Mr. H. J. Carter on Eudorina elegans. 9 



passed directly into the form of sixteen groups with sixteen cells 

 in each group : so that the number 32 is persistent in the 

 former, and 16 in the latter, whether of single cells or groups. 

 Hence my " first stage," in the description to which I have 

 alluded, should be the thirty-two-cell form, to agree with the 

 description of the " third stage," which again should be termed 

 the " second stage ;" for we now see that there is no intermediate 

 form : that which I have termed the " second stage," then, should 

 have this term changed for " fecundating formj" as this is a spe- 

 cial development for the purpose, consisting more particularly of 

 an enlargement of the thirty-two-cell Eudorina, with the trans- 

 formation of the contents of the four anterior cells only into 

 spermatozoids. I have never found the sixteen-cell form pro- 

 ducing anything like spermatozoids. 



Again, I have stated that Eudorina perishes in the second 

 stage, as we shall now call it, " if the groups do not form new 

 EudorincB." I have now found that the latter is the case, and 

 that this is the way in which this organism is so rapidly mul- 

 tiplied. 



Eut this second stage, as it now stands, may be the Pandorina- 

 form, as I have before stated, in both the sixteen- and thirty-two- 

 cell varieties, in which the groups, though still consisting of 

 sixteen and thirty-two cells respectively, obtain a tabular arrange- 

 ment ; and here I am sure the Eudorina does end, though the 

 next form into which they pass when liberated, viz. Gonium 

 pectorale, Ehr., may, I think, be again repeated, in the trans- 

 formation of the contents of each cell of the Gonium again into 

 a young Gonium ; at least, I once sasv three cells in this condi- 

 tion united together, which seemed rather to belong to Gonium 

 than to Eudorina : however, for the most part, Gonium seems to 

 break up and perish, which would therefore make this one ter- 

 mination of the existence of the Eudorina. 



By the aid of a higher magnifying power, I have also been 

 able to see that each pair of cilia slightly diverge from each 

 other as they leave the cell, and thus pass through the external 

 envelope, not together, as I had formerly supposed, but by 

 separate apertures, here as well as in the Volvocinea, which 

 separation increases with the size of the organism, so that in the 

 larger forms there appears to be only one cilium to each cell, on 

 account of the latter not coming mto focus at the same time ; 

 and this is probably the explanation of Ehrenberg having given 

 many of these forms only one cilium to their cells. 



In neither of the tanks to which I have alluded, nor anywhere 

 else, have I met with the '^fecundating form" of Eudorina seen 

 at the commencement of June, so that that only appears to be 

 the season for this development : but, as I have before stated. 



