253 



gatioü, an apparent stumbling-block is met with in the fact of the- 

 occurrence of three divisions of the micronucleus instead of two. 



There might have been some hesitation in explaining away the 

 first of these, were it not that Maupas, who is justified more than 

 any one else in expressing an opinion on the matter, had already 

 given a verdict') favourable to all my desires. He regards the first 

 division of the three (which also happens in both the conjugating in- 

 dividuals of Euplotes patella) as a formation of two micronuclei. 

 The reasons assigned may be found in his memoir as cited below'). 

 Leaving the first division out of account, as Maupas has also done, 

 we have then in the micro-zooid two divisions B and C, which may 

 be interpreted as spore-formation and reduction. Of the eight spores 

 (c) only one is functional. It, like the corresponding sporozooid of 

 the macro-zooid, divides once (D) and the abortion of one of its pro- 

 ducts, or gametes (c?^), has already been commented upon, and the 

 obvious reason given. 



At the time of writing the present paper it is quite out of question 

 to construct diagrams from Maupas' accounts of the conjugation of 

 other forms, which he has studied, but of which he has furnished no 

 schemes. And the risk must be taken of postponing another study 

 of the whole of his immense monograph, until more leisure is available. 

 It might well happen that some details of the explanation of his results 

 here suggested may have already been put forth by Maupas himself. 

 If so, there is neither wish nor intention of detracting from his merits. 

 What has really been my concern was the demonstration of an anti- 

 thetic alternation of generations and of a spore-formation with reduc- 

 tion in the Infusoria. All else has only been offered in order to con- 

 vince the reader of the inherent probability of the truth of the 

 attempted solution. This is certainly new, and Maupas could not 

 have entertained the slightest idea of it. This is certain from the 

 general discussion in his memoir. 



Before the close of my remarks on the conjugation of the In- 

 fusoria, I should like to quote a passage from R. Hertwig and express 

 entire agreement with it. As against Maupas on p. 214 of his work 

 on Paramecium Hertwig writes: "Bei den meisten Infusorien 

 copuliren weder sexuell differenzirte Kerne, noch auch Kerne sexuell 

 differenzirter Tiere, sondern gleichwertige Kerne, welche in gleich- 

 wertigen, aber getrennt und unabhängig von einander entwickelten 

 Tieren entstanden sind. Damit fehlt aber die Basis für die Begriffe 



1) p. 364 and p. 341. 



