48 TUANSACTION.S AND FUOCEEDINGS OF 'i'HE [.Se.ss. LXV. 



organism in a nutrient solution aVjstracts substances 

 chemically different from itself, and tranfornis them into 

 substances like itself. Dead substances reacting on other 

 compounds are transformed, and lose their individuality ; 

 living substance, on the other hand, not only preserves its 

 individuality, but has the power of forming more living 

 substance in the process. Some have credited living sub- 

 stance with a special faculty of making more, but this, as 

 the author points out, is like explaining that opium induces 

 sleep because it is possessed of a special soporific virtue 

 whose nature is to soothe the senses. Attempts to explain 

 it by physical phenomena, such as morphological structure, 

 crystallisation, and osmosis, will obviously lead to no satis- 

 factory result, for the phenomenon is a chemical one, and 

 cannot be explained by physical laws. Osmosis, of course, 

 is very important in vital phemomena and nutrition, but 

 does not explain assimilation, for without the intervention 

 of a chemical phenomenon assimilation could not take 

 place. 



Those biologists who have recognised the chemical nature 

 of assimilation have explained it as a contact action, analo- 

 gous to the formation of sulphuric acid by nitric acid in 

 chambers of lead. The analogy is imperfect. What is the 

 mysterious force which can detach from dead substances 

 the necessary atomic groups, and arrange them so as to 

 form molecules identical with those of living substance ? 

 Further, the nitric acid does not form more nitric acid, but 

 sulphuric acid. Further, supposing that living molecules 

 have the power only of forming other similar molecules, 

 this would not explain the phenomena of ontogenetic 

 differentiation. The molecules could not be transformed ; 

 from the molecules of an egg would be obtained other 

 molecules of egg, that is an egg. 



The living molecules must be admitted to have not only 

 the power of forming other living molecules, similar or 

 slightly different, but also of undergoing modifications 

 during assimilation. 



The true basis of assimilation is to be sought and found 

 in the " biomolecule " — the living unit. The author starts 

 to elucidate this point by reference to the life phenomena 

 of a simple unicellular organism. A single micrococcus 



