408 THE LIFE OF MATTER. . 



M. Charles Edward (hiillaiune speaks somewhere of "the heroic resist- 

 ance of the bar of nickel-steeL"" The term "defense" has been also 

 applied to the behavior of chloride or iodide of silver when exposed to 



There has ])een no hesitation in using- the term "memory" concur- 

 rently with that of hysteresis to designate the behavior of bodies sub 

 mitted to the action of magnetism or of certain mechanical forces. It 

 is true that M. H. Bouasse protests in the name of the phj^sico-math- 

 ematicians against the emploj'ment of these figurative expressions. 

 But has he not himself written "a twisted wire is a watch wound up," 

 and elsewhere " the properties of ))odies depend at every moment upon 

 all anterior modifications f Is this not to say that they retain in some 

 manner the impression of the changes the}^ have experienced? Power- 

 ful deformative agencies leave a trace of their action, they modify the 

 state of molecular aggregation of the bod}-, and some physicists go so 

 far as to say that the}' even modif}- its chemical constitution. With 

 the exception of M, Duhem, the mechanicians who have studied elas- 

 ticity admit that the effect of an exterior force upon a body depends 

 upon the forces to which it has been previously sul)jected, and not 

 merely upon those which are acting upon it at the time. Its present 

 state can not be predetermined, it is the recapitulation of preceding- 

 states. The effect of a torsional force upon a new wire will be differ- 

 ent ironi that of the same force upon a wire previously subjected to 

 torsions and detorsions. It was with reference to actions of this kind 

 that Boltzmann in 1876 declared that a wire that has been twisted or 

 drawn out remembers for a certain time the deformations to which it 

 has been subjected. This memory is defaced and lost after a certain 

 definite period. Here then, in a problem of static equilibrium, there 

 is introduced an unexpected factor — time. 



To summarize, it is the physicists themselves who have indicated 

 the correspondence l)etween the state of existence in many l)rute 

 bodies and that in many living bodies. It can not be expected that 

 these analogies will in any wav serve as explanations. We should 

 rather seek the dciixation of the vital phenomenon from the physical 

 phenomiMioii. This is [ho sole ambition of the physiologist, and the 

 inverse of this would be unreasonable. We do not assume to do tiiis 

 here. It is nexcrtheless true that analogies are of ser\ice, were it 

 oidy to shake th(> confidence which, smce the time of Aristotle, has 

 l)een accorded to the division of the bodies of nature into jjs>/('/i/(/ and 

 ajMur-/r!a, that is to say, into li\ iiig and brute bodies. 



2. TIIK 1U{()WNIAN MONKMKNT. 



The i-xixttucr of lh< Ilrownhdi in<tr( nunt. — The most simple means 

 of judging of th(> working activities of matter is to observe it in the 

 case where the liberty of the particles is not interfered with by the 



