516 Biologie. 



sufficient rapidity and when applied against the stigmatic surface. 

 If mechanical Stimulus is applied so as to bend only the cells within 

 a particular zone of the stigma-lip, the curvature response is con- 

 fined to the stimulated zone. There appears to be no cumulative 

 effect of mechanical Stimuli of slight amount, each ineffective in 

 itself. Mechanical Stimulation of the papillae of the stygmatic sur- 

 face, sufficient to bend these, but not the lip, is non-effective. The 

 presence of pollen does not prevent a reopening of the stigma-lips 

 when these are closed at the time of pollination by mechanical 

 Stimulus. 



A comparison of the conditions in Dionaea and Diplocus, sug- 

 gests the view that mechanical Stimulus is made effective through 

 a stretching of the sensitive cells, either local or involving the 

 entire cell. Moore. 



Lovell, J. H., The color sense of the honey-bee; the pol- 

 lination of green flowers. (Amer. Nat. XVI. p. 83 — 107. Feb. 

 1912.) 



From various experiments with bees and flowers and objects 

 to which honey had been added it is concluded 1) That green flo- 

 wers are not well adapted to entomophily and many species, possi- 

 bly all, have been derived by retrogression and degeneration from 

 larger more highly developed entomophilous forms. 2) Any surface 

 whether it is bright or dull colored, on which there is nectar or 

 honey, will be freely visited by bees after these liquids have been 

 discovered; but they will not be discovered as quickly on a surface 

 that does not contrast in hue with its surroundings, as on one 

 which does so contrast. 3) The experiments and observations of 

 Plateau on green or greenish flowers, are fallacious, as pointed out 

 by Knuth, and do not prove that "all flowers might be as green 

 as their leaves without their pollination being compromised." 4) When 

 honey-bees are given the choice between a conspicuous and an in- 

 conspicuous object under similar conditions, they exhibit a prefe- 

 rence for the former. This preference is sufficientry marked to account 

 for the development of color contrast in flowers. Moore. 



Villani, A., Dei nettarii di alcune Crocifere dicentriche. 

 (Bull. Soc. bot. ital. p. 160—169. 1910.) 



La disposition de quelques genres de Cruciferes dicentriques 

 serait la suivante: 



Cruciferes dicentriques: 



A. toujours dicentriques: 



1. Un nectaire insere ä la base exterieure de chaque filet court; 



a. non eperonne, en forme de tubercule ou de coussinet( Heliophila); 



b. non eperonne, avec des prolongements lateraux (Schisopetalum); 



c. avec eperon binde (Aubrietia). 



2. Un nectaire place entre chaque etamine courte et l'ovaire 

 (Malcolmia p. p., Moricandia). 



3. Un nectaire entourant interieurement et lateralement chaque 

 filet court (Malcohnia p. p., Conringia). 



4. Un nectaire entourant entierement la base de chaque filet 

 court {Cheiranthus , Hesperis, Chorispora, Diphtychocarpus strictas, 



Lunaria). 



B. Dicentriques et quadricentriques. 



