MEMOIRS. 



Observations on the Early Development of the Common 

 Trout (^alrno fario). By Dr. E. Klein, F.R.S. 

 (With Plate VI.) 



In March, 1872, a paper was read before the Royal Micro- 

 scopical Society, in which I described and illustrated the 

 segmentation and spontaneous movement of the germ of the 

 fertilized trout's ovum, as observed in the living condition. 

 These observations, as far as the segmentation is concerned, 

 were in accordance with the older assertions of Rusconi, 

 Vogtji LerebouUet,^ and Coste, on Teleostean fishes, and 

 were opposed to those of Strieker.^ In that paper (which 

 was printed in the * Monthly Microscopical Journal,' May, 

 1872) I have stated that in the germ of the trout's ovum 

 segmentation, at least in its earlier stages, is of the same 

 regular type as in other Teleostean fishes, and that only in 

 the more advanced stages the blastoderm presents the appear- 

 ance as if the elements of cleavage — i. e. the embryo-cells — 

 originated by being constricted off" from the main body 

 of the blastoderm, in a manner similar to that described by 

 Strieker. 



Independently and almost simultaneously,"^ Oellacher^° de- 

 scribed the movement and segmentation of the fertilized 

 blastoderm of the trout's ovum, in a manner which is in 

 complete accordance with the description given by myself. 



In that paper I have also mentioned the spontaneous 

 movements and the appearances of division presented by the 

 embryo-cells, while in a living condition, between the fourth 

 and tenth days. The same has been afterwards noticed also 



* The Reporter on Embryology, in ' Jahresbericlit iiber die Leistungen 

 und Fortschritte in der Anatomic und Physiologic ' for the year 1872, edited 

 by Virchow and Hirsch, while making an imperfect abstract of an abstract 

 that had appeared in this journal, leads the reader to assume — of course 

 incorrectly — that my observations were made after those of Oellacher. 

 VOL. XVI.— NBW SER. H 



