220 M. M. Mercaur 
Contrary to ToOnnicEs (1898) I do not find the endosare spherules 
much, if any, more numerous near the periphery of the body even 
in O. ranarum. TONNIGES says that these spherules very frequently 
divide. According to his description they become first dumbbell- 
shaped, then still more constricted, the connecting portion becoming 
a mere thread and then breaking, the two halves separating. He 
says that, before division, a spherule becomes smaller and more 
dense, loosing its visible alveolar structure, doubtless by exuding 
the liquid in the alveoles, and that in this condition they stain more 
strongly. In my preparations, the dumbbell-shaped spherules are not 
on the whole smaller than the others, nor do they show less internal 
organisation (Figs. 11 and 10, last two spherules, Pl. XIV). 
KunstLer & Gineste (1905) describe the endosare spherules of 
O. dimidiata as containing a central granule. They say the spherules 
divide by constriction, the central granules first dividing. This I 
cannot confirm. 
I am unable to convince myself that the endosarc spherules 
divide. The dumbbell-shaped forms are not infrequent, but after 
long search I have not found a single spherule in which the con- 
necting portion is very slender as if ready to part. By for the 
most constricted one I have seen is shown in Fig. 11. This point 
is an important one, affecting the question of the nature of these 
bodies, so I have studied it with care. At the time I wrote my 
preliminary paper (Metcaur 1907a) I assumed that the frequent 
dumbbell shape indicated division, but I now think that these 
bodies do not divide any more than do the ectosarc spherules. One 
never finds two of either sort of spherule in one alveole or any 
other indication of division in them. 
The endosare spherules are more numerous in the anterior part 
of the body, where the endosarc itself is denser (Fig. 1). 
In O. obtrigona certain strands of minutely alveolar protoplasm 
stretch out from the endosare and, passing between the large alveoles 
of the ectosarc, join the subcuticular layer (rather poorly shown in 
Fig. 6). Along these strands, and in the subcuticular layer near the 
outer ends of the strands, one finds endosare spherules. In no other 
species have I seen the endosare spherules outside the limits of the 
endosare proper. 
even among the Ciliophora as to the character of their refractive spherules, and 
it is probable that the spherules in Opalina are more or less different from those 
in Euglena. 
