148 



SCIENCE. 



[N. S. Vol. XVII. No. 421. 



The lecturer also discussed the subject of 

 •vulcanization, pointing out that it consists 

 simply in the addition of sulphur, no hy- 

 drogen sulphide being formed if pure rub- 

 ber is used. The result of vulcanization not 

 only depends upon the amount of sulphur, 

 the heat and the time, but also on the state 

 of the rubber at the moment of vulcanization. 

 The amount of sulphur may vary from that 

 necessary to form a compound, Ci„|,H„„S, to 

 that for C„„H„„S,„. The state of the rubber 

 ■can be greatly changed before vulcanization, 

 as for instance by manipulation between roll- 

 ers, whereupon it becomes more plastic and 

 loses in elasticity. This is due to the break- 

 ing down of the molecules, (C„Hi„)^, into 

 molecules of lower molecular weight, that is 

 .where (n), which may be 100 or more in 

 x3rude rubber, becomes a smaller number. 

 This is shown by the fact that the rubber 

 ■becomes more easily attacked by oxidizing 

 •agents, and is in many ways more reactive, 

 as is to be expected from a highly unsatu- 

 rated compound, where the higher the mo- 

 •lecular weight the less easily is the molecule 

 attacked by reagents. 



Dr. Weber showed how many of the tech- 

 nical problems that continually occur in the 

 rubber industry can be solved by the applica- 

 tion of theoretical considerations, and closed 

 with an appeal for workers on this very in- 

 teresting but comparatively little investigated 

 field of organic chemistry. 



Arthur M. Comey, 



Secretary. 



TORREY BOTANICAL CLUB. 



At the meeting of Wednesday, November 

 •26, 1902, Dr. W. MacDougal spoke on some 

 ■examples of propagation by bulbils. Two 

 tinds of bulbils were spoken of, namely, those 

 which morphologically are stems, and those 

 that morphologically are roots. He exhibited 

 •specimens of Dioscorea villosa which bore in 

 the axils of the leaves large bodies described 

 as bulbils of the first sort, and Ranunculus 

 Ficaria and Glohia Schomhurghii which had 

 similarly placed bodies, much smaller, how- 

 ever, which were morphologically roots. In 

 any case the bulbils reproduce the plant by 



germinating after falling to the ground. 

 Drawings of Lysimachia terrestis were shovsm 

 that represented the changes effected in the 

 habit of the plant brought about by being 

 grown in water. 



A specimen of the so-called ' wood-rose ' of 

 Guatemala was also presented by Dr. Mac- 

 Dougal. This curious malformation is a 

 hypertrophy of a branch of some species of 

 the Leguminosse and is caused by an unknown 

 species of Lbranthus. 



Dr. N. L. Britton made remarks on the 

 plant conditions and the general plant forma- 

 tions of the island of St. Kitts, British West 

 Indies. The meeting then adjourned to the 

 conservatories, where the members of the club, 

 under Dr. Britten's guidance, examined some 

 of the plants that have recently been brought 

 to the Botanical Garden from St. Kitts. 

 W. A. Cannon, 

 Secretary pro tern. 



At the meeting of December 9, 1902, the 

 first paper was by Professor A. P. Selby, on 

 ' Culture of the Grape-rot Fungus,' with ex- 

 hibition of culture-tubes containing its fully 

 developed spore-sacs and spores, derived from 

 pycnospores upon the grape leaf. This fun- 

 gus has menaced the industry in Ohio, pro- 

 ducing rotting of both fruit and leaf. 



The second paper, by Dr. H. H. Eusby, was 

 on ' The Flora of the Orinoco Delta,' a delta 

 extending about 200 miles along the sea, and 

 as far inland, if we include the region of 

 rocky islands and deep rocky river-channels 

 in addition to the area of silt-deposits. It is 

 doubtful if the part visited by Dr. Rusby had 

 been botanically explored before his visit. 

 Its characteristic features are: 



1. A hill flora which covers islands never 

 submerged, and rocky banks of the river to- 

 ward the interior; trees and Bignoniaceous 

 vines characterize it. Mounted sheets exhib- 

 ited (from Dr. Eusby's collecting) included 

 Spondias, the hog-plum, Anona, the custard- 

 apple, palms of the genus Bactris, and repre- 

 sentatives of the many large trees (reaching 

 often 100 feet high) as a Vitex of the Ver- 

 bena family and an Aliberta of the Eubia 



