626 THE AM ERIC AX XA rCRALlST. XXXVIIL 



In the best cases the i)hysical imitations arise as fohows : 

 There is first a study of certain vital activities. This is fol- 

 lowed by construction of a hypothesis as to the nature of the 

 factors at work, — an explanation of the activities in terms of 

 phenomena already known. The third step is to determine by 

 experiment whether the supposed known factors can produce 

 such activities ; these factors are combined in appropriate ways 

 and the results observed. If they bring about activities similar 

 to those shown in the vital phenomena, then the explanation 

 gains much in probability, and we have an " imitation " of the 

 vital activities. What the imitation shows is then, as Rhumbler 

 ('98, p. 108) has well said, that the factors assumed to be at 

 work really can produce such activities as we attribute to them, 

 — and this is a long step in advance. There still remains the 

 question whether the factors in our imitation actually arc those 

 at work in the vital phenomena. 



To enable us to judge intelligently on this final question we 

 need an accurate knowledge of the phenomena to be explained 

 and of the forces at work in the imitation, that they may be 

 closely compared; imitations founded on external resemblance 

 are likely to be misleading. We have indeed three factors to be 

 compared, — the explanation as it exists in the mind of the 

 mvestigator, the physical experiment, and the vital activity. In 

 the best cases these three must agree ; the explanation fits the 

 experiment, and the experiment is essentially similar to the vital 

 phenomenon, so that the explanation fits the latter also. But the 

 explanation given may fit the physical experiment and not the 

 vital activity, or it may not even fit the experiment ; we shall 

 find examples of both these cases. 



In the commoner case, where the explanation given does fit 

 the physical experiment, how are we to judge whether the vital 

 activity is to be similarly explained .? Evidently an explanation 

 based on an imitation can at best fit the vital activity only in so 

 far as the latter agrees with the imitation. Points in which it 

 does not agree must be attributed to other factors, and if these 

 points are essential ones for the explanation given, then we must 



conclude that the vital 

 posed. Furthei 



anation giv 

 tivity is not explicable in the way pro- 

 : determine whether certain conditions,. 



