1903.] The Hydrolysis of Fats in vitro by means of Steapsin. 33 



experiments with A B and C were started on February 19th, and those 

 with D on March 5th. The first observations were made after a lapse 

 of 4 days. The delay was caused through some of the emulsions 

 having separated into two layers, which necessitated the re-establishing 

 of the state of emulsion by frequent shaking. It will be noticed that 

 in those experiments with cotton-seed oil, in which neither acid nor 

 alkali had been added, hydrolysis had reached after four days, in the 

 case of preparation C, from 22 '9 per cent. (No. 5) to 32 '8 per cent. 

 (No. 6), and in the case of preparation D, from 31 per cent. (No. 11) to 

 37'1 per cent. (No. 9). After another 7 days, samples Nos. 11 and 9 

 had reached 46*3 per cent, and 44 '3 per cent, respectively. As it was. 

 not expected that further hydrolysis would proceed very rapidly, some 

 time was allowed to elapse before the next tests were taken. It will be 

 seen from the table that the highest percentages of hydrolysis, when, 

 neither acid nor alkali was added, were 86*7 per cent, in the case of 

 preparation C (No. 6), and 83*8 per cent, in the case of preparation 1> 

 (No. 10). In both cases the steapsin had been allowed to act for 56 days-. 

 Whereas the experiments made with C show that the amount of 

 hydrolysis increases with the amount of steapsin mixed with the oil, no 

 such striking regularity is apparent in the case of preparations D (Nos, 

 9 to 11). 



Further experiments were made with cotton-seed oil under the same 

 conditions, only with that difference that either dilute acid or dilute 

 caustic soda was added . So far, no decisive influence of either acid or alkali 

 has been noticed, and from the experiments recorded here, no definite 

 conclusions can be drawn. 



Curiously enough, the hydrolysis of lard proceeds at a very much 

 slower rate, reaching only about one-third of the hydrolysis noticed in 

 the case of cotton-seed oil. Since the consistency of lard favours the 

 state of emulsion, one would have expected the opposite result. The 

 last two experiments with lard seem to show that an increased amount 

 of caustic soda, whilst favouring hydrolysis at the commencement, 

 seems later on to retard the action of the steapsin, notwithstanding 

 the larger amount of the latter. 



The numbers recorded in the table show that the steapsin is not 

 capable of producing the reversible reaction which it was thought, 

 reasoning by analogy, this enzyme might produce. 



These preliminary experiments are very interesting from a physio- 

 logical point of view ; they prove for the first time that it can be 

 demonstrated by the usual quantitative methods of fat analysis that 

 steapsin is a very powerful fat-splitting ferment. 



We are now investigating the action of steapsin and of lipase on 

 fats, in the presence of bile, small quantities of soaps, and a number 

 of other substances which suggest themselves from a physiological 

 point of view. 



VOL. LXXII. D 



