690 .lOIIN MKAliD, 



(litl'cront ])ren)isses, in important respects resemble the earlier ones of 

 Wkismann. His iiisiglit into tliescî prol)l(;ins, (>s[)(îcialiy when one con- 

 siders that the essays dejiJing with these questions were written so 

 long ago, is something marvellous. 



One may express the hope, then, that in the above statement 

 Wkism Ann's. i)riority in certain points would be fully acknowleged : in 

 other matters I have no wish to attemi)t to commit this great zoo- 

 logist to individual views of my own. 



My approach of these (piestions is i)urely from the morphological 

 standi)oint. From this aspect the formati<m of an embryo is a 

 mere in(-ident - tin; lot drawn by one unfortunate germ-cell — 

 the morj)iiological continuity of the germ-cells , on the contrary, 

 and with it the recognition of their nature as unicellular organisms, 

 is everything. 



In Nature, then, the multicellular individuals or Metazoa are the 

 drones of tiu^ hive — only retained until their ])uri)ose is carried out. 

 Their task is to harbour and nourish the unicellular org;unsms, known 

 as germ-cells, during a certain portion of the life-cycle. This ac- 

 comidished, their part is played. 



Wkismann writes "es besteht eine vollkonmiene Continuität des 

 Lebens" — Nature deniands a continuous and constant successi(m of 

 life, and this she can only obtain by the aid of unicellular organisms. 



The Metazoan individuals are but her tools! 



XVII. TIiC! so-called (jleriniiial Kpithcliiiin. 



Kor nearly thirty years embryologists have l)eli(wed and taught 

 the origin of germ-C(^lls or "piimitive ova" tVom epillielial cells of the 

 embryo, more particularly from the germinal fold of the peritoneum. 

 This doctrine is based on the classic investigations of Waldkyek ('71). 



There is no germinal epithelium! 



The germ-cells of Vertebrates do not arise from any part of the 

 embryo. They are not products of any organ, of any epithelium of 

 the embryo. The embryo oidy forms those structures, which make up 

 its own body, which are parts of its soma. The germ-cells are in no 

 sense |)arts of the soma,'). They are distinct entities, not really 

 necessary for the individual existence of the, embryo. In the skate 



1) Originally "as Wioismann has iiiHisted" was horo written, but a 

 renewed reference to his works showed, that in many cases at least he 

 had maintained an origin ol" genn-cells from somatic cells. 



