310 General Notes. [ March, 
posed to the light, only lost one specimen, and that on the rooth 
ay. 
Dr, Graff concludes that the Algz or pseudochlorophyll bodies 
of Hydra have no significance as means of nutrition; the fact 
that all the specimens in filtered water died by the 87th day 
seems to show that the Hydra died from the want of animal food, 
and that the green bodies do not serve as such, as Brandt supposes. 
The most unexpected and perhaps the most remarkable fact 
is that whether the Hydra were exposed to the light or placed in 
the dark, they in all cases retained their green color through life. 
Dr, Graff has lately been able to make some observations on 
the Mesostoma viridatum, three out of five examples of which 
were richly provided with chlorophyll-corpuscles; these varied 
very considerably in size, and no nucleus was to be detected in 
the smaller specimens; starch granules of proportionate size to 
that of the chlorophyll-bodies were found in them. The larger 
green bodies were arranged in closed groups, and the smaller 
examples lay between the groups; most of the bodies were 
rounded, but a few of the larger were oval.— Fourn. Royal Micro- 
scopizal Society, Dec., 1884. 
A FREE-SwimMinG Sporocyst.—The egg in the digenetic Tre- 
matode worms, as is well known, does not at once give rise to 
the adult Distome, but to a brood-sac which produces directly or 
. indirectly in its interior a greater or less number of larval Dis- 
tomes. The brood-sacs live parasitically within mollusks, and 
tailed larvæ or Cercariz, but the tail may be very short as in 
micrura Filippi, or entirely absent as in C. globipora Ercolani, 
again the cylindrical sporocysts produce Cercariz with furcate 
tails like C. furcata, and the remarkable Bucephalus-larve are 
_ produced in branched tubular sporocysts. 
_The object of the present note is to indicate the existence of a 
hitherto unknown form of sporocyst, one specimen of which I 
_ observed recently swimming very actively in an aquarium con- 
~ taining a few water plants’ and fresh-water mollusks. In form and 
_ Size it recalls the larger Cercarie with forked tails, and contains - 
_ a single tailless Cercaria or istome. In accordance with 
its free life, the muscular system is much better developed than 
