THE ELECTRICAL ORGANS. 57 



part fi'om tlie perforating flexor; or it may be closely 

 cijnnected with the tendons of the plantaris. The peronwus 

 brevis represents the flexor carpi ulnaris by its insertion, 

 but it arises no higher than the fibula, and has no sesamoid. 



Two most important muscles yet remain to be con- 

 sidered in the leg. The one o£ these is that which is in- 

 sei'ted by the tendo-achillis into the calcaneum, and arises 

 by four heads, two from the condyles of the femur (called 

 gastrocnemius), and two from the tibia and fibrda (called 

 soletis). The other muscle is the peronceiis longus, arising 

 from the fibida, passing behind the external malleolus, and 

 then crossing the foot to the base of the metatarsal of the 

 hallux. 



The latter muscle does not appear to have any represen- 

 tative in the fore limb. The gastrocnemius and soleus may 

 possibly represent the crural part of the perforated flexor, 

 since in many of the Vertehrata, the tendo-achillis is but 

 loosely connected with the calcaneum, and passes over it 

 into the plantar fascia and the perforated tendons. A 

 peculiar adductor muscle of the hallux in Man and Apes is 

 the transversalis pedis, which is inserted into the basal 

 phalanx of the hallux, and arises from the distal ends of 

 the metatai-sals of the other digits. The muscle sometimes 

 has an analogue in the manus. 



Electrical Organs. — Certain fishes belonging to the genera 

 Torpedo (among the Elasmobranchii), Gymnotus, Malap- 

 tenirus, and Mormyrus (among the Teleostei), possess 

 organs which convert nervous energy into electricity, just 

 as mxiscles convert the same energy into ordinary motion, 

 and therefore may well be mentioned in connection with 

 the nervous system. The " electrical organ " is always 

 composed of nearly parallel lamellae of connective tissue, 

 inclosing small chambers, in which lie what are termed the 

 electrical plates. These are cellular structures, in one face 

 of which the final ramifications of the nerves, which are 

 supplied to the organ by one or many tiiinks, are dis- 

 tributed. The face on which the nerves ramify is in all 



