32 l^i". f"- Blocliniann on tlip. 



port for such a supposition. Accordini^ to them a nu'iiber of 

 the divisional products of each nucleolus would perish, as 

 indeed was previously known, whilst of the two nucleolar 

 derivatives remaining in each of the conjugated animals one 

 would pass over into the other animal and become amalga- 

 mated with that remaining in it. By this, as Maupas points 

 out, the conjugation of the Infusoria is brought into closer 

 relation to the process of fecundation in the Metazoa than was 

 previously possible. 



According to this line of thought we might find a certain 

 relation between the process described in Euglypha and the 

 formation of the direction-corpuscles in the ova of the Meta- 

 zoa. In both cases the final result is the removal of a part 

 of the nuclear substance. In both cases this is effected by 

 an indirect division of the nucleus connected with a cell- 

 division. But whether these suppositions have any real 

 foundation must be left to further extended investigations to 

 show. 



Similar processes to those here described in the case of 

 Eiiglypha have not hitherto, so far as I know, been noticed in 

 any other Rhizopod. I think, however, that careful investi- 

 gation will show a wider diffusion of these processes. Thus 

 I feel certain that the supposed copulation-stage of Difflugia 

 globulosa, Duj., described by Jickeli *^ was a similar case of 

 retrogressive division with expulsion of the nucleus. He 

 states expressly that one of the two shells (i. e. the newly 

 produced one) was clearer, and that in forty-eight hours the 

 whole of the plasma, originally filling both shells, had passed 

 over into the darker {%. e. the original) one, in which careful 

 examination showed two normal nuclei and one in course of 

 disintegration. 



All this agrees with the processes observed by me in 

 Evglypha. We should therefore have to understand that 

 Jickeli discovered a completely finished division of the Diffiii- 

 gia, that this then retrograded, the plasma withdrawing itself 

 from the newly formed shell, leaving behind it the nucleus, 

 and that it then subsequently again took up the dead nucleus. 

 After this had taken place the animal was killed ; but the 

 decaying nucleus would certainly afterwards have been again 

 expelled. 



In another case, in the formation of the resting-cysts of 

 Actinosphcerium Eichhornii, Ehrb. t? it has been directly 



* " Ueber die Copulation von Difflugia globulosa, Duj.,'' in Zool. Anz. 

 Jahrg. vii. pp. 449-451 (1884). Translated in 'Annals/ ser. 5, vol. xiv, 

 p. 297. 



t On the literature see Biitschli, ' Protozoa.' 



