280 OF THE BLOOD: ITS VITAL PROPERTIES, 



when the nutrient matter of the blood has been exhausted in the production 

 of new epidermic tissue. 1 



217. That condition of the corpuscular element of the blood which is normal 

 in the Insect, must be considered as decidedly abnormal in the Vertebrated 

 animal, in which the circulating fluid goes on to a higher phase of develop- 

 ment ; and the excess of Colorless corpuscles in the latter seems always to be 

 associated (save in the early part of life) with an imperfect performance of 

 their nutritive operations. Thus, according to the observations of Mr. Paget, 2 

 they are especially abundant in the blood of frogs that are young, sickly, or 

 ill-fed ; and as regards the human subject, he confirms the statement of Mr. 

 Wharton Jones and Prof. J. H. Bennett, that the increased proportion of 

 Colorless corpuscles in inflamed blood is most frequent when the subjects of 

 the disease are persons in weak health, or of the tuberculous diathesis. Mr. 

 Paget has also furnished a remarkable confirmation of this view, in the 

 observation, that the inflammatory exudations produced in different indi- 

 viduals, by the application of the same stimulus on the same tissue (e. g., by 

 the action of a blister on the skin) are found to present a predominance of 

 thefibrinous or of the corpuscular element, according to the general condition 

 of the patient. "The highest health is marked by an exudation containing 

 the most perfect and unmixed fibrin ; the lowest by the formation of the most 

 abundant corpuscles, and their nearest approach, even in their early state, to 

 the characters of pus-cells." From such evidence we seem forced to the con- 

 clusion, that, whether or not the Colorless corpuscles are to be regarded in 

 any other light than as blood-cells not yet fully developed, their multiplica- 

 tion is not the source of increase in the fibriuous constituent of the liquor 

 sanguiuis. 



218. The fitness of the Blood for circulation through the body is main- 

 tained partly by the action of the proper excretory apparatus, and partly by 

 the power which every tissue possesses of withdrawing from the circulating 

 fluid some particular material, or combination of materials, which constitutes 

 its own special pabulum; and as the " pabulum" of each tissue is different, 

 it follows that the normal composition of the blood can only be preserved, 

 without waste of substance, by the existence of such a balance between the 

 appropriative action of the several parts, as shall cause a certain equivalent 

 of blood to supply, without deficiency or surplus, the materials which they 

 collectively require. Such a balance is, in fact, ordinarily preserved ; and its 

 maintenance is one of the most marvellous of those exemplifications of Design, 

 which the vital economy of the body presents in no less a degree than its 

 organized structure ; an exemplification, however, which becomes yet more 

 marvellous, when it is shown that not only every kind of tissue, but every 

 spot of every organ, has its own special "pabulum;" drawing something from 

 the blood, which is different from that appropriated by every other part of 

 the body, save the corresponding spot on the opposite side. This position 

 seems fully established by the researches of Dr. W. Budd and of Mr. Paget 

 on "Symmetrical Diseases," 3 the phenomena of which are full of interest, as 

 illustrating the ordinary operations of Nutrition. From a general considera- 

 tion of these as displayed in various rheumatic and syphilitic affections, the 

 conclusion seems unavoidable, that, however closely one portion of skin or 

 bone may seem to resemble another, the only parts that are exactly alike are 

 those which repeat each other symmetrically on the opposite sides of the body; 

 for, although no power of artificial chemistry may determine the difference, 



1 Pliilosoph Mii^a/.ine, May, 1845. 



2 yiir;irjil Pathology, vol. i, pp. 313, 314. 



3 Sec their original essays on this subject in the Med.-Chir. Trans., vol. xxv. 



