BLOOD AND BLOOD DERIVATIVES * 



By Edwin J. Cohn 

 Department of Physical Chemistry, Harvard Medical School 



[With 1 plate] 



Our understanding of the circulation of the blood followed the rapid 

 development during the sixteenth and seventeenth centuries of our 

 knowledge of anatomy. William Harvey (1578-1657) studied at 

 Padua where the Chair of Anatomy had been held successively by 

 Vesalius, by Realdo Columbus, by Gabriele Fallopio, and by Fabricius 

 of Aquapendente, the latter carrying on the tradition in Harvey's time. 

 Returning to England, Harvey continued his studies and published his 

 great work "De Motu Cordis" in 1628. 



Our understanding of the cellular composition of the blood followed 

 the development of the microscope. Leeuwenhoek (1632-1723) , fasci- 

 nated by the phenomena revealed by the lenses he ground, achieved 

 magnifications with the aid of which he described the blood corpuscles 

 first in the frog and then in man. 



Comparably, our understanding of the molecular composition and 

 the multiple functions of the blood is following the beginnings in the 

 nineteenth century and the rapid development in the twentieth of pro- 

 tein chemistry. Just as the development of the microscope made it 

 possible to distinguish the cellular elements of the blood, so advances 

 in the methods of protein chemistry are making it possible to distin- 

 guish a large number of substances dissolved in the blood, each with 

 different physicochemical and physiological properties. The separa- 

 tion and concentration of these substances make possible a new mastery 

 and give promise of a new therapeutic control of the composition and 

 the functions of this complex body fluid. 



Blood has always been accorded a unique status in the minds of men. 

 It was early associated with the seat of the soul. The Bible distin- 

 guished repeatedly between the tissues and the blood. Association 

 with the spirit of man is further attested by the large number of ex- 



1 From American Scientist, vol. 33, No. 2, 1945 (reprint from Science in Progress, Series 

 IV, April 1945), and here reprinted by permission from The Society of the Sigma Xi and 

 tale University Press. 



676212—46 27 413 



