228 Theories Treating of Inheritance 
formation of a few new nerve paths, at the same time 
reproduce those parts of the organism which remained 
entirely unaffected by this local change? 
Finally, how can the hypothesis of Spencer account 
for the law of repetition of phylogeny by ontogeny? If 
the explanation of the inheritance of acquired characters 
by means of physiological units were accepted, this law 
would be futile. For the new physiologic units with 
changed polarity must take on at once in the daughter 
organism that form to which the parent organism had 
last attained, without needing to pass first through the 
preceding forms. 
The physiologic units were devised in order to permit 
the comparison of the formation of the organism with 
that of a crystal. But a substance which because of a 
slight qualitative alteration of its molecules changes its 
form of crystallization, goes over from the very first 
commencement of crystallization into a form different 
from the preceding, and takes on at once the form which 
it will have after the completion of crystallization, A 
comparison between organisms and crystals is therefore 
inadmissible; and this inability is especially evident when 
it is attempted in this way to explain the laws and 
phenomena of development, in which organisms and 
crystals are totally different and are even antagonistic. 
Haacke 
The conception of Haacke is much like that of 
Spencer. 
“According to my view,”’ says he, ‘we have to do not 
only with the genetic continuity of the germ cells of one 
generation with those of the generation immediately pre- 
ceding and following, but also with a material continuity 
