704 MISS ANNIE PORTER ON A [June 16, 



state. The specific name " muris " has been applied by Balfour 

 [2, 2 a] * to the parasite he described from Mus decumanus at 

 Khartoum. A similar parasite has been described by Adie [1] 

 from Mus rattusva. the Punjaub, under the name of L. ratti, while 

 a third has been described by Cleland [7] from Perth, Western 

 Australia. 



I think it is very probable that this Leucocytozoon is different 

 from that in rats. In this connection it is worthy of note that 

 the Trypanosomes of rats and mice belong to diflferent species. 



The name that I propose for this parasite from the leucocytes 

 of white mice is, then, Leucocytozoon muscidi. 



II. Materials. 



The first infected animal received was a white mouse which 

 came from a stock kept at St. Mary's Hospital Medical School. 

 This white mouse, when in an almost comatose condition, was 

 brought to the notice of Dr. Fanthani. Some symptoms were 

 feebleness of movement (constantly moving slowly, more or less 

 in a circle, with a tremor or waltz, though the animal did not 

 appear to be related to Japanese waltzing mice), partial closure of 

 the eyes with discharge therefrom, and incontinency of urine. 



A few parasites were found in the peripheral blood of this 

 mouse, but the rodent soon died. As soon after death as possible, 

 smears were made of the heart, spleen, kidney, liver and gut- 

 contents. There was an extravasation of blood into the gut of 

 the mouse and in this parasites were found. However, in the 

 gut many Bacteria occurred, and it is not suggested that the 

 Leucocytozoon was the sole cause of the death of the mouse. 



A second white mouse, from the same stock as the first one, 

 was procured and kept under observation for nearly three weeks. 

 A few parasites only occurred in its peripheral blood. Accidental 

 death overtook this mouse and immediately smears were made of 

 its internal organs. In these parasites were seen but in much 

 fewer numbers than in the first specimen. A third mouse from 

 the same stock was found to be infected to a greater extent than 

 the preceding one. 



The first two mice were scarcely, if at all, verminous, but on 

 the third one, many lice, HcemcdopimtjS spinulosus, were seen. 

 These were dissected and examined for stages in the life-history 

 of the parasite, as stated in the sequel. 



The material was examined as far as possible in both the living 

 and fixed condition, as the examination of living material is most 

 important and tends to be overlooked. 



The above-mentioned material was kindly given to me by 

 -Dr. Fantham. 



Ill, Occurrence of Parasite, 



The blood of the mouse contained parasites of two forms : — 

 (1) large, vermiform organisms, free-living in the plasma ; and 



* The numbers in square brackets refer to the list of Literature at the end of 

 ■this paper, ' ' ^ 



