Oct. 2, 1916 
Effect of Blackrot Fungus on the Apple 
3 i 
Fehling's solution after hydrolysis with dilute hydrochloric acid. About 
one-third of this material appears to be starch, as determined by diges¬ 
tion with malt diastase. 
There was a large and consistent increase in the yield of reducing sugar 
given by the insoluble residue after five hours' hydrolysis with 2.5 per 
cent of hydrochloric acid under a reflux condenser. In the normal tissue, 
the amount of hydrolyzable carbohydrate material, after deducting the 
amount of starch found by separate determinations, was 0.315 gm. In 
half-decayed tissue, the quantity had risen to 0.771 gm., and in wholly 
decayed tissue there was a further increase to 1.086 gm., or a total gain 
of 0.771 gm. That this hydrolyzable material is not derived from partial 
decomposition of cellulose or other structural materials is conclusively 
shown by the fact that after deducting from the total weight of the 
insoluble residue of normal fruits, 2.100 gm., the weight of the hydro¬ 
lyzable portion, 0.636 gm. plus the weight of the protein therein con¬ 
tained as indicated by the nitrogen content, 0.2456 gm., we have remain¬ 
ing 1.2184 gm. as the weight of the nonnitrogenous, nonhydrolyzable 
residue. In the half-decayed fruit, after making similar deductions, 
there remain 1.0662 gm. as the weight of this residue, while in the wholly 
decayed fruit this residue amounts to 1.7435 £ m - These results were 
seriously questioned when first obtained; but repeated determinations 
yielded results which were entirely concordant, leaving no question that 
there occurs in the course of the disease a very marked increase in both 
the hydrolyzable and the nonhydrolyzable residues of fraction 3. In 
the early stages of the disease the nonhydrolyzable portion decreases 
very considerably, but subsequently increases to 143.08 per cent of its 
original amount. The increase in hydrolyzable constituents aside from 
starch is 244.76 per cent. These very large increases can be explained 
only as being the results of constructive processes carried on by the 
fungus, in which connection the increase of nitrogen and phosphorus in 
this fraction is significant. 1 In the face of our almost total absence of 
knowledge as to the amount of the carbohydrate synthesis occurring in 
any parasitic fungus and particularly as to the nature of the materials 
loosely designated as “glycogen,” speculation as to the meaning of these 
results would be fruitless, but they indicate an interesting field of inves¬ 
tigation. It is hoped that the study may be continued to the end that 
some information in regard to the nature of the compounds formed in 
these synthetic processes may be gained. 
The variations in total ash content shown by the analyses are ac¬ 
counted for by the fact that determinations are made upon small aliquot 
1 Hawkins (5) found that there was rather vigorous, construction of both hydrolyzable and nonhydrolyzable 
material by Fusarium oxysporum growing on potatoes; the crude fiber content of rotted quarters of tubers 
was uniformly considerably greater than that of sound quarters used as checks, as was the content of 
material reducing Fehling’s solution after acid hydrolysis. The relative amounts of such materials pro¬ 
duced by F . oxysporum are very much smaller than those found by us for Spkaeropsis malorum. 
