N. H. SWELLENGREBEL 
4.)7 
a central position (Fig. 85) and finally assumes a distinct shape with 
well-marked outlines (Fig. 86). 
Case No. 5 (PI. XVII, Figs. 96-106). 
European child having resided in India for several years. Infection 
of Blastocystis and Lirnax amoebae. 
The blastocysts of this case can be referred to forms illustrated 
in Fig. 96 representing small Limax amoebae showing a differentiation 
of their cytoplasm into a dense peripheral zone and a central space 
of loose reticular structure. The vacuoles of this part fuse into one 
central vacuole (Figs. 97, 98), containing several irregular chromatic 
particles which probably arise from the hypertrophying nucleus 
(Figs. 98, 100). Divisional forms occur and also stages (such as are 
represented in Fig. 104) resembling sporulating stages as described by 
Alexeieff, but no other signs of this phenomenon were encountered. 
CONPT.riSIONS. 
1. In two cases Blastocystis was found where the presence of 
Trichomonas or Chilomastix could be excluded with absolute certainty. 
Consequently Blastocystis cannot be a normal developmental form of 
either. 
2. In fresh stools Blastocystis is but seldom found to be alive and 
even when encountered in this state it dies quickly. After death the 
central sphere soon disappears. 
3. The size of blastocysts varies greatly and the larger they grow the 
smaller becomes the peripheral fringe of cytoplasm. Living blastocysts 
are relatively small and rich in cytoplasm. 
4. The blastocysts of the cases mentioned here, although having 
some general characters in common, differed much as to details of 
structure. This difference was especially marked when the associated 
parasites were different. No blastocysts were found without an asso¬ 
ciated parasite. 
5. The occurrence of blastocysts in the stools of a man fed on milk 
and eggs only, and the presence of living blastocysts in the man’s stools, 
exclude the idea of their being remains of solid food. 
6. It is probable from the observation recorded in this paper, that 
‘‘‘Blastocystis''’ is not the name of a zoological genus but of a peculiar 
form of degeneration to which representatives of different genera of 
intestinal protozoa may be liable. The resemblance seen in blastocysts 
