insect Vfsftors. 213 



and even with those species which are capable 

 of fertilizing themselves without any aid there 

 can be no cross-fertilization, and this, as we 

 know, is a serious evil in most cases.* Aristotle 

 noticed that all kinds of bees and certain other 

 insects usually visit the flowers of the same spe- 

 cies as long as they can before going to another 

 species, and it is a well-established fact, readily 

 observable in any flower-garden, that bumble- 

 and hive-bees will visit plants of the same species 

 of opposite colors ; but I am puzzled to account 

 for the marked preference in the instance cited. 

 The plants referred to are situated in a long row, 

 and are considerably more numerous than any 

 other variety. Yet this fact would hardly ac- 

 count for the preference I have noticed, for sev- 

 eral seasons. 



I think we do not accord the Germans suffi- 

 cient credit for what they have accomplished by 

 their painstaking and invaluable investigations in 

 the interest of plant knowledge. The ear-split- 

 ting terms they have to make use of and con- 

 tend with ! Just think of having to know that 

 the " Sauerstoffabscheidung " of green plants is 

 an " Ernahrungsvorgang," and that the latter is 

 closely connected with the " Lichtvermittelter 



* Self- and Cross-Fertilization, chapter xi. 



