472 BEES AND FLOWERS. 



most, cases of plants with the bisexual flowers. For there is that 

 curious fact developed by Darwin and by many botanists, that 

 Avhen pollen of the same flower and pollen from another flower of 

 the same species are j^laced simultaneously on the pistil of an her- 

 maphrodite flower the latter will germinate more rapidly and will 

 in most cases determine the fertilization. Clearly this must render 

 crossing almost inevitable. Although the pollen of an hermaphrodite 

 may fall directly on the contiguous pistil it is more than likely that 

 a pull' of wind or the visit of an insect will place on the same stigma 

 some grains of foreign pollen in time to anticipate it. 



But returning to the bees. We have shown the predominance of 

 cross fertilization among the flowering plants and pointed out the 

 advantages resulting to the plant. Now, if it can be demonstrated 

 that the bees are the most active agents in this cross fertilization 

 there will be no longer any doubt as to their usefulness. 



All flowers, whether their reproductive organs mature simultane- 

 ously or at different times, give \\y> their pollen to insects or to the 

 Avind f)r in a very great majority of cases to both. Plants whose fer- 

 tilization depends entirely upon the action of the wind are called 

 anemophiles. Lacking insect allies, all the primitive Phanerogams 

 were anemophile exclusively, iind have tran?;mitte(l that characteristic 

 to their descendants; they are represented by the Gymnosperms with 

 unisexual flowers, of which the conifers are our best known type. 

 Since the wind is an absolutely blind instrument so much of the pollen 

 is lost that these anemophiles must produce considerable quantities. 

 Walk through the woods at Vincennes a few weeks hence, and if the 

 wind be right you will find the ground tinged with yellow by the 

 pollen of the massive pines. 



However, plants exclusively anemophile are few ; the greater 

 part of the flowering plants disseminate their pollen both by the wind 

 and by insects. Tliese two agents of distribution arc l)y no means 

 equally efficient; the wdnd blows the pollen dust about at random, 

 while the insects carry it direct to the i)istils of the flowers the}' fre- 

 quent. 



Darwin and numerous others found l)y experiment that at least 

 half of llie plants Ave grow are rundered entirely or partially sterile 

 by being covered with a gauze to keep aAvay the insects. 



Generally speaking, the plants which require most insistently the 

 visit of insects are those whose flowers are the most irregularly 

 formed. INIany of tliem lunc tlicir tlowers so arranged (hat the insect 

 is forced in his attem])ts to reach tlie nectar to cover himself with pol- 

 len and thus produce cross fertilization. In no case is this more strik- 

 ing than in that of the sages; in these abnormal T^abiates two stamens 

 have disai)peared and the othei- two have dwindled to a long con- 

 nective loaded with a pollen sac. Entering the throat of the flower 



