92 PHYSIOLOGY OF LIFE. 



term magnetism; because of all the natural bodies at 

 present known, iron, and one or two of its nearest relatives 

 in the family of hard yet coherent metals, are the only 

 ones, in which all the conditions are collected, under 

 which alone the magnetic agency can appear in and during 

 the act itself. When, therefore, I affirm the power of 

 reproduction in organized bodies to be magnetism, I 

 must be understood to mean that this power, as it exists in 

 the magnet, and which we there (to use a strong phrase) 

 catch in the very act, is to the same kind of power, working 

 as reproductive, what the root is to the cube of that root. 

 We no more confound the force in the compass needle 

 with that of reproduction, than a man can be said to 

 confound his liver with a lichen, because he affirms that 

 both of them grow. 



The same precautions are to be repeated in the identi- 

 fication of electricity with irritability; and the power of 

 depth, for which we have yet no appropriated term, with 

 sensibility. How great the distance is in all, and that the 

 lowest degrees are adopted as the exponent terms, not for 

 their own sakes, but merely because they may be used 

 with less hazard of diverting the attention from the kind 

 by peculiar properties arising out of the degree, is evident 

 from the third instance, unless the theorist can be supposed 

 insane enough to apply sensation in good earnest to the 

 effervescence of an acid or an alkali, or to sympathise with 

 the distresses of a vat of new beer when it is working. In 

 whatever way the subject could be treated, it must have 

 remained unintelligible to men who, if they think of space 

 at all, abstract their notion of it from the contents of an 

 exhausted receiver. With this, and with an ether, such 



