10 BULLETIN 183, U. S. DEPARTMENT OF AGRICULTURE. 
starch is the result of the action of maltose-forming diastase. The 
disappearance of the plasmic network of the cells is due to its being 
peptonized by proteolytic enzyms and thus made soluble for absorp- 
tion. Chemistry has made known the processes by which these 
changes are effected. It has found methods to increase the power 
of the grain to digest these various substances. It has invented 
ways of manipulation so as to secure the greatest efficiency of the 
enzyms present. It has not, however, shown any way of increasing 
the capacity of a grain to secrete enzyms, nor has it discovered any 
modification of structure that would lead to a greater economy in 
conversion. 
It is only by a definite location of the sources of these energies 
that a working basis for improvement of the barley grain can be 
obtained. Not only must it be known which of the tissues are 
concerned in these activities, but the extent and nature of the action 
of each tissue must be understood. Upon this point there has been 
much divergence of opinion. The disagreement has been not only 
-as to the parts of the grain concerned, but also as to whether or not 
the various enzyms are secreted by the same or by separate organs. 
Since there are three areas in dispute and three enzyms to be ac- 
counted for, the number of possible hypotheses has occasioned a 
very considerable confusion. 
RESUME OF THE CONCLUSIONS OF OTHER INVESTIGATORS. 
Although the number of investigators who have been interested 
in one or several phases of this subject is great, a brief statement of 
their conclusions is necessary at this point. 
Krabbe ! assigns all diastase secretion to the individual cells of the 
endosperm, based on his assertion that diastase can not pass from 
cell to cell. 
Green? finds in Ricinus communis a marked ability of the endo- 
sperm for self-digestion. 
Hansteen * finds that the endosperms of Zea mays and Hordeum 
vulgare are capable of self-digestion when products of conversion are 
removed, that the aleurone does not supply the diastase, and that 
the scutellum is capable of vigorous corrosion of adjacent starch. 
Pond,‘ in an exhaustive chemical research, fails to discover any 
ability for self-digestion in the date. 
1 Krabbe, G. Untersuchungen tiber das Diastaseferment unter specieller Beriicksichtigung seiner 
Wirkung auf Stiirkekorner innerhalb Pflanze. Jahrbiicher fiir Wissenschaftliche Botanik [Pringsheim], 
Bd. 21, Heft 4, p. 521-561, pl. 13-15, 1890. 
2 Green, J. R. On the germination of the seed of the castor-oil plant (Ricinus communis). (Abstract.) 
Proceedings, Royal Society, London, v-. 47, no. 287, p. 146-147, 1890. 
3’ Hansteen, Barthold. Ueber die Ursachen der Entleerung der Reservestoffe aus Samen. Flora, Bd. 
79, p. 419-429, 1894. 
4 Pond, R. H. The incapacity of the date endosperm for self-digestion. Annals of Botany, v- 20, no. 
77, p- 61-77, 1906. 
