LOCAL NERVE CENTRES. 



675 



cases the small arteries can be kept for many hours, 1 and probably for 

 days and months, in a state of strong contraction ; and it is not to be 

 believed that the breaking down thereby involved could go on if there 

 were not some corresponding fresh formation. 



We seem then driven to suppose, on the lines of the theory, that 

 though anabolism interferes with katabolism, katabolism does not inter- 

 fere with anabolism. But in such cases it is hard to avoid the conclu- 

 sion that different molecules are affected. And then we are at a loss 

 for an explanation of how anabolism in one molecule can stop kata- 

 bolism in another molecule. 



What is required, in the first place, is some means of determining 

 whether anabolism is increased, or not, during inhibition ; and if it is, to 

 what extent it is increased. It need hardly be said that increased 

 strength of contraction after inhibition is not necessarily a sign of 

 increased anabolism ; for the continuance of a previously existing rate 

 of anabolism, unaccompanied by katabolism, would be sufficient to 

 produce this result. 



Dastre and Morat 2 regard the sympathetic ganglia as exercising a tonic 

 action upon the blood vessels ; they state that vaso-dilator action diminishes 

 or disappears as nerve strands are stimulated more and more peripherally, and 

 they conclude that the vaso-dilator fibres run to the sympathetic ganglia and 

 inhibit their tonic action. Thus their view of inhibition is essentially that 

 of Claude Bernard. The general question of tonic action we discuss later (p. 

 676). Here we may consider the particular cases on which Dastre and Morat 

 rest their view. These concern (1) the vaso-dilator fibres for the ear in the 

 rabbit, cat, dog ; (2) the vaso-dilator fibres for the foot of the dog. 



1. According to Dastre and Morat, stimulation of the eighth cervical and 

 first thoracic nerve roots causes primary dilatation of the vessels of the ear. 

 Since stimulation of the annulus of Vieussens and of the cervical sympathetic 

 causes nearly always, if not always, contraction of the vessels of the ear, they 

 consider that the vaso-dilator fibres coming from the spinal cord end chiefly 

 in the ganglion stellatum ; they consider that this ganglion gives off numerous 

 vaso-constrictor fibres, which run to the ear by way of the cervical sympa- 

 thetic. In my experiments, stimulation of the eighth cervical nerve had no 

 effect upon the vessels of the ear. In the cat, the first thoracic nerve 

 produced sometimes, but not usually, a slight vaso-constrictor effect; this 

 was sometimes followed by an after-dilatation of the same kind as, though 

 very much less than, that caused by stimulation of the cervical sympathetic. 

 Further, a study of the effects produced by nicotin seems to me to show that 

 the ganglion stellatum sends, at least as a rule, no vaso-constrictor fibres to 

 the ear by way of -the cervical sympathetic. 



2. Dastre and Morat find that stimulation of the sympathetic, above the 

 second and third lumbar ganglia, causes primary dilatation of the vessels of the 

 digits of the hind-foot, whilst stimulation below these ganglia causes primary 

 contraction. They consider that the second and third lumbar ganglia send 

 vaso-constrictor fibres to the vessels of the foot, and that the tonic action of 

 these ganglia is inhibited by vaso-dilator fibres running to them from the 

 spinal cord. I have not been able to observe such a difference, except in so 

 far that more care is required to avoid reflex dilatation when stimulating above 

 than when stimulating below the ganglion. And the action of nicotin in the 

 cat shows, I think, that the second and third lumbar ganglia send no nerve 

 fibres of any kind to the foot. 



1 Of. Eve, Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 344. 



2 "Recherches expe'rimentales sur le systeme nerveux," Paris, 1884. 



