324 DARWINISM chap. 



and as the chief use of these is to attract insects, they could 

 hardly have existed in primitive flowers. 1 We know, moreover, 

 that when the petals cease to be required for the attraction of 



1 The Rev. George Henslow, in his Origin of Floral Structures, says : 

 " There is little doubt but that all wind-fertilised angiosperms are degradations 

 from insect - fertilised flowers. . . . Poterium sanguisorba is anemophilous ; 

 and Sanguisorba officinalis presumably was so formerly, but has reacquired 

 an entomophilous habit ; the whole tribe Poteriese being, in fact, a degraded 

 group which has descended from Potentillese. Plantains retain their corolla 

 but in a degraded form. Juncese are degraded Lilies ; while Cyperacese and 

 Gramineae among monocotyledons may be ranked with Amentiferae among 

 dicotyledons, as representing orders which have retrograded very far from 

 the entomophilous forms from which they were possibly and probably de- 

 scended" (p. 266). 



" The genus Plantago, like Thalictrum minus, Poterium, and others, well 

 illustrate the change from an entomophilous to the anemophilous state. 

 P. lanceolata has polymorphic flowers, and is visited by pollen-seeking insects, 

 so that it can be fertilised either by insects or the wind. P. media illustrates 

 transitions in point of structure, as the filaments are pink, the anthers 

 motionless, and the pollen grains aggregated, and it is regularly visited by 

 Bombus terrestris. On the other hand, the slender filaments, versatile anthers, 

 powdery pollen, and elongated protogynous style are features of other species 

 indicating anemophily ; while the presence of a degraded corolla shows its 

 ancestors to have been entomophilous. P. media, therefore, illustrates, not 

 a primitive entomophilous condition, but a return to it ; just as is the case 

 with Sanguisorba officinalis and Salix Caprea ; but these show no capacity of 

 restoring the corolla, the attractive features having to be borne by the calyx, 

 which is purplish in Sanguisorba, by the pink filaments of Plantago, and by 

 the yellow anthers in the Sallow willow" (p. 271). 



" The interpretation, then, I would offer of inconspicuousness and all kinds 

 of degradations is the exact opposite to that of conspicuousness and great 

 differentiations ; namely, that species with minute flowers, rarely or never 

 visited by insects, and habitually self-fertilised, have primarily arisen through 

 the neglect of insects, and have in consequence assumed their present floral 

 structures " (p. 282). 



In a letter just received from Mr. Henslow, he gives a few additional 

 illustrations of his views, of which the following are the most important : 

 " Passing to Incompletse, the orders known collectively as ' Cyclospermeae ' 

 are related to Caryophyllese ; and to my mind are degradations from it, of 

 which Orache is anemophilous. Cupuliferae have an inferior ovary and rudi- 

 mentary calyx-limb on the top. These, as far as I know, cannot be inter- 

 preted except as degradations. The whole of Monocotyledons appear to me 

 (from anatomical reasons especially) to be degradations from Dicotyledons, 

 and primarily through the agency of growth in water. Many subsequently 

 became terrestrial, but retained the effects of their primitive habitat through 

 heredity. The 3-merous perianth of grasses, the parts of the flower being in 

 whorls, point to a degradation from a sub -liliaceous condition." 



Mr. Henslow informs me that he has long held these views, but, as far as 

 he knows, alone. Mr. Grant Allen, however, set forth a similar theory in his 

 Vignettes from Nature (p. 15) and more fully in The Colours of Flowers 

 (chap, v.), where he develops it fully and uses similar arguments to those of 

 Mr. Henslow. 



