90 Kraemer : Color in plants 





Summary 



My observations on the subject of color in plants, may be 

 summarized as follows : 



i. There are two classes of color-substances til plants : 



(a) Organized color-principles which are characterized by be- 

 ing an organic part of the plastid body, and insoluble in water or 

 dilute alcohol, but soluble in xylol and similar solvents. 



(b) Unorganized color-principles, which are not a fundamental 

 or organic part of the plastids, and occur either in the vacuoles of 

 the cells of higher plants as well as fungi, or in the vacuolules of 

 the plastids of the brown and red sea-weeds. They are further dis- 

 tinguished by being soluble in water and dilute alcohol, and insolu- 

 ble in xylol and similar solvents. 



2. The plastid pigments, or organized color-substances, may 

 be divided into three groups according to their origin. 



(a) Chlorophyl, which occurs in the chloroplastids in both 

 higher and lower plants, and is especially distinguished by the ap- 

 pearance of its solution when viewed by means of the spectroscope. 



(d) Chromophyl, which occurs in the chromoplastids, plastid 

 bodies which are peculiar to the higher plants. The chromoplas- 

 tids together with the accompanying pigment are found in many 

 flowers, in certain roots, and follow the development of the chloro- 

 plastids in the ripening of many fruits. 



( 



Sp 



romo 



foetida. It is distinguished from cl 

 greenish when reduced with zinc. The etioplastid is distinguished 

 from the chromoplastid by the fact that its development precedes 

 that of the chloroplastid. 



3. In the photosynthesis of the chloroplastid, unorganized 

 color-substances may be produced in comparatively large amount, 



as in 



(a) Early spring foliage ; 



(6) The foliage of alpine plants as well as autumnal foliage ; 



(c) The brown and red marine algae ; 



(d) The foliage of certain species or varieties of rose, beech, 

 nasturtium ; etc. 



4. Unorganized or cell-sap color-substances are distributed 



