360 HOW CROPS GROW. 
The coats of the dry seed when put into the moist soil 
imbibe this liquid which follows the cell-walls, from cell 
to cell, until these membranes are saturated and swollen. 
At the same time these membranes occasion or permit os- 
mose into the cell-cavities, which, dry before, become dis- 
tended with liquid. The soluble contents of the cells or 
the soluble results of the transformation of their organized 
matters, diffuse from cell to cell in their passage to the ex- 
panding embryo. 
The quantity of water imbibed by the air-dry seed commonly amounts 
to 50 and may cxceed 100 per cent. R. Hoffmann has made observations 
on this subject, (Vs. St., VII, p. 50.) The absorption was usually com- 
plete in 48 or 72 hours, and was as follows in case of certain agricultural 
plants :— 
Per cent. Per cent. 
MUSEOPO Lo s.0 cece eieise doce 8.0 Oats: sais csieosiaieetnadee' 59.8 
Millets se sasainaie epeie'eie 25.0 Hemp 'eie.ois veiss te cases 60.0 
MaIZe.... eee cece eee ee 44.0 Kidney Bean.......... 96.1 
WHERE cissccracs teisisrsieinare oe 45.5 Horse Bean...........- 104.0 
Buckwheat............. 46.8 PCO csasderes HSNO se ees te 106.8 
Barley:. vis cssis sive siesbacs eas 48.2 CLOVES pisteiarsis essa deeewss 117.5 
THIDIp saicaces sche cesta’ 51.0 Beet viasrar sane nvens xe 120.5 
PRY Cisis Gis scieisies sabia e eieye,e sie 57.7 White Clover.......... 126.7 
Root-Action.— Absorption at the roots is unquestiona- 
bly an osmotic action exercised by the membrane that 
bounds the young rootlets and root-hairs externally. In 
principle it does not differ from the absorption of water 
by the seed. The mode in which it occasions the surpris- 
ing phenomena of bleeding or rapid flow of sap from a 
wound on the trunk or larger roots is doubtless essentially 
as Hofmeister first elucidated by experiment. 
This flow proceeds in the ducts and intercommunicating 
wood-cells. Between these and the soil intervenes loose 
cell-tissue surrounded by a compacter epidermis. Osmose 
takes place in the epidermis with such energy as not only 
to distend to its utmost the cell-tissue, but to cause the 
water of the cells to filter through their walls, and thus 
gain access to the ducts. The latter are formed in young 
