AND ITS RELATIONS TO THE LIVING ORGANISM. 283 



tained, the Blood, like the solid tissues, has a formative power of its own, 

 which it exerts in the appropriation of the new material supplied to it from 

 the food; and that, like all the other parts descended from the component 

 cells of the 1 germinal mass, it goes through a succession of phases, which are 

 partly the cause, and partly the effect, of developmental changes in the organ- 

 ism generally. The self-maintaining power of the Blood is yet more shown 

 in the phenomena of Disease; and especially in its spontaneous recovery of 

 its normal condition, after the most serious perversions; as we see more par- 

 ticularly in febrile diseases of definite type (such, for example, as the Ex- 

 anthemata, Typhoid, Typhus, etc.), of whose origin in the introduction of 

 specific poisons into the blood, there is no reasonable ground for doubt. In 

 studying the mode in which these and other "morbid poisons" act upon the 

 blood, and through it upon the system at large, we may derive important 

 assistance from a previous inquiry into the history of the action of such 

 poisonous agents, which, from their being .more readily traceable by chemi- 

 cal analysis, can be more satisfactory made out. Such an inquiry has a 

 most important bearing, also, on the modus operandi of medicines. The 

 operation of medicinal or poisonous substances for the most part depends 

 upon the power which they possess, when introduced into the current of the 

 circulation, of effecting some determinate change in the chemical, and there- 

 by in the vital condition, either of the components of the blood, or of some 

 one or more of the tissues which it nourishes; and their determination to 

 some special part or organ must be attributed to the same kind of elective 

 affinity, as that by which the normal constituents of the blood are so deter- 

 mined ( 217). Now of nearly all these substances it may be said, that the 

 system if left to itself, tends to free itself from them, provided time be 

 allowed for it to do so; and that, when death results from their introduction 

 into it, the fatal result is to be attributed to the fact, that the disorganiza- 

 tion of structure and disturbance of function are too rapid and violent to 

 allow the eliminating processes to be set in efficient operation. When 

 smaller doses are taken, their effects are evanescent, unless the abnormal 

 action to which they may have given rise is of a kind to perpetuate itself; 1 

 and their cessation is obviously attributable to the removal of the agent 

 from the system, whereby the continuance of its deleterious agency is pre- 

 vented. Of this removal, we have of course the most satisfactory evidence 

 in the case of those substances which can be detected by ordinary chemical 

 tests in the excretions, such as the alkaline and earthy salts, arsenic, tar- 

 tarized antimony, and a variety of other metallic compounds, which may 

 readily be detected in the urine for some days after they have been ingested ; 

 clearly showing that their elimination is a work of time. On the other 

 hand, the salts of copper appear rather to be removed from the blood by the 

 liver, and also by the bronchial secretion. And lead, which passes off but 

 little by the ordinary excretions, is withdrawn from the circulation by vari- 

 ous tissues and organs, but particularly by certain parts of the muscular ap- 

 paratus, with the substance of which it becomes incorporated, producing a 

 most injurious influence upon its vital endowments. 2 The only exception to 

 the general rule above stated, seems to be in the case of those medicines 



1 Such a perpetuation is seen in the chronic inflammation, thickening and contrac- 

 tion of the cesophageal walls, consequent upon the deglutition of strong acids and 

 caustic alkalies. 



2 This has been shown by the analyses of M. Devergie (see the Traite des Maladies 

 de Plomb of M. Tanquerel, torn, ii', pp. 401-6), and of Prof. Miller (see Dr. W. 

 Budd's essay on The Symmetry of Disease, in the Med.-Chir. Trans., vol. xxv). 

 M. Malassez (Gaz. Med. de Paris, Nos. 1 and 2, 1874) has shown that under the toxic 

 influence of lead the number of red corpuscles falls to 2,200,000: they at the same 



