PROTOPLASM AND PLANT-CELLS. 



13 



(1) Masses of protoplasmic matter, usually small and 

 rounded, which are stained green by chlorophyll ; these are 

 called chloroplasts, or in higher plants chlorophyll-granules 

 (Pig. 8). The chlorophyll is a stain made by the cell itself, 

 the chloroplast being only the portion of the protoplasm 

 stained by it. The two may be separated by alcohol, which 

 dissolyes out the chlorophyll, leaving the chloroplast as a 

 colorless mass. Chloroplasts occur in the cytoplasm of cells 

 in all green parts of plants, and increase in numbers by fis- 

 sion. In some lower plants they are star-shaped or bandlike, 

 but in all higher plants they are small, rounded bodies. 

 They develop chlorophyll in the light 

 only, and in prolonged darkness even that 

 which is already formed disappears. 

 Parasites and saprophytes generally pro- 

 duce no chlorophyll. 



(3) In many flowers and fruits the 

 chromatophores are needle-shaped or 

 angular, and of a yellow or red color. 

 These are known as chromoplasts, and 

 are supposed to be related to chloroplasts, 

 but they are stained with xanthophyll 

 instead of chlorophyll. They occur, 

 also, in the roots of some plants, as for „ „ „ 



' ^ Fig. 8.— Two ceU3 



example the carrot, where the staining °Lfa)fmagnffled ™ 

 matter is carotin. i"lSoplasts.'^TrSI 



(3) In parts of plants not exposed to straaburger.) 

 the light the chromatophores are colorless, and bear the 

 name of leucoplasts. On exposure to the light they 

 become green by the formation of chlorophyll, thus de- 

 veloping into chloroplasts. 



Practical Studies. — (a) Mount a leaf of a moss and examine for 

 cUoroplasts. 



