vi PREFACE 



book, although, in conformity with the general plan, I have kept 

 the subject-matter as elementary as possible. Moreover, I have 

 included in it certain matters, such as a description of the develop- 

 ment of the embryo and a short account of the phenomena of 

 hereditary transmission, which are not found in "The Physiology 

 of Reproduction." 



Lastly, I make no apology for concluding the work with a 

 reference to the birth-rate in man and the problem of human 

 population. My final paragraph is quoted from an article by 

 Mr J. M. Keynes, published in a special supplement to The 

 Manchester Guardian, and dealing witli " Reconstruction in 

 Europe " (No. VL, 1922) ; to this the reader is referred for much 

 detailed information, as well as for the views of a symposium 

 of thinkers, concerning the post-war position of a problem, the 

 biological interest of which is only surpassed by its supreme social 

 importance. 



F. H. A. MARSHALL. 



Christ's College, 

 Cambridge, 2oM March, 1925. 



