628 



SCIENCE 



[N. S. Vol. XXXIII. No. 851 



Ninety-six hours after the setting of the cul- 

 tures the following results were noted. In both 

 cases where the gallic acid and enzyme were not 

 present together there was a heavy fungus 

 growth; but in both cases where they were 

 present together there was a very slight 

 growth in all media. Thus the conclusion 

 would be that the body formed by the action 

 of the enzyme and gallic acid had a marked 

 inhibitive effect on fungus and bacterial 

 growth. It was apparent that for these ger- 

 micidal effects to be of any value to the fruit 

 it would necessarily have to have quite a 

 rapid reaction in order to keep out any chance 

 of infection, and also from the almost instan- 

 taneous appearance of the precipitate; and 

 from the data obtained for the transforma- 

 tion of the soluble nitrogen it was inferred 

 that the action was comparatively rapid, and 

 accordingly an experiment was planned to 

 obtain further data on this point. A solution 

 consisting of 100 c.c. of albumen solution, 

 200 c.c. of 1 per cent, gallic-acid solution, 

 50 c.c. of enzyme suspension, and 50 c.c. of 

 3 per cent, hydrogen peroxide was prepared 

 and diluted to 500 c.c. Another solution 

 which was the same in every respect with the 

 exception of the hydrogen peroxide, which was 

 omitted, was prepared at the same time. 

 Samples of these two solutions were taken 

 every fifteen minutes, for about two hours, 

 and the soluble nitrogen determined. The so- 

 lution could not be obtained clear on filtering 

 and no flocculent precipitate separated out as 

 in the previous cases. The determinations of 

 nitrogen also showed no decrease in the sol- 

 uble nitrogen. Thus it was apparent that for 

 some reason the action was not taking place 

 as before, but on adding 60 c.c. more of the 

 enzyme suspension in each case, a heavy floc- 

 culent precipitate immediately formed and 

 settled rapidly, and the first sample was taken 

 ten minutes later, filtered as rapidly as pos- 

 sible, and the soluble nitrogen determined 

 showed a decrease of 42 per cent, in the solu- 

 tion containing the hydrogen peroxide and 53 

 per cent, in the other. 



The same experiment was then repeated 

 with the constituents in the same proportions. 



but the quantity of the enzyme suspension 

 was increased to 150 c.c. The flocculent pre- 

 cipitate appeared at once and settled im- 

 mediately. Samples were taken every 15 

 minutes for the first hour, and at longer inter- 

 vals thereafter for 4J hours. The decrease in 

 the soluble nitrogen amounted to about 30 

 per cent, in the first 15 minutes in the solu- 

 tion containing the hydrogen peroxide, and 

 about 23 per cent, in the other. There was, 

 however, practically no further change in the 

 soluble nitrogen, up to four and one half 

 hours, when the sampling was discontinued. 



These results no doubt show conclusively 

 that the action carried out by the enzyme is 

 very rapid, but will take place only when the 

 concentration is above a certain undeter- 

 mined minimum, which point is of very great 

 importance when acting as a protective agent 

 for the fruit. 



Analysis of the fruits (apples and pears) 

 made throughout the season, where identical 

 conditions were adhered to, showed a gradual 

 decrease in tannin content. It is well known 

 that fungus parasites increase in activity 

 throughout the season and are most destruc- 

 tive as the fruits approach maturity. Later 

 in the season tests were made for the determi- 

 nation of the localization of the enzyme in the 

 fruit by the use of the guiacum solution, 

 which showed that in the case of pears the 

 blue color developed first around the core and 

 immediately under the peel, but finally de- 

 veloped uniformly over the freshly cut surface. 

 As cold weather approached, the pears were 

 removed from the trees and stored in a cool, 

 dry place, by which means it was hoped that 

 the work might be continued for some time. 

 An attempt to prepare some of the enzyme 

 from these pears eight days after their re- 

 moval from the tree resulted in a preparation 

 which had lost practically all its power. On 

 testing the freshly cut surface with guiacum 

 solution no blue color was developed, except- 

 ing rather faintly immediately around the 

 core. The supply of pears having been ex- 

 hausted, apples were examined in the same 

 manner from time to time, and showed a 

 gradual decrease in the amount of enzyme 



