A HiKMOGREGAKINE OF MAMMALS 105 



usually Pnlc.i: dcupatrcv (Eof/ischilil),* und I have dissected and examined the internal organs 

 of engorged fleas taken from infected animals. At first my observations were limited to the 

 stomach of the flea in which at first I only found the trophozoites which had been sucked up Possible stage 



• ' in Hea 



With the peripheral blood, and which I was able to stain in smear preparations. Some blood 

 containing eudoglobnlar trophozoites was placed in the acid citrate solution devised by 

 Kogerst to simulate the conditions present in an insect's stomach. Though kept in this 

 medium for over 48 hours at room temperature, no change took place in the parasites, 

 save that tlieir cytoplasm became more granular. 



Later, on two occasions, in the Malpighian tubes, I found bodies identical in appearance 

 with the free trophozoites of the parasite. In one tube, only a few were present, the other 

 contained a large number. It was quite easy to distinguish them and they appeared to have 

 undergone no change beyond a liberation from the ervthrocvtes which originally contained 

 them. I do not think they indicated any stage in a developmental cycle, but believe 

 they were merely undergoing a process of elimination. The flea may have been a male. 

 The sex was not noted. 



Probable Cycle of Development in the Flea 



At a later date a more systematic examination of fleas by means of fresh dissections aiul 

 stained parafiin sections was conducted and is still in progress. The results, so far, have Results of flea 

 been most interesting as not only has a true cycle of development apparently been found, but 

 bodies resembling very closely those described by Schaudinn]: in the supposed development of 

 Hi(ltcriduim d(niileirs}.-//i in C'v'/r,'.' /);}j/(7« have been encountered. A very brief mention of 

 what has been noted must suffice. 



A flea ^ was dissected thirty hours after removal from its infected host. After 

 pressure had been made on the cover glass there were found lying free, close to the 

 termination of the rectum, spherical forms, vermicules, rosettes of vermicules and tiny 

 flagellates. It looked as though these had been squeezed out of the alimentary tract of Forms of flea 

 the flea. 



(rt) Spherical (gregarine) forms. These at first suggested altered trophozoites, were 

 small and indefinitely granular. They were not numerous. (Plate XIII., Pig. /*.) 



(h) Vermicules. These were small, contained retractile spots, and in several instances 

 showed at one extremity an accumulation of what looked like pigment in active motion. 

 This was cut off from the body of the vermicule by a slight constriction, and the whole 

 appearance markedly resembled certain of Schaudinn's diagrams. (Plate XIII., Fig. h.) 



Some of the vermicules were united end to end, and some possessed short flagella. 

 Many were in active vibratile motion. Forms somewhat swollen at one end (club-shaped) 

 were also noticed. (Plate XIII., Fig. h.) 



('■) Rosettes. These were very remarkable consisting as they did of clumps of 

 vermicules in a state of very active vibratile motion. They varied much in size and in the 

 number of vermicules which formed them, and resembled nothing so much as crowtled clusters 

 of tiny petals. It is possible that these " vermicules " were really flagellated forms, the 

 flagella being very minute. (Plate XIII., Fig. a.) 



* The Hon. N. Charles Rothschild, F.Z.S., has kindly identified this and other species of fleas which have been 

 seut him from the Laboratories. 



t " Lancet," Juue, 3rd, 1905. 



X Geueratious uud Wirtwechsel bei Trypauosuma uud Spirochaete. Arbeit aus dem Kaiserlicheu Qestmdheit- 

 samte. Band XX., Heft 3, 1904. Trans. Brit. Med. Journ., London, 1905, Feb. 2oth, p. 422. 



