BOX.— Vol. II.] PEIRCE— SEQUOIA SEMPERVIRENS. 99 



records are kept. I therefore cannot tell the temperatures 

 prevailing when these buds were forming in darkness under- 

 ground. The darkness is of no significance, for all suckers 

 begin in darkness and ordinarily their leaves are then green. 

 Insufficient warmth seems, then, to be the reason why the 

 chromatophores and the chlorophyll pigments do not form 

 in the cells of these growing leaves. 



Frank (1895) says that it frequently happens that plants 

 with leaves white because of cold at the time of their form- 

 ation often retain these white leaves- even into the summer, 

 subsequent warmth being insufficient to stimulate to chro- 

 matophore and chlorophyll formation. On all such plants, 

 however, the leaves developed later than the white ones, 

 and when the temperature is higher, are green. If this 

 were not the case, the plants would die. 



In the white redwood we have a different state of affairs. 

 Although the first leaves borne on a shoot of one year's 

 growth may all have been formed in the cold, late in the 

 previous year, and therefore may not be able to turn green, 

 the leaves later formed, and the internodes forming or at 

 least elongating later, when there is sufficient warmth, one 

 would expect to find green. On the contrary, once started 

 as white redwoods, the suckers continue white as to leaves 

 and young cortex for an indefinite time. 



The differences in the color, and in the condition of the 

 chromatophores between the white redwood leaves from 

 near the La Honda road, and those from near Gilroy, may 

 be accounted for thus. It is probable that near Gilroy, at 

 least in the spot where the white redwoods grow, the tem- 

 perature is not so low as on the exposed summit crossed by 

 the La Honda road. While the temperature is low enough 

 to prevent chlorophyll formation, it is not low enough com- 

 pletely to suppress the formation of chromatophores, and 

 by no means low enough to interfere with growth. Slight 

 variations in low temperatures at the times when the buds, 

 from which suckers spring, are forming, might permit the 

 formation of green buds, of yellowish buds with rudimentary 

 chromatophores, and of white buds with no chromatophores 



(2) March 18, 190 1. 



