Aug. 1, 1925 
Nitrogen Constituents of Celery Plants 
297 
enzymic and in various organisms, proteases of various types and 
enzymes which split amide bodies have been demonstrated. (Waks- 
nan, 24, 25.) 
In the metabolism of fungi and bacteria the reduction of nitrates 
to nitrites and to ammonia is of common occurrence {11). 
The loss of nitrogen in the celery leaves, through the agency of the 
two fungi, is believed to be not essentially different from the loss of 
nitrogen from a medium in which the organisms are growing. In 
short, the fungus uses the nitrogen compounds of the leaf tissue for 
food. Behrens (3) quotes the work of Muller-Thurgau who had 
noted the lower nitrogen content of the juice from rotted grapes as 
compared with juice from sound grapes. In another series of tests 
Muller-Thurgau grew pure cultures of Botrytis upon the grape must 
and found that the nitrogen content became only one-fifth of the 
initial amount after 21 days of culturing. 
It would seem that the effect of the parasites in the celery disease 
is to bring about a loss of total nitrogen. The mechanics of the proc¬ 
ess in cases of parasitism is not known and the use of the term 
“denitrification” in this connection is misleading. Because of the 
presence of a trace of nitrite in diseased tissue Jodidi {12) has sug¬ 
gested that the action of this compound upon the aminoacid group 
liberated free nitrogen, by a reaction practically similar to the Van 
Slyke reaction. He presents no evidence to support this suggestion. 
The loss of nitrogen as commonly brought about by organisms seems 
to be by the splitting off from proteins ammonia which is later liber¬ 
ated. Reasoning from studies on nitrogen metabolism of fungi in 
cultures the following processes may be assumed to take place 
(Klotz, 14 ): As the strictly carbonaceous food components, such as 
the carbohydrates, of a lesion become exhausted, probably the nitro- 
S en compounds, as the amino acids, peptones, and proteins must be 
ecomposed to furnish the parasite with carbon requisite for meta¬ 
bolism, especially respiration, or the organism may draw upon its 
own cell reserves for the nitrogen and carbon to continue life proc¬ 
esses. Where the proportion of the nitrogen to the nonnitrogenous 
complex of either the substrate or of the mycelium itself is greater 
than is required in the metabolic processes, in protein synthesis 
(or protoplasmic repair) the excess nitrogen appears as NH 3 and is 
lost as such. The basis for the above suggestions is to be found in 
the behavior of fungi in culture since it was found that ammonia 
was never formed in or excreted into the culture fluid when sugar 
was present. t The disappearance of carbohydrate from the culture 
medium was found to be synchronous with the appearance of am¬ 
monia and with the beginning of autolysis of the fungus. Ammonia 
was found to be the chief nitrogenous product of the splitting of 
peptone of the medium in the absence of another carbon source, 
but in the presence of dextrose NH 3 was reassimilated. 
Loss of total nitrogen in the later stage of necrotic diseases is there¬ 
fore to be expected if the relation to the host is -comparable to the 
relation of a fungus to a culture medium. 
Assuming that this is the case in typical parasitic diseases, is one 
justified in concluding that whenever there is a condition where lower 
total nitrogen occurs that one is confronted with the work of 
parasites ? 
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