1914] ATWOOD—GERMINATION OF AVENA 393 
2. WATER INTAKE.—BRrown’s work on the semipermeability 
of Hordeum led to like tests of A. fatua. Distilled water and 
gram-molecular solutions of sodium chloride display on test a 
rather close approximation to perfect semipermeability (fig. 1). 
Later work by SHutt (61) in this laboratory shows that the power 
of excluding various salts in solution by non-living membranes is 
a rather common property of seed coats. It was thought possible 
that there might be some correlation between this behavior of 
Avena and gaseous or water exclusions in unafter-ripened seeds. 
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Fic. 2—Comparative water intake among the Gramineae and in Xanthium; 
increments in percentage of air dry weight; curves: z, wild oats 1911; 2, wild oats 
T910; 3, barley; 4, Avena sativa; 5, wheat; 6, wild oats 1911; 7, Xanthium. 
Tests were thus made of the rate of water intake for seed of different 
crops and for A. sativa, the shell coats being removed in all cases 
(fig. 2). Comparing the data derived with figures given by 
ScHRODER for Triticum and by A. J. BRowN for Hordeum, there 1s 
seen to be a general similarity in the rate and total water intake 
for these grasses. Although much slower than the water intake 
of some other seeds, as for instance Xanthium (x7), there does not 
seem to be any ground for saying that water exclusion in the case 
of A. fatua can explain its peculiarities of germination in the light 
of the general behavior of A. sativa, Triticum, and Hordeum. 
