ZOOLOGV AND BOTANY, MIGROSCOPV, ETC. 61 



General. 



Pedunculate Species of Trillium.* — H. A. Gleason has made a 

 classificatiou of the pedunculate species of Trillium. The three 

 groups are characterised by their stigmas and ovary. In the group 

 typified by T. erectum, each of the carpels is sharply liilobed and 

 terminates in a thick, sessile, recurved stigma. In the second group, 

 viz. that of T. grandiflorum type, the lobing is less distinct and the 

 ovary is more rounded, while the stigmas are of uniform diameter 

 throughout. In the last group, namely, those of T. Gateshmi type, the 

 stigmas are slender and uniform in diameter, but they are united below 

 to form a style. 



The species are distinguished by the length of the stamens, colour of 

 petals and ovary, and length and position of the peduncle. 



Corolla in Relation to Insects.j — E. Giltay has investigated the 

 attraction of the corollas of Pelargoiiiam and of the corn-poppy for bees. 

 Experiments tend to show that neither the scent nor the flower-form 

 are important factors, although in particular cases either may have an 

 attractive influence. The author agrees with those writers who regard 

 colour as the chief source of attraction, but he also shows that the high 

 development of the power of remembrance of places possessed by 

 bees must be largely responsible for the systematic visitation of flowers. 

 There is no proof that one bee brings another to flowers yielding honey, 

 but the same flower-borders are constantly visited by the same bees. 

 Different bees also show great differences in the intelligence displayed 

 in flower- visitation. 



Seed-dispersal in Polyg^onum virginianum.J — H. S. Reed and 

 I. Smoot show that P. virginianum is unique in that the requisite force 

 for ejecting the ripe fruit is derived from tension in the pedicel. At a 

 very early period a separation layer appears, which later on becomes 

 cutinised and extends right across the pedicel. On the side of this 

 layer nearer the achene is a cushion of pith- cells with thin, elastic walls, 

 while the pith-cells remote from the achene have much thickened walls. 

 The achene has a broad base of attachment, and its structure is of 

 sufficient strength to resist fracture at all points except the separation 

 layer. When, owing to external pressure, fracture occurs, the elastic 

 pith-cells are released from the tension under which they are held, and 

 shoot forth the achene with considerable force. 



C RvY P T,0 G A M S. 



Pteridophyta. 



(By A. Gepp, M.A., F.L.S.) 



Ferns of the Philippine Islands. — H. Christ§ has received a second 

 important collection of ferns made by A. Loher in the island of Luzon, 

 coming partly from the centre of the island where Leber's first collection 



* Bull. Torrey Bot. Club, xxxiii. (1906) pp. 387-96. 



t Jahrb. Wiss. Bot., xliii. (1906) pp. 468-99 (3 figs.). 



t Bull. Torrey Bot. Club, xxxiii. (1906) pp, 377-86 (7 figs.). 



§ Bull. Herb. Boissier, vi. (1906) pp. 987-1011. 



