ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 487 



nearly the same extent of evaporative surface, the measurement of 

 which, although difficult, should afford much information as to the 

 effect of moisture in the soil. These effects have been frequently- 

 remarked. The author made experiments with barley grown in soils 

 containing 10, 20, 40, and 60 per cent, of water ; with the higher per- 

 centages, the size of leaf increased proportionally, but when examined 

 under the Microscope the leaves of the plants grown with the lesser 

 quantities of moisture showed far larger numbers of stomata than the 

 others, and in the former the stomata were larger, and the cells more 

 developed. The greater quantity of matter produced by well-watered 

 plants, appears to be due to the quick multiplication and development 

 of the cells; in the less watered plants, the contents of the cells 

 appear to be more concentrated. 



Plants do not possess the power of assimilating the moisture 

 existing as vapour in the air ; the rainfall is therefore a most im- 

 portant factor in the growth of plants in dry soils ; the transpiration 

 from the leaves and the loss of moisture from the soil by evaporation 

 serves to balance the effect of excessive rainfall. The author has 

 observed the fall for fifteen years at one station, but the conclusions 

 drawn are incomplete. Soils possess this power of absorption of 

 moisture from damp air ; the author's experiments show that they do 

 not absorb sufficient for plant-life in the absence of other sources of 

 moisture. The diffusion of rain in the soil depends very much on the 

 physical condition of the soil, which, for this purpose, may be looked on 

 as a mass permeated by numerous capillary tubes of smaller or larger 

 dimensions. One important result of the experiments was the great 

 difference in the absorptive capacity of one and the same soil when in 

 loose or close condition, the proportion in good garden soil being in 

 round numbers 2 : 3, and the author thinks the great advantage of 

 deep cultivation consists as much in imj)roving the power of absorp- 

 tion, as in bringing fresh soil to the surface. 



Apical Growth of Phanerogams.* — The examination of the mode 

 of apical growth in a large number of monocotyledons, dicotyledons, 

 and gymnosperms, leads Herr P. Korsehelt to the conclusion that there 

 is no variation in essential points. A large more or less distinctly 

 tetrahedral cell can always be distinctly detected in the centre of the 

 growing point from which daughter-cells are detached in regular suc- 

 cession from its three lateral walls. The essential principle of the 

 mode of growth is therefore the same with flowering plants as with 

 cryptogams. 



The fact that growth by means of a single apical cell has been 

 established in a very large number of plants belonging to widely- 

 separated natural families, makes it extremely probable that the same 

 mode of growth is characteristic of the entire group of flowering 

 plants. 



Causes of Anisotropy of Organic Substances.f — The unequal 

 growth of organic substances has been attributed to two causes : — the 



* Pringsheim's Jahrb. f. Wiss. Bot., xv. (1884) pp. 642-74 (1 pi.). 

 t Ber, Deutsch, Bot. GeselL, ii. (1884) pp. xlvii.-Iii. 



