FORMATION OF ORGANIC MATTER FROM THE 

 ABSOEBED INOEGANIC FOOD. 



1. CHLOEOPHYLL AND CHLOROPHYLL -GEANULES. 



Chlorophyll-granules and the sun's rays. — Chlorophyll-granules and the green tissue under the 

 influence of various degrees of illumination. 



CHLOEOPHYLL -GEANULES AND THE SUN'S EAYS. 



In the former section of this book it has been described how everything which 

 serves as food for plants is conducted to the green tissues. Food-salts, food-gases, 

 and water arrive at the same goal by the most diverse contrivances — to the green 

 cells as those places where the raw material is worked up and organic substances 

 prepared from it; to the place of need where the materials for further building and 

 development, for rejuvenescence, multiplication, and reproduction of the plants in 

 question have to be provided. The question how living plants manufacture organic 

 substances in the green cells from the raw materials which stream to them, particu- 

 larly from the raw food-sap and carbonic acid, must now be discussed. 



First, it should be remembered that the formation of organic materials always 

 commences with the decomposition of the absorbed carbonic acid. This decom- 

 position, however, is only carried on by that protoplasm in which are imbedded 

 chlorophyll-granules. The protoplasm in qiiestion can only accomplish the indi- 

 cated task by the help of these structures, and the chlorophyll -granules are 

 therefore really the organs on which everything depends. It is in them that 

 those remarkable processes are carried on, upon which depends the renewal, and 

 ultimately the existence, of all life. The description of these organs must, there- 

 fore, precede all further discussion. 



Having regard to the importance of their function, the structure of the 

 chlorophyll -granules appears to be simple enough. It is possible that later 

 researches, with instruments and methods of observation more perfect than those 

 now at our disposal, will furnish more accurate details about their minute structure, 

 and particularly as to their dissimilarity from the protoplasm in which they are 

 imbedded. In the meantime, only this much is known — that the ground-work of 

 the chlorophyll-granules diflfers but little in its structure and composition from the 

 surrounding protoplasm. Like all sharply-defined protoplasmic bodies, chlorophyll- 

 granules exhibit a pellicle-like thickened outer layer; the inner portion, on the 



