444 ELECTRICITY IN THE PHENOMENA OF ANIMAL LIFE. 



clevelojunent the nerve fiber elougates aud becomes the seat of increased 

 electrical resistance. 



Thus the nervous network ceases to be able to carry more than a 

 continually diininishinji' part of the total energy. The greater part, 

 forced to undergo utilization at the seat of its i)roduction, gives to the 

 muscular liber its peculiar cliaracter and brings about its contractility 

 or tonicity, as we have seen (in v). - - - 



If we reHect upon the stage of progressive evolution of an inferior 

 animal, or upon one of the earlier phases of development of an embryo, 

 weunderstaiul that in proportion as nerve trunks take their rise in the 

 neighborhood of each other differences of electric potential, existing 

 between certain iioints of these trunks, tend to give rise to new trunks, 

 superadded to the former, and the presence of which helps to render 

 electrically dependent ni)on each other the different parts of the elec- 

 trogeuic system. 



Let these anastoinoses be multiplied ad infinitum^ without losing 

 sight of the fnndaniental idea of the system, and we shall bo able, as 

 it seems, to succeed in explaining the governmental order which reigns 

 throughout the Avhole nervons system, from the smallest sporadic gan- 

 glia to the brain, which is itself the center of centers. 



VIII. — OF TIIK I'ART I'LAVKn I5V SENSOHV KXCITATIOXS. 



Let us now investigate how the nervous system may play the ])art of 

 stimulator while drawing its functional energy irom the reaction of tlie 

 whole organism, and how it comes to regulate the operation in all its 

 variations of the physiological battery. 



Nothing seems to stand in the way of our looking on the series of 

 multiplied nerve trunks which constitute the nervous system of one of 

 the higher animals as closely analogous to an ordinary system of wires 

 for the distribution of electrical energy, in which whole series of appa 

 ratus for the consum])tion of this energy (hxmps, electric motors, et(;.) 

 are branched off from a great source of production of electricity at a 

 central station. 



We may assume all of these pieces of api)aratus for the utilization 

 of the current to be regulated by instruments electrically connected 

 with the central source of power, which instruments themselves con- 

 sume in their operation a certain share of the available energy, and 

 represent so many secondary derivations of energy from the system. 

 Finally, to complete this ideal scheme, we may imagine each of the 

 pieces of apparatus for the utilization of the current to be furnished 

 with an "annunciator" — an instrument operated electrically — which 

 shall give notice to the regulating apparatus of anything going wrong 

 at the point at which such instrument is placed. 



The aggregate of all the regulating apparatus in such a system 

 forms, to my eyes, an image of the brain, and the instruments which 

 give notice of what may occur at the various outlying points in the 

 system are but the analogues of the organs of sense. 



