THE NITROGEN CONSTITUENTS OF CELERY PLANTS IN 
HEALTH AND DISEASE 1 
By G. H. Coons, Associate Professor of Botany , Michigan State College , and 
L. J. Klotz, Assistant Professor of Botany, University of New Hampshire 
INTRODUCTION 
Studies of the comparative chemical composition of plants in 
health and disease have, in the main, been few and the results ob¬ 
tained have not been such as to warrant generalizations as to the 
effects the various pathogenes bring about. Plant pathology has 
lagged conspicuously behind animal pathology in this regard, for 
in the latter science chemical pathology is a definite field with a 
large accumulation of data {27), 2 and these facts have permitted 
certain generalizations. In plant pathology the nature of the 
disturbance caused by the parasite can omy be surmised, as the 
physiology of plants in disease is largely unknown and awaits a 
fuller knowledge of the physiology of plants in health. 
In the early developments of agricultural chemistry, countless 
analyses catalogued the composition of plants. But these analyses, 
largely made to determine relative food value, do not permit the 
contrasting of plants in health and in disease. There have been 
observations made upon the development of certain chemical sub¬ 
stances in the course of disease—pigments, toxic substances, enzymes, 
etc.—but these results are fragmentary and restricted in application. 
That diseased plants are profoundly changed by the action of 
pathogenes is common knowledge, and the terms applied, decom¬ 
position or decay, indicate the general concept of the nature of the 
process which has taken place in disease production. 
REVIEW OF LITERATURE 
MuUer-Thurgau (17, p. 61) has shown that the must from rotted 
grapes is poorer in nitrogen than that from sound grapes. The 
organisms producing the rot were found to use first the easily assimi¬ 
lated stuffs and accordingly the must from rotted berries was found 
to have nitrogen compounds present in far less extent and in a form 
less suitable for fungous growth than was the case with-must from 
sound fruit. Similarly, he has also shown (16) that with rotted 
pome fruits, a clear sap almost free from nitrogen is obtained, in 
marked contrast to what is obtained from sound fruit. 
Recently more comprehensive studies on the chemistry of healthy 
and diseased plants have been published. In a preliminary article, 
Boncquet (5), in discussing the Ghemistry of the mosaic disease in 
sugar beets, states, that dentrification sometimes takes place in 
1 Received for publication July 25, 1924; issued September, 1925. The chemical analyses presented in this 
paper were made by L. J. Klotz U4) who has developed the special methods for dealing with the Septoria 
apn material. The work with Cercospora apii was conducted in the laboratory of R. C. Huston at the Michi¬ 
gan Agricultural College. The writers wish to acknowledge indebtedness to him for advice. They are 
also indebted to C. S. Robinson for criticism of the manuscript. 
2 Reference is made by number (italic) to “Literature cited,” p. 299. 
» 
Journal of Agricultural Research, 
Washington, D C. 
( 287 ) 
Vol.XXXI, No. 3 
Aug. 1, 1925 
Key No. Mich.-15 
