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posure of the tissues to atmospheric oxygen, in the presence of 

 oxidizing enzymes, causing the oxidation of colorless substances 

 to those of varied color. During the normal life of the plant 

 it seems to be able to hold these enzymes in check, but after 

 death or interference with its functions, the enzymes run 

 riot; thus causing blackening and colorations of many sorts. 

 The blackening of the foliage of many plants after a frost 

 and the production of the red and gold of our atuumn forests 

 may well be due to the excessive activity of the oxidizing 

 enzymes. The color of black tea, the odor of valerian, the aroma 

 of vanilla-beans, etc. have all been attributed to this same cause. 

 The presence of these ferments in the roots of growing plants 

 seem to enable them to destroy certain poisonous substances in 

 the medium in which they grow. There is a disease of tobacco 

 known as the 'mosaic disease' which is characterized by the 

 checkered appearance of the leaves, these checkered places being 

 yellow in color. Woods showed that rapid growth, produced 

 by cutting back or by excessive manuring, often caused this 

 disease which he attributed to an abnormal activity of the oxi- 

 dizing enzymes. It has also been shown that they may cause 

 the destruction of chlorophyll. Now, most of the lower fungi 

 contain these enzymes, so the yellowing produced by their at- 

 tacks upon green leaves may be due to their activity. It is 

 evident then, that in the plant the oxidizing ferments have a 

 physiological and also a pathological role that are not well under- 

 stood but which deserve further investigation." 



Dr. P. A. Rydberg reviewed the Monograph of Sambucus by 

 Fritz Graf von Schwerm. This paper will be published at a 

 later date. 



Adjourned. Percy Wilson, 



Secretary 



OF INTEREST TO TEACHERS 

 The Botany Unit 

 At the March meeting of the Commission on Accredited Schools 

 of the North Central Association (including 13 states), the botany 

 unit statement mentioned earlier in Torre ya was adopted. 



