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perties, and by the more copious accession of the fluids, the necessary 

 consequence of that excitement; 2nd. the action of the glands; that is, 

 its secretion, properly so called; 3d. lastly, the action by which the organ 

 parts with the fluid which it has prepared: this is the last process, it is 

 called excretion, and is promoted by the action of the neighbouring parts. 

 The determination of fluids to the part, the secretion and excretion suc- 

 ceed each other; they are preceded by the excitement, which is the pri- 

 mary cause of all the subsequent phenomena. The circulation is, at first, 

 excited, more blood is sent into the part, and penetrates into the tissue of 

 the gland. Dr. Murat has had occasion to open a considerable number 

 of old men, who died at the Bicetre, and who were known to be great 

 smoakers of tobacco. He uniformly observed, that their parotid glands, 

 continually called into action by that habit, were larger than in those 

 who were not given to it, and that they were remarkably red, in conse- 

 quence of the blood with which they were constantly injected. 



What is the office of the nerves in the act of secretion? what share has 

 the nervous influence in the elaboration of the fluids furnished by the 

 glandular organs? All the glands which receive their nerves from the 

 system of animal life, such as the lachrymal and salivary glands, appear, 

 in certain cases, to receive, from the brain, the secretory excitation. The 

 influence of the imagination is sufficient to determine it; thus, we shed 

 involuntary tears, when the mind is taken up with painful thoughts; and 

 the mouth fills with saliva, on the recollection of a grateful meal*. In 

 such cases, the influence of the nerves on the process of secretion, is in- 

 disputable: it is not so, however, with the conglomerate glands that re- 

 ceive their nerves from the great sympathetics. The secretion of the 

 kidneys, of the liver, and of the pancreas, appears less influenced by affec- 

 tions of the mind; the brain, besides, has no immediate connexion with 

 these glands; their nerves are, almost entirely, given off by the great 

 sympathetics; the kidneys in particular, receive no nerves from the brain, 

 or from the spinal marrow ; hence the secretion of urine seems, more 

 than any other, to be independent of the nervous influencef. 



* These glands, viz. the lachrymal and salivary, receive nerves both from the nearest 

 ganglions, and from the nerves of voluntary motion : the former set of nerves mos.t pro- 

 bably enables them to perform their ordinary functions, the latter excites or reinforces 

 these functions whenever the mind is under certain impressions. 



f- Although these organs are not directly influenced by the cerebral and spinal nerves, 

 it cannot be satisfactorily denied that the ganglial nerves, which are so abundantly dis- 

 tributed to the blood-vessels supplying these organs, bestow on these vessels that pe- 

 culiar influence which determines the nature and quantity of the secretion ; for how can 

 we suppose the capillary tubes, through which the blood flows, to be able to secrete a 

 peculiar fluid of themselves, without resorting to the position that the nerves, which so 

 abundantly supply the ramifications of the blood-vessels, and the substance of the se- 

 creting organs, actually influence, and, through the medium of those vessels, even 

 produce the secretions in question ? Are not these nerves requisite to the vital actions 

 of the viscera which they supply? Do we know an animal that does not possess them 

 as a most essential part of its organization ? And can we suppose that they are distri- 

 tributed in so abundant a manner to the vessels of a secreting organ, without perform- 

 ing a most requisite part in the production of the fluids which that organ secretes ? A 

 close investigation ot the structure of the secreting viscera and surfaces shows that their 

 blood-vessels, which bear in their number and size a close relation to the extent of func- 

 tion which such viscera individually perform, are more amply supplied with this class of 

 nerves than the vessels of any other of the animal textures : indeed every important se- 

 creting gland has a distinct g'anglion, or plexus of these nerves surrounding the blood- 

 vessels which belong to it , but more especially the arteries, and some of these organs 



