'S THEORY OF THE GERHPLASM 31 



animal and in the vegetable kingdom, have the 

 morphological value of cells. 



In this point I am in opposition to Naegeli, 

 although otherwise I agree with much in his con- 

 ceptions. 



A theory of heredity must be reconciled with the 

 cell theory. In investigating Darwin's pangenesis, 

 Galton's doctrine of the stirp, Naegeli's idioplasm, 

 Weismann's germplasm, the intracellular pange- 

 nesis of De Vries, His' doctrinal of germinal foci 

 for the formation of organs, or Roux's mosaic 

 theory, I believe that one must face the question : 

 How far do these doctrines agree with what we 

 know about the structure and function of the cell ? 

 Moreover, in deciding between the alternatives 

 preformation and epigenesis I believe that it will 

 profit us to start our critical investigation with the 

 cell itself. With this object, I shall now sum up in 

 a few sentences as much of our present knowledge 

 of the life of cells as, I believe, must be reckoned 

 with in any theory of propagation. 



The cell, which consists of protoplasm and a 

 nucleus, is an elementary organism, that, by itself, 

 or in combination with other cells, forms the basis 

 of all animal and vegetable organisation. In minute 

 structure it is so extraordinarily complicated that 

 its essential constitution (its micellar or molecular 

 structure) eludes our observation. It is a medley, 

 composed of numerous, chemically distinct par- 

 ticles that may be divided into two groups, 

 organised and unorganised. The latter are free, 

 or in solution ; they are such as albuminates, fats, 



