210 OF THE BLOOD. 



chemistry of the living body makes it evident, the morbid material testing out 

 the parts for which it has the greatest affinity, uniting with these alone, and 

 passing by the rest. It is continually observable, moreover (as Mr. Paget has 

 remarked), that a poison of the same kind will attack corresponding spots, not 

 merely on the two sides of a single individual, but also on the two sides of any 

 others who may have imbibed it into their systems. Thus the syphilitic poison 

 has its " seats of election" when it begins to attack the bones, fixing upon cer- 

 tain parts of the tibiae and of the skull with great uniformity; and in the Hun- 

 terian Museum are the pelves of two lions, on both of which new osseous deposit 

 has taken place (as the product of some disease resembling rheumatism in man) 

 in a most complex and irregular pattern, this being so similar in the two, that 

 almost every spot and line of the one is represented in the other, with an exact- 

 ness only inferior to the symmetrical correspondence between the two sides of 

 each. 1 It has been further pointed out by Dr. W. Budd, as indicated by the 

 phenomena of these diseases, that, next to the parts which are symmetrically 

 placed, none are so nearly identical in composition as those which are analogous, 

 such as the corresponding parts of the superior and inferior extremities. All 

 these facts tend to demonstrate the perfect and most minute exactness of the 

 adaptation which must exist in the state of health between the blood and all the 

 tissues, as well as the almost inconceivable minuteness of the departure from 

 this adaptation which may become a source of disease ; and it is a sure indication 

 of the safety with which we may found such inferences upon them, that the 

 phenomena of symmetrical disease are most distinct, when the disordered action 

 is most conformable, as to its character and its rate, to the normal nutrition of 

 the structure ; it being in diseases which (though dependent upon a poison in 

 the blood) are of an inflammatory or other violent nature, that the symmetry of 

 the morbid change is least obvious. 



202. Thus, then, we are led to the conclusion that, as Treviranus phrased 

 it, "each single part of the body, in respect of its nutrition, stands to the whole 

 body in the relation of an excreted substance ;" or, in other words, each part 

 of the body, by taking from the blood the peculiar substances which it needs 

 for its own nutrition, does thereby act as an excretory organ, inasmuch as it 

 removes from the blood that which, if retained in it, would be injurious to the 

 nutrition of the body generally. Thus, the phosphates which are deposited in 

 our bones, are as effectually excreted from the blood, and as completely pre- 

 vented from acting injuriously on other tissues, as those which are discharged 

 with the urine. The applications of this doctrine have been greatly extended 

 by Mr. Paget, who has given the following among other examples of its bearing 

 upon the general relations between the blood and the tissues. The hairy cover- 

 ing may be considered to serve, over and above its local purposes, for the removal 

 of certain components of the blood, which would be injurious to its constitution 

 if they remained and accumulated in it ; and accordingly we do not find that its 

 development is delayed, until near the period when its protection will be required ; 

 for a complete coat (the lanugo of the human foetus) is formed in the foetus of 

 mammals generally, whilst they are still within the uterus, removed from all those 

 conditions against which hair is a defence; and this coat is shed very soon after 

 birth, being replaced by another of wholly different color, the growth of which had 

 begun within the uterus. The same principle leads to the apprehension of the 

 true import of the hair which exists in a kind of rudimental state on the general 

 surface of our bodies ; and thence to the real meaning of the existence of other 

 organs which permanently remain in a rudimental state, such as the mammary 

 glands of the male. For, as Mr. Paget justly remarks (loc. cit.), " these rudi- 



1 See Mr. Paget's "Lectures on Nutrition, &c.," in the "Medical Gazette" for 1847: 

 Lect. I. 



