48 The Significance of Chemical Molecules 



such an ancillary hypothesis the meaning of the hypothesis 

 as a whole is changed. For, with the same right, one 

 might say that the plastidules are not molecules at all, in 

 the sense of physics, but are distinguished from them 

 by their very life-properties. 



It would be easy further to criticise the plastidule- 

 hypothesis in the same direction. It leads to pure specu- 

 lation. According to Haeckel, we must attribute sensa- 

 tion and will power to atoms. 18 The plastidules possess 

 memory, according to his theory ; this faculty is lacking 

 in all other molecules. 19 We shall not discuss, either, the 

 wave motion of the plastidule. 



What is of interest to us, is to show that any attempt, 

 at the present time to reduce life-phenomena to the prop- 

 erties of the molecules of living matter, is, to say the 

 least, premature. We must either limit ourselves, with 

 Elsberg, to such deductions as can be derived from Dar- 

 win's gemmule-hypothesis, or be compelled to resort 

 everywhere to ancillary hypotheses, in place of explana- 

 tions. If we choose the first method, we arrive naturally 

 at the assumption of invisible units, of a higher order 

 than the molecules of chemistry, and of such a compli- 

 cated composition that every one of them must be made 

 up of a large number of chemical molecules. To these 

 units we must attribute growth and multiplication as 

 qualities which so far cannot be explained. In a like in- 

 explicable manner we must further assume that they are 

 the material substratum for hereditary characters. Leav- 

 ing this part unexplained, we can clear up many other 

 things. But in that case we cannot revert to the mole- 

 cules of protoplasm. 



"Haeckel loc. cit. p. 38. 

 Loc. cit. p. 40. 



