Apeil 21, 1911] 



SCIENCE 



625 



Among other things brought to light by 

 these studies was the very great variability in 

 the amount of tannin at different times and 

 under different conditions. It is well known 

 that tannin occurs in great abundance in cer- 

 tain tissues of the plant and in injured parts, 

 and these facts led to original studies on the 

 possible function of tannin in plants. How- 

 ever, we did not expect to find the great varia- 

 tion in amount of tannin dependent upon the 

 length of time between the removal of the 

 fruit from the tree and the analysis of this 

 same fruit, for it was finally learned that there 

 was a rapid increase in the amount of tannin 

 or like bodies in the normal fruit immediately 

 after removal from the plant, and that the 

 tannin continued to increase in quantity for 

 some time. Although the greatest increase 

 was, as previously stated, immediately after 

 removal from the plant. 



For instance, a sample was taken by drop- 

 ping the fruit into boiling water immediately 

 after plucking to stop all enzyme action, 

 and the tannin determined at once. At the 

 same time another sample of the fruit on the 

 same tree was injured by repeated puncturing 

 of the stem and fruit with a pin and allowed 

 to remain on the tree for 48 hours, when the 

 tannin was determined. In the latter case the 

 tannin was about three times as great as in 

 the former. Apples which had fallen from 

 the tree were also analyzed for tannin and 

 showed about twice as much as in the case 

 where the enzyme action was stopped if such 

 was the cause of the action. However, it was 

 thought that this action should be traced even 

 further than shown in the above preliminary 

 experiments and the first and best method that 

 suggested itself (Thompson) was to follow 

 the action by tracing the soluble nitrogen in 

 content which would decrease if tannin or a 

 tannin-like body was formed which would 

 unite with the proteid bodies in the fruit 

 juices. Accordingly, juices were prepared 

 from a number of different fruits and sub- 

 stances where such action might occur. The 

 materials used were green walnut hulls, ripe 

 apples, green apples and pears ; they were first 



ground through an ordinary meat chopper 

 and pressed through canton flannel. These 

 juices were sampled immediately after press- 

 ing out and every 24 hours thereafter, until 

 fermentation was apparent, the samples being 

 filtered through asbestos by suction, and the 

 soluble nitrogen determined with the follow- 

 ing results :" 



Eipe apples — ^no decrease. 



Green apples — 64 per cent, decrease in 48 hours. 



Pears — 14 per cent, decrease in 48 hours. 



Walnut hulls — 16 per cent, decrease in 94 hours. 



To further prove that the action might be 

 due to enzyme action one sample of the above 

 walnut juice was brought to boiling tempera- 

 ture and kept there 30 minutes. In this case 

 for the first 48 hours there was practically no 

 decrease in the soluble nitrogen, but after 94 

 hours it showed about 6 per cent. 



In these experiments it will be noted that 

 there was positive proof of the formation 

 of a tannin-like body that had the power 

 of precipitating proteid matter, thus causing 

 part of the nitrogen to be precipitated in the 

 insoluble form, but as yet the nature of the 

 enzyme was not determined further than this 

 property, although it had been previously 

 shown that the juices had the power of de- 

 composing hydrogen peroxide. 



Therefore, a similar series of experiments 

 were carried out by grinding the fruit with 

 calcium carbonate, as suggested by Apple- 

 man's work on catalase, in which he showed 

 that the activity of the catalase could be pre- 

 served by such treatment. However, when the 

 juices were filtered off and the soluble nitro- 

 gen determined, there was no decrease in any 

 case, but fermentation set up in about 36 

 hours, which was a considerably shorter time 

 than in the previous experiments. 



On allowing the calcium carbonate precipi- 

 tate to settle and testing both the precipitate 

 and the supernatant liquid with H,0. by the 

 method given by Appleman, it was shovsm that 

 aU of the catalase was carried down by the 



" Conaplete data in ' ' The Preparation and Prop- 

 erties of an Oxidase Occurring in Fruits," by 

 H. P. Bassett and Firman Thompson, Journ. 

 Amer. Chem. Soc, 33: 416-423, 1911. 



