454 
Blastocystis hominis 
sometimes it consisted of nothing but a line around the sphere (Figs. 19, 
20). No trace could be found of a cyst-wall, pellicula, or mucous mem¬ 
brane, not even in specimens showing shrinkage. The chromatic 
granules were generally found in the plasmatic fringe (Figs. 14, 17), 
sometimes within the sphere (Fig. 15). There may be one chromatic 
body, surrounded by a clear zone (Fig. 14), sometimes showing a granule 
in its centre (Fig. 16), or there may be two or more of them of equal or 
unequal (Fig. 23) dimensions, some of them showing an internal struc¬ 
ture (Fig. 27). The sphere may be hyaline and without any internal, 
structure (Figs. 14-i8) or small alveolae may be present (Figs. 13, 20, 
24, 27). Sometimes it stains uniformly yellowish-grey with iron- 
haematoxylin, or deep black (Fig. 25), sometimes the centre stains 
black and the periphery yellow-grey (Fig. 27). 
In the stools of this case all blastocysts had their cytoplasm stained 
red after treatment with eosin, which shows that none were found 
living. Consequently all the forms mentioned here must show more 
or less marked necrotic changes. Which forms show the least de¬ 
formity? I believe that the least altered forms are those possessing 
the broadest cytoplasmatic fringe because in Case No. 3, the only one 
in which still living blastocysts were seen, most of them showed a broad 
cytoplasmatic layer. In Case No, 2, most of the blastocysts only showed 
a very narrow cytoplasmatic layer (Figs. 19 and 20), therefore I believe 
that such forms should be considered as the final stages of necrosis, 
although some persons might be tempted to consider them as represent¬ 
ing stages of sporulation. The problem now arises as to the origin of 
the stage’s with broad cytoplasm (Figs. 13-17). 
Sometimes blastocysts were observed vdth a chromatic reticulum 
within the sphere (Fig. 12) nearly (Fig. 11) or wholly (Figs. 9, 10) filling 
the latter. Apparently there is a genetic relationship between these 
forms, but what is the first stage? Here Figs. 5-7 may suggest a 
solution. Fig. 5 represents an amoeba of the 'Limax type, showing 
within its cytoplasm a dark staining part of reticular structure sur¬ 
rounded by a pale staining part of alveolar structure. In Figs. 6 and 7 
this differentiation is more distinctly marked and these forms are not 
to be distinguished from those represented by Fig. 10. In Fig. 9 there 
is a distinct demarcation between the two plasmatic components, also 
shown by differences in colour, the peripheral crescent-shaped cyto¬ 
plasm being coloured grey and the -alveolae between the chromatic 
reticulum of the centre being coloured yellow-grey. A similar differ¬ 
entiation is shown in Fig. 8, but here the central cytoplasm does not 
