SUMMARY AND CONCLUSION 45 1 



soria ; and there might, moreover, be a permanent aperture in 

 the firmer outer layer through which sohd food passed into the 

 interior, and so on. 



When the body thus became constructed, in a more or less 

 complex manner, of various kinds of biophors arranged in a 

 definite manner, simple binary fission no longer sufficed for the 

 transmission of the characters of the parent to the offspring. 

 If the parts situated in the anterior, posterior, right, left, 

 dorsal, and ventral regions differed from one another, all the 

 elements — /.6\, all the kinds and groups of biophors — could not, 

 by any method of halving, be transmitted to both the offspring 

 resulting by division so that they could develop by mere growth 

 into an organism resembling the parent. Special means must 

 then have been adopted to render such a completion and con- 

 sequent perfect transmission possible ; and this was attained 

 by the for/nation of a nucleus. 



We may, with de Vries, regard the cell-nucleus as having 

 originally served merely for the storage of reserve biophors, 

 which were destined to become doubled on the division of the 

 organism, each half rendering the completion to an entire 

 individual possible when those kinds of biophors which were 

 wanting were transferred to it. Subsequently — that is, in the 

 multicellular organs possessing highly differentiated cells — the 

 nucleus took on other functions, which regulated the specific 

 activity of the cell, though it still retained biophors capable of 

 supplying the characters of the cells which were still wanting, 

 and therefore still served as the bearer of the biophors con- 

 trolling the character of the cell. 



If, therefore, a special apparatus for transmission became 

 necessary in the hetero-biophorids or unicellular organisms, and 

 appeared in the ' cell ' in the form of a ' nncleiis^'' it must 

 have become still more complex on the introduction of the 

 remarkable process of amphimixis, which, in its simplest and 

 original form, consists in the complete fusion of two organ- 

 isms in such a manner that nucleus unites with nucleus and 

 cell-body with cell-body. In the higher unicellular organisms 

 this process is in most cases restricted to the fusion of the 

 nuclei, half the nucleus of one animal uniting with half that of 

 another. The process of division shows that the nucleus has a 

 structure precisely analogous to that of the nucleus in multi- 

 cellular organisms ; we may therefore assume that the hereditary 



