88 THE POPULAR SCIENCE MONTHLY. 



instance, in the fly-flora of New Zealand and the bird-flora of 

 Juan Fernandez. Indeed, M. Sevali claims that grasshoppers 

 fertilize the Leguminosce of New Zealand, and Delpino thinks 

 that Ehodea, which is self-sterile, depends for the production of 

 seeds upon snails ! 



In order that the selection of insects may cause change in the 

 characteristics of flowers, two things are necessary on their part. 

 Their visits must be methodic — we have seen that they are so for 

 the most highly specialized groups. They must be frequent. 

 Any one who has followed a " busy bee " for half a day will be 

 ready to witness that they are. A bumble-bee in mid-Sweden 

 was seen to suck honey from the monk's-hood at the rate of from 

 960 to 1,200 visits an hour ; a butterfly visited 194 violets in six 

 minutes and three quarters; 2,155 bees were actually counted 

 on a single head of the " honey plant " between 5 a. m. and 7 

 P. M., the thirty heads of one plant furnishing supplies for over 

 64,000 bees in one day. Some one has calculated that 2,500,000 

 visits are made to the red clover for every pound of honey. The 

 United States, by the census report of 1880, produced 25,743,208 

 pounds, representing, therefore, 64,358,020,000,000 visits of hive- 

 bees alone in this country, and this includes only that used for 

 economic purposes, not at all that kept by the bees themselves. 

 Add to these visits those of the wild bees, bumble-bees, flies, but- 

 terflies, birds — which are by no means indiscriminate — and surely 

 here is a force whose selective influence must be enormous, which 

 might easily bring about a comparatively rapid evolution. May 

 not this shed some light on the mystery of the rapid floral de- 

 velopment of Phanerogams after their initiation in geologic 

 ages ? Gardeners and farmers have, in relatively short time, been 

 able to introduce and establish new forms of flowers, fruits, and 

 grains, but the results of the industry of this vast army of 

 workers must have been inconceivably larger. 



This brings us to the other side of the question. Something is 

 necessary on the part of the flowers, which must themselves be 

 capable of great variation in color and form in order that selec- 

 tion may have material to choose from. Every one knows that 

 they are so. As the latest production of the vegetable world they 

 are the most plastic, the most easily influenced by alterations of 

 the environment. (Old traits are not easily changed.) Many of 

 them in their individual development pass through a series of 

 changes which sometimes, perhaps, represents the color phylo- 

 geny of the species — e. g., several species of honeysuckle are 

 white the first day, become yellow the second, wither the third. 

 A certain hibiscus is white in the morning, rose-color during mid- 

 day, and red in the evening, repeating these transformations each 

 day as long as the flower lasts. Such changes are supposed to be 



