10 
THE ORGANIC CELL 
the mind are hidden in the ganglion-cell. ... If then 
Physiology is not to rest content with the mere extension of 
our knowledge regarding the gross activities of the human 
body, if it would seek a real explanation of the fundamental 
phenomena of life, it can only attain its end through the study 
of cell-physiology.’ 1 
It seems strange that the above conceptions of the cell, 
originated by Schwann and elaborated by Kolliker, Virchow, 
and Hackel, did not for many years affect the speculative 
aspect of biology. In that great work ‘ The Origin of Species,’ 
published in 1859, Darwin does not mention it except in regard 
to his provisional theory of pangenesis, about which I shall 
have more to say later. 
The factor which brought the cell theory into line with 
the evolution theory was the series of researches (made twenty 
years later) on the early history of the germ cells, and the 
result of the union of the germ and sperm cells. Through the 
agency of these researches it became for the first time apparent 
that phenomena associated with embryology, heredity, and 
evolution are closely connected with cell structure ; and that 
a full understanding of them can only be attained by the closest 
and most careful cytological research. Shortly after this it 
was clearly demonstrated that the nucleus of the cell contained 
the substance of inheritance, and at very nearly the same 
time the classical researches of van Beneden on the early 
changes taking place in the animal egg opened up a wide 
field for original work on the various details of cell phenomena. 
To form an estimate of the full value of the discoveries 
made during this brilliant period it will be useful to very 
briefly examine the earlier opinions on embryology and 
inheritance. The modern thinker looks upon the germ as 
4 simply a detached portion of the substance of a pre-existing 
living body ’ carrying with it a definite structural organisation 
characteristic of the species. By the earlier embryologists, 
however, the matter was very differently regarded ; for their 
views in regard to inheritance were vitiated by their acceptance 
of the Greek doctrine of the spontaneous generation of life. 
The great Harvey himself did not escape from this error. His 
1 Verworn, Allgemeine Physiologie (1895), p. 53. 
