108 A H.KMOOREOAKINK OF MAMMALS 



soiiii' of tlii'Sf crescent bodies to lieiiuui' lriiiisfiiriiii(l into large vermicules which, after 

 being kept in the incubator ut ;i7 (!., were found to possess the curious property of 

 rotating the red cells by means of their niirniw extremities, ('hristophers regards this 

 bi'liiiviour as very significant of the proliuldc nutiiod of infection. Up to date I do not 

 know that iir lias added anything furtliir tn I Ik sc ulisi rvations, which, as he points out, are 

 of special interest, "since ulthough the transmission of nniiiy protozoa by biting insects has 

 been demonstrated by experiment, the only instance, of which we have actual knowledge 

 of the stages gone tlirough in tin- carrier, is that relating to the developmental stages of 

 certain parasites in the mosijuito.'' 

 Dcvdopmcniai In the case of the ha'mogregarine ol' jrilidas and tin Ilia it was tduiid that the hirge cyst 



lyssin e.i |^^^ I ,.,||,(,,,.|,||^ .,.^ evidenced by its burst and shrunken wall. Certain parts of the Held were 

 crowdcil with the smaller " daughter " cysts, most of wliii li were nearly spherical in shape 

 and varied in size, nu asuiini; iVinu l(i I /< iit 'irrCt /< in their greatest diameters. Each 

 possessed a well-markcii wall with a ii<juiili- outline, and tlicv containeil slightly curveil 

 sporozoites with rounded ends. These latter mcasureil about Ui (i in length by 4'20 /j in 

 breadth and tlie whole ajjpearance was, as I have indicated, precisely similar to the small cysts 

 described by Christophers. It was evident that a great multiplication had taken place, the 

 first stage of which is no doubt the production of travelling vermicules. I kept these cysts 

 under observation for 24 hours but no marked change took place in them or in any of the 

 freed sporozoites. At the end of that time a stained preparation was made, but the sporo- 

 zoites were found to have degenerated in the citrate solution an<l took the colour badly. 

 They were distimtiy of a sau.sage shape. Tlie cysts also diil not stain well ami it is 

 unfortunate that a fresh jirejiaration could not be obtained lor staining. My ob.servations 

 have not proceeded beyond this point. It is curious that though a large number of tieas 

 were examined these appearances have only been foinid in one case. It is possible the flea in 

 question was not /'. r/nijin/nr but belonged to anotlur species whi( h alone may be capable of 



acting as host. This, and the further develop- 

 ment, are (juestions reijuiring elucidation and 

 wliicli I hope may ere long be settled. 



I have also examined the small ndtes 



wliicii intVst jerboas. They are never very 



nuiiu r(ius (iU the rats, but, as a rule, three 



or four can be obtained from each animal 



ii\' careful scarcli. I fnunil tiny luloiii^iil to 



the genus /Ji'iiiiiiiii/Ksiis, and believe them to 



be identical with />. iihIHiki , which, though 



liriiiiariK a parasite of fowls, is known to 



attai'k niamiiials and even man. In the female 



tlir cliclicera' were seen to be in the form 



of l(jng thin stylets (Fig. 60). I proceeded to 



dissect these mites and their larvaj, no very 



easy task, at lea.st when tluir diverticula are 



gorged with blood. If a nute is dissected imnicdiattly after it has been feeding on 



its infected ho.st the blood whii h has been sucked up presents no differences from that 



in the jerboa. In other words, the trophozoites, either free or still contained in the 



erythrocytes are to be seen. If such blood be citraird and kcjit for twenty-four 



Fii;. 60.— MiTK OF Jkkmia ( X 42 diam.) 



