PHYSIOLOGY. 75 



as we can irritate the muscular fibre to contraction by a stimulus 

 of any kind applied to its fibres, so long we can excite the con- 

 traction, by applying the same stimulus to a portion of the 

 nerve; and the power if shewn to proceed from an inch of 

 nerve is equally nervous as if proceeding from the brain. I 

 wonder that Dr. Haller missed this fact. The explanation is, 

 that the power belongs to the medullary fibres, and therefore 

 subsists so long as certain conditions subsist ; what these are 

 it is not necessary to determine, but they are the same in both. 

 ' Subprimitur a vinculo nervo injecto.' This does not touch the 

 question of the nervous power ; only, because a nerve is tied, 

 the animal power no longer exerts itself in the muscle. This 

 does not affect the question, whether these two powers are one 

 and the same, or different ; only that a motion cannot be pro- 

 pagated after a ligature is applied. ( A laeso cerebro, a propi- 

 nato opio.' This amounts to the same, and relates to the animal 

 power, which cannot be in these cases propagated from the brain. 

 ' Motus insitus ab iis omnibus nihil patitur.' This is not true; 

 the motus insitus suffers from all these, and is affected by every 

 affection of the brain, and even by its ordinary action. With 

 regard to the * propinato opioj Dr. Haller, in contradiction to 

 several other experimenters, is disposed to refuse that opium has 

 the effect of destroying the inherent power ; he maintains that 

 opium properly acts only on the brain, and particularly rejects 

 the commonly received notion of its power over the heart. You 

 will find experiments to this purpose fully detailed and frequent- 

 ly repeated by Dr. Whytt, and our colleague, Dr. Monro, who 

 show that it acts upon the brain, and thereby destroys the in 

 herent power in the same manner as when it is applied to the 

 muscular fibres themselves. Haller adds, ' et superest nerva 

 revincto, resecto, in intestino de corpore revulso.' I have al- 

 ready said that this is no proof of the different nature of these 

 powers ; only the animal power is taken away. ( Viget in ani- 

 malibus cerebro destitutis."* Here we are engaged in an ana- 

 tomical dispute with Dr. Haller, viz. whether any animals are 

 without a brain. He complains that we suppose the existence of 

 a brain where we do not see it ; but he should admit that there 

 are animals in which, from their transparency and minuteness, 

 we are not allowed to discern the distinction of parts, and are 



