TIME RELATIONS OF THE ORGAN RESPONSE. 



575 



4 per cent, solution) are injected into the blood stream of Torpedo, 

 there is a final diminution in the organ response to both indirect and 

 direct excitation. 1 In this connection it is interesting to note that 

 Waller has observed a diminution in the nerve electrical response to 

 follow the action of large doses of curari. It thus appears that, unlike 

 muscle, the nerve organ mechanism is one in which there are no con- 

 necting links between nerve-endings and organ to be affected by curari, 

 and that no distinction between direct and indirect excitability can be 

 brought out in the case of the electrical organ by the use of this drug. 2 



The same is true of solutions of atropin, which paralyse many of 

 the neuro-muscular and neuro-glandular mechanisms. Portions of 

 Malapterurus immersed in such solutions are as readily excited, and 

 give as intense responses, as they did before the immersion. 



Experiments made by the author show that when portions of 

 Malapterurus organ are submitted to chloroform and ether, the re- 

 sponses fail ; in the case of ether, recovery may follow the removal of 

 the vapour. 



It will be clear from this brief description of the influence of 

 various conditions upon the excised organ, that the response presents 

 far more striking analogies to that of efferent nerves and nerve-endings 

 than to that of muscle, although the plates of which the organ is com- 

 posed appear to have been developed by the transformation of muscle. 

 With reference to such transformation, it should be remembered that 

 the essential elements are nervous and that these are the processes of 

 central cells, which do not correspond in position with those innervating 

 the muscles. The difficulty thus offered to those who would view the 

 organ as a transformed muscle, has not so far received the attention it 

 merits. 3 



The time relations of the organ response. The most interest- 

 ing features of the response are undoubtedly those brought to light by 

 the study of its time relations. In the first place, the response is so 

 intense, even in isolated portions of tissue, that its commencement can 

 be ascertained with more precision than that of the excitatory electro- 

 motive change in other forms of excitable tissue. In the second place, 

 the analogy between the pronounced organ response and the comparat- 

 ively feeble nerve excitatory change makes the precise determination 

 of the former most suggestive in regard to the characters of the latter. 



The time relations may be most easily determined by photographing 

 the excursions of a known and accurately calibrated capillary electro- 

 meter, but, owing to the difficulties in getting fish, in suitable condition, 

 to laboratories containing photographic appliances for this purpose, this 

 has at present been done in the case of one organ only, that of the 

 Malapterurus. 



The time relations of the response have been determined in the case 

 of the organs of Torpedo and of Eaia by means of rheotome methods, the 

 galvanometer, a special telephone, or the nerve muscle preparation of the 

 frog, being used as the recording instrument. A convenient rheotome 

 is that of the spring myograph, or pendulum, which at each passage 

 opens three keys. The opening of the first key (Kj) causes an exciting 

 break-induced current ; that of the second (K 2 ) opens a short circuit, 



1 Schonlein, Ztschr. f. Biol., Mtinchen, Bd. xxxi. 



2 Gotch and Burch, loc. cit. 



3 See Fritsch, "Die elektrischen Fische," Leipzig, 1887, 1890. 



