232 



SCIENCE 



[N. S. Vol. XXXVII. No. 945 



than 34 hours, and after 12 hours in about 

 20 hours. In the receiver charged for 12 

 hours, however, the pressure fell from 75 to 

 50 lbs., so that no difference vs^orthy of note 

 may be seen as between this and the corre- 

 sponding experiment for 45 lbs. The diiier- 

 ence in effect of the 6 and 9 hour exposures 

 was very small with both 45 and 75 lbs. pres- 

 sure, a fact which I am unable to elucidate. 

 Aside from this, the period required for be- 

 coming nonastringent was, roughly speaking, 

 in inverse ratio to the time of exposure to the 

 gas. It will be readily understood by those 

 who have worked with such objects as ripen- 

 ing fruits that it is often difficult to fix upon 

 a suitable indicator of the final limit of any 

 of the physiological processes involved. Thus, 

 in these experiments just described, the dif- 

 ference in rate of change in green and orange- 

 colored fruits makes it difficult to decide on 

 what is to be regarded as the final point at 

 which nonastringency ensues. Furthermore, 

 there is the more variation between different 

 fruits the longer the period of ripening, and 

 the end point is correspondingly difficult to fix. 



I have, therefore, endeavored to apply a test 

 different from that of tasting, at least for pur- 

 poses of control. The mucous membranes 

 are of course extremely sensitive; neverthe- 

 less, it becomes difficult, as the end point is 

 approached, to judge clearly. It is further- 

 more of the highest importance to examine 

 the physical characters of the tannin-mass, 

 which has been shown to be a colloidal com- 

 plex," in order to determine whether the con- 

 dition reached by it when nonastringency has 

 been accomplished quickly is identical with 

 that reached after a slow process. A former 

 study of the reaction of alkaloids* with the 

 tannin-mass showed me that as nonastrin- 

 gency is approached, the coarsely granular 

 precipitate gives way to an increasingly finer 

 one, so that an ultramicroscopic and eventu- 

 ally an amicroscopic suspensoidal condition is 

 reached. The only change obvious on apply- 

 ing the reagent then becomes one of color, 



* Lloyd, F. E., ' ' The Tannin-colloid Complexes 

 in the Fruit of the Persimmon," Biochemical 

 Bulletin, 1: 7, September, 1911. 



the tannin-mass becoming brown, lighter 

 browuj darker and paler yellow as the defini- 

 tive state is approached. By reflected light 

 the changes are evident as a decreasing 

 milkiness.° By correlating these progressive 

 changes with the disappearance of astrin- 

 gency, it has become evident that it is quite 

 possible to decide whether a fruit is astringent 

 or not without tasting it. This is because 

 the physical condition of the tannin-mass is 

 the same on the arrival of nonastringency, 

 whether this has been accomplished in 15 

 hours or as many days. 



There remains one further point of which 

 to speak. When one uses such an expression 

 as " the period required to become nonastrin- 

 gent," an incorrect notion may be implied. 

 It is not to infer that in one case the process 

 itself is slow and in another rapid (though 

 this may be the case), but that the time re- 

 quired to start the process may diiier. It 

 remains to determine the actual fact, and this 

 is necessary to an understanding of the whole 

 matter. 



Note. — The work, of which the above is a partial 

 account, was done at the Alabama Agricultural 

 Experiment Station as an Adams Fund Project. 

 I have to thank Dr. F. A. Wolf for hearty and 

 arduous cooperation in carrying on the experiments. 

 Francis E. Lloyd 



McGiLL Univeesity 



THE AMERICAN FB.YSIOLOGICAL SOCIETY 

 The society held its twenty-fifth annual meet- 

 ing in Cleveland, Ohio, December 29, 1912, to 

 January 1, 1913. Sixty-nine members were in 

 attendance. Two executive sessions and six scien- 

 tific sessions were held, two of the latter being 

 joint sessions, one each with the American Society 

 of Biological Chemists and Section K of the Amer- 

 ican Association for the Advancement of Science. 

 The joint session with the American Society of 

 Biological Chemists was opened with exercises in 

 memory of the late Waldemar Koch. After the 

 ' These changes are analogous to those seen first 

 by Loew and others, and recently described in 

 detail by Czapek. Czapek, F., "Ueber Pallungs- 

 veactionen in lebenden Pfl^anzenzellen und einige 

 Anwendung derselben," Ber. deut. hot. Ges., 38: 

 147-159, 1910. 



