THE APPEARANCE OF LIFE 67 



with other albuminoids, possesses the property of forming from 

 the carbon dioxide of the air and from water-vapour the 

 carbo-hydrates that represent the most important primary 

 foods. This substance is chlorophyll, the green colouring- 

 matter of plants. After the carbo-hydrates have once been 

 formed, the albuminoids already existing and the ferments 

 accompanying them utilize the carbo-hydrates in the 

 manufacture of new quantities of albuminoid substances, 

 including chlorophyll. It is therefore through the agency of 

 chlorophyll that life can be perpetuated, and this leads us to 

 think that the first masses of living matter were green, and if 

 they still existed would be classed in the vegetable kingdom. 



Water-vapour and carbonic acid from the air are unable 

 to penetrate any organic compound except through the 

 surface. It is therefore very important that the latter should 

 develop as far as possible. Under the most propitious con- 

 ditions this result could be achieved by a pulverization of the 

 initial mass into small globules and microscopic granules such 

 as those formed on the moist trunk of trees by Protococcus 

 viridis. After they have attained a certain size these granules 

 multiply by fission. This is the origin of the cellular consti- 

 tution of living creatures. A pulverulent form like that of 

 Protococcus results no doubt from certain advantages it 

 presents in respect of nutrition. This we may well believe on 

 the grounds that certain organisms such as the tan mould 

 (Fuligo septicum), which do not absorb nourishment through 

 their surface, but introduce into their substance digestible 

 food particles, are able to form gelatinous masses, two to 

 three decimetres in diameter and two or three centimetres 

 in thickness, and can move themselves about by crawling. 



It is possible that the animal and vegetable kingdom might 

 already have been differentiated in this fashion. The green 

 colouring-matter of the plants, chlorophyll, cannot combine 

 atmospheric carbon dioxide and water-vapour, and at the 

 same time eliminate oxygen, except by the action of the 

 sun's rays. This process can be accomplished by living matter 

 only through a surface that is free and exposed to the light. 

 Nothing, however, prevents the soluble carbo-hydrates from 

 penetrating the entire living mass if they are present in sufficient 

 quantity, or, consequently, prevents the nutrition of which they 

 are the basis from taking place, at some part far removed from 



