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lung were made. The parasite was found in rather more than half the 

 newts, in some cases 80 per cent of the red blood corpuscles being infected. 

 Double infection of corpuscles sometimes occurred. We are here deal- 

 ing with large red blood corpuscles infected with very small parasites, 

 (figs. 1 and 2). The long diameter of the erythrocytes of the newt averages 

 from 29 to SO /n, while the parasite varies in size from 2 to 6 ^i/, as stated 

 in greater detail below. On this account then it will be seen that the 

 work has not been easy, and the investigation is being continued. How- 

 ever, the observations up to the present seem sufficiently advanced to 

 warrant publication. I have only, with certainty^ seen the trophozoites 

 and schizogony of this haemogregarine , especially the schizont dividing 

 into merozoites, forming "rosette stages". At present the material has 

 yielded fewer examples of vermiform or crescentiform stages, though the 

 observations have extended over more than three months, and on newts 

 procured from four different agencies in the neighbourhood of London. 

 I have examined the parasite with Zeiss' 2 mm and 3 mm lenses, 

 aperture 1,40 mm, and with Zeiss' s compensating oculars 8, 12 and 18, 

 more especially the combinations 2 mm lens and 12 ocular, and 3 mm 

 lens and 18 ocular. The vermiform stages vary in length from b to 6 jli 

 when apparently full-grown, and average 1 to 1,5 ,« in breadth. The 

 young trophozoites are about 2 i^i in length (fig. 3). Several modes of 

 distribution of the chromatic material in the vermiform trophozoites 

 occur, as shewn by the stains used. Sometimes there are several deeply 

 staining dots, often about eight in number; such forms are apparently 

 trophozoites (figs. 4 and 5). In other cases fine closely packed granules 

 are generally distributed throughout the cytoplasm of the parasite; such 

 are perhaps microgametocytes (fig. 6). I have often noticed these in 

 preparations of the spleen. Others again (but at present only a few 

 examples have been seen) have comparatively large chromatic dots, fewer 

 in number than in the cases previously mentioned. These are possibly 

 macrogametocytes (fig. 7). A minute vacuole may perhaps occur in 

 some forms of trophozoite. Some crescent-shaped forms, broader in the 

 centre, are shown in fig. 8. Similiar figures are given by Lab be [5] in 

 the case of his Drepanidium princeps of the frog but I would emphasize 

 the difficulty of clearly defining the exact extent of the cytoplasm of 

 this haemogregarine. In a successfully stained preparation by the Roma- 

 no wski method, the cytoplasm of the parasite appears to be of a pale 

 blue tinge. When a special plasma stain is not used after haematoxylin, 

 the cytoplasm of the parasite is seen to be highly retractile, and even 

 on using eosin, little, if any, of the eosin is taken up by the cytoplasm 

 of the parasite. But it is characteristic of Sporozoa to find their proto- 

 plasm difficult to stain. 



