358 GENERAL VIEW OF THE HUMAN FUNCTIONS. 



in its relations to the functions of the Mind, it is strikingly confirmatory of the 

 views formerly expressed (CHAP. in. SECT. 2), to find that its connection with 

 the Physical forces is so peculiarly intimate. 



a. Although for the sake of convenience, Electricity and Nervous power are spoken of, 

 here and elsewhere, as actual entities or agents, travelling in currents along the wires or 

 cords that conduct them, it must not be forgotten that the present tendency of scientific 

 inquiry leads us to abandon such an idea, in the former case at least ; what is commonly 

 termed the transmission of electricity being the result of a molecular change, instantaneously 

 occurring along the whole length of the conducting body, in virtue of a disturbance in the 

 polar arrangement of its particles, at one extremity, which causes a similar disturbance to 

 manifest itself at the other. Thus, if 



ab ab ab ab ab ab ab ab 



represent the arrangement of the particles, in the condition of equilibrium or quiescence, 

 and this condition be disturbed at one extremity, by the operation of a new attraction upon 

 the first particle a, a new arrangement will instantaneously take place throughout : this 

 may be represented by 



a ba ba ba ba ba ba ba b, 



which shows b in a free state at the opposite end, ready to exert its influence upon any- 

 thing submitted to it. It is probable that in this respect there is an analogy between the 

 Nervous and Electrical forces; and that, instead of speaking of the "transmission of 

 Nervous influence" along a nerve, we should describe the change as the production of a 

 "polar state" in the nervous trunk ; as was first pointed out by Messrs. Todd and Bow- 

 man ("Physiological Anatomy," p. 220, Am. Ed.}. 



CHAPTER VI. 



GENERAL VIEWS OF THE FUNCTIONS OF THE HUMAN BODY. 



1. Of the Mutual Dependence of its Vital Actions. 



366. BY the study of the various forms of Elementary Tissue of which the 

 Human fabric is made up, we are led to the very same conclusion with that 

 which we draw from the observation of the simplest forms of organized being, 

 or from the scrutiny into the earliest condition of the most complex; namely, 

 that the simple Cell may be regarded as the type of Organization ; and that on 

 its actions rest our fundamental idea of Life. Between the humblest Plant, 

 and the embryonic Human organism, there is originally no perceptible differ- 

 ence; they may be said to have a common starting-point; and the subsequent 

 difference of their course consists essentially in this that the successive gene- 

 rations of cells, which are the descendants of the former, are all similar to it 

 and to each other, each cell being capable of maintaining an independent ex- 

 istence; whilst the subsequent generations which originate from the latter, pro- 

 gressively become more and more dissimilar to each other, and more and more 

 mutually dependent; so that whenever it is thrown entirely upon its own re- 

 sources, the integrity of the whole fabric becomes essential to the continued life 

 of any individual cell. Every individual part, however, even in the most com- 

 plex and highly-organized fabric, has its own capacity of development ; and the 

 properties which it possesses are the result of its exercise. But instead of the 

 power of cell-growth being exerted, as in the Plant, upon the inorganic elements 

 around, it can only be put in action, in the Animal, upon certain peculiar com- 



