472 BEES AND FLOWERS. 



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

 curious fact developed by Darwin and b}^ many botanists, that 

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

 the same species are placed simultaneousl}^ on the pistil of an her- 

 ]na])hrodite flower the latter will germinate more rapidly and will 

 in most cases determine the fertilization. Clearly this must render 

 crossing almost ineyitable. Although the pollen of an hermaphrodite 

 may fall dii'cctly on the contiguous pistil it is more than likely that 

 a puit' of wind or the yisit 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 floAvering 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 dilferent times, give u]) their pollen to insects or to the 

 Avind or in a very great majority of cases to both. Plants whose fer- 

 tilization depends entirely u])on the action of the wind are called 

 anemophiles. Lacking insect allies, all the primitive Phanerogams 

 were anemoiDhile exclusively, and have transmitted that characteristic 

 to their descendants; the}' 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. 

 AValk through the Avoods at Vincennes a few weeks hence, and if the 

 wind be right you will find the ground tinged Avith yelloAV by the 

 pollen of the massive pines. 



TIoAveATr, plants exclusiA-ely anemophile are few ; the greater 

 part of the floAvering plants disseminate their pollen both by the Avind 

 and by insects. These tAvo agents of distribution arc l)y no means 

 equalh^ efficient; the Avind bloAvs the pollen dust about at random, 

 while the insects carry it direct to the pistils of the (lowers they fre- 

 quent. 



DarAvin and numerous others found by experiment that at least 

 half of the plants we grow are randered entirely or partially sterile 

 by being coA-ered with a gauze to keep aAvay the insects. 



Generally speaking, the plants Avhich require most insistently the 

 visit of insects are those Avhose floAvers are the most irregularly 

 formed. Many of tliem have their floAvers so arranged that the insect 

 is forced in his attempts to reach tlic nectar to coA^er himself Avith pol- 

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

 ing than in that of the sages; in these abnormal Labiates tAvo stamens 

 have disappeared and th.e other two have dAvindled to a long con- 

 nective loaded Avith a pollen sac. Entering the throat of the floAver 



