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V. H. Blackman. 
the egg so as to allow of a satisfactory distribution to all the eight 
portions. 1 
The hypothesis that the nucleus is of the chief importance in 
the transmission of hereditary properties, and possibly holds the 
monopoly in such transmission, is thus seen to be widely based 
on circumstantial evidence drawn from a variety of cytological 
phenomena, and it explains many processes which would otherwise 
be almost meaningless. It also fulfils the other test of a satis¬ 
factory working hypothesis, for it has certainly been productive of 
valuable results; in fact, we owe to its stimulus many of the most 
important investigations on cell-structure. 
We may now turn to some of the criticisms which have been 
levelled at the hypothesis and we may consider first some of the 
more general objections. 3 
Verworn, Rabl, Fick and Conklin hold that there can be no 
such localization in the nucleus as has been hypothesized above, 
and that the cell as a whole must be the carrier of the hereditary 
properties. Conklin has spoken out very strongly against the 
Hertwig-Strasburger view. He says :—“ Since heredity includes 
a series of fundamental vital processes such as assimilation, growth, 
division and differentiation there is something primitive and naive 
in the view that this most general process can be localized in one 
specific part of the cell—something which recalls the long-past 
doctrines that the life was located in the heart or in the blood, or 
the ancient attempt to find the seat of the soul in the pineal gland 
or in the ventricles of the brain.” 
The criticism seems really based on a misunderstanding, as 
Hertwig has pointed out. The hypothesis in question is not 
concerned with the metabolism of the cell or the processes of 
assimilation, growth, etc., but simply with the problem of the 
localization of a special function in a special part of the cell. 
Nucleus and cytoplasm are clearly of equal importance in the 
1 To these arguments may be added the definite association, 
shown by Wilson and others to exist in many insects, between 
the accessory chromosome and femaleness. 
2 Some of the points dealt with in this article are more fully dis¬ 
cussed in O. Hertwig’s “ Der Kampf urn Kernfragen der 
Entwickelungs- und Vererbungslehre,” (pp. 1-122, Jena, 1909), 
and in C. Godlewski’s “ Das Vererbungsproblem im Lichte 
der Entwicklungsmechanik betrachtet,” (pp. 1-301, Leipzig, 
1909). The original references to papers quoted in this article 
have not been supplied when they can be obtained from these 
works. For the lower forms M. Hartmann’s “ Die Konsti- 
tution der Protistenkerne,” (p. 1-54, Jena, 1911), may be 
consulted. 
