MECHANICAL EFFECTS OF OSMOSE ON THE PLANT. 869 
water, W, which is put under pressure by pouring mercury 
into the upper extremity of the syphon-tube. Horse- 
chestnut and grape twigs cut in February and Magch and 
thus treated,—the pressure of mercury being equal to 6-8 
inches above the level, M,—after 4-6 weeks, unfolded their 
buds with normal vigor, while twigs similarly circum- 
stanced but without pressure opened 4-8 days later and 
with less appearance of strength. 
Fr. Schulze (Karsten’s Bot. Unters., Berlin, II, 148) 
found that cuttings of twigs in the leaf, from the horse- 
chestnut, locust, willow and rose, subjected to hydrostatic 
pressure in the same way, remained longer turgescent and 
advanced much farther in development of leaves and flow- 
ers than twigs simply immersed in water. 
The amount of water in the soil influences both the ab- 
solute and relative quantity of this ingredient in the plant. 
It is a common observation that rainy spring weather 
causes a rank growth of grass and straw, while the 
yield of hay and grain is not correspondingly increased. 
The root-action must operate with greater effect, other 
things being equal, in a nearly saturated soil than in one 
which is less moist, and the young cells of a plant situated 
in the former must be subjected to greater internal stress 
than those of one growing in the latter—must, as a con- 
sequence, attain greater dimensions. It is not uncommon 
to find fleshy roots, especially radishes which have grown 
in hot-beds, split apart lengthwise, and Hallier mentions 
the fact of a sound root of petersilia splitting open after 
immersion in water for two or three days. (Phytopathol- 
ogie, p. 87.) This mechanical effect is indeed commonly 
conjoined with others resulting ‘from abundant nutrition, 
but increased bulk of a plant without corresponding in- 
crease of dry matter is doubtless in great part the conse- 
quence of large supplies of water to the roots and its vig- 
orous osmose into the expanding plant. 
16* 
