215 



to each of them a peculiar sensibility, by means of which they discover in 

 the blood which the vessels bring to them, the materials of the fluid which 

 they are destined to secrete, and these they appropriate to themselves by a 

 real selection. Besides, the nerves communicate to them a peculiar mode 

 of activity, the exercise of which makes those separated elements undergo 

 a peculiar com position, and bestows on the fluid which is the product of it, 

 specific qualties always bearing a certain relation to the mode of action of 

 which it is the result. Thus, the liver seizes the materials of the bile con- 

 tained in the blood of the vena portae, elaborates, combines those materials, 

 and converts them into bile, an animal fluid, distinguishable by peculiar cha- 

 racteristic properties, subject to certain variations, according as the blood 

 contains in different proportions, the elements of which it is formed; ac- 

 cording as the gland is more or less disposed to retain them, and to blend 

 them together. The qualities of the bile depending on a concurrence of 

 all these circumstances, must present as many differences as the blood which 

 contains its elements, and the liver may present varieties, with regard to 

 the composition of the former, and to the activity of the latter. Hence 

 the many changes in the qualities of the fluid, the slightest of which, not 

 affecting the health, escape observation, while those changes which are 

 greater, and which disorder the natural order of the functions, show them- 

 selves in diseases of which they maybe considered as the effect and at other 

 times, as the cause. These changes in the condition of the bile (and what is 

 now said applies to almost all the secretions of the animal economy), these 

 changes are never carried so far as to make the bile lose all its distinguish- 

 ing characters, it never takes on the qualities belonging to another fluid, 

 it never resembles semen, urine, or saliva. 



The secretory glands do not carry on an uninterrupted action ; almost all 

 of them are subject to alternate action and repose: all as Bordeu observed, 

 sleep or waken, when irritation affects them, or their neighbouring parts, 

 and determines their immediate and sympathetic action. Thus, the saliva 

 is more plentifully secreted during mastication ; the gastric juice is poured 

 within the stomach, only while digestion is going on ; when the stomach 

 is emptied of food, the secretion ceases, and is renewed^ when the pre- 

 sence of food again excites a sufficient degree of irritation*. The bile 

 flows more abundantly, and the gall bladder frees itself of that which it 

 contains, while the duodenum is filled by the chymous mass. 



When a secretory organ is in action, it determines the motion of the 

 parts in its vicinity, or, as Bordeu expresses it, within its atmosphere. 

 A part is said to belong to the department of a certain gland, when it par- 

 takes in the motion affecting the latter, during the process of secretion, 

 or when it is employed in functions subservient lo that of the gland ; 

 these departments are of different extent, according to the importance of 

 the action of the gland. Thus, one may say that the spleen and most of 

 the viscera of the abdomen are of the department of the liver, since they 



salivary glands receive from the seventh paii> from the maxillary nerve from the fifth 

 pair, and from the cervical nerves, a number of nerves that will "appear very great, if 

 the bulk of those glands is considered Author's J\ote. 



* This is very contrary to the observations of Wilson Philip, whose experiments show, 

 that the secretion of the gastric fluid precedes the reception of food, and may be es- 

 teemed the immediate cause of the sensation ot'bunger. According 1 to him, the secre- 

 tion is suspended, as soon as the stomach receives a certain quantity of food. See his 

 Treatise on Pevers, appendix to Vol. 2. and ius Inquiries on Indigestion. Godman, 



