February 7, 1913] 



SCIENCE 



231 



the receivers at different pressures and open- 

 ing them at stated intervals, the period re- 

 quired for processing could be determined 

 with all necessary accuracy, certainly within 

 a very few hours. Both time and circum- 

 stance prevented a high amplitude of experi- 

 mentation, so that pressures between 15, 25, 

 45, 75 and 90 lbs. were not tried. Concerning 

 the highest of these (90 lbs.) it may be stated 

 summarily that the fruit was killed, and on 

 being taken out, at the expiration of 24 hours, 

 was discolored (brown) and watery. It was, 

 however, nonastringent. Whether the cause 

 of death was due to rupture of the cells conse- 

 quent on the too rapid increase or decrease of 

 pressure, or on asphyxiation accompanied by 

 change in permeability of the protoplast, I 

 can not say. If the fruit was too soft, and 

 the pressure released too rapidly, even when 

 the initial pressure was no higher than 15 lbs., 

 the fruit was burst, and microscopic examina- 

 tion showed that many individual cells were 

 also in the same case. 



The experiments were, moreover, designed 

 to determine (1) the minimum period of time 

 required to cause nonastringency at the pres- 

 sures used; and (2) the after-effect of dosage 

 at given pressures applied for periods insuffi- 

 cient in themselves to produce nonastringency. 

 Aside from the theoretical interest attaching 

 to the latter question, the possible economic 

 application of short dosage, if followed by 

 nonastringency within definite periods, was 

 contemplated. The minimum period required 

 to effect nonastringency was determined crit- 

 ically for normal, 15 and 45 lbs. pressure, the 

 volumes of CO, being 1, 2 and 4, respectively. 

 The after-effect of dosage at 45 and 75 lbs. 

 was determined with sufficient accuracy to 

 indicate definite quantitative relations. 



It was found, in the first place, that at the 

 end of 36 hours with 15 lbs. pressure (experi- 

 ment 12 a — d, 1912) the fruits were nearly 

 nonastringent. Further treatment for three 

 hours produced complete astringency. It is 

 probable that the period required is nearer 36 

 than 39 hours, but not less than the former 

 nor more than the latter. At 45 lbs. 12 hours 

 was found insufficient (experiment 11 d, 1912), 



while at the close of 15 hours there was a 

 scarcely perceptible astringency (experiment 

 9, 1912). It may be recalled that the variety 

 in question {Hyakume, an " astringent va- 

 riety ") had been found in 1911 to require 

 6-7 days at normal pressure, and less than 

 46 hours at 15 lbs. Controls in air this year 

 remained hard and astringent during the 

 whole period of experimentation, nearly three 

 weeks. It therefore emerges that, as I have 

 previously maintained, there is a quantitative 

 relation between the amount of CO, available 

 and the rate at which the astringency disap- 

 pears. Green fruits yielded as readily to both 

 pressures as yellow or pale orange, which ap- 

 pears to indicate that, during the natural 

 course of events, after the fruit has its full 

 growth at any rate, the tannin cells are ready 

 for the change leading to nonastringency, and 

 that this change is induced by some condition 

 set up in the tissue external to the tannin 

 cells themselves. The graph determined by 

 the data above indicated is that of a rectan- 

 gular hyperbola, and this may be held tenta- 

 tively as expressing the relation of time and 

 pressure to the disappearance of astringency. 

 In the second place, the fact was established 

 that nonastringency ensues the more rapidly, 

 the longer the exposure to CO,, though this 

 in itself is not sufficient to bring about the 

 result. Pressures of 45 and 75 lbs. were used, 

 the treatments being for 3, 6, 9 and 12 hours. 

 After a pressure of 45 lbs. applied for 3 hours, 

 nonastringency ensued in from 71 hours (for 

 orange-colored fruits) to 192 hours (for yel- 

 low and green fruits). After 6 and 9 hours 

 exposure, 45 hours were required, the evidence 

 being that the period was somewhat less for 

 the longer exposure. After 12 hours, the 

 fruit became nonastringent in something over 

 18 hours. After 75 lbs. pressure, nonastrin- 

 gency was effected in a somewhat shorter 

 period, but in view of the possible significance 

 of the quantitative relations indicated above, 

 but little difference should be expected be- 

 tween the results caused by 45 and 75 lbs. 

 After 3 hours exposure, nonastringency fol- 

 lowed in 62 to 185 hours; after 6 hours in 

 something over 34 hours, after 9 hours less 



