The Food of Plants. 345 
those plants from which potash was eliminated, there was a 
most marked deficiency in growth. This was traceable 
to the fact that in the absence of potash, the plant was 
incapable of fixing carbon, and therefore unable to produce 
the ordinary products of digestion, such as starch, sugar and 
oils, and hence was practically in a condition of starvation. 
In a second series of experiments, potash was supplied in 
the requisite quantity, but chlorine was eliminated from 
the food supply. A most curious result was found. While 
an abundance of starch was produccd in the first instance, 
it was unable to reach those parts where growth was most 
active, and thus became accumulated in unusual quantity in 
the leaves and other green tissues where formed. A 
secondary effect of this was a change of color from green 
to yellow, whereby the further formation of starch was 
anrested, and the final result was a general arrest of growth. 
So that there was established the anomalous condition of a 
plant containing an excess of tissue-forming material, but 
unable to use it for want of a certain element in the food 
supply, which would effect a transfer of that material to the 
centres of active growth. Further observations confirmed 
the view that chlorine was the particular element needed 
for this purpose. 
Acting upon the suggestions contained in these results, 
Dr. Goessmann, the foremost agricultural chemist in the 
United States, and Director of the Massachusetts Experi- 
ment Station, a few years since, in company with other 
investigators, undertook to apply these principles of 
nutrition to the treatment of certain diseases of plants, 
which, up to that time, had baffled all attempts at control, 
and which, in the seriousness of their operations, threatened 
to destroy some of the most important fruit interests of the 
country. 
It was found, in the first place, that in the common and 
destructive disease known as Peach Yellows, there were 
conditions of growth in all essential respects the same as 
those artificially produced in buckwheat by elimination of 
chlorine. It was therefore assumed for the purposes of’ ex- 
