A CTION OF CER TAIN POISONS. 2 2 T 



tion of muscular tissue was a sign of anabolism in that tissue, just as 

 contraction of the tissue is a sign of katabolism in that tissue. 

 Subsequently, I have put forward the proposition that all muscular 

 tissues are probably supplied with anabolic and katabolic nerves, the 

 one causing relaxation of the tissue and diminution of its contractions, 

 the other causing contraction of the tissue. 



Such double nerve supply has been proved for very many muscular 

 tissues, both unstriped and striped. Thus the muscles of the vascular system are 

 supplied by vaso-dilator as well as vaso-constrictor nerves ; the unstriped 

 muscles of the bladder and other visceral muscles are supplied with two 

 opposite kinds of nerves ; among these the recent observations of Langley 

 and Anderson 1 have shown a specially good example in the case of the 

 retractor penis, supplied as it is with motor nerves from the lumbar region and 

 inhibitory nerves from the sacral region ; the adductor muscles of Anodon are 

 supplied with two nerves of opposite function, according to Pawlow 2 and 

 Heidenhain. And the most suggestive case of all, in connection with the 

 question of the action of antagonistic striated muscles in vertebrates, the 

 adductor and abductor muscles of the claw of the crayfish are, according to 

 Biedermann's researches, supplied with two nerves, of which the one is motor 

 and the other inhibitory. 



In close connection with this question of the meaning of relaxation of tone, 

 when brought about by the action of an inhibitory nerve, is the meaning of 

 the relaxation phenomenon, brought about in a tonically contracted muscle by 

 the passage of a constant current through it. Such relaxation has been 

 shown by Biedermann to occur in the snail's ventricle, when the ventricle has 

 been thrown into a state of tonic contraction by too great a pressure within 

 its cavity, in the tonically contracted muscle of Anodon, in the veratrinised 

 sartorius, and has led him to the conclusion that such relaxation of muscle 

 upon the passage of a constant current is evidence of assimilation. 



This is, however, not the place to discuss the nature of the action of the 

 constant current upon muscular tissue ; it is sufficient to point out that the 

 view of the action of the inhibitory nerves of the heart which I put forward 

 in 1881, and which was subsequently in 1882 restated by Lowit 3 in the terms 

 of Hering's theory, is a view which is not opposed by the observations of 

 Biedermann and others upon the phenomena of relaxation of muscle, brought 

 about by the direct action of an electrical current. 



It may, I think, fairly be said that this view, that the action of the vagus 

 nerve is to promote the anabolic or assimilatory processes in the cardiac muscle, 

 is steadily gaining ground ; while the alternative view, that a special inhibitory 

 nervous mechanism is situated in the heart, which causes inhibition by 

 interference with motor impulses, is becoming more and more discredited. 

 Such a view has been supposed to receive special support from the study 

 of the action of various heart poisons, especially curari, nicotine, atropine, 

 and muscarine. 



With respect to these poisons, there is no evidence that they possess any 

 selective power over one set of nerve fibres and nerve cells rather than another j 

 the question is rather, do they act on the junction of the pre-ganglionic nerve 

 fibre and the ganglion cell, or on the junction of the post-ganglionic nerve fibre 

 and the muscle, or on the muscle itself ? 



The Action of Certain Poisons. Nicotine, as already mentioned, acts 

 in all probability on the junction of the pre-ganglionic fibre with the nerve 

 cell. 



1 Journ. PhysioL, Cambridge and London, 1895, vol. xix. p. 71. 

 " Arch. f. d. ges. PhysioL, Bonn, 1885, Bd. xxxvii. S. 6. 

 ., Bd, xxix. S. 503. 



