Biologisches Centralblatt, 



Unter Mitwirkung von 



Dr. K. Goebel and Dr. R. Hertwis 



Professor der Botanik Professor der Zoologie 



in Miinchen 



herausgegeben von 



Dr. J. Rosentlial 



Prof, der Physiologic in Erlangen. 



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XXII. Band. is. Juni 1902. u r . 12. 



In halt: Beard, Heredity and the epicycle of the germ-cells (Fortsetzung). Schultz, 

 Ueber das Verhaltnis der Regeneration zur Embryonalentwicklung und Knospuug. 

 Laiiillicl, Ueber periodische Variationen in Organismen. Marchand, 



Ueber das Hirngewicht des Menschen. Wasinaiiii, P. Petrus Heude f . - 



Zaeharias, Zur Fauna der Uingebung von Buitenzorg. Bei der Redaktion 

 eingegangene Werke. 



Heredity and the epicycle of the germ-cells 

 by J. Beard, D. Sc., 



University Lecturer in Comparative Embryology, Edinburgh. 



(Fortsetzung.) 



From the existence of a transient nervous system, a blastoderm, 

 and other evanescent structures the conclusion was long ago arrived 

 at, that there was a larva or asexual generation in the life- cycle of 

 the skate. From all the known facts of embryology such a larva 

 cannot arise out of an embryo, it must precede an embryo. Tiiere is 

 no embryo by the time the period P. G. C. is reached, the formation 

 of such commencing here. Therefore, the first products of the cleavage, 

 apart from the line leading to U. K. Z., must be the larva. 



Evidence' from another side will be found in, for instance, 

 E. B. Wilson's published researches on the development of Nereis 1 ). 



There was some hesitation in the writer's mind as to the possibi- 

 lity of using Wilson's results in support of the view here presented 

 as to the nature and destiny of the first cleavage-products. A perusal 

 of the lecture, cited below, served to remove this. His work of 1892 

 and his more recent results must be taken together, for Wilson 

 himself has seen reason to alter his earlier interpretation in some 

 slight but important respects. These amendments are exactly of the 

 kind required for my reading of his table of the cell-lineage. 



1) E. B. Wilson, The Cell-Lineage of Nereis, Jour, of Morph., V. 6, 

 p. 361 480, 1892. Cell-Lineage and Ancestral Reminiscence. Wood's Holl 

 Biol. Lectures, p. 21-42, 1898 (published 1899). 

 XXII. 23 



