[Vor. 4 
188 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
small quantity may be detected in the test solution bathing 
the section. 
A more reliable method is the one based on the reactions of 
sugars with phenylhydrazine to form osazones. This method 
has been developed most satisfactorily by Manghan (715). 
Although the method may be criticized as to the reliability 
of the anticipated reaction of any one sugar in the presence 
of other sugars and as to the justification of attributing cer- 
tain results to the reaction of the reagent with any one саг- 
bohydrate when other sugars are present, it nevertheless 
serves as a pretty fair qualitative test. Separate solutions 
of phenylhydrazine hydrochloride and sodium acetate were 
prepared by dissolving these reagents in sufficient pure sugar- 
free glycerin to make a 10 per cent solution. Small drops of 
these solutions were placed on the slide, mixed with a glass 
needle, and in this the sections to be tested were immersed. 
The mount was then covered with a cover glass and the 
preparation heated for an hour at 100° C. At the end of this 
period and continuing for several days, yellow bodies, re- 
sembling the droplets of syrup described by Manghan for 
maltose, and the small yellow spheres and granules figured 
by Molisch and Tunmann, separated out. The reaction was 
more pronounced in the darker areas of diseased leaves than 
in the lighter tissue. 
From the results reported above it is very evident that one 
great difference between the dark green and chlorotic areas 
of diseased tissue is a difference in the carbohydrate content, 
there being more in the former than in the latter. 
It was originally intended to accompany the above descrip- 
tions with adequate illustrations and to make similar tests 
on all varieties of plants showing mosaic. Microchemical 
methods, however, are very difficult, requiring the finest 
technique and the greatest care in observation and interpre- 
tation. Since, therefore, a general microchemical study of 
plants affected with mosaic is in reality a problem in itself, 
and also because of the nature of the results reported above, 
the microchemical work was deferred for the time being for 
