NOTE ON CHEMICAL STIMUL1 IN REGARD TO CONTRACTION ECC. 457 



that causes contraction and becomes thereby disorganised 

 and taken away. 



Professor Langley has shown that the Iris which is af- 

 fected by the superior cervical ganglion, after the removal 

 of the latter is affected in tirae, by adrenaline. Indeed, Dr. 

 William Alexander, of Liverpool, showed, many years ago, 

 that certain actions usually attributed to the superior cer- 

 vical ganglion come back after the removal of this body, and 

 it was pointed out that the ganglia are not so necessary as 

 was formerly supposed. Langley recalls the faci that nicotine 

 causes muscle to contract after paralysis of the terminals 

 by curari, and that receptive cells may exist that can pro- 

 vide substances that either stimulate or inhibit. It is evident 

 that such cells may cease to form the stimulating substance, 

 if overworked, and a rest must succeed in order that the celi 

 may be able to produce the substance necessary ; so that so- 

 mething is wanting which rest supplies, or enables the cells 

 to supply, to nerve or muscle. 



It has been suggested that the nerve cells themselves act 

 like gland cells, that they supply the very substance that 

 the neuro-muscular system requires, and enable the nerves 

 and muscles to act. Scott (Gh.) holds by the chemical expla- 

 nation as opposed to the physical, wihch was regarded by 

 Huxley as the best explanation. The chemical activities were 

 regarded by J. J. Charles as the main primary and causai 

 origin of nerve activity. 



Professor Mac Donald has advanced and supported a 

 rather seductive theory, viz. : That nerve flbres owe their fun- 

 ctions to the organic salts they contain. One sees a precipi- 

 tate of potassium chloride under the microscope by treating 

 nerve structures microchemically. It seems that the intrave- 

 nous injection of this salt gives tone to the enfeebled heart, 

 and enables one to increase its vibrations by stimuli. The 

 experiments made in the Heidelberg Laboratoy nave been al- 

 luded to in the paper on Muscular action (comptes rendus 

 du congr. Internat. de Médecine). There are other substances, 

 digitaline, atropine, salts of Baryta and Strontium, which 

 give tone to the heart muscles (Dr. Hall u in reviewed in La 





