ON THE ORGANIC FUNCTIONS. 315 



j 



Animal body, it may be observed that, the more Vegetative the nature of any 

 function the less is it connected with the Nervous System ; and all the experi- 

 ments, which have been regarded as proving that the Organic functions are 

 dependent upon Nervous influence, are really explicable, fully as well, upon 

 the supposition that they are capable of being affected by it, either in the way 

 of excitement or retardation (see 237). Moreover, there is abundant evi- 

 dence, that Secretion may take place after the death of the general system, 

 through the persistence of certain molecular changes, of which the essential 

 conditions are not immediately altered ; and the growth of the beard, which 

 has also been occasionally observed, indicates that even Nutrition may continue 

 to a certain degree. In such a case, the Animal body is reduced to the con- 

 dition of a Plant; since the influence of the Nervous ' system must then be 

 entirely extinct. Upon those who maintain that nervous agency is a con- 

 dition essential to those molecular actions, of which Nutrition and Secretion 

 consist, it is incumbent, therefore, to offer some more unexceptionable proof of 

 their position than has yet been given ; since their doctrine is opposed by so 

 many considerations of great weight. 



425. That many of the Organic Functions, however, are directly influenced 

 by the Nervous System, is a matter which does not admit of dispute ; and this 

 influence, exerted sometimes in exciting, sometimes in checking, and some- 

 times in otherwise modifying them, may well be compared to that. which the 

 hand and heel of the rider have upon his horse, or which the engine-driver 

 'exerts over a locomotive. It is most remarkably manifested in the result of 

 severe injury of the nervous centres, such as concussion of the Brain, or of 

 the Solar plexus ;* for this does not merely produce a suspension of the respi- 

 ratory and other movements, which minister to the organic functions, and hence 

 a gradual stagnation of the latter but a sudden and complete cessation of the 

 whole train of action ; which cannot be attributed to any other cause than a 

 positive depressing influence of some kind, propagated through the Nervous 

 System. It will hereafter appear ( 583), that in such cases even the vitality 

 of the Blood is often affected ; the usual coagulation not- taking place after 

 death, so long, at least, as the blood remains within the vessels. A similar 

 general depression may result from Mental Emotion, operating through the same 

 channel ; but this more commonly has rather a local action, or operates more 

 gradually. The influence of the Nervous System is often especially exerted, 

 in giving temporary excitement to a secreting process ; which need not be kept 

 in constant activity, or of which circumstances may occasionally require an 

 increase. This is the case, for example, in regard to the secretions connected 

 with the process of digestion, the Saliva, Gastric fluid, Bile, Pancreatic fluid, 

 &c. ; all of these being excited by the contact of the substances on which they 

 act, with the surfaces on which their respective ducts open. The secretion of 

 Milk, again, in a nursing female, may be excited by irritation of the nipple ; 

 and a determination of blood to the Mammae during pregnancy, must be due 

 to increased action in the part, excited by the changes occurring in the Uterus, 

 which can scarcely operate otherwise than through the Nervous System. No 

 other channel of influence can be well imagined for most of these operations 

 than the Sympathetic system of Nerves ; since the organs in question are for 

 the most part supplied by it. There is an apparent exception, however, in the 

 case of the Salivary and Lachrymal glands, which are supplied by the Fifth 

 pair : but this nerve contains so many organic filaments, and is so intimately 

 connected with the Sympathetic, as evidently to supply (in the head) the place 



* The Author has no doubt, that the occasional occurrence of death from blows on the 

 epigastrium is to be attributed to this cause: in all the instances on record, the stomach 

 has contained food at the time; and the effect of the blow would, therefore, have been 

 propagated to the rest of the viscera, and to the nerves distributed upon them. 



