442 Pioyal Institution of Great Britain. 



nuclei are distributed at intervals. This may be called the proto- 

 plasmic lamina. The under or ventral layer might be called the 

 nerve-lamina, for it is made ^^p of the arborizations of the innu- 

 merable nervous filaments which spread themselves over the proto- 

 plasmic lamina on its under surface. As these filaments branch 

 repeatedly as they approach their destination, their ultimate endings 

 are among the smallest objects which can be distinguished under 

 the microscope. 



The electrical organ offers to the physiologist one of the most 

 striking examples of that adaptation of structure to function which 

 is universal among living beings. A single column of the organ of 

 the torpedo resembles in a very remarkable degree a voltaic pile, of 

 which the plates are the elements, but it is a resemblance with a 

 difference. The difference lies in this, that the organ is only a 

 battery when it is waked into activity by a stimulus. This waking 

 ■up or (to use the ordinary language of physiology) excitation is 

 derived from the animal's brain, which for the purpose has added to 

 it a special electric lobe on each side, from which the enormous 

 nerves, which are so richly supplied to the electrical organ, emanate. 

 The use of this lobe is obvioiisly not to produce electricity itself, 

 but, at the will of the animal, to set free the energy of the organ, 

 i. e. of each of the many thotisand plates of which it consists. Thus, 

 of the two laminae of each plate, the nervous and the protoplasmic, 

 each represents a distinct function — the protoplasmic that of pro- 

 ducing the required electromotive effect, the nervous that of receiving 

 from the brain and communicating to the protoplasm the impulse by 

 which it is discharged. 



In a former lecture it had been shown that all the ordinary 

 physiological changes which occur at every moment of our existence 

 in what Eichat called the organs of animal life, particularly in our 

 nerves and muscles, are accompanied by electrical changes, and that 

 although it is not yet possible to give any phj^sical explanation of 

 these changes, rapid progress is now being made in determining the 

 laws of their association with the other physical concomitants of 

 muscular and nervous action. As it is practically much more 

 important to understand the physiology of muscle and nerve than 

 that of the electrical organs of a few fish, the latter has been com- 

 paratively insufficiently studied. The purpose of the experiments 

 made at Arcachon is to bring the phenomena of the electrical 

 discharge or shock of the torpedo and the physiology of its organ into 

 line with the already very accurately investigated phenomena of 

 nerve and muscle. With reference to these last, certain very defi- 

 nite laws have been established, of which, perhaps, the most funda- 

 mental is that, when functionally at rest, these structures exhibit 

 no electromotive action. The structure must have been previously 

 acted upon by some external agency capable of exciting it. Another 

 established fact is that the effect is of limited duration, and that for 

 its development a certain time must elapse, which under similar 

 conditions is always the same for the same structure. A third is 



