VII.] ANIMALS AND PLANTS. 161 



abundance of their chlorophyll. The few which 

 contain no chlorophyll and are colourless, are unable 

 to extract the carbon which they require from atmo- 

 spheric carbonic acid, and lead a parasitic existence 

 upon other plants ; but it by no means follows, often 

 as the statement has been repeated, that the manu- 

 facturing power of plants depends on their chlorophyll, 

 and its interaction with the rays of the sun. On the 

 contrary, it is easily demonstrated, as Pasteur first 

 proved, that the lowest fungi, devoid of chlorophyll, 

 or of any substitute for it, as they are, nevertheless 

 possess the characteristic manufacturing powers of 

 plants in a very high degree. Only it is necessary 

 that hey should be supplied with a different kind of 

 raw material ; as they cannot extract carbon from 

 carbonic acid, they must be furnished with something 

 else that contains carbon. Tartaric acid is such a 

 substance ; and if a single spore of the commonest and 

 most troublesome of moulds Penicillium be sown 

 in a saucerful of water, in which tartrate of ammonia, 

 with a small percentage of phosphates and sulphates 

 is contained, and kept warm, whether in the dark or 

 exposed to light, it will, in a short time, give rise to a 

 thick crust of mould, which contains many million 

 times the weight of the original spore, in protein 

 compounds and cellulose. Thus we have a very wide 

 basis of fact for the generalisation that plants are 

 essentially characterised by their manufacturing capa- 

 city by their power of working up mere mineral 

 matters into complex organic compounds. 



Contrariwise, there is a no less wide foundation 



