CHLOROPHYL. 21 



Chlorophyl. In the light of more recent investigation, it seems 

 probable that some of the synthetic processes which occur in plant- 

 life may also be referable to the action of enzymes. As a matter 

 of fact, such bodies are abundantly present in the vegetable world, 

 and we know that some of these at least, and probably all, are 

 characterized by a reversible activity. Maltase, a ferment, which, 

 as we shall see later, causes inversion of the disaccharide maltose to 

 glucose, is thus similarly able to bring about the synthetic formation 

 of maltose from two molecules of glucose. On the other hand, it 

 appears that the primary formation of food-stuffs in plants does 

 not occur in this manner, but is referable to the activity of a special 

 body which, as has been stated, is present in the exposed green 

 parts of most plants, and which is termed chlorophyl. This sub- 

 stance occurs widely distributed in the vegetable world, but is also 

 found in those low forms of animal life in which the processes of 

 nutrition are essentially the same as those met with in the higher 

 plants. In itself, however, chlorophyl is incapable of bringing 

 about those syntheses which are characteristic of vegetable life, and 

 in the cells of the foliage of plants it occurs in combination with 

 certain albuminous bodies, in the form of the so-called chlorophylic 

 granules. These are apparently special elementary organisms, and 

 endowed with a power of locomotion analogous to that of amoabse 

 and leucocytes, so that they can approach the surface of the leaf to 

 seek the sunlight, or retreat when this becomes too intense. In a 

 germinating plant which has not been exposed to sunlight the green 

 color is wanting, but in the cotyledons is found a differentiation of 

 the cellular protoplasm into small yellowish bodies, which have been 

 termed leucites. When these bodies are exposed to light, even for a 

 relatively short time, they assume a green color, and then constitute 

 the chlorophylic granules. I have said that chlorophyl that is, 

 the green coloring-matter of plants is unable to effect synthetic 

 changes, and the same is true of the colorless leucites. Chlo- 

 rophyl thus apparently forms an integral constituent of the function- 

 ing leucites, and all those chemical and physical influences which 

 bring about the destruction of the protoplasm similarly destroy the 

 power of chlorophyl to manifest its special activity. In the living 

 plant, however, it becomes active at once upon exposure to sunlight, 

 and is then capable of effecting those complicated syntheses of which 

 mention has been made. In the dark it again becomes inactive, and 

 the plant is then obliged to live like an animal by consuming its 

 stored energy. 



Chemical Nature of Chlorophyl. Of the chemical composi- 

 tion and structure of chlorophyl we know little that is definite. 

 Numerous attempts have been made to isolate it from the living 

 plant, but it is doubtful whether any of these attempts has yielded 

 the actual substance. Only its decomposition-products, or at best 

 very impure forms, have apparently been obtained. Gautier, it is 

 true, claims to have isolated the substance in crystalline form bv 



