EFFECTS OF REORGANIZATION ON VITALITY 553 



present for activity in a renewed cytoplasmic body, the aggregate 

 resulting in a new organization and new vitality. 



"Conjugation is a physiological necessity for maintenance of the 

 race" (Hartmann, 1921; p. 114). This indeed is one of the oldest 

 views as to the effect of conjugation of the ciliates. It is unfortunate 

 perhaps that the phenomena involved became labeled with fanciful 

 terms signifying renewal of youth (Verjungung of Biitschli, 187(), 

 Rejuvenescence of Maupas, 1SS9), terms which many hard-headed 

 biologists find it difficult to accept. It might or might not have 

 made some difference if the phenomena had been interpreted as 

 a series of reactions w'hereby protoplasmic impedimenta are removed 

 leaving a renovated organism and a possibility of imhampered 

 vitality. It is in this sense that the term rejuvenescence is used 

 in these pages. 



Another interpretation of the phenomena, however, was early 

 given in connection with theoretical biologx'. The union of two 

 individuals in conjugation or in fertilization generally, involves 

 the fusion of two organizations represented either hy nuclei alone 

 as in conjugation, or by nuclei and cell bodies as in merogamy. 

 The term amphimixis (Weismann) was applied to this phenomenon 

 and its significance w-as interpreted as a means of inaugurating 

 variations which would turn out to be iiseful or not in the grilling 

 process of natural selection. 



Of the two interpretations the former appears to be the more 

 comprehensive and fundamental since it deals with vitality and 

 applies not only to phenomena of fertilization but to effects of 

 parthenogenesis as well, and may be still further extended to 

 include the effects of periodic reproduction by cell division. The 

 general truth of the latter interpretation is undeniable and has 

 been repeatedly confirmed in experimental zoology, but we avoid 

 the stigma of teleology by assuming that amphimixis arose in con- 

 nection with the satisfying of some fundamental protoplasmic need. 

 In other words and on this supposition, gametes were developed 

 not as a means of ensuring amphimixis but as a result of vital 

 activities and changes in organization which rendered them unable 

 to continue metabolic activities without fusion. 



It would seem that the fundamental truth of this generalization 

 requires no argument insofar as it concerns merogamy. The fer- 

 tilized egg cell is a new organism with a new potential of vitality 

 having the possibility of development with differentiations leading 

 to the adult organism. It is the beginning of a new life cycle for 

 which the stimulus to development is furnished by the sperm cell. 

 The facts of parthenogenesis how^ever, show that this potential 

 is in the substance of the egg itself and that it, without participation 

 of the sperm cell, may likewise be the beginning of a life cycle. 

 The egg cell furthermore does not have the same organization as 



