236 Dr. C. F. J. Lachmann on the Organization of Infusoria. 



bryos, in a drop of water upon an object-glass_, and then observed 

 the escape, the roving, and lastly the quiescence of the bud. 

 Thus I could even quit the microscope for some time, and yet 

 be sure of again finding the same individual, and not con- 

 founding it with others ; in some cases I remained the whole 

 time at the microscope. I first succeeded in the summer of 

 1853j when in Wiii-zburg, in tracing the fate of some buds of 

 Acinetce, which I at first regarded as Stein^s Acineta of the 

 Duckweed, but which I do not now consider to be distinct from 

 Stein's Acineta of the Cyclops, although it attached itself to the 

 Duckweed or swam about freely in the water*. Cienkowskyf 

 also has recently followed the destiny of the embryo of an Aci- 

 neta, which appears probably to be identical with that above 

 mentioned, for, that Cienkowsky (as well as Stein for his Acineta 

 of the Cyclops) figures the embryo much smaller than I have 

 ever seen it, can certainly not constitute a specific distinction, 

 as in other Infusoria also, the buds of one species, nay even of 

 one individual, may be of very different size. Cienkowsky 

 arrived at the same result as myself: after roving about very 

 rapidly for a time, the bud became quiescent, lost its cilia, 

 and developed the radiate suckers which characterized it as an 

 Acineta. The period of the rapid swarming of the embryos of 

 Acineta is very variable : I have observed some which attached 

 themselves to become converted into Acinetce within half an 

 hour, whilst in other cases I had to wait for several hours. 

 Cienkowsky states that he has followed the embryo for more 

 than five hours before it became quiescent. Embryos of the 

 Acineta ferrum-equinum, Ehrbg., I certainly did not follow during 

 the whole period of their swarming under the microscope ; but, 

 by careful isolation, I had ensured the identity of the individual 

 without uninterrupted observation. I then always found, after 

 the lapse of several hours, besides the old Acineta, a young one 

 of the size of the gemmule. I once followed one of these, until, 

 after some hours of roving, it reposed upon a fragment of Lemna ; 

 a few hours afterwards I found in the same spot a young Aci- 

 neta of exactly the size of the bud. Similar observations were 

 afterwards made by E. Claparede and myself upon some other 

 Acineta, and always with the same result, although sometimes 

 the bud died before becoming converted into an Acineta. 



If proof was thus furnished that the embryos of Acineta were 

 again converted into Acineta, the objection might still be raised 

 that this was perhaps to be laid to the unfavourable circum- 

 stances to which the animals were exposed in the little drop of 

 water under the microscope, and that, under more favourable 



* Stein's Acineta of the Duckweed may probably be a peculiar species. 

 t Bull, de I'Acad. de St. Petersb. 1855, p. 2.97. ' 



