PREFACE. 



IN preparing this book it has been the purpose of the 

 author to acquaint his readers with the peculiar nature 

 and interesting reactions of " Living Substance"; to help 

 him trace it to its probable, though unknown, beginnings 

 and follow it through its multifarious differentiations 

 to its highest complexity. 



In so far as this has been accomplished, the work is a 

 General Biology. But more has been attempted, for 

 the problems have been so considered as to show that 

 man is no separate entity, apart from the general world 

 of living things, but is a unit in the general scheme of 

 things and subject to the same laws that apply through- 

 out the universe. 



Inasmuch as many of the subjects treated are of 

 importance to students contemplating future medical 

 studies, and inasmuch as all of them are of interest and 

 importance to students of medicine and physicians, the 

 work may, with justification, claim to be a Medical 

 Biology. 



All of the problems of medical science are in a sense 

 biological, and many of the problems of biological science 

 medical. Medical science is, in fact, a branch of biology 

 and should be studied as such. 



Each chapter treats of some subject or subjects upon 

 which the pen would gladly linger and upon which a 

 volume might be written, and professional biologists 

 will, no doubt, be disappointed at the brief treatment 

 their pet theories receive as well as astonished at the 

 space devoted to other, and to them less important, 

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