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The Transmission of Trypanosoma leM^isi hy the Rat~fiea 

 (Ceratophyllus fasciatus). [Preliminarif Communication.) 

 By E. A. MiNCHiN, M.A., and J. D. Thomson, M.A., M.B., CM. 



(Communicated by Sir R,iy Lankester, K.C.B., F.R.S. Eeceived January 7, — 



Eead February 3, 1910.) 



Since the spring of 1909 we have been engaged in conducting experiments 

 and observations upon the transmission of Trypanosonia lewisi by rat-fleas, 

 and we hope at some future period to publish a full account of the whole 

 work, including the development of the trypanosome in the flea. The 

 experiments here recorded have been selected for special publication because 

 they are complete in themselves and because they appear to us decisive on a 

 point of fundamental importance, namely the method of transmission by the 

 flea. 



Nuttall (1908) reviews the subject of the transmission of T. lewisi and records 

 experiments of his own on that subject up to December, 1908. Eeference 

 will be made to JsTuttall's experiments later on, and we will first proceed to 

 describe the experiments that form the subject of the present communication 

 under the following headings : — 



I. The object of the experiments. 

 II. Account of the experiments (general and detailed). 

 III. Conclusions to be drawn from the results of the experiments. 



I. The Object of the Experiments is chiefly to make clear the method of 

 transmission ; subdivided it may be stated tiius : — first and incidentally, to 

 confirm conclusions that fleas are capable of transferring T. lewisi from 

 infected to "clean" {i.e. non-infected) healthy rats, but secondly and 

 principally, to determine the mode of infection, whether " direct " or " cyclical," 

 and thirdly, when the cyclical method was indicated by the progress of the 

 experiments, to confirm results and to ascertain further facts connected with 

 the cyclical method. 



In order to avoid confusion and misconception, it may be well to make 

 clear what we mean by the terms " direct " and " cyclical " in this connection. 

 The Editor of the Bulletin issued from the Sleeping Sickness Bureau (1909) 

 writes : — " There are two methods of transmission of trypanosomes generally 

 recognised: {a) that which is mechanical, dependent on physical conditions alone, 

 and {h) that which occurs after a ' cycle of development,' an expression which 

 implies the conjugation of two individuals. The work of Novy and MacXeal 



