Endosperm of Hordeum vulgare during Germination. 2;\ 



nised as taking part in the preparation of the food-material for the 

 embryo, since no evidence can be obtained of any changes being 

 initiated by the starch-containing cells themselves ; in fact, the 

 highly disintegrated appearance of the nuclei of these cells would in 

 itself suggest they had ceased to function. 



If we were to limit ourselves to the observations on degermed 

 endosperms in water-culture, we should conclude that the diastatic 

 function of the "aleurone-layer " is very small indeed, and this is 

 also apparently confirmed by the impossibility of demonstrating the 

 existence of such a function in the " aleurone-layer" when we employ 

 the methods which have been so successful in this direction in the 

 case of preparations of the scutellum. 



When the integuments with tho " aleurone-layer " attached are 

 perfectly freed from the starch-containing cells, and are placed face 

 downwards on starch-gelatine, we have never been able to obtain 

 any evidence of action.- on the starch, and even when the preparation 

 was made so as to include a layer of the amyliferous cells, which were 

 kept moist on gelatine, no influence was exerted on the contained 

 starch. Under these circumstances, however, there is an entire 

 absence of cytohydrolytic as well as of amylohydrolytic action, and 

 since the former is so well marked in degermed endosperms in 

 water-culture, we can only conclude that the separated " aleurone- 

 layer" for some reason or other will not exercise its normal function 

 in the same manner as the scutellar epithelium placed under similar 

 conditions. 



It is also to be remembered that in those cases where the endo- 

 sperm is in actual contact with the embryo, either as in natural 

 germination, or as in the " grafting " experiments, the special 

 changes induced by the "alenronic" layer proceed much more 

 rapidly than in isolated endosperms in water-culture, and this accele- 

 rated action is much more evident in the case of the diastatic than 

 of the cytohydrolytic action, 



It would appear, therefore, that although one of the principal func- 

 tions of the " aleurone-cells " is to break down the cell-membrane of 

 the amyliferous endosperm, these cells also share with the scutellum 

 the power of eroding starch-granules. 



Owing to the different method of attack on the starch, it now 

 becomes possible, for the first time, to discriminate one form of action 

 from the other, but it is very difficult to apportion the part played by 

 scutellum and " aleurone-layer " respectively, for the amount of 

 action of either depends not only on the enzymic intensity for 

 equal areas of the two tissues, but also on the total areas facing 

 the endosperm-contents in each case. 



Since the total area of the " aleurone-layer " is considerably 

 greater than that of the scutellar epithelium, the influence of the 



