Reproduction o/'Eiiglyplia alveolata, Daj. 29 



thinner, by the flux and reflux of plasma from the large 

 plasma-mass. All at once, however, the thread becomes 

 thinner and thinner, until it is suddenly ruptured. At the 

 same moment a distinct reticulated structure (fig, 3) makes 

 its appearance suddenly and sharply in the nucleus («^) , which 

 was previously perfectly limpid, like the nuclei of Euglypha 

 in general, a structure such as we can call forth in the normal 

 nucleus by the addition of acetic acid or any other reagent 

 causing coagulation. From this, as also from the further 

 behaviour of this nucleus, which will be immediatelv described, 

 it follows with great certainty that at the moment when the 

 plasma-thread is ruptured it also dies. This fact is of parti- 

 cular interest on account of the close relation of the nucleus to 

 the plasma which is proved by it. The nucleus therefore is 

 not capable of retaining its normal vital condition even for a 

 moment Avhen isolated from the plasma. 



The nucleus thus thrown off remains enclosed in a thin 

 layer of plasma, as shown in the figures ; this appears to be 

 only the peculiar plasma-zone which may be detected even 

 in normal individuals in the neighbourhood of the nucleus, 

 and which also behaves towards colouring-matters differently 

 from the rest of the plasma. 



After the cell-nucleus of the newly formed individual has 

 been thrown off in this way two cases may occur. In the 

 first case the plasma withdraws itself comjjletely from shell 

 11.^ and the normal animal separates from it. In water wliicli 

 contains numerous * Euglyplice in process of division there are 

 therefore always empty shells which show at the bottom the 

 expelled cell-nucleus as a yellowish strongly refractive cor- 

 puscle. 



The second case, which probably occurs just as frequently, 

 is represented in figs. 5-9. In this, after the plasma has 

 been retracted almost entirely into the old shell, it suddenly 

 begins again to flow over towards II., during which process 

 one (fig. 5) or more thickish or very fine pseudopodia are 

 formed, wdiich move about, as if groping, through the cavity 

 of shell II. As soon as they meet with the expelled cell- 

 nucleus they flow round it, just like any foreign body serving 

 for food. It becomes detached from the bottom of the shell 

 where it was seated, and is carried away with the plasma, 

 now again flowing back towards I. (figs. 6-8). We see that 

 it is finally drawn into shell I. Here it may now remain 



* In our waters the animals were so numerous that every drop taken 

 from the bottom of the vessel aud put upon a slide showed twenty or 

 thirty specimens. 



