16 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



process in terms of the concept of radiation pressure. 

 But we must not conclude that carbohydrate synthesis is 

 essentially or primitively a process of this nature, for we 

 have the case of the nitrifying bacteria which synthesise 

 carbohydrate in darkness, and in the absence of a 

 chlorophyll mechanism. And, generally speaking, we 

 must not conclude that in the accumulation of energy by 

 the organism we have a process which involves simply 

 an absorption of radiant energy, for an analogous 

 synthetic process is to be seen in the fixation of atmo- 

 spheric nitrogen by certain forms of bacteria. It is 

 indeed possible to say that, in the case of the bacteria 

 found on the roots of leguminous plants, the energy 

 necessary for the synthesis is derivable from the 

 metabolism of the plant, but then we have nitrogen- 

 fixing organisms living in the open. 



When we speak of life in general we are obliged to 

 cease to distinguish between individual organisms, and 

 we must regard its general tendency as that of the total 

 mass of animal and vegetable life contained on the earth. 

 Looking broadly at the distinctions between animal and 

 plant we see that the latter is characterised by torpor and 

 immobility, and by its tendency to accumulate energy in 

 the shape of chemical compounds of high potential. The 

 animal, on the other hand, is characterised by the 

 possession of a sensory-motor system, and by its tendency 

 to form compounds which exist in its tissues in a state 

 of " false equilibrium " : most of its metabolic processes 

 have for their object the formation of these so-called 

 " explosive " compounds, which become stored in its 

 muscle fibres, and then more or less suddenly decomposed 

 with the production of energy. This energy is liberated 

 along almost infinitely variable paths in the higher 

 animal, the mechanism employed being that of the 



