H^EMOGREGARINA STEPANOWI 783 



in the fold of the wing with a needle after plucking a few feathers. The 

 blood should be collected in a pipette. 



[Manson says : " The pad of the terminal phalanx of the bird's toe is 

 cleaned with spirit, dried and deeply pricked with a needle : a droplet of 

 blood is then expressed and mounted in the usual ways."] 



Films should be prepared and treated in the same way as human malarial 

 blood (p. 771). 



Padda oryzivora [Java sparrow] is a very suitable species for the study of the 

 hsematozoa of birds : it is easily obtained from bird dealers and in three cases out 

 of four in birds recently imported from Indo-China the blood contains H. danilewskyi 

 (Laveran). 



SECTION II. THE GENUS H^JMOGREGARINA. 



The blood parasites of the cold-blood vertebrata (fish, tortoises, crocodiles, 

 pythons and all kinds of snakes, frogs, salamanders, tritons, etc.) belong to 

 the genus H cemogregarina (Laveran, Mesnil) with which must be included 

 the genus Drepanidium of Lankester and the genus Danilewskya of Labbe. 

 These haematozoa are very numerous and some sixty species have been 

 described. 



It is now known that several species of the genus are also parasitic in the 

 mammalia (Gerboises, etc.). S. P. James has described a parasite, Leuco- 

 cytozoon canis, inhabiting the white blood-cells of dogs in India, which should 

 apparently be included in the genus H cemogregarina. 



1. Hremogregarina stepanowi. 



This Hsematozoon was discovered by Danilewsky in the common tortoise 

 (Cistudo europcea) in which it is a very common parasite especially of the 

 adult tortoise and particularly in spring and summer. 



I. Laveran describes two forms of the parasite in the blood of the peripheral 

 circulation : 



(i) Reniform, intra- corpuscular parasites measuring 10-14//, long, with rounded 

 extremities and granular protoplasm with a nucleus near the centre, but containing 

 no pigment. In the fresh condition, the nucleus appears as a clear, rounded or 

 oval space which stains more deeply than the cytoplasm with methylene blue. This 

 form of the parasite predominates in the blood of some tortoises. 



(ii) Worm-like parasites situated within the red cells and nearly always folded 

 upon themselves. This form is derived from that just described in the following 

 manner : When a reniform parasite has attained a length of about 10/z it gives 

 origin to a segment which is folded back upon the original parasite and gradually 

 increasing in length gives to it the worm-like appearance. 



The vermicules thus folded upon themselves measure 15-18/z long ; one segment 

 has a swollen extremity while the other is pointed : the nucleus is generally seen 

 at the bend and is sometimes compact, sometimes elongated, and sometimes divided 

 into two, the two portions being connected by a fine thread of protoplasm (en besace) ; 

 more uncommonly it consists of two distinct parts. It is especially well seen in 

 stained preparations. The vermicules are never pigmented. 



If the blood be fixed immediately it leaves the body only intra- corpuscular vermi- 

 cules will be seen, but if the blood be kept for an hour or so, free motile vermicules 

 will be found. These movements are very active and varied, and during progression 

 it will often be noted that an annular constriction seems to form round the anterior 

 end of the parasite and pass in a peristaltic wave like a series of rings towards the 

 posterior end. 



II. The reproduction forms of the parasite are found in the bone marrow (Danilew- 

 sky) but especially in the liver (Laveran). 



According to Laveran, the forms corresponding to the reproduction phase consist 

 of ovoid parasites measuring 10-18//, long, at first intra-corpuscular and later free : 

 they contain granules of chromatin staining with methylene blue and several nuclei 



