VI 
THE MINUTE STRUCTURE OF CELLS IN 
RELATION TO HEREDITY 
By EpUARD STRASBURGER, 
Professor of Botany in the University of Bonn. 
SincE 1875 an unexpected insight has been gained into the 
internal structure of cells. Those who are familiar with the results 
of investigations in this branch of Science are convinced that any 
modern theory of heredity must rest on a basis of cytology and 
cannot be at variance with cytological facts. Many histological 
discoveries, both such as have been proved correct and others which 
may be accepted as probably well founded, have acquired a funda- 
mental importance from the point of view of the problems of heredity. 
My aim is to describe the present position of our knowledge of 
Cytology. The account must be confined to essentials and cannot 
deal with far-reaching and controversial questions. In cases where 
difference of opinion exists, I adopt my own view for which I hold 
myself responsible. I hope to succeed in making myself intelligible 
even without the aid of illustrations: in order to convey to the 
uninitiated an adequate idea of the phenomena connected with the 
life of a cell, a greater number of figures would be required than 
could be included within the scope of this article. 
So long as the most eminent investigators! believed that the 
nucleus of a cell was destroyed in the course of each division and 
that the nuclei of the daughter-cells were produced de novo, theories 
of heredity were able to dispense with the nucleus. If they sought, 
as did Charles Darwin, who showed a correct grasp of the problem 
in the enunciation of his Pangenesis hypothesis, for histological con- 
necting links, their hypotheses, or at least the best of them, had 
reference to the cell as a whole. It was known to Darwin that 
the cell multiplied by division and was derived from a similar pre- 
existing cell. Towards 1870 it was first demonstrated that cell-nuclei 
do not arise de novo, but are invariably the result of division of pre- 
2 As for example the illustrious Wilhelm Hofmeister in his Lehre von der Pflanzenzelle 
(1867). 
