154 niYSlOl.iHiY OF MUSCLES AND NERVES. 



everywhere to lie found. In the researches in which 

 \\c are about t<> engage, we must always endeavour as 

 far as possible to exclude these accidental currents, or 

 at least to distinguish them from those currents which 

 it is our task to examine. ;ind the causes of which lie 

 in the animal tissues themselves. Apart from muscles 

 and nerves, but one tissue seems endowed with some-* 

 what strong elect lie action ; this is that of the glands. 

 This has, indeed, not as yet been fully proved, but it 

 ha- lieen shown to be in a very high degree probable. 

 In connection with this it is a very interesting fact that 

 the glands are in some physiological respects very similar 

 to the muscles, and that they bear the same relations 

 to nerves as do muscles. 



2. There is, on the other hand, a tissue in which 

 electric action is exhibited in far greater strength, so 

 that its nature was known long before it was recog- 

 nised that muscles and nerves possess the same capa- 

 city. This tissue does not, however, occur in all 

 animals, but only in a few fishes, which on this account 

 are called electric tishes. In these animals special 

 organs of peculiar structure occur, in which, as in an 

 electric battery, currents of very considerable strength 

 arise, the discharge of which is caused by the influence 

 of t lie will, the animal using t his power to frighten its 

 enemies, or to benumb and kill its prey. Long before 

 the world knew anything accurately as to the phvsical 

 nature of elect ric phenomena, such powerful influences 

 a- are exhibited in elei-trie li.-hes did not fail to attract 

 the attention of chance observers. Notices of these 

 remarkable phenomena are actually found in ancient 

 writers; and the h'.imaii pod Claudius Claudianus 1 



1 He lived in Alexandria toward ti.rcnrl nf tbe fourth century. 



