664 : The American Naturalist. [August, 
late these types with prepotency, replacement, and fusion. 
Where characteristics do not blend, as in eye-color, it is evi- 
dent that, while the offspring must receive from both parents 
the material basis for the formation of the complete color of 
the eye, either the maternal or paternal material must be pre- 
potent and exclude the development of the other; the logical 
inference is that the former actively replaces the latter ; but it 
is not necessary that exclusion from the cell chromatin should 
follow. Now, while some blends seem to support the theory of 
fusion, the sum total of facts of heredity are strongly against 
this as a universal principle, for many maternal and paternal 
structures are preserved in their absolute integrity for genera- 
tions without the least indication of mixture. 
Cell Forces and Heredity.—We have thus far been con- 
sidering only the chromatin as the heredity substance par 
excellence, and have disregarded for the time the archoplasm or 
_ dynamic material of the cell. If we advance upon the hypoth- 
esis that a typical cell contains the more or less passive chro- 
matin, and the archoplasm playing upon this chromatin in 
course of every phase of redistribution, it seems á priori. 
improbable that elements which are associated with every vital 
change should be dissociated in the phenomena of heredity. 
We might suppose that the mechanics of karyokinesis are 
exactly similar in every cell of one individual, but it is highly 
improbable that they should be exactly similar in two indi- 
viduals. We should, therefore anticipate the joint transmiss- _ 
ion of the chromatin and archoplasm, implying by the latter 
the dynamic centers especially connected with hereditary func- 
oi as distinguished from the general functions of metabo- 
ism. 
This leads us to look for evidence from the life of the cell 
in its totality. We owe to Dr. Max Verworn” a fresh treat- 
ment of this subject, based upon experimental researches 
among the Infusoria, mainly by the extirpation method. As 
his experiments included only the phenomena of living cells 
AOD epee Bedeutung des Zellkerns, Archiv fiir Physiologie, 1891, pp- 
: 5. 
