Red sea-weeds 



COLOR 185 



far as composition and use are taken into ac- 

 count. 



The color of the red seaweed is due to the 

 presence of phA^co-erythrophyll which is pres- 

 ent in the protoplasm associated with chloro- 

 ph\dl. It is to be noted here that the antho- 

 cyansare dissolved in the cell sap of the plants 

 in which they occur. The gradation of the 

 amount of phyco-erythroph3dl at different 

 depths suggests that the color serves the pur- 

 pose of converting light into heat useful in 

 promoting metabolism. The presence of a 

 red pigment in Haematococcusand the resting 

 spores of many algcC is doubtless a protection 

 against the disintegrating effect of light on 

 chlorophyll and protoplasm. 



Effects quite as marked as those produced 

 by colors may be brought about by the pres- 

 ence or mechanical arrangement of certain Markings not 

 cells. The shade of green presented by a leaf ^"^ *° ^°^°^ 

 will be determined by the number and posi- 

 tion of the chlorophyll bodies with respect to 

 the surface. Coatings of wax, min-eral salts, 

 and hairs also, bring about modifications. 

 The silvery or silver gray or whitish appear- 

 ance of surfaces is due to the loose arrange- 

 ment of the sub-epidermal cells forming great 

 intercellular spaces, The multifold refractions 

 offered by the numerous free walls of the cells 

 prevents the penetration of the leaf by light. 



