STARCH AND SUGAR; CHLOROPHYLL. J 'I 



which has passed in solution. Thus the functions of the chloroplast are 

 twofold, that of photosynthesis and the formation of starch grains. 



149. In the translocation of starch when it becomes stored up in various 

 parts of the plant, it passes from the state of solution into starch grains in 

 connection with plastids similar to the chloroplasts, but which are not green. 

 The green ones are sometimes called chloroplasts, while the colorless ones 

 are termed leucoplasts, and those possessing other colors, as red and yellow, 

 in floral leaves, the root of the carrot, etc., are called chromoplasts. 



150. Photosynthesis in other than green plants.- While carbohydrates 

 are usually only formed by green plants, there are some exceptions. Ap- 

 parent exceptions are found in the blue-green alga 3 , like oscillatoria, nostoc, 

 or in the brown and red sea weeds like fucus, rhabdonia, etc. These plants, 

 however, possess chlorophyll, but it is disguised by another pigment or 

 color. There are plants, however, which do not have chlorophyll and yet 

 form carbohydrates with evolution of oxygen in the presence of light, as 

 for example a purple bacterium, in which the purple coloring substance 

 absorbs light, though the rays absorbed most energetically are not the 

 red. 



151. Influence of light on the movement of chlorophyll bodies. In fern 

 prothallia. If we place fern prothallia in weak light for a few hours, and 

 then examine them under the microscope, we find that the most of the chloro- 

 phyll bodies in the cells are arranged along the inner surface of the hori- 

 zontal wall. If now the same prothallia are placed in a brightly lighted 

 place for a short time most of the chlorophyll bodies move so that they are 



Fig. 70. Fig. 71- 



Cell exposed to weak diffused light Same cell exposed to strong light, 



showing chlorophyll bodies along the showing chlorophyll bodies have 



horizontal walls. moved to perpendicular walls. 



Figs. 70, 71. Cell of prothallium of fern. 



arranged along the surfaces of the perpendicular walls, and instead of hav- 

 ing the flattened surfaces exposed to the light as in the former case, the 

 edges of the chlorophyll bodies are now turned toward the light. (See figs. 



