VI 



THE MINUTE STRUCTURE OF CELLS IN 

 RELATION TO HEREDITY 



BY EDUARD 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 1 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- 



1 As for example the illustrious Wilhelm Hofmeister in his Lehre von der Pflanzenzelle 

 (1867). 



