12 MANURES FOR FRUIT TREES 



matter in the leaves, (2) light, and especially 

 certains rays of white light, and (3) iron com- 

 pounds. 



The green pigment known as chlorophyll occurs 

 in all plants except the fungi, and is frequently 

 associated with other pigments which may mask 

 it, or may replace it in special parts of the plants. 

 The chief pigment associated with chlorophyll is 

 xanthophyll (a yellow lipochrome), and the mixing 

 or blending of these two pigments in different 

 proportions gives most of the various tints or 

 shades of leaves. There may be many other 

 pigments (lipochromes and non-lipochromes) asso- 

 ciated with chlorophyll, but the function of 

 xanthophyll, and probably of other pigments, is 

 unknown. It may be that they protect the 

 protoplasm from the injurious effect of certain 

 rays of white light (rays known and unknown) 

 by absorbing them, or that they assist in the 

 function of assimilation, or that they are instru- 

 mental in the polymerisation of formaldehyde and 

 its conversion into starch. 



Chlorophyll, according to the investigations of 

 the older workers, was stated to be a mixture of 

 phylloxanthin (yellow) and phyllocyanin (blue). 

 Schunck stated that acids transform "leaf-green" 

 into phyllocyanin and phylloxanthin ; that alkalis 



