1909] HILL— POLLINATION IN LIN ARIA 455 



during the operation. That which was left on the stigma of the 

 flowers by the entering and withdrawing of the bees was the extent 

 of pollination as viewed by Sprengel. It was an aid to the plant 

 in securing fertilization indispensable in the case of some, but the 

 full significance in the economy of its life was left for others, especially 

 for Darwin, to show. Sprengel clearly describes the process in 

 the text and figures illustrating Antirrhinum Linaria, 2 and in reading 

 his book one wonders at the sagacity of the man so far in advance 

 of his time. The relative position of anthers and stigma, coupled 

 with their simultaneous maturing, can also, as stated by Hermann 

 Muller, lead just as readily to self-pollination, and in the absence 

 of visits by insects makes it the only possible means of fruitfulness. 3 



lp 



Muller 



The common toad-flax of Europe, L. vulgaris, has been natural- 

 ized in this country, and is most frequently seen along roadways 

 or in waste grounds. Two native species are generally recognized, 

 L. canadensis (L.) Dumort. and L. fioridana Chapm. A third, L. 

 texana Scheele, is made by some, but by others is considered a large- 

 flowered form of L. canadensis. This seems to be the only one that 

 has been studied with regard to its pollination. It is widely distrib- 



dry 



ip 



like these it is adapted to pollination by insects. Charles Robert- 

 son observed the flowers in Florida, and found that they were visited 

 by bees, but more often by butterflies. He says of them: "The spur 

 is very slender and the tube has become so contracted that bees can 

 only insert their tongues, and butterflies cannot suck without touch- 

 ing the anthers and stigma The palate, which in L. vulgaris 



permits the visits of bumble-bees only, seems to have lost its function, 

 for it is so weak that it entirely fails to exclude butterflies or even 

 flies." 5 Where I have noticed it in the dune region near Chicago, 



* Sprengel, Das entdeckte Geheimniss der Natur fan Bau und in der Befruch- 

 tung der Blumen 317. pi. !?■ fig s - 5~ IT > T 4> l8 > *9- x 793- 



3 Muller, Die Befruchtung der Blumen .lurch Insekten 279. 1873. 



, Alpenblumen 275. 1881. 



s Robertson, Zygomorphy and its causes. III. Box. Gazette 13:228. 1888. 



