g6 BIOLOGICAL LECTURES. 



capsule died, while the other Radiolarian which had lost its 

 nucleus and then regained it, by the acquisition of a central 

 capsule of another individual, throve well, and could not be 

 distinguished from the normal ThalassicoIIa in the first vessel, 

 upon which no operation had been performed. 



This is, in my judgment, a genuine case of synthesis of a 

 living nucleated cell, by bringing, from two dissimilar sources, 

 the cytoplasmic and nuclear elements together. If Stahl's and 

 Bonnier's results, on the synthesis of lichens are the conclusive 

 evidence of their symbiotic character, may not the Verworn's 

 experiments on ThalassicoIIa be interpreted as equally conclu- 

 sive evidence of the symbiotic origin of the nucleated cell .'' 

 In fact, the process of fecundation is nothing more than a 

 synthetic production of one nucleated cell from two nucleated 

 cells that are derived from independent sources. And, further, 

 there is good ground, as the phenomena of heredity show, for 

 believing that each germ substance retains the individual 

 qualities characteristic of its origin, throughout all stages of 

 later development of the organism. 



It is true that, in the case of a lichen, the algal and the 

 fungal elements may exist independently, while in case of the 

 nucleated cell, all investigation leads to the conclusion that 

 when the nucleus is separated permanently from the cytoplasm 

 or the cytoplasm separated from the nucleus, they invariably 

 die, sooner or later.^ 



This is, however, no objection to the idea of the symbiotic 

 origin of the nucleated cell, as a moment's reflection will 

 show, for the more perfect the symbiotic adaptation of two 

 organisms, the greater is their inability to live independently, 

 until at last the symbiotic existence between the two organisms 

 becomes imperative, if they are to continue to exist. Remove 



1 For recent contributions and a general summary of our knowledge on the 

 relation between nucleus and cytoplasm, see O. Ilertwig : Die Zdk und dU 

 Gi-iuche, Jena, 1893 ; E. G. Balbiani : A'ouvcUes recherches exphimcntalcs sur la 

 tnerotomie c/cs iitfusoires cities. Annales de micrographie, Nos. 8, 9 and 10, t. IV, 

 1892, Paris; Verworn : Die fhysiologische Bedeutuiig des Zell kerns, Bonn, 1891 ; 

 Korschelt : Beitrdge zur Morphologic itnd Physiologic des Zellkernes, Jena, 1S89 ; 

 Whitman : The Seat of Formative and Regenerative Energy, Journal or Mor- 

 phology Vol. II, 1888, Boston. 



