46 



and Arbacia in the way described in chapter 7. A deep-depres- 

 sion slide was now filled with this fluid and a drop of olive 

 oil added. The sample was covered with a cover-glass and 

 put into the incubator. At different intervals these tests were 

 inspected. 



In none of these tests I could see a dispersion or emulsification 

 of the oil amounting to anything. Occassionally the drop was 

 found to be split into two, sometimes even more (5 or 6) parts. 

 A true emulsification which would have a biological importance 

 could never be seen however. Shaking of the samples was of 

 course avoided as much as possible. 



Another possibility is the assumption of the hydrolytic disso- 

 ciation of the fats. Gri ffi ths 48), Stone 124), and Clerc 16 a ) 

 in fact report that they found steatolytic enzymes. I studied 

 this problem on digests of the same kind as those described 

 in the chapter on the enzymes, using olive oil as a substrate. 



A large quantity of starfish radial sac material was ground 

 up with sand and put into an incubator after olive oil and an 

 ample quantity of toluene had been added. At regular intervals 

 the mass was shaken vigorously and 20 c. c. samples of the 

 homogeneous mass taken. These were titrated with 0.05 N KOH. 

 The results obtained are represented in the following little table : 



Table 7. 

 Titrable acidity of digests of radial sacs and fat. 



Moment. 



c. c. 0.05 N KOH. 



Control on initial sample. Monday 



Tuesday, 6 p.m. 

 Wednesday, 6 p.m. 

 Thursday, 7 p.m. 

 Friday, 7 p.m. 



evening. 



1.20 

 6.35 

 8.05 

 8.40 

 8.36 



These figures show a regular increase in acidity and super- 

 ficially one might consider them as a proof for the presence of a 

 lipolytic enzyme. The fact that the process goes on rapidly at 

 first, then slows down, would be explained by the assumption 

 that the enzyme had been destroyed by the accumulation of the pro- 

 ducts of its action. It is strange however, that the process takes 

 place with such surprising rapidity, practically the whole acidi- 

 fication has taken place on the first day. 



For such reasons it seemed advisable to me to run a control. 

 A similar digest was made and no olive oil added this time. 

 Toluene was added as always and some water. The titrations 

 were not made every day, since I was only interested in the 

 end-result. The results of this experiment are given in table 8. 



