Embryo and Aleurone Layer of Hordeum . 
1167 
TABLE XXXII. 
Influence of Cane and Invert Sugar on the Amyloclastic 
Secretory Activity of the Aleurone Layer. 
African barley. Seeds steeped in (1) CuS 0 4 1 10 %, 24 hours, (2) water; 24 hours. 
Exp. 
Medium. 
Amylase per 20 objects per 
Duration of culture. 
hour., equivalent to mg. 
Cu in culture medium. 
1. 
0-55 asparagin-M.S. 
4 days 
365 mg- 
2. 
°*55 asparagin-M.S. + 5 % cane sugar 
5 » 
215 » 
3 - 
°*55 asparagin-M.S. + 5 % invert sugar 
4 „ 
200 „ 
Since the material used in these experiments was prepared under 
identical conditions, the results given above are comparable among them¬ 
selves. Apparently these sugars exercise little or no influence on the 
secretion of amylase by the aleurone layer. It must not, however, be 
regarded as demonstrated that the cells of this tissue do not exercise that 
regulative control over the secretory function which they undoubtedly 
possess. The apparent indifference of the aleurone layer to changes 
in the nutrient substrate is due to the fact, as already insisted, that we 
are dealing with an isolated fragment of a tissue, and not with a complete 
highly organized organism. When in contact with its natural substratum, 
the inner endosperm, it is highly probable that, just as in the case of the 
epithelium of the scutellum, the aleurone layer regulates its secretory 
activities according to the special demands of the moment. 
IX. Investigation of the Amylase Content of the Scutella 
of Barley Seedlings. 
In dealing with the amyloclastic secretory capacities of the embryo and 
aleurone layer (Sections III and IV) it has been suggested that the Uutput 
of amylase by these objects as measured by the quantitative examination 
of the culture medium is probably inferior to that which obtains under 
natural conditions of germination. 
It will be generally accepted that the embryo and aleurone layer 
function best when, as in the germinating seed, they are in close relationship 
with the inner endosperm. There is, as we have seen, more especially 
(because more easily demonstrable) in the case of the embryo (see Sections 
III and VIII), a marked tendency to modify the extent and character of 
the activity of secretory mechanism localized in its scutellar epithelium 
according to the composition of the substratum on which it is placed. The 
exercise of a similar regulative control by the aleurone-layer fragment 
is not so clearly shown, the reason as already suggested being largely 
1 Special reference will be made to the influence the copper salt has on the secretory activity 
of the aleurone layer, see Section XIII, p. 1181. ^ 
4 G 2 
