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SOME DETAILS IN THE ANATOMY OF THE RAT-FLEA, 

 CERATOPHYLLUS FASCIATUS BOSC. 



By Prof. E. A. Minchin, M.A., Hon. Ph.D., F.R.S. 



{Bead January 2Qth, 1915.) 



Plates 26-32. 



During the past five years I have been engaged, in collaboration 

 with a friend, upon investigations, recently published,* into the 

 development of the rat-trypanosome in its invertebrate host the 

 rat-flea (Ceratophyllus fasciatus). In the course of this investi- 

 gation we have dissected and examined some 1,700 fleas ; and 

 although these dissections were not undertaken with the 

 primary object of studying the anatomy of the flea, but only 

 with the intention of extracting and examining those organs of 

 the flea likely to contain stages of the trypanosome, it goes 

 without saying that we have not pulled so many fleas to pieces 

 without gaining some insight into the structure of the insect, 

 and it seemed to me worth while to study some anatomical points 

 of structure in more detail and in special preparations. Some 

 parts of the flea are very interesting as regards their structural 

 relations and make very beautiful microscopic preparations which 

 can be mounted with very little trouble. I thought it might 

 interest the members of the Club if I laid before them a brief 

 account of some points of flea-anatomy seen by the way obiter 

 visa, if I may use the expression, 



Before describing these observations, I wish it to be clearly 

 understood that this paper does not pretend to give a complete 

 anatomical description either of the flea as a whole or even of 

 the systems of organs that are dealt with. There are many 

 structural details which could only be made out by sections, and 

 I have had no leisure for the task of section-cutting, always a 

 difficult and laborious undertaking in the case of insects, on 

 account of the toughness of the chitinous cuticle, which cannot 



* Minchin and Thomson, " The Rat-trypanosome, Trypanosoma lewisi, 

 in its Relation to the Rat-flea, Ceratophyllus fasciatus" Quarterly 

 Journal of Microscopical Science, Vol. LX., Part 4, 1915. 



Journ. Q. M. C, Series II. No. 76. 31 



