92 'Journal of Comparative Neurology and Psychology. 



of the nervous system in the arthropod types. The reason why ontogeny has not 

 so far revealed this form of evolution is said to be because all the energies of the 

 embryologists have been bent to the study of the matter from the standpoint of the 

 germ layer theory. A new embryology is, therefore, necessary, according to 

 Gaskell. Numerous charts and diagrams illustrated the paper, but in so limited 

 time it was not possible to go into the matter in sufficient detail that the reader 

 could point out the relation of the hypothesis to conditions of disease, but the 

 main points were well shown. 



"The salts of nerve, their importance to its function" was discussed by Prof. J. S. 

 Macdonald (Sheffield), H. The paper gave an account of experiments to deter- 

 mine the changes in the chemical composition of nerves, especial!)' when injured. 

 Macdonald found that when a nerve is injured there results a precipitation of some 

 of the colloid substance of the intramyelin material, (he precipitation being accom- 

 panied by the appearance of potassium salts capable of reacting with cobalt nitrate, 

 and of chlorides capable of reacting with silver nitrate. This change in composition 

 is taken to indicate the explanation of the current of "injury" which is found in 

 injured tissues, and the inference was drawn that the nerve current is about the same 

 sort of change in the composition of the nerve, though in the normal uninjured 

 nerve the salts do not leave the nerve, but change their position. The potassium 

 salts are normally deposited about the nodes of Ranvier, which act as cathodes by 

 which the electrical current leaves the fiber. There is also a deposition of the 

 chloride salts at these points. 



Further experiments to indicate the chemical character of the nerve-muscle 

 activity were reported by Langley (Cambridge), H. He gave the results of work 

 to indicate that the effect produced by a motor nerve depends upon the nature of 

 some receptive substance or substances formed by the cell in the region of the nerve 

 ending. In such a muscle as the sartorius of the frog it can be seen that after the 

 application of a dilute solution of nicotine the muscle contracts, but that the greatest 

 thickening is in the regions where nerve endings are most numerous. When the 

 nicotine is applied to points the response is found only from the parts where the 

 nerve endings are. Other experiments with nicotine, curari, sodium chloride, and 

 adrenalin show that there are in the muscle probably two substances, radicles, one 

 causing the slow the other the brief quick contraction. These substances are 

 believed by Langley to be radicles of the contracting molecule in the neighborhood 

 of the nerve ending. The functions that have been attributed to the nerve endings 

 are in reality, according to the author, functions of the muscle plasm, and the 

 "motor nerve endings are not organs with specific properties." It is difficult to 

 understand the last statement in a literal manner, for the motor nerve endings must 

 have some relation to the production of the contraction of the muscle, if it be only, 

 and the writer believes this to be Professor Langley's opinion also, that of starting 

 the chemical change in the muscle protoplasm which we call "contrac ion." 

 Curari, according to the work already finished, may no longer be considered to act 

 on the nerve endings, but is active on the "receptive radicles" of the muscle sub- 

 stance, and is partly antagonistic to the action of nicotine. 



Dr. R. Hober (Zurich), H, read a paper "Der Erregungsvorgang als Kolloid- 

 prozess" in which he brought forth strongly the chemical view of nerve and muscle 

 activity. The alterations in the excitability which are produced in mu cles and 

 nerves by the application of various salts were formerly attributed by Hober to the 



