Evolution of Veyetal Life. 131 



for the pollen of a plant to reach the stigma of the same, 

 but that fertilization is effected by bees, butterflies, and 

 other insects, which bring pollen from other plants while 

 seeking for nectar, the flowers being usually so constructed 

 as to make it impracticable for them to withdraw without 

 carrying away the pollen-masses from the anthers, or to en- 

 ter the nectaries of other flowers without placing these 

 masses upon the stigmas. The book in which he explains 

 this process, you will find most fascinating. 



Among the trees upon my rocky hillside, I found last 

 summer numerous specimens of a showy, rose-purple or- 

 chid, one of the Cypripediums, called indifferently, wild 

 lady-slipper, Koah's-ark, or moccasin flower. If I were 

 to tell the whole truth, I might have to confess that it was 

 partly because of its presence that I was induced to buy the 

 property. This belongs to a genus which Darwin believes, 

 from its structure, to have been one of the earlier forms, 

 in which the fertilization of the flower by its own pollen, 

 or that of another plant, depends upon whether the insect 

 enters it first by one of the side notches or by that in the 

 middle. In most orchids, there is no option, the flower 

 must be fertilized from another ; and this is the case with 

 one of the most attractive of the smaller species, the lovely 

 little white spiranthes, or ladies'-tresses, of our meadows. 



Perhaps I might venture to mention just one other in- 

 stance of complicated relations, of especial interest to our 

 single sisters. Darwin found that the fertilization of red 

 clover depends largely, if not solely, upon the visits of 

 humble-bees ; that the number of bees is greatly reduced 

 in a district where field-mice are numerous ; and that the 

 number of field-mice is dependent upon the number of cats. 

 Huxley carries the chain one link further, and throws out 

 the suggestion that it is the abundance, or otherwise, of the 

 old-maids who cherish the cats, upon which rests the fate 

 of the red clover, and indeed, as Carl Vogt says, the fate 

 of the English race, whose staple food is the beef grown 

 from the red clover. So you see that starting with the 

 women, by a devious course we reach the men at last. 



Why do these changes of form occur ? I cannot tell you : 

 no man can to-day tell you. We only know that variations 

 are constantly taking place ;} that one form is developed 

 from another ; that these variations result from tendencies 



