Oct. 2 ,1916 Effect of Blackrot Fungus on the Apple 23 
Ammonia determinations were made in all cases upon fraction 2 by 
aerating the alkaline solution, passing the escaping air through an ab¬ 
sorption tube containing Nfio sulphuric acid, titrating the acid, and 
estimating the ammonia from the decrease in acid strength. In the case 
of both normal and diseased fruits, fraction 1 gave by the Kjeldahl 
method only slight traces of nitrogen, and the figures are consequently 
omitted from the tables. 
Carbohydrates. —In the case of fraction 2, the portion taken for 
sugar estimation was freed from organic acids and tannins by adding 
normal lead acetate in excess, diluting, filtering, removing the excess 
of lead by the addition of saturated sodium-sulphate solution, and again 
filtering (26, p. 43). An aliquot portion of the neutral solution was then 
taken for determination of reducing sugar by the Bertrand volumetric 
method (16, p. 228-229) and the amount of sugar calculated as dextrose 
by the use of the Munson and Walker tables (26). Total sugars were 
determined by the same methods upon a second portion of the solution, 
after inversion by heating for 10 minutes in a water bath kept at 70° 
with 3.5 per cent of hydrochloric acid and subsequent neutralization of the 
cooled solution. Total sugars were estimated as invert sugar, and the 
disaccharids were determined by a difference of readings before and after 
inversion. 
The polysaccharids in fraction 3 were estimated as dextrose, by five 
hours hydrolysis with 2.5 per cent of hydrochloric acid under a reflux 
condenser, neutralizing the cooled solution, clearing of nonsugars with 
lead acetate, filtering, and employing the Bertrand method. No attempt 
was made to secure a quantitative separation of the mixture of sugars 
resulting from the hydrolysis into its various constituents. It is probable 
that the figures are low and that longer hydrolysis would have slightly 
increased the yield. The figures given, however, afford a safe basis for 
such general comparisons of the chemical composition of normal and 
diseased fruits as it is the purpose of the writers to make. 
Very considerable difficulties were encountered in attempting to esti¬ 
mate the sugars in the lipoid precipitate, fraction 3. In the analytical 
scheme originally developed by Koch and his coworkers (10), sugars in 
this fraction are determined by evaporating a portion of the solution to 
an alcohol-free paste, taking up with water, hydrolyzing for 24 hours with 
4 per cent of hydrochloric acid under a reflux condenser, concentrating 
the solution, drawing off the aqueous layer through a separatory funnel, 
clearing the solution with anhydrous sodium sulphate, and making a 
determination of sugar by the Bertrand method. The lipoid precipitate 
obtained from plant tissues contains true fats, waxes, lecithins, chloro¬ 
phyll and derived or associated pigments, tannins and their derivatives, 
and resins. In the course of a 24-hour hydrolysis very considerable 
changes occur in some of these constituents, with the production of com¬ 
pounds which reduce Fehling’s solution. Glycerol, which is absent 
