238 . Phillips on a Comparative Study of the 
Darwin the efforts of biological investigation have been 
largely directed towards the solution of this problem. But 
many of the investigators worked wholly upon gross anat- 
omy, as it might be termed, in distinction to the study of 
the cell. They failed to realize that, as the alchemist was 
being driven from masses to atoms as a basis for his investi- 
gations, they too, if they were to solve the questions which 
interested them most, must get down to the minutest struc- 
tural elements of plants and animals. 
The introduction of the cell theory by Schleiden in 1838 
completely revolutionized the older ideas of transmission, 
and concentrated attention upon the cell and its contents 
as the true vehicles of heredity. Even here again war waged 
between conflicting theories. Darwin’s “gemmules,’ Weis- 
mann’s “germ plasm,” His’s “germinal location,’ Naegeli’s 
“idioplasm” have all had their turn in the arena of conflict, 
and from this discussion has come the conviction that in the 
chromatin and linin of the nucleus is to be found the real 
hereditary material as is well indicated by Wilson (86), 
who says: “In accepting this view we admit that the cyto- 
plasm of the egg is, in a measure, the substratum of inheri- 
tance, but it is only by virtue of its relation to the nucleus, 
which is, so to speak, the ultimate court of appeal. The 
nucleus cannot operate without a cytoplasmic field in which 
its peculiar powers may come into play; but this field is 
created and moulded by itself. Both are necessary to devel- 
opment; the nucleus alone suffices for inheritance of specific 
possibilities of development.” 
But the cells in which nuclei have been undoubtedly 
demonstrated in the past are in the plants above the Cyano- 
phyceze. In the group of Protophyta, lying at the base of 
the vegetable kingdom, a nucleus has not, heretofore, been 
conclusively demonstrated. It would seem, from their varied 
mode of life, that these organisms are probably not only 
the lowest in the scale of life, but that they were probably 
the first to appear upon the earth when it was ready to sup- 
