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to the kidneys, testes, prostate, &c. The natural secretions may 

 be thus affected by properties of the occasional kind ; and by simi- 

 lar occasional causes secretions might be produced, de novo, as 

 exemplified in some forms of disease, as when the fore arm sup- 

 purates from an injury of a finger, &c. 



16. There is no other mode of distinguishing whether 

 functional properties, regularly operating, inhere altogether with 

 the organs, or are habitually derived from another seat, than that 

 division before proposed as a test. We commonly regard the 

 nerves as constituting the medium of intercourse of the vital pro- 

 perties of different seats. We possess a few facts which indicate 

 in the organic system that the nerves are the medium of this in- 

 tercourse: in the animal system these facts are more numerous and 

 less equivocal. Accordingly, an examination instituted to dis- 

 criminate between the assimilating and the regular dependent 

 forms of life would be directed according to the analogy furnished 

 by these facts. 



17. If then the inquiry was concerning the function of the 

 kidneys, we should thus be led to make a division of the renal 

 plexus, or of the contiguous trunks, from which this plexus is 

 formed. Supposing it possible to complete this object in a satis- 

 factory manner; either, 1st, the secretion of urine would proceed; 

 or, 2nd, it would cease. The unconnected inference from the first 

 would be, that the functional properties of the kidneys are inde- 

 pendent on another source ; from the second result, the inference 

 would be that these properties are communicated from a nervous 

 centre. The first inference would be liable to this doubt, viz. that 

 although the organ is independent of any properties communicated 

 through the nervous trunks, yet does it not follow but that pro- 

 perties might be derived from another sphere, by relations with 

 the spirit residing in other, as the mixed, structures, which are 

 also continuous. Thus we find in our experiments upon nerves, 

 that the division of the brachial plexus may produce a sloughing, 

 perhaps followed by suppuration of the extremities; in which case 

 a dependence is exhibited upon related properties, which are not 

 furnished by a centre of nerves. This objection, though proper to 

 qualify the inference, is perhaps not entitled to any great weight, 

 any further than, that it indicates the design of additional inquiry. 

 The inference from the second result, viz. that the secretion ceased 

 upon the division of the nerves, is liable only to this objection, 

 viz. that, from injury of parts, the function might be destroyed by 

 modified communicated properties, and not by an impeded com- 

 munication of habitual ones, necessary to produce it. How far 

 this latter doubt is entitled to consideration it has before been at- 

 tempted to decide. In a general way the cessation of an office in 

 the seat of the inferior distribution of a nerve in consequence of a 

 division of its trunk, has been admitted to prove a dependence, as 

 on properties derived from a source ; but if the nerve is deeply 



