MECHANICAL EFFECTS OF OSMOSE ON THE PLANT. 369 
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 March and 
thus treated,—the pressure of mercury being equal to 6-8 
inches above the level, 1/,—after 4-6 weeks, unfolded their 
buds with normal vigor, while twigs similarly cireum- 
stanced but without pressure opened 4-8 days later and 
with less appearance of strength. 
Fr. Schulze (Aarsten’s Bot. Unters., Berlin, I, 143) 
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, otber 
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 rvots and its vig 
orous osmose into the expanding plant. 
16* 
