Vitality and Organization of Protoplasm. 65 



has first chemically to reorder itself, so as to form- a germ representing 

 an initial stage of ontogenetic evolution. This reduction of artificial 

 fragm.ents to germinal totipotence occurs more readily when they are 

 derived from lower stages of ontogenetic and phylogenetic evolution. In 

 Infusoria, during the process of their self-division, the formation of 

 two exceedingly minute totipotent germs or centers of reproduction, 

 and the gradual reintegration therefrom of complete adult organisms, 

 can be observed from beginning to end. 



The more developed the organism from which the fragment is de- 

 rived, the more it is found to resist reduction into ontogenetic totipo- 

 tence. And the more will it possess only the power of regenerating the 

 part or the tissue of which it is an immediate fragment. Fragments of 

 highly developed tissues, or even of entire organs, when left attached 

 after almost complete loss or extirpation of the respective tissue or 

 organ, may reproduce or regenerate the same. An extreme instance of 

 this circumscribed and localized regenerative power in an animal high 

 in the scale of development is afforded by the remarkable regenerative 

 processes observed in Triton. Gus. Wolff's startling discovery of the 

 regeneration of the lens from the iris, and of the injured iris itself, not 

 from the injured surface, but by a deep-seated formative process, may 

 possibly find their explanation in such localized and partial regenerative 

 potency. In certain worms such localized and partial regeneration is 

 plainly exemplified when, for instance, whole segments with all their 

 tissues are regeneratively intercalated; or, in other cases, when after 

 partial resection some internal organ is regenerated. Yet, though local- 

 ized and partial, these regenerated tissues or organs are incorporated as 

 integrant constituents of the entire organism. The formative process 

 is still under the control of the whole. It may be conjectured as highly 

 probably that this power of localized regeneration is a phenomenon in- 

 dicative of such localized germinative processes occurring normally 

 during the ontogenetic evolution of separate tissues, complicating 

 thereby the epigenetic process, without interfering with the general pre- 

 determined tendency of reproducing the organism as a formative whole. 

 And it may possibly also help to account for the reduced size of repro- 

 duced structures and forms, when only a reduced amount of assimila- 

 tive material is given for chemical reintegration. 



Normal germ-plasm is never derived from highly differentiated tis- 

 sues, never from muscles, nerves or sensory organs. This fact sufficiently 

 refutes, if such refutation were necessary, the fanciful notion of some 

 biologists, that the successively differentiated cell-generations of onto- 

 genetic evolution represent "alternate generations." 



As regards the definitely discernible structural differentiations of the 

 evolving germ-plasm, they start into perceptible existence more or less 

 early and more or less distinctly, probably in proportion as the germ- 

 plasm is representing a higher or lower stage of ontogenetic elaboration 

 or "maturation," and in proportion as the adult organism in the course 

 of reproduction is itself of a higher or lower order in the scale of 



