Reproduction o/Euglypha alveolata, Duj. 31 



the dark zone formed by aggregation of granules, which is 

 wanting in freshly divided animals. In the latter the granules 

 are uniformly distributed throughout the plasma, and for this 

 reason and on account of the inception of water requisite 

 during division, the plasma of divided individuals appears 

 much lighter, so that with a little practice one may distin- 

 guish a divisional pair from a conjugation-pair even with the 

 lens. 



The consideration of all these differences would not, how- 

 ever, completely exclude mistakes. To attain this object I 

 isolated animals in which the plasma was just beginning to 

 protrude from the aperture as small buds covered with shell- 

 plates, and which therefore were certainly at the beginning of 

 division. As the division advanced, the division of the 

 nucleus might also be observed with facility in living animals. 

 By this mode of investigation all mistakes are excluded. In 

 this way I isolated and observed a great number of EuglyphcBj 

 and it appeared that after the conclusion of the division either 

 the two individuals separated and continued to live indepen- 

 dently, as was already observed by Gruber {loc. cii.), or that 

 the process above described took place, so that only one indi- 

 vidual resulted, wliich, indeed, contained nearly the whole of 

 the plasma of the parent animal, but only half its nuclear 

 substance. 



I have investigated the most different stages of both pro- 

 cesses of division and of nucleus-expulsion in preparations 

 killed with chrom-osmium-acetic acid and stained in different 

 ways, without, however, observing in them anything essen- 

 tial more than in fresh objects or objects treated with 1 per 

 cent, acetic acid. 



If we ask ourselves what significance this remarkable pro- 

 cess has for the animal, it is at present very difficult to find 

 any answer that may be satisfactory even to a limited extent. 

 In the individuals thus produced I have observed nothing 

 remarkable ; they lived for a time in the preparations like 

 others, then perished or became encysted. 



At the first glance one might imagine a comparison of this 

 process of nucleus-expulsion with the removal of the products 

 of division of the nucleoles in the conjugation of the Infusoria. 

 In connexion with this Prof. Biitschli has suggested that 

 possibly such animals as had lost in this way the half of their 

 original nuclear substance afterwards proceeded to copulation. 

 Hitherto, however, we have no positive observations in favour 

 of this view. But in the most recent observations of Maupas* 

 upon the conjugation of the Infusoria we may find some sup- 

 * ' Oomptes Reudus,' Juue 28 and September 6, 1886. 



