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 fundamental 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 (As for example the
illustrious Wilhelm Hofmeister in his "Lehre von der Pflanzenzelle"
(1867).) 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 connecting 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-existing nuclei. Better methods of investigation
rendered possible a deeper insight into the phenomena accompanying cell
and nuclear divisions and at the same time disclosed the existence of
remarkable structures. The work of O. Butschli, O. Hertwig, W. Flemming
H. Fol and of the author of this article (For further reference to
literature, see my article on "Die Ontogenie der Zelle seit 1875",
i