940 REPORT— 1900. 



MONBAY, SEPTEMBER 10. 



1. A Joint Discussion with Section C was held on the Conditions 

 under which the Plants of the Coal Period grew.— See p. 746. 



The following Papers were read : — 



2. Further Investigations on the Intumescences of Hibiscus 

 vitifolius {Linn.). By Elizabeth Dale. 



The author previously examined the structure of certain intumescences (out- 

 growths) on the green parts of Hibiscus vitifolius, and made some preliminary 

 experiments which pointed to the conclusion that the conditions determining the 

 formation of outgrowths were moisture, warmth, and light.' 



During the present summer (1900) the experiments have heen extended. The 

 effects of moist air and moist sod were tested, and plants were also grown under 

 glass of various colours, in bright sunlight, in shade, and under whitewashed 

 glass at different temperatures. The following results were obtained. In a 

 moist atmosphere, bright sunlight, and a high temperature, large numbers of 

 intumescences were formed in two or three days. The most striking results were 

 obtained by isolating a single normal branch (still attached to the plant) in a 

 hell-jar containing damp air, and exposed to direct sunlight, in very hot weather. 



Outgrowths were also formed under red, yellow, and whitewashed glass, but 

 not under blue or green» glass, nor on plants grown in the open air. The distri- 

 bution of the outgrowths is dependent upon that of the stomata, both in Hibiscus 

 and also in other plants. There is no doubt that the checking of transpiration 

 (which is very active in this plant) by a damp atmosphere is one cause of the 

 development of outgrowths ; but this by itself is not sufficient, as the experiments 

 under blue and green glass show. It is necessary that assimilation also be active. 

 There is further evidence (partly furnished by the plants grown under coloured 

 glass) that an altered course of metabolism is also involved; a conclusion to which 

 the abnormally abundant development of oil also points. It seems clear that what 

 occurs is (1) a lack of salts owing to the arrested transpiration ; (2) the assimilated 

 carbohydrates are therefore being employed in metabolism with a deficiency of 

 nitrates; and (3) the tissues blocked with water are not respiring normally. That 

 the abnormal outgrowths and accumulation of oil are indications of the disturbed 

 metabolism is not surprising. 



The formation of outgrowths often begins round the teeth of the leaf. The 

 structure of the bundle-endings in the teeth of a normal leaf is that which 

 characterises water-glands ; and this fact, taken in connection with the position 

 and structure of the intumescences, suggests that they may be organs for the 

 excretion of water. 



3. On the Osmotic Properties and their Causes in the Living Plant and 

 Animal Cell. By Professor E. F. Overton. 



A very great number of experiments on the permeability of the living proto- 

 plasm of plant and animal cells has led to the conclusion that the general osmotic 

 properties of the cell depend on a phenomenon of elective solubility, certain layers 

 of protoplasm being impregnated with a mixture of lecithin and cholesterin. All 

 substances that are soluble in this mixture, and they include by far the greater 

 number of organic compounds, are able to penetrate into the living cell. The 

 rapidity of the passage of different compounds into the cell depends on their rela- 



E. Dale, ' On certain Outgrowths (Intumescences) on the Green Parts of 

 Hibiscus vitifolius (Linn.),' Proc. Cavib. Phil. Soc. (1900), vol. s. Ft. IV. p. 192. 



