1913.] 



Studies on Enzyme Action. 



589 



seed in a mortar and digesting the oily mass with petroleum spirit : after 

 24 hours, the greater part of the oil is removed by squeezing it through 

 calico cloth. The residue is treated twice in the same manner, using ordinary 

 ether instead of petroleum spirit ; it is then ground up in a mortar and 

 digested during about 15 minutes with 80 c.c. of X/10 acetic acid to every 

 10 grm. of the meal. The liquid having been filtered off, the residue is 

 washed several times by alternately transferring it to a beaker containing 

 water and pouring off the liquid through a filter : it is then dried in a vacuum 

 desiccator and, when dry, ground up and sifted through fine muslin. Succinic 

 acid can be substituted for acetic but when tartaric acid is used the product 

 is less active. During the washing process about 40 per cent, of the material 

 goes into solution. The amount of powder obtained is about 9 per cent, of 

 the weight of the seeds. Our preparation has not proved to be so active as 

 that described by Tanaka but we have obtained better results with it than 

 with a preparation made according to his directions. 



Experimental Method. — The hydrolytic experiments were all carried 

 out in 50 c.c. Jena hard glass flasks closed with rubber stoppers. These 

 were maintained at a constant temperature in a Hearson incubator, 

 14 by 12 by 12 inches, heated electrically and provided with an electrically 

 controlled regulator. 



In order to agitate the contents of the flasks during the experiments, they 

 were fixed by rubber bands to paddles carried on a central steel shaft, 

 | inch in diameter, passing through the horizontal axis of the chamber ; this 

 shaft was rotated at a rate of about six revolutions per minute by means of 

 a small motor outside the chamber. The shaft carries a square metal block 

 attached to which are four brass fins at right angles to each other. A wooden 

 plate, 4f by 10 inches, about \ inch thick, forming the paddle, is screwed to 

 each of the brass fins ; a narrow strip of wood is fixed near the edge of the 

 paddle and grooves are cut in this to receive the necks of the flasks ; the 

 bodies of the flasks rest in corresponding holes cut in the paddles. The 

 arrangement will be obvious from the figure on p. 590. 



The titrations were carried out in 50 per cent, alcoholic solutions, using 

 normal or N/10 alkali and phenolphthalein. 



Acidity of the Enzyme. — The untreated oil-free seed residue is distinctly 

 acid, neutralising from 2 to 4 c.c. of N/10 alkali per gramme; whilst it 

 hydrolyses succinic ether nearly as well as the acid treated material, it has 

 very little action on fatty oils. 



When either acetic or succinic acid is used and the meal is washed until 

 the filtrate is no longer acid to phenolphthalein, the product is still acid, that 

 prepared with the aid of acetic acid requiring from 4 to 5 c.c. of X/10 alkali 



