Chap. VllLlELECTRICAA'DPlfOSPORESCENTORGANS. 269 



the whole surface of the body (Malapterurus). They 

 are very richly supplied with nerves, and appear to be 

 modifications of muscular tissue, which they so far 

 resemble in physiological activity that they are under 

 the control of the fish ; are exhausted after a certain 

 period of activity ; and are brought into a tetanic 

 condition in which a number of discharges succeed 

 one another involuntarily, when their possessor is 

 treated with strychnine. In the Torpedo the organs 

 are made up of a number of hexagonal bodies, each of 

 which is divided into a number of cells by intervening 

 septa, between which is a clear gelatinous fluid, or 

 mucous tissue ; the Torpedo has about a thousand 

 electric prisms, and Gymnotus is said to have two 

 hundred and forty electric cells in one inch of its 

 electric organ. Though the effect of these bodies has 

 no doubt been exaggerated by travellers, it is clear 

 that they are capable of producing sufficiently remark- 

 able results. 



Curiously allied in the details of their structure to 

 the organs just mentioned are the so-called eye-like 

 spots found in various fishes (Argyropelecus, etc.), 

 and best developed, apparently, in deep-dwelling 

 forms. The special activity of these organs does 

 not, however, exhibit itself in the production of 

 electricity, but of light ; they are phosphorescent 

 organs. Kolliker, more than a quarter of a century 

 ago, suggested that the luminous organs of insects, 

 such as the Lampyridse and Elateridae, were allied to 

 the electric organs of fishes. So far, however, as we 

 know anything as to the mode of activity of these 

 bodies, which are richly supplied with tracheae, and 

 appear to vary in brightness with the movements of 

 expiration and inspiration, we are led to suppose that 

 the oxygen taken in from the air is a factor of con- 

 siderable importance. 



Phosphorescence is exhibited by such simple 



