10 
H^MOGREGARINID^ OF MAMMALS. 
Although the first protozoan blood parasites to be observed, vdth 
the exception of trypanosomes, were hsemogregarines, and since that 
time a great number have been discovered in cold-blooded animals 
and more or less completely described, knowledge of such forms in 
warm-blooded animals dates back only three or four years. 
In 1905 James ^ pubbsbed a description of a new parasite found in 
the wliite blood cells of pariah dogs in India, their occurrence barfing 
been previously noted by Bentley.^ James did not regard the para- 
site, winch he named Leucocijtozoon canis, as a bsemogregarine, but 
considered its relationslnp to parasites in the blood of birds, certain 
forms of winch appear to infect the wliite blood corpuscles. 
These so-called leucocytozoa ” were first described by Danielewsky^ 
in the blood of owls. 
Quite recently Scbaudinn,'^ Laveran,^ and Berestnefi^’ have sbovm 
that the forms of tliis parasite (now known as Leucocytozoon ziemanni), 
wliicb resemble parasites in leucocytes, are in reality macrogametes 
to which are attached portions of the nucleus of the red cell originally 
invaded. The name is somewhat misleading. 
James found Leucocytozoon canis present in the blood of 6 out of 45 
dogs examined. The polymorphonuclear cells were the only variety 
affected. The largest percentage of infected corpuscles recorded was 
9 per cent. In one single instance only was a parasite found free in 
a stained blood smear. On one occasion a free form was seen in a 
fresh preparation, having escaped from the leucocyte by reason of 
its continuous vernncular movements. The wormlike body remained 
in contact vdth the host cell, but continued its movements for an 
hour or more. 
The intracorpuscular forms, when stained by Komanowsky’s method, 
are described as oblong bean-shaped bodies enveloped by the proto- ' 
plasm of the leucocyte and apparently surrounded by a delicate cyst. 
In addition to the bean-shaped bodies, James describes parasites, 
almost round in shape, with a very indistinct capsule. The leuco- 
« James; On a parasite found in the white corpiiscJ.es of the blood of dogs. Sci. Mem. 
Officers Med. & San. Dept. Govt. India, 1905, n. s., no. 14. 
^ Bentley; Preliminary note upon a leucocytozoon of the dog. Brit. med. jomm.. 
May 6, 1905, p. 988. 
c Danielewsky, B.; La pai’asitologie comparee du sang. Kharkoff, 1889. Also, 
Developpement des parasites malariques dans les leucocytes des oiseaux. Ann. de 
rinst. Pasteur, 1890, p. 427. 
d Schaudinn, F.; Generations- und Wirtswechsel bei Trypanosoma und Spirochsete. 
Arb. a. d. Kaiserl. Gesundheitsamte, vol. 20, 1904, p. 387-439. 
« Laveran, A.; Contribution a I’etude de Hxmamceha ziemanni. C. B. Soc. Biol , 
vol. 55, 1903, p. 620-623. 
Berestneff, X.; Ueber das Leucocytozoon Danielewsky. Arch. f. Protistenkde, 
vol. 3, 1904, p. 376-386. 
