i908.j BLOOD-PARASITE OF WHITE MICE. 707- 



described by Wenyon [14] were not seen. The average size of 

 endo-globular forms was 8fi long by 5/x broad. 



Among the free forms, some are relatively shorter and broader 

 than the others (PL XXXIX. figs. 1, 6). Some writers [12, 13] 

 would consider these broader forms as female Leucocytozoa, while 

 the longer thinner ones (PI. XXXIX. figs. 5, 8) would be regarded 

 as male. I have no evidence to support this view, but i-egard 

 them as extreme forms of a continuous series. 



YI. Movements. 

 (a) Moveinents of Trophozoites, 



When a parasite has penetrated a leucocyte, it remains at first 

 near the periphery and so directs its movements that it ultimately 

 comes to surround the nucleus to a very great extent. 



Osmotic diffusion between host cell and parasite occurs and 

 produces movement within the cell. When this is very vigorous, 

 the oscillation produced may be so great as to cause semi-rotation 

 of the leucocyte, even to the extent of 180°. 



The movement of the parasite is more noticeable at one end. 

 This appears to advance steadily by an outflow of the cytoplasm. 

 This outflow is easily seen, for the protoplasm is richly granular 

 and stains readily intra vitam with methylene-blue. The para- 

 site lies near to the nucleus of the leucocyte, and its presence 

 causes a movement of the nucleoplasm which appears in a state 

 of agitation. Osmosis seems to be taking place from the leucocyte 

 nucleus to the parasite, and the latter rapidly grows during this 

 period (text-fig. 154, A-E). 



The gliding movement continues, and the nucleus of the 

 leucocyte, which was originally globular, becomes much altered in 

 shape. Its nuclear membrane becomes less and less distinct, and 

 at times it resembles a somewhat lens -shaped mass lying within 

 the horns of a crescent formed by the parasite (text-fig. 154, D, E). 



The organism continues its gliding movements and one end 

 becomes much larger than the other. This is the more obvious 

 and may be termed the anterior end. A comma-like appearance 

 then results (text-fig. 154, G-J). The posterior end, being 

 thinner, might be termed a tail, though this is not an accurate 

 description. It certainly appeal's very filamentous at times, but 

 this is because the organism has turned on its side and so exposed 

 an edge to view. 



On examining the surface of the parasite, numerous granules 

 are evident. These are usually arranged in more or less regular 

 rows. During movement of the organism as a whole, movements 

 of the rows occur, and this suggests that the arrangement of the 

 granules in rows is due to myonemes upon the body. Stained 

 preparations show that such is the case (PI. XXXIX. fig. 7). 

 The slow gliding movement would be due then to contractions 

 of these myonemes, and, further, the bowed appearance of the 

 parasite within the cell could be explained as being the result 



