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SOME REMARKS ON DR SMMNGLE’S PAPER, “THE 
TRANSMISSION OF TRYPANOSOMA LEWISI BY 
RAT FLEAS,” ETC. 
By N. H. SWELLENGREBEL, Ph.D. 
{Amsterdam), 
AND C. STRICKLAND, M.A. 
{From the Quick Laboratory, Cambridge.) 
In a recent paper (1911), Swingle describes some stages of the life- 
history of (1) Trypanosoma lewisi in Ceratophyllus fasciatus and Pulex 
(sp. ?), and (2) a new species of Herpetomonas {“ H. pattoni”) found in 
these fleas. 
With regard to T. lewisi, he states that in the flea (a) it first 
becomes smaller, taking on the cliaracteristic facies which we have 
called “ the small trypanosome,” (6) it then assumes the crithidia 
form, and (c) at last loses the flagellum and becomes a “cyst.” To 
complete the life-cycle he describes small round cells, which have 
only one chromatin granule; they occur in the head and gut of the 
fleas and are regarded presumably as the infective forms of T. leivisi. 
“Conjugation” between male and female gametes is hinted at, in 
accordance with the present fashion of protozoologists to consider as a 
sexual process every accidental connection of two cells of different size 
in fixed and stained preparations. 
In a concluding Note to the paper, Swingle states that we (1910) 
have described and interpreted some of his H. pattoni forms as part 
of the life-cycle of T. lewisi, but that our view is discredited by our 
having found 4 "/o of our control fleas infected. 
AVe shall first offer some criticisms of his statements regarding the 
life-cycle of T. leiuisi. 
