ELECTRICAL ORGANS IN FISHES. 301 



cit.) considered the perpendicular prisms in Toi-pedo as gal- 

 vanic piles, the horizontal series in CJyninotus as trough 

 arrangements ; hut without entering into the details of the 

 comparison. This view of their action does not explain the 

 intermittent and voluntary character of the discharges. For, 

 as Valentin {loc. cit.) has stated, the organs in the fish caimot 

 be complete galvanic Latteries, or they would be continually 

 charged, and a discharge would follow every suitable closure 

 of the circuit. Valentin {Ivc. cit.) proposes the following 

 theory of the api)aratus, based on Moser's (Dove and Moser's 

 Hcpcrtorium der riiysik, 1837) hjqiothesis of the action of the 

 fluid of the cells of the battery on the substance of the nerves 

 contained in it. He assumes the structure of the batter}' to 

 be a series of closed spaces ; the series enveloped in tliicker, 

 the spaces separated by thinner aponeurotic lamina* ; each 

 space being lined by a vascular epithelium, under which the 

 nervous plexuses lie ; and tilled with fluid, lie supp().'5es 

 that there results from the organic or nutritive reactions of the 

 circulating blood, the epithelium, and the contained fluid of 

 each space, a certain amount of electric force, not, however, 

 suflicient to overcome the insulating obstacle opposed to it in 

 the aponeurotic walls ; all the spaces in the battery are, 

 therefore, so far only insulated electrical spaces. As soon, 

 however, as the will of the animal determines a flow of 

 nervous force into the spaces, the organic reactions become so 

 much exalted, that the resolved electric force overcomes the 

 insulating power of the laminie, and a current is produced — 

 the cunent being confined to the series by their thicker 

 aponeurotic walls. This theory, although it may account for 

 a sudden increase of electricity in the organ, affords no ex- 

 planation of its progressive character ; the current is not 

 accounted for. 



The theory which most satisfactorily combines the nna- 

 tomico-i>hysiological as well as the electrical plu'nomena ol 



