On the Regeneration Hypothesis . 
185 
adaptation involves change, heredity preserves in the progeny the 
constitution of the parental organisms as it is at the time of 
mixture. The degree or amount of actual change which has taken 
place in an organism after a long series of generations is a very 
complicated resultant, the individual factors of which, science is at 
present only extremely seldom able to show. 
Without prolonging this article by the attempt to follow in 
detail any of the innumerable generations through which the proto- 
plasm had to pass to be developed into a higher organism, I will 
simply state that the hypothesis of regeneration seems to me to ho 
in accord with all the hitherto ascertained facts of development, to 
explain in an unconstrained and natural manner many of them, 
and to run counter to none. 
1. The most highly developed organisms are the oldest existing, 
those in their constitution nearest to protoplasm the youngest ; 
2, the furrowing or division of a germ into innumerable parts is 
caused by mixture of different plastidules having occurred innume- 
rable times ; 3, the plastidules to be mixed though differing, must 
not differ more than to a certain, relatively very small, degree ; 
greater dissimilarity prevents the mixture ; 4, the germs of various 
organisms existing at the present day, though they may appear 
ever so closely related or alike, are, if they have passed through 
different stages of development, so completely dissimilar in their 
actual constitution or mixture of plastidules, that the one organism 
can never be developed from the germ of the other ; 5, the deriva- 
tion from lower organisms is the cause of the various stages of 
development through which the germ of higher organisms passes, 
and on this depends the fact so prominently stated and illustrated 
by Haeckel that “ the ontogeny of every organism repeats in brief 
time and in great general outlines its phylogeny,” i. e. the individual 
development of every organism, or the series of forms through 
which it passes from germ to completed form, repeats approxi- 
mately the development of its race, or the series of forms through 
which its ancestors have passed ; 6, that the various organisms now 
existing form a series, or so to speak a chain of gradations, more or 
less resembling the series of forms through which higher organisms 
have passed phylogenetically and do pass ontogenetically (embryoni- 
cally), is due to the greater or less resemblance of the influences 
to which organisms originally derived from more or less similar 
protoplasmic matter have been and are subjected. 
Finally, the hypothesis of regeneration does not necessarily 
oppose the hypothesis which Darwin names pangenesis, and advo- 
cates so learnedly, in the essential features of which Darwin has 
been anticipated already by (if my memory serves me correctly) 
Dr. Benedict Hosch in the beginning of this century. 
