If these conclusions are well founded, no amount of feeding or fasting on the part of the female could affect the sex of the off spring in animals; and culture media applied to the female would be equally futile in plants.
It has become increasingly evident that not only spermatogenesis, oogenesis, fertili zation and development of the embryo, are cell problems; but also that mutation, Mendelism genetics and other phases of the great problem of heredity must find their basis in the indi vidual cell. Plant physiologists are also turning more and more to the individual cell as the unit of physiological activity.
Cytology is too recent a sub ject to have given rise to many textbooks, most of the literature being in the form of articles in leading botanical and zoological jour nals. Probably the most important book on the subject is Prof. E. B. Wilson's The Cell in De velopment and Inheritance.) The following head ings of chapters in Professor Wilson's treat ise indicate quite accurately the subject mat ter of cytology as presented in the few univer sities which offer courses in this subject: (I) General sketch of the cell; (2) Cell division; (3) The germ cells; (4) Fertilization of the ovum; (5) Reduction of chromosomes, oogen esis and spermatogenesis; (6) Some problems of cell organization; (7) Some aspects of cell chemistry and cell physiology; (8) Cell division and development; (9) Theories of inheritance and development. This book contains a very
complete bibliography. Other books on the sub ject are Hertwig's The Cell) and Hacker's and Theorie der Zellen-und Befruch tungslehre.) All volumes cited above are by zoologists; no similar books have been written by botanists. A part of the subject is covered by Professor Strasburger's book on 'Reduk tionstheilung, Spindelbildung, Centrosomen, and Cilienbildner iin Pflanzenreich.) 'Zellen-und Gewebelehre,' by the same author, published in 1913 as the second volume of the fourth part of the third section of 'Kultur der Gegenwart,) is the latest authoritative treatment of plant cytology. The chief scientific journals in which the great majority of cytological investiga tions are published are (Botanical), Annals of Botany, Botanical Gazette, Jahrbiicher fur wissenschaftliche Botanik, Berichte der Deutschen Botanischen Gesellschaft, Flora, and Annals des Science Naturelles Botanique, (Zoological), Journal of Morphology, La Cellule, Anatomische Anzeiger, Archives de Biologie, Sitzungsbericht der Gesellschaft fur Morphologie and Physiologie Munchen, and Bulletin Acad. Roy. de