N. H. SWELLKNGREBEL 
455 
show a reticular structure and the nucleus has assumed the shape of 
a crescent, a deformity often found in degenerating amoebae of this kind 
(cf. Fig. 1). 
Another way in which Blastocystis may arise from Limax amoebae 
is represented in Figs. 1-4. The centre of the cytoplasm shows large 
vacuoles (Fig. 1) which become fused and produce one large vacuole 
(Fig. 2) filled with a grey granular or reticular substance. The nucleus 
breaks up in chromatic granules (Figs. 3, 4). Similar changes were 
observed in case No. 5 (see below). 
Case No. 1 (Pis. XVI, XVIT, Figs. 28-64). 
(For particulars regarding this case see p. 453 .) 
The smaller forms perfectly resembled the blastocysts of the former 
case. A peculiarity of this case was the presence of large blastocysts, 
their size being due to the growth of the sphere accompanied by a re¬ 
duction in the volume of the plasmatic fringe (Figs. 56, 57) and of the 
number of chromatic granules. Within the plasmatic fringe a peculiar 
differentiation was to be observed, consisting of the splitting up of this 
fringe in an outer filamentous often contorted part (Fig. 54) and an 
inner plasmatic part. Fig. 56 shows the beginning of this differentia¬ 
tion. The inner part disappears completely, finally leaving nothing 
but the sphere surrounded by the filamentous part (Fig. 58). 
Divisional stages, mentioned by various authors, were often met 
with in this case (No. 1), showing all stages of division (Figs. 59-64). 
It was noticed that division was more often seen in the blastocysts 
showing the filamentous deformation of the cytoplasm mentioned 
above, which is accompanied by the complete disappearance of the 
cytoplasm. Consequently I think that this division is due to an un¬ 
balanced condition arising from the hypertrophy of the sphere com¬ 
bined with a gradual disappearance of the enclosing cytoplasm, which 
causes the sphere to break up into two or more parts (Figs. 62, 64), 
which are kept together by the surrounding cytoplasm. 
As in Case 2, the blastocysts of Case 1 could be referred to Limax 
amoebae (Fig. 28) showing within their cytoplasm a more or less compact 
agglomeration of chromatic substance (Figs. 29-31). This agglomera¬ 
tion grows (Figs. 32-34) and gradually (beginning at the periphery) is 
converted into a structureless hyaline mass (Figs. 35-38). The nucleus 
is often situated within the latter mass and generally disappears, being 
replaced by chromatic granules at the periphery which can sometimes 
