376 MR. 8. LE M. MOORE'S STUDIES 
Sexual Reproduction. 
During the month of June I was fortunate enough to find the 
zoospores of Apiocystis in the act of copulation. The zoogametes 
seem precisely similar to the asexual reproductive cells, and the 
gametangium resembles the zoosporangium. The conjugating 
cells get involved in pairs; and after remaining so for a little 
time they touch and then fuse at the eolourless extremity, and 
ultimately form one mass. The zygote remains oblong in contour 
— at least this was the form of the few observed; but what 
becomes of it I am unable to say. As the event proved, it was 
fortunate tbat a few drawings of the copulation were made 
(the principal ones form figs. 31, a, b, c of this memoir), because 
its closer study being for the moment deferred, almost imme- 
diately thereafter heavy rains set in, which, stirring up the 
mud at the bottom of the pond, caused interference with the 
growth of the Apiocystis, and propitious weather was not expe- 
rienced until September, when no sexual reproduction was met 
with. For these reasons all that can at present be said upon 
this head is that Apiocystis reproduces itself in the isogamous, 
not in the oogamous manner. 
Classification. 
Although several points in the life-history of Apiocystis re- 
main to be worked out, it is submitted that enough evidence has 
now been proferred to warrant readjustment of its position in 
the algal system, former relegations (Palmellacee, Kuetzing*, 
Rabenhorst f, Cooket, Nordstedt §; Characiacee, Bennett ||) 
being obviously unsatisfactory. In determining the position of 
Apiocystis it seems impossible to ignore the coenobial phases ; and, 
heretical though it may at first sound, to deny, in face of the 
frequent—if not under normal circumstances constant—presence 
of external cilia, that its affinity is with those motile organisms 
which do not lead an attached existence. I propose, therefore, 
to place our plant among the Volvocinee, where, iu consequence 
of its isogamous reproduction, it will stand close to Pandorinee. 
Objection may perhaps be urged against the use of the term Vol- 
* “Species Algarum,’ p. 208. 
t “Fl. Eur. alg. Aq. dul. et submar.’ sect. iii. p. 43. 
$ ‘ Brit. Freshwater Alge,’ p. 18. 
$ Loc. cit. p. 20. 
I |j) and : ‘ . 
| Loc. cit, and Journ. Linn. Soc. vol, xxiv. p. 55. 
