P RE FAC E. 



T~) ATHER more than three years ago, in the course 

 JL V of some investigations upon the microscopical 

 characters of the blood of persons suffering from acute 

 diseases, my attention was first thoroughly given to the 

 great question of the Origin of Life. And as so 

 much depended upon the proper solution of this 

 problem not only for Science generally, but even with 

 reference to the scientific basis of Medicine I deter- 

 mined to undertake some investigations and endeavour 

 to revise the grounds of opinion upon the subject. 



I did investigate, and in consequence was after a 

 time compelled to renounce my old prepossessions, 

 and adopt views concerning the origin of c living' 

 matter which are as yet only very partially accepted 

 in the world of science. The state of professional 

 opinion on these questions, moreover, was such that it 

 would have been unsuitable for me to have taught 

 new doctrines based upon facts ascertained during 

 these investigations, without having fully and publicly 

 stated the grounds upon which I had adopted them. 



At much personal sacrifice, therefore, I resolved to 

 attempt to produce a statement of the facts which 

 should carry conviction to the minds of others. And 



VOL. i. b 



