The Organism and Its Cells 1G7 



wrought before there was any cell-theory, are unscientific. 

 But not quite all writers of guides for the young see the mat- 

 ter this way. B. Hatschek may be mentioned as one excep- 

 tion. In his Lchrbuch he writes: "If therefore we raise the 

 question why one cell body undergoes this, another that 

 transformation, we shall indicate as a chief cause the rela- 

 tion of the cells first of all to their neighbor cells, and then 

 to the totality of the body." For the moment we will be 

 satisfied with this recognition that in the relation of the 

 cells to the totality of the body as well as to one another, 

 resides a cause of differentiation of the cells in the com- 

 pleted organism, and will not be querulous over the state- 

 ment that this relation stands "first of all" as a cause. 



I believe enough has now been brought forward on the 

 pros and cons of the cell-theory of development to establish 

 two things : Those biologists who by reason of their own 

 researches, either through unaided observation or through 

 observation assisted by experiment, are most deserving of 

 being heard on the subject are persuaded, first, that not- 

 withstanding the fact that the developing and developed 

 organism is wholly produced through the multiplication and 

 differentiation of cells, these cells are not an adequate ex- 

 planation of embryogeny ; and, second, that the organism 

 as a totality must enter as an essential element into any 

 adequate explanation of the phenomenon. 



(6) As Tested by Isolated Cells and Tissues 



Before Lillie's contention that the traditional explanation 

 of the developing embryo has "become untenable and must 

 be replaced by the view that there are certain properties 

 of the whole, constituting a principle of unity of organiza- 

 tion, that are part of the original inheritance,^^ can gain 

 much influence on biological thinking, it will have to be 

 examined from many directions. 



