een investigated with great ingenuity by M. 
| Dubrunfaut ; and MM. Persoz and Payen suc- 
ceeded in separating the peculiar matter in bar- 
| ley malt which possesses the property of convert- 
| ing starch into sugar. This matter has been 
| called diastase. 
“Diastase exists in the seeds of all the cereals) 
which have germinated; it is met with more’ 
especially near the germs, it seems even that the 
| yadicles contain none of it. Nor is diastase ob-. 
served in the shoots or roots of the potato ; it is 
to be met with only in the tubers, around the 
eyes or points where the young sprouts are de- 
veloped, precisely as M. Payen has remarked, in’ 
| the place where we should conceive its presence 
to be necessary for effecting the solution of the 
fecula. It is also found to exist in the bark and 
beneath the buds of trees, always in contact with 
starch. Diastase is generally obtained from malt ; 
and when carefully prepared, its peculiar power 
is such, that one part by weight is sufficient 
completely to liquefy two thousand parts of 
starch. Diastase is solid, white, amorphous, in- 
soluble in pure alcohol, soluble in water and 
weak alcohol. The solution very readily under- 
goes change ; it becomes acid, and then no lon- 
ger exerts any action on fecula. When dried, it 
keeps much better ; still, at the end of two years, 
it seems to have lost its distinguishing proper- 
ties, Diastase has no action on vegetable tinc- 
tures,.on albumen, gluten, cane-sugar, gum- 
arabic, or the woody-fibre. That which more 
especially. characterizes it, is its powerful action 
on fecula; it may be advantageously used to 
separate and purify the preceding substances, 
when they are mixed with starch. The presence 
of diastase in malt explains the phenomenon of 
the liquefaction of starch effected by the action of 
a small quantity of that substance. This solu- 
tion is not effected by gluten, nor by hordein, as 
M. Dubrunfaut had imagined. By the action of 
diastase, or of malted barley, the starch on being 
liquefied is not entirely converted into sugar ; 
there are other distinct products to be considered 
-in this change. The syrup obtained by concen- 
-trating the liquefied starch, contains sugar capa- 
ble of undergoing the vinous fermentation, and.a 
gummy matter, dextrine. These two substances 
‘may be separated by means of dilute alcohol, 
‘which dissolves the sugar and leaves the gum 
untouched. The:relative quantities of dextrine 
and sugar produced by the action of diastase are 
variable, and depend both on the temperature at 
which the process is conducted, and on the.con- 
‘tinuance of the reaction. In the first period of 
the process, the dextrine predominates ; but it 
becomes less and less by degrees, and finally gives 
place to sugar. M. Guérin ascertained a curious 
fact, which shows how the diastase developed in 
plants may act.on their starch: reaction takes 
place even at ordinary temperatures. In one of 
M. Guérin’s experiments, at a temperature no 
higher than 68° Fahr., a quantity of starch, at 
“STARCH. 
bules which constitute starch increase in num- 
it was subjected to the vital influence, and that 
point or hilum, which, according to some ob- 
considers it as the orifice of the duct by which | 
329 | 
the end of 24 hours, was converted into syrup, | 
which yielded 77 per cent. of saccharine matter. | 
“M. Payen freed dextrine from the sugar | 
which usually accompanies it by precipitating | 
a syrup of fecula previously dissolved in dilute | 
alcohol, by means of alcohol nearly free from | 
water. Dextrine well dried, and reduced to pow- | 
der, has a specific gravity of 1:51. The specific | 
gravity of pure starch is 1°51; that of the sugar | 
of starch 1:61. M. Payen found dextrine dried. 
at a temperature of 212° Fahr. to consist of 44:3 
per cent. of carbon, 6 of hydrogen, and 49-7 of 
oxygen,—a composition identical with that of 
starch. We have seen that water, acidulated 
with sulphuric acid, transforms starch into sugar ; 
and that in this respect, the acid acts precisely 
in the same way as malted barley, like which, | 
the acid first causes the fecula to pass into the 
state of dextrine. By checking the reaction at 
the proper moment, this substance may thus be 
obtained, as was show by Messrs. Biot and | 
Persoz. When starch, for instance, is triturated | 
with concentrated sulphuric acid, if the mixture 
be diluted with half.its volume of water, and be | 
left at rest for an hour, alcohol will throw down | 
almost the whole of the starch employed in the | 
state of dextrine. | 
“M. Payen has remarked that starch.is never | 
met with in the vegetable tissues whilst in the | 
rudimentary state; the spongioles, the radicles, | 
the foliaceous buds, the interior of the ovules con- 
tain none of it. Nor is starch found in the epi- | 
dermis, nor in the primary cells of the subjacent | 
tissues. This proximate principle seems to be | 
excluded from those parts of vegetables that are 
more directly exposed to atmospheric influences: 
it is only met at a certain depth ; and the glo- 
ber and in size in the cells most remote from the 
surface. The subterraneous organs of plants, 
—certain bulbs, most. tubers,—abound in amyla- 
ceous matter. It might be maintained that light 
modified this substance, at. the very moment that : 
it was only preserved in the dark. On the glo- 
bules of some.species of fecula, there is found a 
servers, serves to fix hea to the.parietes of the 
cells which enclose them. It often happens, how- 
ever, that no hilum can be distinguished, even 
by the help of the most powerful microscopes ; 
to render it apparent, recourse must be had to 
desiccation, which, by causing the globular mass | 
to shrink, lame the part carrying the hilum, to 
project, by. reason of its stronger cohesion. M.. 
Payen does not regard the hilum as a point 
of permanent attachment, connecting the grain — 
of starch to the interior wall of the cell. He 
growth is effected through intersusception. In 
support of this view, M. Payen observes, that in 
a great number of vegetable cells, especially in 
those of the potato, and of. the rhizomas,. the 
