Aug. 1, 1U25 
Nitrogen Constituents of Celery Plants 
289 
Reference also should be made to the contribution of Doby (8) 
who studied the biochemical relations of healthy potatoes and pota¬ 
toes affected with leaf roll and who found lower insoluble protein 
content in diseased than in healthy tubers, the low protein content 
being the net result of higher oxidase content of the diseased tubers 
which lead to a great combustion of the cleavage products of the 
protein. 
EXPERIMENTAL WORK 
It was thought desirable to secure for comparison with the work 
on a mosaic disease which has been cited, analyses from fungous 
leaf blights where the effect of the parasite brought about a definite 
circumscribed killing effect upon the leaf tissue. Celery leaves 
affected with the disease known as “early blight” caused by the 
fungus Cercospora apii Fres. were first used for this purpose. The 
analyses along with a statement of the methods employed are given* 
below. 
For further evidence upon the nature of the changes in the nitrog¬ 
enous constituents of plants as brought about by fungous attack, 
material from another celery disease, “leaf spot” caused by Septoria 
apii Chester, was taken. In this disease, the effect upon the tissues 
is more pronounced than in the “early blight,” the fungus commonly 
producing in its last stages a complete rotting of the affected leaflets 
and stalks. 
The materials chosen, therefore, represent two rather widely differ¬ 
ing types of disease, and the analyses given reveal something of the 
type of decomposition produced by the parasites. 
METHODS USED WITH CELERY BLIGHTED BY CERCOSPORA APII FRES 
The methods used were in the main those employed by Jodidi 
and his collaborators ( 13 ). All the determinations, except water 
content, were made with diseased and healthy celery of one variety, 
Easy Bleaching, which was collected from plants of the same age 
growing in the same garden plot. The work was done entirely on 
mature leaflets. The lesions on the blighted leaves involved approxi¬ 
mately from one-sixth to one-fourth oi the leaf area. The leaflets 
were spread in thin layers on cheesecloth and dried at room tem¬ 
perature for three days and then placed for three days in an electric 
oven which was maintained at a temperature of 49° to 54° C. The 
dried materials were next rubbed through a 40-mesh sieve, then 
mixed to assure more uniform sampling and finally placed in jars 
and tightly sealed. The dried, powdered leaflets thus made ready 
for use were of about the fineness of table pepper. The color of 
the powdered blighted material was an ashen, grayish green, while 
that of the healthy material was distinctly chlorophyll green. 
The total nitrogen was determined by the Kjeldahl and Kjeldahl- 
Gunning methods, 2 gm. samples of the dry, unpowdered leaves 
being used in the first method, 2 gm. samples of the more repre¬ 
sentative powdered materials being used in the second method. It 
may be said here that in all ammonia distillations 4 per cent boric 
acid solution was used as the receiving liquid and brom-phenol blue 
indicator in the titration (19). 
Nitric nitrogen was estimated by two different methods, F. M. 
Scales’ zinc-copper couple reduction method ( 9 ), and the Schulze- 
