214 OF THE BLOOD. 



itself, tends to free itself from them, provided time is 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 disorganization 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 evan- 

 escent, 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 prevented. 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. Thus, as a general rule, alkaline, and earthy salts that 

 have been absorbed into the blood, are discharged in the urinary secretion, 

 which is itself increased in amount, showing that their action is specially deter- 

 mined towards the kidneys. So again arsenic, tartarized antimony, and a 

 variety of other metallic substances, have also been detected in the urine, for 

 some days after they have been ingested; 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 .which passes off but little by the ordinary excretions, is withdrawn from the 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 various tissues and organs, but particularly by certain parts of 

 the muscular apparatus, with the substance of which it becomes incorporated, 

 producing a most injurious influence upon its vital endowments. 3 The only ex- 

 ception to the general rule above stated, seems to be in the case of those medi- 

 cines, which have what is called a "cumulative" tendency; this tendency being, 

 in fact, simply the result of their want of stimulating influence upon the excre- 

 tory organs, whose functional activity is rather impeded than promoted by them. 

 This is pre-eminently the case in regard to lead, which is probably the most 

 cumulative poison with which we are acquainted; its continual introduction in 

 doses of even extreme minuteness being capable, if sufficiently prolonged, of 

 causing the most serious disturbance in almost every function in the economy. 

 Even here, it is rather in the tissues than in the blood that it accumulates 

 as is indicated by a variety of facts, but more especially by the difficulty with 

 which it is eliminated from the system by means that would be probably effectual 

 in removing it from the circulating current; and thus we see that, in default 

 of other provisions for maintaining the purity of the blood, the whole body (so 

 to speak) acts as an excretory apparatus, and draws into itself the noxious 

 substance. 



208. There is a large number of cases, moreover, in which, although the 

 poisonous or medicinal substances cannot be traced in the excretions by chemical 

 tests, their effects, when moderate doses have been taken, pass off so completely, 

 that there can be no doubt of their not being any longer present, as such, in the 

 system; and the substances of this class are of a nature and composition which 

 render them peculiarly susceptible of change, when subjected to the influences 

 which they will encounter in the living body, and more especially when exposed 

 in a state of very fine division to the agency of oxygen. A familiar exemplifica- 

 tion of this mode of elimination of poisons is furnished by the transient duration 

 of the effects of a dose of alcohol, even when this is large enough to produce 

 insensibility; recovery from them being merely a question of time, provided that 

 the state of torpor, produced by the action of this poison on the centre of the 



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

 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 " Medico-Chirurgical Transactions," vol. xxv. 



