128 HETEROSTYLED DIMORPHIC PLANTS. CHAP. III. 



styled, and the divergent stigmas are likewise rather 

 larger. The anthers in the long-styled form stand 

 low down within the corolla, and are quite hidden. 

 In the short-styled flowers the anthers project just 

 above the mouth of the corolla, and the stigma stands 

 low down within the tube. Considering the great 

 difference in the length of the pistils in the two forms, 

 it is remarkable that the pollen-grains differ very little 

 in size, and Fritz Miiller was struck with the same 

 fact. In a dry state the grains from the short-styled 

 flowers could just be perceived to be larger than those 

 from the long-styled, and when both were swollen by 

 immersion in water, the former were to the latter in 

 diameter in the ratio of 100 to 92. In the long-styled 

 flowers beaded hairs almost fill up the mouth of the 

 corolla and project above it; they therefore stand 

 above the anthers and beneath the stigma. In the 

 short-styled flowers a similar brush of hairs is situated 

 low down within the tubular corolla, above the stigma 

 and beneath the anthers. The presence of these beaded 

 hairs in both forms, though occupying such different 

 positions, shows that they are probably of considerable 

 functional importance. They would serve to guard 

 the stigma of each form from its own pollen; but in 

 accordance with Professor Kerner's view * their chief 

 use probably is to prevent the copious nectar being 

 stolen by small crawling insects, which could not render 

 any services to the species by carrying pollen from one 

 form to the other. 



The flowers are so small and so crowded together 

 that I was not willing to expend time in fertilising 

 them separately; but I dragged repeatedly heads of 

 short-styled flowers over three long-styled flower-heads, 



* ' Die Schutzmittel der Bliithen gegen unberufene Gaste,' 1876, 



