Mutations and Evolution. 
221 
there is multiplication of free nuclei, 1 which arrange themselves in 
a particular manner, but without the formation of cell walls until 
later. That cells can develope within a cell is also well exemplified 
in the development of the embryo-sac of Angiosperms. 
In the same year Whitman (1894), in a notable paper, attacked 
the cell theory on fundamental theoretical grounds. He concluded 
that the formation of the embryo is not controlled by the form of 
the cleavage. “ The plastic forces heed no cell-boundaries, but 
mould the germ-mass regardless of the way it is cut up into cells.” 
His position was that “organization precedes cell-formation and 
regulates it.” 
It is impossible here to enter into a discussion of the various 
views which grew out of the extensive studies on cell-lineage, but 
granting the accuracy of the above limitations of the cell theory, it 
will be seen that they are in no way out of harmony with the view of 
mutations as cell variations, or rather nuclear variations, previously 
expressed. Another limitation of the cell theory will be considered 
in the next chapter. 
1 Incidentally it may be pointed out that any comprehensive theory of 
heredity must be one which is applicable equally to those cases in which 
regular cleavage of the egg takes place and those in which in one stage the 
embryo contains free nuclei. Since the nuclei are the only structures in 
common, and the laws of inheritance remain the same in both cases, ergo the 
nuclei and not the planes of cleavage must determine those laws. 
