1236 General Notes. [December, 
it from the standpoint of the embryologist, it seems to me, fully 
warrants its discussion in this department. 
With the help of Mr. Potts, who has generously given me per- 
mission to do so, I propose at an early date to prepare a more 
extended paper on this organism, with good illustrations. As it 
is, I must express my great obligations to its discoverer for the 
free use of many of the facts detailed above.—/ohn A. Ryder. 
[As this note on Microhydra goes to press, I have met with a 
paper’, published in the Proceedings Royal Society, London, Vol. 
XXXVIII, No. 235, Dec. 11th, 1884, pp. 9-14. According to this 
account, the supposed hydroid phase of Limnocodium is without 
tentacles; it was found attached to roots of Pontederia in the 
tanks of the Royal Botanic Society, Regent’s park. The figures 
given by Bourne of the suspected hydroid phase of the singular 
fresh-water Medusa known as Limnocodium, are certainly very 
similar to Microhydra, but the former is larger than the latter and 
measures from ;;th to }th of an inch long. Colonies of three or 
four individual zodids were frequently met with. No true perisarc 
or cuticula was observed as in Microhydra, but the surface is cov- 
ered with particles of mud and other débris, which becomes glued 
together by some secretion of the animal, and forms a sort of 
tubular casing. In internal structure this hydroid stage of Lim- 
nocodium differs considerably from Microhydra, however, judg- 
ing from Bourne’s description and figures. Is it possible after all 
that Microhydra is only the hydriform stage of fresh-water 
Medusa? If so, it is very probable that it may be allied to Lim- 
nocodium, the latter of South American origin, has in all proba- 
bility a very different life-history from the North American 
Microhydra, if we may go so far as to assume that the latter has 
a medusiform adult stage. No lateral budding and dehiscence has 
been observed to occur in the supposed hydroid phase of Limno- 
codium, such as takes place in Microhydra, besides the larger 
zooids of the former were over six times as long as those of the 
latter, otherwise there are many striking similarities. _Notwith- 
standing the existence of these resemblances, I think we may 
‘assume that if Microhydra should turn out to be only the hydroid 
Stage of a mature medusa-form the latter will be found to be 
generically distinct from Limnocodium, in which case it might be 
called Pottsia—/f. A. R.] ; 
PHYSIOLOGY.” 
_ _ RECENT BELIEFS CONCERNING CELL-sTRUCTURE?—Probably no 
_ branch of biology has been so richly developed during the last five 
years as that which concerns the intimate physical and chemical 
chen by Alfed Giobe asawa phase of Limnocodium sowerbii Allman and 
is edited | y Professor Henry SEWALL, of Ann Arbor, Michigan. 
waire, par le Chanoine J. B. Carnoy, Lierre, 1884. 
