Vlll 



PREFACE 



to cover a large field, in each and every point of which there 

 are opposing- views, both as to the facts themselves and to 

 their interpretation, errors and misinterpretations are inev- 

 itable, and the writer craves the indulgence of those who have 

 directed their special attention to any one of the subjects 

 touched upon here. The book is primarily intended as an 

 interpretation of the work of the specialists in anatomy, 

 especially during the last half-century, and its mission will be 

 accomplished if it serves to render the facts obtained more 

 accessible to the general reader. 



DRYADS' GREEN, NORTHAMPTON, 

 May, 1909 



