8 9 



for this function is the protoplasm which forms as it were 

 a matrix in which the green colouring matter lies. For 

 chlorophyll does not usually occur, staining the whole pro- 

 toplasm of the cell after the fashion of a dye ; but when the 

 cell is examined by the microscope, under a power of a quarter 

 of an inch objective, it is seen that the green colouring matter 

 occurs in grains or granules of a rounded or angular form ; and 

 on treating these grains, granules, or corpuscles, with reagents 

 such as alcohol and ether, it has been found possible to remove 

 the colouring matter and leave the isolated grains or granules 

 unstained. These isolated grains are nothing but living pro- 

 toplasm, and it is in them that the first formation of starch from 

 carbon and the elements of water takes place under the action 

 of light. 



If we place a plant in the light, we find that minute starch 

 grains appear in these chlorophyll corpuscles of the leaves ; if 

 we then place it in darkness, we no longer find starch grains 

 present in this position : the starch grains, then, which were 

 formed in the light have been conveyed away in the dark. In 

 what way is this starch conveyed away from the leaves and 

 transmitted to the various parts of the plant ? The cells of the 

 leaves are completely closed, and starch cannot be conveyed 

 away bodily from one part of the plant to another. Starch is 

 also practically insoluble in water ; hence, it must have been 

 converted into some soluble substance, and one, moreover, 

 which will pass by diffusion through the cell-wall. In the 

 bodies of animals processes of conversion of this kind are always 

 going on — e. g., in the stomach, starch is converted into sugar 

 under the action of certain bodies called ferments, and analogy 

 leads us to believe that the same is the case in plants : that is 

 to say, starch is converted into sugar, and into the particular 

 form of glucose which is a substance soluble in water by the 

 action of unorganized ferments ; and then this sugar formed by 

 the process of fermentation is removed from the leaves and 

 carried away in solution to the other parts of the plant. These 

 ferments are not only supposed to exist in plants, they have 

 actually been discovered to do so in the cells of buds and leaves. 



