146 PHYSIOLOGICAL BOTANY. 



373. Chlorophyl. In the living cells of those 

 parts of plants exposed to sunlight, granules appear, 

 resembling protoplasm grains in all respects except 

 color. These minute bodies are green, and furnish the 

 green color to leaves and all other green parts of 

 plants; the name applied to these granules is due to 

 their color, and as the leaf is the most conspicuous 

 green part of the plant, the term Chlorophyl (Leaf 

 Green) has been applied to this green color. Some 

 authors have called chlorophyl grains stained proto- 

 plasm, viewing chlorophyl as the stain, and the 

 chlorophyl granule as colored protoplasm (Figs. 466, 

 467). 



374. Starch is a most important plant product, 

 and is formed by the action of protoplasm and chloro- 

 phyl under sunlight ; it is found sparingly in the 

 leaf, and when more than enough to supply the plant's 

 daily wants is produced, the surplus is stored up in 

 some other part of the plant, as the tuber of the 

 Potato, the grains of Wheat, and other cereals, in 

 which form it is utilized for animal food. Its com- 

 ponent parts are identical with those of cellulose. 



Forms of starch-grains are shown in 

 Figs. 469-473. The form of starch- 

 grains is very various, differing in dif- 

 ferent plants, and 

 even in the same 

 parts of the same 

 plant. Fig. 473, 



469, Cells of Potato containing starch-grains. 470, Starch grains A /y 7) ^ fr /7 flrP 

 from the Potato. 471, from the E. Indian Arrowroot. 472, Starch - -) "Tl Yf ;V* u ^ J/J ' 

 granules from W. Indian Arrowroot. Starch-grainS f rOm 



a grain of Indian Corn. Fig. 473, B, shows starch- 

 grains from a grain of Wheat; these are more nearly 





