CAUSES OF THE MOTION OF JUICES. 399 



that we can never expect to understand all its mysteries. 

 From what has been briefly explained, we can compre- 

 hend some of the more striking or obvious movements 

 that proceed in the vegetable organism. 



Absorption and Osmose in Germination. The 

 absorption of water by the seed is the first step in Ger- 

 mination. 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 occa- 

 sion or permit osmose into the cell-cavities, which, dry 

 before, become distended with liquid. The soluble con- 

 tents of the cells, or the soluble results of the transforma- 

 tion of their organized matters, diffuse from cell to cell 

 in their passage to the expanding embryo. 



The quantity of water imbibed by the air-dry seed commonly 

 amounts to 50 and may exceed 100 per cent. R. Hoffmann has made 

 observations on this subject (Vs. St.,\II, p. 50). The absorption was 

 usually complete in 48 or 72 hours, and was as follows in case of certain 

 agricultural plants : 



Per cent. Per cent. 



Mustard 8.0 



Millet 25.0 



Maize 44.0 



Wheat 45.5 



Buckwheat 46.8 



Barley 48.2 



Turnip 51 .0 



Rye 57.7 



Oats 59.8 



Hemp 60.0 



Kidney Bean 96.1 



Horse Bean 104.0 



Pea 106.8 



Clover 117.5 



Beet 120.5 



White Clover 126.7 



Root-Action. Absorption at the roots is unquestion- 

 ably 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 sur- 

 prising phenomena of bleeding or rapid flow of sap from 

 a wound on the trunk or larger roots is doubtless essen- 

 tially as Hofmeister first elucidated by experiment. 



This flow proceeds in the ducts and wood-cells. 

 Between these and the soil intervenes loose cell- tissue 



