1 4 IN TR OD UC TION 



evolution-theory into organic connection. It is from the point of view 

 thus suggested that the present volume has been written. It has 

 accordingly not been my primary object to dwell on the minutia of 

 histology, still less to undertake an exhaustive description of all the 

 modifications of cell-structure and cell-action ; and for these the stu- 

 dent must refer to other and more extended treatises. Yet the broader 

 questions with which we have to deal cannot profitably be discussed 

 apart from the concrete phenomena by which they are suggested, and 

 hence a considerable part of the text is necessarily given over to 

 descriptive detail; but I hope that the reader will not lose sight of 

 the relation of the part to the whole, or forget the primary intention 

 of the work. 



We shall follow a convenient, rather than a strictly logical, order 

 of treatment, beginning in the first two chapters with a general sketch 

 of cell-structure and cell-division. The following three chapters deal 

 with the germ-cells, the third with their structure and mode of 

 origin, the fourth with their union in fertilization, the fifth with the 

 phenomena of maturation by which they are prepared for their union. 

 The sixth chapter contains a critical discussion of cell-organization, 

 completing the morphological analysis of the cell. In the seventh 

 chapter the cell is considered with reference to its more fundamental 

 chemical and physiological properties as a prelude to the examination 

 of development which follows. The succeeding chapter approaches 

 the objective point of the book by considering the cleavage of the 

 ovum and the general laws of cell-division of which it is an expression. 

 The ninth chapter, finally, deals with the elementary operations of 

 development considered as cell-functions and with the theories of 

 inheritance and development based upon them. 



SOME GENERAL WORKS ON THE CELL-THEORY 1 



Bergh, R. S. Vorlesungen liber die Zelle und die einfachen Gewebe : Wiesbaden, 

 1894. 



Carnoy, J. B. La Biologic Cellulaire : Lierre, 1884. 



Delage, Yves. La Structure du Protoplasma et les Theories sur THere'dite' et les 

 grands Problemes de la Biologic Generate : Paris, 1895. 



Geddes & Thompson. The Evolution of Sex : New York, 1890. 



Hacker, V. Praxis und Theorie der Zellen- und Befruchtungslehre : Jena, 1899. 



Henneguy, L. F. Lecons sur la Cellule : Paris, 1 896. 



Hertwig, 0. Die Zelle und die Gewebe: Fischer, Jena, I., 1893, II., 1898. Trans- 

 lation, published by Macmillan, London and New York, 1895. 



Hofmeister. Lehre von der Pflanzenzelle : Leipzig, 1867. 



Huxley, T. H. Review of the Cell-theory : British and Foreign Medico-Chirurgical 

 Review, XII., 1853. 



1 See also Literature, I., p. 61. 



