PREFACE vii 



If these views appear in some cases to be subversive of modern 

 biological doctrine it must be remembered that biological 

 thought is progressive ; were it otherwise the claims of bio- 

 logical science to a foremost place in our educational system 

 might well be considered questionable. The doctrine of 

 Organic Evolution, for example, looms large in several of the 

 lectures, and a certain advance is to be observed from the 

 position held by Charles Darwin and his immediate followers. 

 The foundations of this doctrine, however, remain unshaken, 

 and it is only the superstructure which has been, perhaps too 

 hastily, erected upon them that is being more or less recon- 

 structed in accordance with recent investigations. 



The unexpectedly large audiences which were attracted 

 to the lectures, and the great interest evinced in them at the 

 time of delivery, seem to justify the hope that in their present 

 form they may appeal to an even larger circle. 



Our great indebtedness to the distinguished men of 

 Science who collaborated in the lecture -course has already 

 been expressed, but I may be pardoned for once more 

 thanking them in my capacity as Editor for the great trouble 

 which they have taken to make this volume a success. I 

 must also express my gratitude to Miss Margaret Tribe, 

 M.Sc., of King's College, for the care and skill with which 

 she has compiled the Index. 



ARTHUR DENDY. 



KING'S COLLEGE, LONDON, 

 October 1918. 



