Chap. III. ERYTHROXYLUM. 121 



as 100 to 75 : here, then, the grains from the short-styled 

 form were considerably smaller than those from the long- 

 styled, which is the reverse of what occurred in the former 

 instance, and of what is the general rule with heterostyled 

 plants. The whole case is perplexing in the highest de- 

 gree, and will not be understood until experiments are tried 

 on living plants. The greater length and more papillose 

 condition of the stigma in the short-styled than in the 

 long-styled flowers, looks as if the plant was heterostyled ; 

 for we know that with some species — for instance, Leu- 

 cosmia and certain Rubiaceae — the stigma is longer and 

 more papillose in the short-styled form, though the re- 

 verse of this holds good in Gilia, a member of the same 

 family with Phlox. The similar position of the anthers in 

 the two forms is somewhat opposed to the present species 

 being heterostyled ; as is the great difference in the length 

 of the pistil in several short-styled flowers. Eut the ex- 

 traordinary variability in diameter of the pollen-grains, 

 and the fact that in one set of flowers the grains from the 

 long-styled flowers were larger than those from the short- 

 styled, is strongly opposed to the belief that Phlox subulata 

 is heterostyled. Possibly this species was once heterostyled, 

 but is now becoming sub-dioecious; the short-styled plants 

 having been rendered more feminine in nature. This 

 would account for their ovaries usually containing more 

 ovules, and for the variable condition of their pollen- 

 grains. Whether the long-styled plants are now changing 

 their nature, as would appear to be the case from the varia- 

 bility of their pollen-grains, and are becoming more mas- 

 culine, I will not pretend to conjecture; they might re- 

 main as hermaphrodites, for the co-existence of herma- 

 phrodite and female plants of the same species is by no 

 means a rare event. 



Erythroxylum [sp.?] (Erythroxylid^e). 



Fritz Muller sent me from South Brazil dried flowers 

 of this tree, together with the accompanying drawings, 

 which show the two forms, magnified about five times, with 

 the petals removed. In the long-styled form the stigmas 

 project above the anthers, and the styles are nearly twice 

 as long as those of the short-styled form, in which the 



