, Studies on Enzyme Action. 607 
Animal lipase, however, from the liver or pancreas of the pig, according to 
Kastle and Loevenhart,* manifests considerable activity in hydrolysing simple 
ethereal salts, the action being greater in the case of the higher than of the 
lower terms of the series, as shown by the fact that ethylic butyrate is more 
readily hydrolysed than is ethylic acetate. Dakin’s observations may be 
regarded as confirming this conclusion. Whether animal lipase acts on 
natural fats is not yet satisfactorily determined. Lewkowitsch states that he 
could not carry the hydrolysis of cotton-seed oil beyond 3 per cent.; he is 
inclined to attribute this want of success, however, to the fact that he could 
not secure a satisfactory emulsion. 
The activity of animal lipase, it should be mentioned, is said by Magnusf 
to be conditioned by two substances, one of which is dialysable and not 
destroyed by boiling whilst the other is destroyed by heat and not dialysable. 
Judging from my own experiments, it is clear that the investigation of 
lipase presents peculiar difficulties. It would scarcely be worth while to put 
the results on record, were it not desirable to call attention to issues which 
they raise. 
The material used was simply ground castor-oil seed, free from husk, when 
the action of the enzyme on castor oil was under consideration; whilst for 
the purpose of studying the action of the enzyme on other ethereal salts, this 
material was carefully freed from oil by washing it with ether and dried by 
exposure to the air on a porous plate. In nearly every case, toluene was 
added to maintain sterile conditions. 
Connstein’s contention has been confirmed that the presence of acid is. 
necessary to condition the hydrolysis and that practically any acid is effective, 
provided a sufficient amount be used. Aspartic and glutamic acids—which 
are formed at an early stage of the germination of seeds—were found to be 
highly active ; glycin and asparagin, however, were practically without effect. 
Thus, in an experiment in which a mixture of 5 cc. of olive oil, 1 gramme 
fat-free castor-oil seed and 10 c.c. 3/100 N sulphuric acid was digested at 38° 
during 18 hours, the amount of oleic acid liberated was 4145 grammes. In 
a blank experiment from which the enzyme was omitted, the amount of oleic 
acid liberated at the end of 18 hours was 0:1087 gramme; at the end of 
24 hours 01128 gramme; and at the end of 48 hours 0:132 gramme. On 
digesting 5 grammes of castor-oil seed paste at 38° with 5 c.c. of a 1-per- 
cent. solution of aspartic acid, 4 c.c. of water and 1 cc. of toluene, the 
amount of ricinoleic acid liberated at the end of 19 hours was 2:99 grammes. 
In a similar experiment with glutamic acid, the amount liberated was 
* © American Chemical Journal,’ 1900, vol. 24, p. 491. 
t+ ‘Zeit. Physiol. Chem.,’ 1904, vol. 42, p. 149. 
