494 H. B. FANTHAM. 



coveries in the [etiology of protozoal diseases, tlie other two 

 being tlie discovery of the human malarial parasite by Laveran 

 in 1882, and the Trypanosome of ''Nagana" by Bruce in 

 1895. 



Since 1893 other species of Piroplasma have been notified 

 in horses, dogs, and sheep in various parts of the world. 

 Recently Wilson and Chowning (50) have described P. 

 hominis (Manson),the pathogenic agent of Rocky Mountain 

 or Spotted Fever, while the parasite of '^ kala-azar " has been 

 referred by Laveran and Mesnil to this genus. 



Some months ago I had three white rats (Mus rattus, 

 albino variety) affected with ulcerations on the ears and tail, 

 and alopecia. On further examination all of these white rats 

 were found to be suffering from piroplasmosis ; one died 

 almost immediately, another lived but a short time, while the 

 third and last one died towards the end of November, 1905. 

 Unfortunately pressure of work precluded my devoting much 

 time to the examination of these rodents when they first came 

 into my possession, and I was only able to give undivided 

 attention to the last one, having, perforce, to be content 

 with a partial examination of the others. Attempts at inocu- 

 lation of infected blood from diseased into healthy white rats 

 were unsuccessful, and the strain has thus been unfortunately 

 lost. Under these circumstances, and in view of my non- 

 success, up to the present, in procuring other white rats 

 suffering from piroplasmosis, I have thought it might be of 

 interest to publish my results on the morphology of the para- 

 site, hoping later on to continue my researches, if possible, 

 on fresh material. 



Preparations of the blood of infected white rats were ex- 

 hibited by me before the Zoological Society of London on 

 December 12th, 1905 (12). I then proposed for the parasite 

 the specific name of muris,i from its habitat. I would then 



' It might, perhaps, be urged that "muris" at, once suggests "mouse," 

 whereas the parasite occurs in "rats." However, I have followed the well- 

 established custom of naming the species of the parasite after the genitive of 

 the generic name of the host. 



