SUMMARY AND CONCLUSION 467 



and that, consequently, the individuals subsequently arising by 

 division will be approximately intermediate in structure between 

 the two parents. 



In the multicellular forms exhibiting cell-differentiation, the 

 apparatus for transmission becomes more complicated the more 

 numerous and diversified are the kinds of cells composing the 

 organism. Multiplication can only take place if each individual 

 originates in, and again returns to, the unicellular condition. 

 The division of the entire organism would only result in the 

 production of two unequal halves, which could not of themselves 

 undergo completion, and would require a special apparatus for 

 the purpose. In order that this may arise, the previous prodnc- 

 tioti of aji apparatus for transmission, adapted for reproduction 

 by unicellular germs, is indispensable. 



The production of this apparatus results from the formation 

 of a gerin-plasui, i.e., a nuclear substance which contains 

 reserve biophors for the construction of the corresponding 

 cell-body, as well as for the formation of all the cell-bodies 

 of the entire organism ; and all of which are connected together 

 into a definitely arranged structure, in such a manner that the 

 constituent parts share regularly and successively, and not 

 simultaneously, in the control of the cell-body. In order that 

 this result may be produced, the smaller vital units or biophors 

 are combined to form those of the next higher order — the deter- 

 minants, — each of which controls 07ie kind of cell, and conse- 

 quently includes all the biophors required for the determination 

 of this particular kind of cell. The germ-cell coiitains at least 

 as inany determinants as there are different cells or groups of 

 cells in the fdly-formed organism ivhich are capable of being 

 individually determined from the gerin ojiwards. 



Since the process of amphimixis or ''intermingling of indi- 

 vidual differences ' is also retained in multicellular forms, the 

 individual germ-cells must for this reason alone contain a mass 

 of germ-plasm, each unit of which contains all the kinds of 

 determinants of the species in close combination. The heredi- 

 tary substance of the germ-cell thus came to be composed of 

 ids and idants. 



The multiplicatioti of multicellular orgajiisms by fission and 

 gemmation results from a considerable increase in the com- 

 plexity of the apparatus for transmission, in which process not 

 only the determinants required for the control of their own 



