PAB UL UM IN BLOOD. 9 7 



gradually undergoing disintegration ; and although it seems 

 most probable that the constituents resulting from their 

 decay are eliminated from the body in the form of urinary, 

 biliary, and other excrementitious matters, it is most likely 

 that some of the products take part in nutrition. 



Upon the whole, however, it seems probable that the 

 constituents which form the pabulum of the tissues are 

 those which are contained in the serum of the blood ; and 

 it is impossible to conceive how minute quantities of pabu- 

 lum prone to undergo rapid change could be more perfectly 

 and equally distributed to the textures, without its com- 

 position being materially changed, than in the form of the 

 very thin layers which each red blood-corpuscle carries 

 upon its surface, and smears, as it were, upon the walls of 

 the capillary vessel in intimate relation with the tissue. 

 The arrangement is such as to reduce to a minimum the 

 chances of alteration in the composition of the nutrient 

 fluid as it traverses the vessels in different parts of the 

 body. 



From a careful consideration of the facts, I cannot help 

 drawing the inference that the serum is the pabulum ; that 

 the red-blood corpuscles are concerned in its distribution, 

 and in preventing changes in the composition of the great 

 mass of the blood, as certain constituents are removed from 

 it or -poured into it ; and that the white blood-corpuscles 

 are masses of germinal matter concerned in the formation 

 of the serum, as well as of the red blood-corpuscles. In 

 support of this view, I would venture to direct attention to 

 the following points : 



i st. That fibrous tissue, shell, cartilage, muscular and 



H 



