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Surface Tension and Ferment Action. 

 By E. Beard and W. Cramer. 



(Communicated by Sir Edward Schiifer, F.E.S. Received March 17, 1915.) 

 (From the Physiology Department, Edinburgh University.) 



The following investigations were carried out with the object of determining 

 whether the action of a ferment on a substrate is affected by surface tension. 

 Since in the living organism the action of ferments proceeds in a system in 

 which surface development has reached a maximum, the problem is one of 

 considerable theoretical importance. So far as we are aware, it has not been 

 studied. The experimental difficulty is, of course, to allow the factor of 

 surface tension to operate on the action of ferments in such a way that a 

 sufficient amount of the digest can be obtained at the end of the experiment 

 in which the progress of the ferment action could be determined. Various 

 devices were used to attain this object. In some preliminary experiments 

 the reaction was allowed to proceed in a capillary tube, in others in test-tubes 

 fdled with glass wool, with thin short capillary glass tubes or with glass 

 beads. The reaction as it proceeded in these tubes was then compared with 

 that of a control in an ordinary test-tube. A distinct effect was observed in 

 these preliminary experiments with lipase, diastase, and yeast invertase, all 

 of which showed a retardation. The effect was then studied in some detail 

 in the case of invertase. 



The experiments with invertase were carried out as follows : — -Solutions of 

 sucrose and invertase were mixed in definite proportions. Part of the 

 mixture was placed in a test-tube and served as a control. The rest was put 

 into test-tubes filled with glass beads, 3 to 4 mm. in diameter. Care was 

 taken that the level of the fluid was always well below the top level of the 

 glass beads. The tubes were then closed with a rubber stopper and incubated 

 at a given temperature. After a given number of hours, readings were taken 

 with a polarimeter. In every series of experiments the control tubes were 

 read first, so that the slightly prolonged period of incubation in the tubes 

 filled with beads would tend to diminish any retardation that might occur. 

 Special control experiments showed that the presence of glass beads did not 

 affect the readings obtained with pure sucrose solutions. Similarly the 

 readings obtained with solution of invertase alone remained constant. That 

 the effect of the mutarotation of the glucose formed by the action of invertase 

 could be neglected will be pointed out below. The beads were washed after 

 each experiment for several hours, first in hot running tap water, then with 

 distilled water, and dried in an oven at about 180° C. 



