180 BOTANICAL GAZETTE [AUGUST 
volume, and divided into two portions. Upon one of these a determination 
of direct reduction, representing total dextrose, levulose, maltose, and pentoses, 
is made; the other is employed for determination of cane sugar by inversion 
with ro per cent citric acid and with invertase. The remainder of the 2000 cc. 
of solution is freed of lead and divided into portions. Upon one of these 
maltose is determined by fermentation with S. exiguus or other maltase-free 
yeast, checked by fermentation with ordinary yeast; the remaining portion is 
distilled with HCl for the determination of pentoses. 
The second paper of the series deals with the methods of estimating starch 
in plant material.4 The modified Sachsse method, in which starch is hydro- 
lyzed by boiling HCl, is said to be valueless for two reasons: such plant materials 
as leaves and seeds contain pentosans and other compounds which are broken 
down, yielding reducing sugars which are computed as dextrose, while the 
prolonged boiling with acid destroys some of the dextrose present. O’SULLI- 
van’s method of estimating starch by converting it into a mixture of dextrin 
and maltose by the use of ordinary diastase is also shown to give rise to low 
) 
with basic lead acetate, and a considerable quantity of the dextrin present 
(15-20 per cent under the conditions of the experiments) is carried down by the 
lead precipitate and thus lost to the analysis. The authors show that this loss 
of dextrin is avoided by the use of taka-diastase. When taka-diastase is allowed 
to act for 6 hours at 38° upon previously gelatinized starch, the whole of the 
starch is converted into a mixture of maltose and dextrose, continued action 
resulting in a steady increase in the amount of dextrose, until final equilibrium 
is attained. The authors therefore adopt the following method. Material for 
analysis is prepared by dropping the freshly collected leaves or other parts into 
boiling 95 per cent alcohol to which 1 per cent of concentrated ammonia has 
been added; immediate destruction of all enzymes is thus assured. Sugars 
are removed by 18-24 hours’ continuous extraction in a special apparatus of the 
Soxhlet type; the material is freed of alcohol by pressing in a Buchner press 
and drying 18 hours in a steam oven. It is then ground and bottled for analy- 
sis. Samples taken for analysis are dried in vacuo before beginning actual 
work upon them. As leaf materials usually contain considerable quantities of 
gum, amylans, and other non-starch constituents which yield reducing sugars, 
with water 30 minutes to gelatinize the starch, cooled to 38°, taka-diastase 
added (0.1 gm. for 10 gms. vacuum-dried material), and the mixture kept for 
24 hours at 38° after the addition of a little toluene. The diastase is then 
4 Davis, WILLIAM ~ _ earns Mecheesls JORN, Methods of estimating car- 
bohydrates. II. Th The use of taka-diastase. 
Jour. Agric. Sci. 6:152-168. 1914. 
