BLOOD. 119 



unfortunately almost entirely deficient in positive information 

 regarding the formation of the blood-corpuscles in the mature 

 individual. That blood-corpuscles are formed in adults, cannot 

 admit of a doubt ; for we see that the mass of the blood, and 

 consequently of the blood-corpuscles, is continually increasing 

 from the moment that blood is first produced in the embrj^o, 

 up to the period of full corporeal development. jNIoreover, in- 

 dependently of any considerations founded on the increased 

 mass of the blood, a continuous formation of blood-corpuscles 

 is obviously necessary to compensate for the waste and 

 consumption of blood dependent on the exercise of the ^dtal 

 functions. The immense quantities of extractive matters 

 (abounding in nitrogen and carbon), — of urea, uric acid, 

 bile, mucus, and fat, Avhich are daily secreted in the mine, 

 faeces, and mucous discharges, together with the considerable 

 amount of carbon which is given off as carbonic acid in 

 the process of respiration, — must all be refunded to the 

 system by the blood. To this it may be objected, that the 

 supply takes place on the part of the plasma, which alone 

 therefore woidd requii*e to exist in a state of continuous in- 

 crease, while the corpuscles coexist, and are coeval with the 

 individual in whose blood they occur. Such a view is, how- 

 ever, at variance with all the phenomena of the higher stages 

 of existence ; for no tissue or portion of the body, sohd or 

 fluid, is allowed to remain unchanged or unendowed with \i- 

 tality. The necessity for the consumption and reproduction 

 of the blood-corpuscles has never yet been disputed, but various 

 theories have been propoinided by different physiologists re- 

 garding the seat of their formation and their mode of organic 

 development or metamorphosis. 



Hewson endeavom's to show that the spleen is the principal 

 organ in which the blood-corpuscles are formed, and that they 

 are produced from lymph-granules. Although the functions 

 of the spleen are not even at the present day properly deter- 

 mined, it is an established fact that the spleen may be extir- 

 pated, and the formation of blood not be impeded ; moreover, 

 the red colour of the lymph, upon which Hewson strengthens 

 his opinion, has not always been observed.^ Schultz" con- 



'^J.'Miiller's Handbuch der Physiologie, vol. 1, p. 573. 

 ^ System der Cirkulation, p. 37. 



