I02 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



tendency, which one would expect to find firmly fixed, to 

 develop into independent plants, green and manufacturing 

 their own foods. But these young suckers, originating when 

 the weather is too cool for chlorophyll and chromatophore 

 formation, though warm enough for a certain amount of 

 growth, beginning with white leaves and growing well 

 enough during the season without manufacturing food for 

 themselves, form no chlorophyll even in the leaves and 

 internodes later developed. The effect of low temperatures 

 when the first leaves were forming was either upon the 

 protoplasm itself, preventing its forming chromatophores and 

 chloroph3dl, or upon the chemical processes by which these 

 organs and substances are produced. One naturally as- 

 sumes the former — that the powers of the protoplasm are 

 lessened by low temperatures. In these first leaves, the 

 protoplasm is prevented by the cold from following its in- 

 herited tendency to produce chromatophores and chloro- 

 phyll. In th^ leaves later formed, the inherited tendency 

 to form chromatophores and chlorophyll is not interfered 

 with by cold, but it does not cause these leaves to become 

 green. They do not need to be green; the plant obtains 

 food enough without turning green and manufacturing its 

 own food. The inherited tendency is not aroused by hun- 

 ger into action. The stimulus needed to set it in operation 

 not being given, the inherited tendency remains dormant as 

 long as the white suckers remain connected with the parent. 

 The parasitic habit forced upon the young white sucker by 

 its inability to manufacture its own food, and the parasitic 

 characters assumed by the young white sucker, are continued 

 as the plant grows. Continued healthy existence in spite of 

 inability to manufacture food induces in new leaves and 

 cortex those characters found in the earlier and older ones. 

 Environment, the influence of certain stimuli, induce a re- 

 action ordinarily characteristic of species of plants which 

 have been parasitic for generations. 



The white redwood serves as an index of the relative 

 powers of heredity and of environment, or, more definitely, 

 of heredity and of the influence of, and the power of 



