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help to form, suffer no decomposition If it be urged further, al- 

 though the materials (blood and the structures, or rather the latter, 

 as the former may be supplied, recent, by art) suffer no immediate 

 or sensible decomposition, their latent chymical properties may 

 nevertheless suffer a change, to which the suppression of the pro- 

 cesses of secretion might be imputed. But this evasion will 

 scarcely be admitted unless it be affirmed that all properties which 

 are not mechanical are chymical ; which would leave us still to 

 inquire into the laws of life, only under another title, as, " of the 

 chymical properties which are different from all other chyraical 

 properties, and never met with in the laboratory," &c. For the 

 present, however, it is convenient and methodical to designate 

 these unknown properties by a term expressive of the limitation 

 with which they exist, and we have chosen to consider them, 



1*2. 3. As animal properties, or properties of life, which suffer 

 the conversion from the living to the dead state; in which latter 

 they are no longer capable of producing the secretions, which are 

 to be reckoned only among the phenomena of the former. 



13. If then secretion in general is found to depend upon an 

 assemblage of properties peculiar to the living state, the first 

 question on which we are desirous to be informed is, what are 

 those properties? The answer is, they are not objects of the 

 senses, nor can we even witness their operations; we can infer 

 their existence from results, and we may trace some of their laws 

 by analogy ; but we cannot designate them respectively by appella- 

 tions: or if in some instances, as in those of the powers of con- 

 traction, we do this, our appellations are founded only upon some 

 point of analogy with other more familiar agents; while their real 

 nature, their constitution, their alliances, their relations, are 

 scarcely in the slightest degree indicated by such terms. We will 

 not then pretend to give names to the properties of life engaged 

 in the process of secretion ; but the properties, as a commencement 

 of their investigation, might be inquired into according to those 

 classes of animal properties before suggested, as whether they are 

 of the assimilating, of the regular dependent, or of the oc- 

 casional kind? 



14. In deciding upon these alternatives, the choice appears 

 to lie between the two former; natural secretion being, as we have 

 reason to suppose, unremitting, we cannot attribute the function 

 to properties obtained from another sphere, by the operation of an 

 occasional cause. 



15. But although the natural, unremitting secretions cannot 

 be attributed to those vital properties which we have considered 

 as occasional, yet even these are liable to be modified by coinuiuiii- 

 cation of properties from a distant seat which is primarily affected. 

 Thus, the passions influence in well known instances the functions 

 of the organs of secretion : the first impression is upon the senses, 

 the next upon the brain, and thence the effect may be propagated 



