March 28, 1902.] 



SCIENCE. 



497 



gelation occurring suiSciently abruptly to 

 cause tetanus during the passage of the 

 current. A true condition of katelectro- 

 tonus may also be produced by taking 

 water from the nerve. 



10. The current of injury may also be 

 explained on this hypothesis. At the cut 

 end aggregation or gelation is taking place 

 as a result of the disturbance of the me- 

 chanical conditions of the nerve. Here 

 positively charged colloids are going out of 

 solution and negative charges are tempo- 

 rarily set free. The cut end becomes nega- 

 tive to the uninjured portion. This conclu- 

 sion is supported by the fact that warming 

 the nerve locally causes the warmed por- 

 tion to become electro-positive to the un- 

 warmed, and cooling it causes the cooled 

 portion to be electro-negative to the rest of 

 the nerve. It is similar to what occurs 

 when zinc goes into solution. The undis- 

 solved zinc becomes negative to the solu- 

 tion. It is also well known that if by heat 

 we produce an irreversible gel (artificial 

 heat section) of the nerve, the coagulated 

 portion is negative to the rest.* 



11. Mechanical stimulation may possibly 

 be understood as follows: By the mechan- 

 ical coalescence of the neighboring col- 

 loidal particles their surfaces become less 

 than the sum of the surfaces of the sepa- 

 rated particles. A portion of the negative 

 charges formerly induced in the water sur- 

 rounding each particle is accordingly set 

 free. These immediately act like nega- 

 tively charged ions and precipitate the next 

 layer of colloids. The process may pos- 

 sibly be similar to that which occurs on 

 jarring an unstable hydrosol or a supersat- 

 urated solution. The obsei-vations of Dar- 

 win and others show that jarring will 

 bring about aggregation in protoplasm. 



12. The nerve impulse may consist in 



* The relation of this explanation to Waller's 

 idea that the cut end is positive will be discussed 

 in the full paper. 



the following process. By the precipita- 

 tion of each layer of colloids negative 

 charges are regenerated; these precipitate 

 the next layer of colloids and are again 

 regenerated, and so on. That something 

 of this sort occurs is indicated by the fol- 

 lowing facts : 



(a) Darwin's observation that the pass- 

 ing of the impulse in plant cells is accom- 

 panied by a progressive precipitation. 



(&) The facts that negative charges are 

 set free in the nerve by the action of each 

 successive segment. These charges consti- 

 tute the negative variation. 



(c) The fact that negative charges pre- 

 cipitate positively charged colloids. 



(d) The fact that negative charges stim- 

 ulate the nerve. 



(e) The fact shown by the action of 

 ether and other poisons that the negative 

 variation is not a simple movement of inor- 

 ganic ions, but is dependent for its propa- 

 gation upon the state of irritability (state 

 of the colloids) of the nerve. This fact 

 has already led many physiologists to infer 

 that the negative variation stimulates each 

 successive segment of the nerve and is 

 regenerated by the change it itself has 

 brought about. 



13. The action of anaesthetics. This con- 

 sists, on the hypothesis so far sketched, in 

 increasing the stability of the hydrosol or 

 solution, and so preventing precipitation. 

 There can be no doubt that the antesthetics 

 have this action as is shown by the follow- 

 ing facts: Darwin observed that they pre- 

 vent the process of aggregation or precipi- 

 tation in plant cells, and it has been shown 

 by Loeb, Budgett, Zoethout and others that 

 ■ they liquefy or dissolve the cells of infu- 

 soria and other animals and egg cells. The 

 effect of a mixture of ether and water on 

 starfish eggs is remarkable. The egg dis- 

 solves in it very rapidly. Furthermore, 

 Overton and Meyer have shown that the 

 anesthetizing action of substances is pro- 



