14 Transactions Texas Academy of Science. 
segmentations of the egg are likewise no genuine cell-divisions ; but divi- 
sions which are all participating as complemental parts in the structural 
differentiation and development of one and the same organic individual. 
The germ-cell itself, far from being essentially an elementary organism, 
such as a genuine cell ought to be, is, on the contrary, embodying in 
potential concentration all the results of phyletic elaboration. Its visible 
divisions signify, not any kind of propagation, but the actuation and un- 
folding of definite potentialities, within which all ensuing structural evo- 
lution is strictly predetermined. In its minutest details the adult organ- 
ism is potentially predetermined in the egg-plasm. 
It is not far-fetched to regard ontogenetic reproduction as a normally 
established case of regeneration. Lillie found that a piece of the highly 
differentiated infusorium, — Stentor, — measuring only the one twenty- 
seventh part of the volume of the entire individual, is still capable of 
fully regenerating its highly differentiated form. Boveri succeeded in 
evolving fully formed plutei from pieces of the egg of echinodermata 
measuring only one-twentieth of its volume. And Morgan observed that 
pieces less than one-fortieth of its volume can still produce gastrulae. 
Consequently, when even small fragments of egg-plasm have power to 
reproduce or regenerate the entire form and structure of the embryo, it 
is obvious that essentially the same reproductive or regenerative process 
enables the egg itself to evolve normally the embryo, and eventually the 
adult organism. 
Eugen Schulz, who has carefully investigated many phenomena of re- 
generation, does not hesitate to conclude, that “regeneration is a primary 
property of living beings, 77 and that “upon the original capacity of re- 
generation depends the evolution of the embryo/ 7 In this light onto- 
genetic evolution consists in the reproduction or regeneration of the 
adult organism from a fragment of its substance. And this » fragment 
represents, therefore, potentially the future or prospective organism as 
a whole. The regeneration of the organism as a whole is what is aimed 
at from the very beginning in ontogenetic evolution. Pflueger’s experi- 
ments with the eggs of frogs, an account of which he published in his 
Archive as early as 1883, involved logically the same conclusion. And 
in consequence of it Otto Hertwig and others had to admit that the 
whole exerts somehow an influence upon the evolution of its parts, 
Driesch concluded from his admirable researches in experimental onto- 
geny, that, — stated in his own words, — “not only as regards form, but 
also functionally is the adult organism structurally reproduced from the 
egg as a unitary whole/ 7 And that the construction of the whole “is 
the clearly recognized goal of the entire process of development. 77 The 
main drift of Morgan’s excellent work on “Regeneration 77 leads to the 
