480 



BEES AND FLOWERS. 



sep 



from the Italuiii variety with its yellow fuzz, l)ut both are even 

 still farther renuned from the tropical bees, especially those of the 

 islands. Careful study is necessary to assign all these varieties to the 

 same type; there are thirty forms, most of which lia^e been taken by 

 many zoologists for distinctive species. 



To-day hardly anyone disputes the adaptation of bees to food- 

 gathering in the flowers, but the adaptation of the flowers to these 

 visitors remains an object of heated controversy. One of the schools, 

 headed by Darwin and Sir John Lubbock, exaggerates the influence, 



while the other, M. Gaston Bonnier 

 and his pupils, denies its existence. 



Before entering upon this deli- 

 cate question let me recall the pas- 

 sage in which Sir John Lubbock has 

 lixed its extent and portent. " Not 

 only,'' says he, " have the form and 

 the colors, the bright tints, the sweet 

 odors, and the nectar been gradually 

 developed by force of an uncon- 

 scious selection exercised by the in- 

 sects, but even the arrangement of 

 the colors, the shape, the size and 

 the position of the petals, the rela- 

 tive position of the stamens and 

 pistil, are all determined by the 

 visits of the insects, and in such a 

 way as to assure the great object 

 (fertilization) that these visits are 

 intended to effect." 



In his beautiful work on tlu> nec- 

 taries, Gaston Bonnier has fur- 

 nished numerous irrefutable argu- 

 ments against the theory that that 

 nectar is an adaptation to attract 

 insects. According to this author the nectaries are organs of reserve 

 where the cane sugar, dissolved in the cellular juice, is elaborated 

 and stored. As night falls, closing the air-stomata and arresting 

 the chlor<)vaj«)rization, the emission of water vapor by the plant is 

 replaced by a sort of sweat iug, which conies slowly from all points of 

 the surface and the nectaries in the form of little drops more or less 

 rich in sugar. Thus the drops of nectar have the same origin as the 

 water given forth by the water-carrying stomata. They are the result 

 of a stoppage in the (ranspii-alion and do not present any peculiar 

 character other than that of havin"- traversed organs rich in sac- 



FiG. 8.— Nectaries and exiidatiuii of nec- 

 tar, much enlarged. (After Q aston Bon- 

 nier.) 



1. Longitudinal cross section of the Scilria 

 lantanifolia: to ?, insertion of the calyx; 

 cor, insertion of the petals; n, nectaries 

 with carpels; /e, vessels leading to car- 

 pels; fn, vessels leading to nectaries, 'i. 

 Longitudinal cross section of Aubrietia 

 coluninae: sej>, sepals; et, stamens; ?(, 71, 

 nectaries; g, drop of nectar falling into 

 reservoir. !!. Nectary of a peach flower, 

 showing the nectar (g) which accumu- 

 lates in the chamber (c) of a stoma. 



