82 ELEMENTS OF BIOLOGY. 



second place, it leaves us wholly in the dark as to why the 

 albuminoid or other matter of a Protophyte should have 

 this power, whilst the very similar living matter of a Pro- 

 tozoon should be wholly without it. Lastly, this explana- 

 tion could, at best, but apply to the nutritive processes of a 

 plant, and would not by any means wholly elucidate these. 

 The phenomena of reproduction cannot be explained by the 

 action of any known chemical or physical forces ; though 

 such forces are necessary conditions for these, just as they 

 are for the phenomena of nutrition. To say that a plant 

 could not perpetuate its species unless it were supplied with 

 solar light and heat, would be true enough ; but, after all, 

 it would amount to no more than saying that the plant 

 would not be alive at all except under these conditions. 



In the present state of our knowledge, therefore, we 

 must conclude that we cannot refer all the forces which we 

 see at work in the vegetable organism to known chemical 

 or physical forces. Even those physical and chemical 

 forces which we know to be present in the plant, act in a 

 manner different to what they would do in any collocation 

 of dead matter, or in any animal ; whilst there are super- 

 added other phenomena which we cannot at present ex- 

 plain, and which we cannot therefore refuse to call " vital." 

 Admitting that the conversion by the plant of inorganic 

 materials into organic compounds is a purely chemical 

 operation, there would still remain the fact, as pointed out 

 by Dr Beale, that it is a chemical process differing alto- 

 gether from any and all processes which we can imitate in 

 the laboratory. Thus the most degraded of the plants 

 effects " silently and in a moment, without apparatus, with 

 little loss of material, at a temperature of 60 or lower, 

 changes in matter some of which can be imitated in the 

 laboratory in the course of days or weeks by the aid of a 

 highly-skilled chemist, furnished with complex apparatus 

 and the means of producing a very high temperature and 

 intense chemical action, and with an enormous waste of 



