DR. EBERHARD, ON SEXUAL REPRODTTCTION. 157 



the median furrow. Towards the anterior pointed end, on 

 one side, was situated the contractile vesicle, and behind 

 this tlie rounded nucleus. The hinder end was more 

 obtuse. The surface of the body, as has been said, was 

 furnished all over with the knobbed tentacular processes, 

 which, however, were more closelj- set towards either 

 end. In a short time the entire surface became covered with 

 cilia, from amongst which the tentacles projected. The 

 creature now began to exhibit a slow and clumsy kind of 

 movement, which became more and more brisk in proportion 

 to the progressive development of the cilia. The mouth 

 might be perceived in the anterior part of the longitudinal 

 furrow. This end is termed the anterior, because it was in 

 the direction towards which the movement tended. 



Here, the author remarks, we have an Acinetaform, which 

 at the same time belongs to the group of the Ciliata. The tenta- 

 cular processes gradually disappeared, and the transformation 

 of the animalcule was completed into a ciliated Infusorium, 

 with whose aspect the author had often been familiar, and 

 which he had hitherto regarded as an independent species. 



The case above described, so far as he is aware, is the first 

 recorded instance, in the young of Infusoria, of a transition 

 from the Acineta- into the ciliate-form. 



The observation, moreover, confirms Stein's notion that 

 the minute Acineta proceeding from Paramoecium are in 

 reality its offspring, and not parasites, as asserted by Bal- 

 biani. It is no longer doubtful that these forms also even- 

 tually assume the ciliate-aspect, which approximates them to 

 that of the parent. 



The author has satisfied himself that the embryos of Bur- 

 saria truncatella above described originate from the nucleus 

 of the parent body. Those individuals which Avere entirely 

 crammed with embryonal globules had either no nucleus 

 whatever remaining, or merely portions of it, in a decided 

 state of disintegration. 



In conclusion, it should be remarked that the diameter of 

 the globular bodies was about twice the usual diameter of the 

 strap-shaped nucleus, and that the length of the ciliated form 

 into which they passed was about two thirds of that 

 diameter. 



It would seem, therefore, that the points with respect to 

 which the author is at issue with Stein are — 



1. That whilst the latter observer insists upon the pre- 

 sence of a nucleus in all the individuals filled with embryos, 

 the author denies its existence. 



2. Stein positively denies the occurrence of the Acineta- 



