge). 
{From the Quick Laboratory, Cambridge.) 
With 21 Diagrams. 
CONTENTS. 
PAGE 
1. Introduction ........... 360 
2. Material and methods ......... 362 
3. The development of T. lewisi in the rat flea ( Ceratophyllus fasciatus) 362 
4. The development of T. leivisi in the rat louse ( Haematopinus spinulosus) 378 
5. The behaviour of T. lewisi in Ornithodoros moubata .... 384 
6. The development of T. lewisi in the gut of Acanthia lectularia . . 386 
Summary.388 
1. Introduction. 
Since the publication of Prowazek’s paper (1905) on the develop¬ 
ment of Trypanosoma•, lewisi in the rat louse {Haematopinus spinulosus) 
our knowledge about this question has not been increased very much. 
When we consider the papers of Prowazek, Baldrey (1909), Rodenwaldt 
(1909) and Breinl and Hindle (1910) we may state the following facts : 
The trypanosomes may develop in the louse under certain circum¬ 
stances not exactly known. They change their form, become first 
1 A short account of these investigations was given at the meeting of the Cambridge 
Philosophical Society of June 6, 1910. 
