Aug 1, 1925 
Nitrogen Constituents of Celery Plants 
299 
food substance of the host, especially the proteins. As in higher 
plants and animals, the breaking down of proteins and other com¬ 
plex nitrogenous compounds by fungi is accomplished by proteolytic 
enzymes. These may arise from the host cells themselves in the 
form of autolytic enzymes which may be released for action by the 
conditions which the parasite sets up, or the invader may furnish 
the proteolytic enzymes. By a study of these conditions and 
especially by studies on the fungous proteases one shall be approach¬ 
ing closely toward a solution of the problem of selective parasitism. 
Here also lies the domain of immunity to disease, and biochemical 
studies to determine the nature of immunity must logically turn in 
this direction. 
SUMMARY 
Comparative analyses of healthy and diseased celery leaves affected 
with Cercospora apii a,ndSeptoria apii have been made and it has 
been found that in the leaves affected with these necrotic diseases 
there is a lower percentage of total nitrogen in the diseased than in 
the healthy tissue. Nitrites are present in the diseased material. 
A comparison of the nitrogenous compounds present show in per cent 
of total nitrogen,, greater ammonia, greater numin, greater protein, 
less hydrolyzable, less acid amide, less basic and less nonprotein 
nitrogen in the diseased than in the healthy tissues. 
It is believed that these results can best be explained as due to 
the decomposition of the host by the parasite in a simple food relation. 
The existence of a similar chemical picture in the spinach mosaic 
and in the unknown cabbage disease studied by Jodidi and his 
associates does not warrant the assumption that the spinach mosaic 
is of parasitic nature, although* the results are very suggestive, nor 
can the cabbage disease be diagnosed on the basis of mere chemical 
analyses as a true mosaic. 
The importance of the nitrogen metabolism of parasitic fungi is 
stressed as a possible explanation of selective parasitism and .as 
a point of attack in immunological research. 
LITERATURE CITED 
(1) Abderhalden, E. 
1912. HANDBUCH DERBIOCHEMISCHEN ARBEJTSMETHODEN. Bd* 6. Berlin 
and Wien. 
(2) Association of Official Agricultural Chemists. 
1920. OFFICIAL AND TENTATIVE METHODS OF ANALYSIS. AS COMPILED BY 
THE COMMITTEE ON REVISION OF METHODS. REVISED TO NOVEMBER 
l, 1919. 417 p., illus. Washington, D. C. 
(3) Behrens, J. 
1911. FXULNISERSCHEINUNGEN AN TRAUBEN UND ANDEREN ROHMATERIAL- 
-ien her weinbereitung. Lafar, F. Handbuch .der; technischen 
Mykologie. Aufl. 2. 5: 361-380. 
<4) Benecke,'W. 
1904. allgemeine ernahrungsphysiologie. Lafar; F. Baudbuch der 
technischen Mykologie. Aufl. 2. 1: 303-381. 
'(5) Boncquet, P; A. 
1916. PRESENCE OF NITRITES AND AMMONIA IN DISEASED PLANTS. Jour. 
Amer. Chem. Soc. 38: 2572-2576. 
?(6) Butkewitsch, W. 
1902. UMWANDLUNG DER EIWEISSSTQFFE DURCH DIE. NIEDEREN PILZE .IM 
ZUSAMMENHANGE MIT EINIGEN BEDINGUNGEN IHRER ENTWICKELUNG. 
Jahrb. Wiss. Bot. 38: 147-240. 
(7) Davisson, B. S., and Parsons, J. T. 
1919. THE DETERMINATION OF TOTAL NITROGEN INCLUDING NITRIC NITRO¬ 
GEN. Jour. Indus, and Engin. Chem. 11: 306-311, illus. 
