APPLICATIONS OF THE GRAPHIC METHOD. 199 
ASCENDING. DESCENDING. 
STRENGTH OF CURRENT. 
On closing. | On opening. | On closing. | On opening. 
WeeHhe iodo ls Giese ace ean Cc R Cc R 
Medium..........0...e000ss00 soe Cc C C C 
StH gS cccccrcidcinee Re htiew ademas R Cc Cc R 
R = rest; C = contraction, 
Electrical Organs.—Electrical properties can be manifested. 
by a large number of fishes; and the subject is of special 
theoretical interest. It is now established that the development 
of electrical organs points to their 
being specially modified muscles 
—tissues, in fact, in which the 
contractile substance has disap- — 
peared and the nervous elements 
become predominant and peculiar. 
No work is done, but the whole of 
the chemical energy is represented 
by electricity. Functionally an 
electric organ (which usually is 
some form of cell, on the walls of 
which nerves are distributed, in- 
closing a gelatinous substance, 
the whole being very suggestive 
of a galvanic battery) closely re- 
sembles a muscle-nerve- prepara- 
tion or its equivalent in the nor- 
malbody. The electric organs ex- 
perience fatigue; have a latent Fie. 192—The electric - fish torpedo, dis- 
period; their discharge is tetanic {Huxley} Dranchie sc brainy e, 
(interrupted) ; is excited by me- en eas a au, 
chanical, thermal, or electrical rer eeraes. ee eae cee orbane 
stimuli; and the effectiveness of °° 
the organs is heightened by elevation of temperature, and the 
reverse by cooling, etc. 
MuscuLaR WORK. 
If during a given period one of two persons raises a weight 
through the same height but twice as frequently as the other, 
it is plain that he does twice the work; from such a case we 
may deduce the rule for calculating work, viz., to multiply the 
weight and height together. 
