332 OHIO EXPERIMENT STATION: BULLETIN 214 
methods upon many crops. In the case of grain diseases, notably 
anthracnose and scab upon wheat, rye, oats and grasses, inocula- 
tions may be made by spraying the cultures upon the grain ata 
proper stage of its development. 
While some groups of fungi do not lend themselves readily to 
culture upon the usual media, it is the aim of plant pathology to 
make this possible witha constantly increasing number of these 
parasites. 
CULTURE PROOF NOT ALWAYS POSSIBLE 
While in all cases of bacterial diseases where the body of the 
organism is so little different from that of the bacteria of decay, 
fermentation, etc., these rigorous proofs are required before the 
disease is listed as of proven bacterial origin, we do not find it nec- 
essary in practice to reprove again the case as against frequently 
occurring species of fungi associated with particular plant diseases. 
This does not make it less necessary to prove all cases as to para- 
sitic cause, although the practicability in any single laboratory of 
pathology is admittedly one of narrow limits. 
ENZYMATIC DISEASES OF PLANTS: CHLOROSIS OR PANACHURE 
To this form of physiological breakdown, induced however, by 
specific causes recently determined, we attribute some very wide- 
spread and injurious diseases which belong under the head of 
chlorosis. Peach yellows, possibly peach rosette, frenching or mosaic 
disease in tobacco, and in general variegated or special yellow foliage 
types of plants as in Arundo, Acer and other genera of plants belong 
here. The yellows in peach has long been studied, as also the 
tobacco mosaic disease. In yellows the contagious character of the 
disease and its transmission in pruning by contact of parts of the 
harness of team and by or through the atmosphere has been 
recorded. 
A few years ago it was determined by Beierjink and by Hunger 
that this infection exists as a chemical compound or compounds of 
complex nature belonging to the oxidizing ferments ofa group called 
the oxidases. Oxidase, peroxidase and others of these ferments are 
known. They act by breaking down or oxidizing the plant leaf 
tissues and especially the chlorophyll or leaf-green of foliage and 
young tissues, converting it into xanthophyll. The tests for these © 
ferments are of some importance. Woods and others have shown 
their action with peroxid of hydrogen. 
From a practical point of view the transmission of the ferments, _ 
and, therefore, of the disease, by touching first diseased and then 
healthy foliage is: rather surprising. The work of Hunger in Java | 
