CHAPTEE IV 



THE BLOOD : FORMED CONSTITUENTS 



SUMMARY. 1. Arrangement of human physiology, and classification of 

 functions. 2. Importance of the blood as centre of the vegetative system 

 and agent of general metabolism. 3. Historical development of haematology. 

 4. General physico-chemical characters of the blood. 5. Estimation of total 

 quantity. 6. Physical and morphological characters of erythrocytes, and 

 estimation of their relative quantity. 7. Chemical composition. Properties of 

 haemoglobin and its derivatives. 8. Character, composition, and physiological 

 properties of leucocytes. 9. Blood platelets, and elementary granulation of the 

 blood. Bibliography. 



JUST as no absolute difference can be admitted between the vital 

 activities of plants and animals, so no absolute difference can be 

 recognised between the functions of the individual living cells, 

 tissues, organs, and systems of which the higher organisms, 

 including man, consist. It is nevertheless to be observed that in 

 all complex organisms, whether animals or plants, there is pari 

 passu with the morphological differentiation of the primitive cell, 

 which occurs during ontogenic development, a functional differ- 

 entiation, resulting in a division of labour, i.e. in the greater 

 or less specialisation of the capacities or functions of the different 

 parts. As in the great industries an ever-increasing development 

 and perfection of industrial products is obtained with the pro- 

 gressive division of the work assigned to the various groups of 

 workmen, so the increasing perfection observed in the scale of 

 living beings is essentially the result of progressive morphological 

 differentiation and functional specialisation in the cells of which 

 the organism is composed (Milne Edwards, 1827). It is evident 

 that the arrangement of the special physiology of man, and 

 the rational classification of his functions, must rest upon this 

 specialisation of the different organs and systems in the higher 

 animals. 



I. At the commencement of the nineteenth century Xavier 

 Bichat, in his inspired book Sur la vie et la mort, made a sharp 

 distinction between two orders of functions in the higher 

 organisms, which he designated as the functions of organic (or 

 vegetative) life and the functions of animal life respectively. 



91 



