XI 



ELECTRICAL FISHES 



383 



Here we no longer have undeveloped embryonic muscle-fibres, 

 but such as are completely differentiated, striated, and capable of 

 functioning, from which, " at a late moment of post -embryonic 

 life," a special modification gives rise to the elements of the 

 electrical organs. 



It can be demonstrated in all certainty that the meandering 

 layer of the plate, as described above, is directly derived from the 

 striated substance, more especially in Raja radiata, where, as 

 Ewart shows, it has the appearance of normal striated muscle 





FIG. 251. Raja batis. Section through a compartment with developed electrical plates. n = 

 nervous layer; fc=nucleated layer; i= layer; a = alveolar layer; m/= remains of muscle- 

 fibre (stalk of plate). (Ewart.) 



substance, even in the fully-developed animal. Between this, the 

 phylogenetically lowest, to the highest forms, which are dis- 

 tinguished by a complicated meandering course (R. circularis, latis), 

 there is every possible transition. 



As has been said, each single plate of Raja latis consists, 

 apart from the surrounding connective tissue and ingoing nerves 

 and vessels, of an anterior stratum of plasma with embedded 

 nuclei, which is very probably homologous with the motor end- 

 plates of striated muscle, and in which the numerous and at first 

 dichotoniously branching nerves terminate. 



Then follows the non-lamellated layer, of parallel striation in 



