422 HEPBURN— BIOCHEMICAL STUDIES 



was as follows. The liquor was acidulated with dilute phosphoric acid, 

 and a thin suspension of calcium carbonate in water was added until 

 effervescence ceased; the precipitate of calcium phosphate, which ad- 

 sorbed the enzyme, was permitted to stand for 24 hours, then was sepa- 

 rated from the supernatent liquid by decantation, and was dissolved in 

 very dilute hydrochloric acid. A saturated solution of cholesterol in a 

 mixture of absolute alcohol and absolute ether was added to this solution. 

 The precipitated cholesterol, which adsorbed the enzyme, was dissolved 

 in absolute ether. The aqueous layer now contained the enzyme as a 

 gray, amorphous, fiocculent, suspended soUd, which was partly soluble 

 in distilled water, msoluble in boiling water, very soluble in glycerol, and 

 produced a characteristic viscid change in a small quantity of fresh milk. 

 Unfortunately the power of the enzyme to digest proteins was not tested; 

 and its action on milk recalls that of rennin, rather than that of a true 



protease. - 



Tait permitted the Hquor from four virgin pitchers of N. phyllamphora 

 to act for 28 hours on cubes of albumen (volume of each cube 1 cubic 

 millemeter). The substrate remained unchanged. But one sample of 

 the liquor was acid; the other three samples were absolutely neutral; the 

 enzyme described above was found in-but one sample. 



After the pitchers had opened, the liquor became changed in its 

 reaction, and m its proteolytic power. "Fluid taken from pitchers into 

 which flies have previously found their way is always very acid, has a 

 large quantity of the ferment, and acts in a few hours on cubes of albu- 

 men, making them first yellow, then transparent, and finally completely 

 dissolvmg them. " The liquor in a pitcher, in which insects were under- 

 going digestion, was "very viscid and very acid. " 



Tait sums up: — "In the unopened pitcher the secretion is only faintly 

 acid and not at all viscid. The secretion is increased therefore, . . . 

 , in quahty after food has been taken in." 



The work of von Gorup and Will (4) was largely carried out on the 

 secretion of N. phyllamphora, Willd. and N. gracilis, Korth. Separate 

 studies were made, in vitro, on (a) liquor from pitchers which were free 

 from insects, and (b) liquor from pitchers which had been entered by 

 insects and contained their remains. These may be spoken of as non- 

 stimulated and stimulated pitchers respectively. 



The liquor was almost colorless, famtly opalescent or entirely clear, 

 odorless, without any distinct taste, and of varying consistency— some 

 samples being thick, others being thm like water. The liquor from non- 

 stimulated pitchers was neutral or, at the most, very famtly acid; that 



