ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 315 



as a white flocculent amorphous powder. Other leaves of the same 

 plant were dried at 100° C, and from the fine green powder prepared 

 from them the enzyme was also extracted by glycerin in the same 

 manner as with the fresh leaf. If the powder be placed in distilled 

 water, evolution of oxygen accompanied by formation of formic- 

 aldehyde was observed. The green powder freed from the ferment was 

 unable to effect photosynthesis, but this action was manifested imme- 

 diately on addition of a small quantity of the ferment. The amount of 

 gas evolved was proportional to the intensity of the light-rays to which' 

 the solution was exposed. The author contends that his researches prove 

 undoubtedly that the principal agent of chlorophyll-assimilation in the 

 green plant, and of photosynthesis outside the organism, is a soluble 

 enzyme, and that the chlorophyll pigment apparently functions as a 

 chemical sensitiser. 



Ripening of Seeds and Power of Germination.* — P. Maze finds, 

 that unripe seeds which will not germinate properly when taken from 

 the plant, will acquire the power to germinate if they are more or less 

 rapidly dried. Seeds of pea and maize, collected when still soft and 

 milky, were placed in tubes containing distilled water. When placed on 

 a stove at 30° C, the maize developed seedlings which grew vigorously, 

 but a large number of the peas refused to germinate, while in the 

 majority of those that did germinate, the radicle was unable to pierce 

 the seed-coat. If, however, the seeds were previously dried at 30° C. in 

 contact with air over concentrated sulphuric acid for 24 to 48 hours, the 

 maize germinated in the same way as would perfectly ripe seeds, while 

 the peas also yielded normal plants. 



Effects of Water and Aqueous Solutions on Foliage Leaves.f — 

 J. B. Dandeno after giving a historical resume of work by previous- 

 observers on the vexed question of water-absorption by leaves, describes 

 a large series of experiments made by himself on this and kindred 

 subjects. His results and conclusions are as follows : — Wilted leaves, 

 whether detached from the plant or not, will absorb water if immersed, 

 or if water be applied to the surface in the form of spray. Special 

 parts of leaves of certain plants seem to be adapted to the purpose of 

 absorption, as shown by the surface of the epidermal cells over the veins 

 (as in Ampelopsis), at the base of the hairs (as in Primula) and elsewhere.. 

 Hairs in some cases are very susceptible to the action of water and of 

 solutions. Striations and hairs aid in spreading liquids over the regions- 

 which seem to be adapted for absorption, and trichomes also prevent a 

 rapid evaporation of the liquid thus spread. Absorption of water may 

 also take place through the surface of the petiole. Guttation drops and 

 dewdrops contain dissolved substances which are generally absorbed by 

 the plant. Carbonates as incrustations may serve to store up carbon 

 dioxide, in the presence of moisture at night, which may be utilised as. 

 the bicarbonate is reduced to carbonate in the day-time. Incrustations 

 may be, therefore, not only an adaptation to retain water, but also to 

 utilise to the full the loss of C0 2 by respiration. • 



* Comptes Rendus, cxxxv. (1902) pp. 1130-2. 



t Trans. Gmadian Inst., vii. pt. 2 (1902) pp. 237-350(2 pis. and 15 figs, in text). 



