GAGER: GLANDS IN THE EMBRYO OF ZEA 197 
In the same year (1785), Irvine * pointed out the fact that, in 
malting, not only did the malt become sweet, but the endosperm 
of crushed seeds, when mixed with the malt, also became con- 
verted into sugar. 
Further advance seemed to await the discovery, by Colin and 
Claubry,"’ in 1814, that starch is colored blue by iodine.* This 
discovery became a great aid in endosperm studies. 
In the following year Kirchhoff, on the basis of his experi- 
ments, concluded that the gluten accomplishes the formation of 
Sugar in germinating seeds, and in farina that has been scalded 
with hot water.: He also stated that the gluten attains through 
germination the property of transforming into sugar a much greater 
quantity of starch than is to be found in the seeds, and further 
clearly saw that the production of sugar in germinating seeds 
is a chemical process, and not a consequence of vegetation. 
Experiments of a similar nature to those of Kirchhoff led 
Thomson,”* in 1818, to the extreme view that the essential con- 
stituent of yeast is ‘‘a species of gluten,” and ‘‘that it is some 
Substance connected with the gluten that acts upon the starch, and 
converts it into sugar. 
The studies of Proust and of Saussure,” in 1819, and of 
Dombasle,” in 1820, on the conversion of starch to sugar by the 
action of gluten, contributed only slightly to the solution of the 
real question, but thirteen years later, in 1833, Biot and Persoz* 
announced the discovery of dextrine, which they had produced 
from starch by’ the influence of acids.+ Vogel, by similar means, 
had, in 181 2, produced what was probably the same substance, 
but its name and the recognition of its true nature must be 
attributed to Biot and Persoz. 
Previous to this, Braconnot,” in 1824, isolated a ‘ special 
Principle”? which changed to sugar the starch from tubers of 
Helianthus tuberosus, and in the same year in which dextrine was 
'scovery to Stromeyer, but gives no citation. ; 
‘ il,#® who discovered the mark; or “hilum” on starch-grains, stated his 
Pelief in 1826, that “the carbonic-acid of the air is sufficient to efiect the transforma- 
won of starch to sugar” (page 335). : 
