F. KiDD AND C. West 247 



comes into contact with tiieni is clearly shown by the work of Brown and 

 Morris (3), Buckner and Kastle(4), and others. 



Brown and Morris in dealing with the utilisation of sugar by barley 

 embryos, demonstrated the interesting fact that if cane-sugar be supplied 

 to the seed in such a way that it can enter and come into contact with the 

 embryo, it is utilised in growth in preference to the food-reserves in the 

 endosperm, which are left untouched^. Barley grains, after 24 hours 

 soaking, had their distal ends cut across and were then set with their 

 proximal ends uppermost in loosely packed glass wool saturated with 

 (a) distilled water, (6) a 3-5 per cent, solution of cane-sugar. Vigorous 

 and normal growth followed in both cases, but when the grains were 

 critically examined at the end of 4 days it was found that whereas in 

 the case of (a) the endosperm was completely disintegrated and the 

 starch had been attacked, in the case of (b) the endosperm was still as 

 tough as before germination and the starch had scarcely been attacked. 



Little definite evidence is available as to how far treatments, 

 which stimulate germination, do so in virtue of their influence upon the 

 rate of consumption of food-reserves by the embryo. It is probable, of 

 course, that most of the many arbitrary treatments, which have been 

 found to favour germination, bring about at the same time a quicker 

 consumption of the food-reserves under the action of the specific 

 enzymes concerned, but evidence is lacking in most cases as to the 

 manner in which this result is produced. 



In the case of acid treatments, which have been shown to increase 

 the vigour of germination and of subsequent growth (see following 

 chapter in this series), the enhanced rate of food-reserve consumption 

 recorded as the result of these treatments may probably be attributed 

 to the action of acids in liberating enzymes from pro-enzymes. Brown 

 and Morris (I.e.) found that they could obtain a larger secretion of 

 diastase from excised barley embryos when these were placed on a 

 slightly acid medium than when laid on a neutral substrate. On a 

 neutral gelatin medium they obtained from 50 barley embryos after 

 3 days an amount of diastase equivalent to 0-1186 gm. CuO (0-0708 gm. 

 equivalent from the embryos and 0-0478 gm. from the medium). The 

 corresponding figures when 0-0065 per cent, formic acid was added to 

 the medium show a total diastase equivalent of 0-1450 gm. CuO, of 

 which 0-0904 gm. was obtained from the embryos and 0-0546 gm. from 

 the medium. This amounts to an increase of 22 per cent. 



1 Brown and Morris (I.e.) showed that the presence of assimilable susjars inhibited the 

 secretion of diastase by the scutellum. 



