214 M. M. Mercaur 
stretching across the interior of the spherule and connecting certain 
of the deeply stained granules which lie at the periphery of the 
spherule with smaller granules in the interior. I have never seen 
ectosarce spherules showing indication of division. 
The ectosare spherules do not stain at all with potassium iodide, 
so they cannot be composed of glycogen. They do not stain at all 
with a solution of iodine in aqueous potassium iodide. They do 
stain strongly with safranin in sections of animals fixed in absolute 
alcohol and treated, after sectioning, with tannin and potassium 
bichromate. FiscHEer (1905) regards this staining after such treat- 
ment as indicative of glycogen, but the entire absence of any re- 
action to iodine on the part of these spherules seems to indicate 
that they are not glycogen and probably are not of a substance 
closely related to glycogen. 
It is difficult to form an idea of the function of the ectoplasmic 
spherules. The internal structure demonstrated by iron-haematoxylin, 
and less well by certain other stains, seems to argue against their 
being wholly secreted bodies. On the other hand, their position 
within the alveoli rather than upon the alveolar walls, would suggest 
that they are a product rather than a constituent part of the proto- 
plasm. The fact that with certain dyes they readily stain intra 
vitam casts further doubt upon their interpretation as living con- 
stituents of the cell, though these dyes, neutral red, methylen blue, 
and toluidin blue, are well known to stain some kinds of living 
tissue in Metazoa. Litarr & Dusoscg (19046) think that the similar 
bodies in O. saturnalis are probably connected with nutrition and 
may be of a nature similar to lecithin. In the species I have 
studied, however, they are not soluble in warm alcohol and ether, 
so that they cannot be composed of lecithin. I know of nothing to 
indicate that they are excretory. They have no connection with the 
system of excretory vacuoles I have described (Mercaur 19076 and ¢). 
The ectosarc spherules are present in all species I have studied, 
though they are very small in some forms of O. dimidiata. In 
O. caudata they resemble closely those of O. intestinalis. In O. ra- 
narum and O. obtrigona they are smaller, but otherwise similar. In 
O. zelleri they are still smaller, but are clearly recognised. In 
O. dimidiata, in all but the minute forms in the spring and the 
young forms in the tadpole, one almost fails to find them with cer- 
tainty, for, they are little if any larger than the largest of the 
ordinary granules of the ectosarc. On the other hand, yellow ecto- 
sarc spherules of large size are abundant in this species in the 
