THE MOST IMPORTANT SPECIES. 



21 



These dry stems are not unlike the woody base, which always carries 

 less rubber than the green middle portions. 



TABLE 1. Chemical analyses of Asclepias subulata. 1 



1 In this and in all following tables the acetone extract includes the resins and other acetone- 

 soluble substances, whereas the benzene extract is taken to represent the amount of crude rubber, 

 although a negligible amount may have been extracted with the acetone (see p. 14). With 

 few exceptions the percentages are based on absolutely dry weight of the plant parts analyzed. 



2 Growing in depression. 3 From granite slope. 4 Estimated weight, 27 pounds, green. 



