484. 



existing Protozoa, displayed actions verging little by little 

 into those called vital — actions which protein itself exhibits in a 

 certain degree, and which the lowest known living things exhibit 

 ouly in a greater degree. Thus, setting out with inductions from 

 the experiences of organic chemists at the one extreme, and 

 with inductions from the observations of biologists at the other 

 extreme, we are enabled deductively to bridge the interval- 

 are enabled to conceive how organic compounds were evolved, and 

 how, by a continuance of the process, the nascent life displayed in 

 these became gradually more pronounced. And this it is which 

 has to be explained, and which the alleged cases of " spontaneous 

 generation" would not, were they substantiated, help us in the least 

 to explain. 



It is thus manifest, I think, that I have not fallen into the alleged 

 inconsistency. Nevertheless, I admit that your reviewer was 

 justified in inferring this inconsistency ; and I take blame to myself 

 for not having seen that the statement, as I have left it, is open to 

 misconstruction. 



I pass now to the second allegation — that in ascribing to certain 

 specific molecules, which I have called " physiological units," the 

 aptitude to build themselves into the structure of the organism to 

 which they are peculiar, I have abandoned my own principle, and 

 have assumed something beyond the re-distribution of Matter and 

 Motion. As put by the reviewer, his case appears to be well made 

 out ; and that he is not altogether unwarranted in so putting it, 

 may be admitted. Nevertheless, there does not in reality exist the 

 supposed incongruity. 



Before attempting to make clear the adequacy of the conception 

 which I am said to have tacitly abandoned as insufficient, let me 

 remove that excess of improbability the reviewer gives to it, by the 

 extremely-restricted meaning with which he uses the word mechani- 

 cal. In discussing a proposition of mine he says : — 



" He then cites certain remai-ks of Mr. Paget on the permanent effects 

 •wrought in the blood by the poison of scarlatina and small-pox, as justify- 

 ing the belief that such a 'power' exists, and attributes the repair of a 

 wasted tissue to ' forces analogous to those by which a crystal reproduces 

 its lost apex.' (Neither of -which phenomena, however, is explicable by 

 mechanical causes.)" 



Were it not for the deliberation with which this last statement is 

 made, I should take it for a slip of the pen. As it is, however, I 

 have no course left but to suppose the reviewer unaware of the fact 

 that molecular actions of all kinds are now not only conceived as 

 mechanical actions, but that calculations based on this conception of 

 them, bring out the results that correspond with observation. There 

 is no kind of re-arrangement among molecules (crystallization 

 being one) which the modern physicist does not think of, 



