[Vor. 4 
180 ANNALS ОЕ THE MISSOURI BOTANICAL GARDEN 
desirable to know whether the chlorotic area differed mark- 
edly in its nitrogen content from that of the adjacent green, 
and apparently healthy, tissue. In this work some of the 
older leaves had to be used, since the younger leaves, because 
of the limited amount of differentiated tissue, did not enable 
one to obtain enough material from adjacent areas to carry 
on the tests. 
The Folin micro-Kjeldahl method was employed in this 
work. The results, however, especially for total nitrogen, 
were somewhat inconsistent, and the analyses can only be 
regarded as preliminary. The tests, nevertheless, showed no 
marked difference between the nitrogen content of diseased 
and healthy tissue. In fact, the nitrogen content of the lighter 
areas seemed to be slightly in excess of that of the darker 
areas. More extensive analyses are in progress at present, 
the results of which will be reported at a later date. 
PROTEINS 
The interesting results obtained from the nitrogen analyses 
suggested their possible correlation with the protein con- 
tent of the differentiated areas. The limited amount of ma- 
terial made the extraction of protein impossible and micro- 
chemical tests were therefore resorted to. The tests com- 
monly used in biochemical work were applied to both mace- 
rated tissue and hand-cut sections. Those used with advan- 
tage were the following: 
1. Millon’s test: Millon’s reagent was applied to the ma- 
terial and the slide warmed gently over a micro-burner. А 
brick-red color developed, signifying the presence of protein. 
Millon’s reagent consists of mercury dissolved in nitric acid 
(sp. gr. 1.42) in the proportion of 1:2 by weight. When the 
action of the acid on the mercury has ceased, the solution is 
diluted with water to twice its volume. 
2. Biuret test: The material to be tested was placed on 
the slide and treated for about 15 minutes with a few drops 
of strong sodium hydroxide. The alkali was then allowed to 
drain off, and the material was rinsed with water and treated 
with a trace of 5 per cent copper sulphate. After several 
