352 



Scientific Proceedings, Royal Dublin Society. 



Experiment I. 

 In this experiment the viseosimeter was immersed in a large beaker of 

 melting ice, whicli was kept well stirred. 1 e.c. of freshly extracted sap from 

 the leaves of Syringa vulgaris was mixed with 2 c.os. of 1 per cent, pectin solu- 

 tion, and the mixture immediately tranferred to the viseosimeter. Determi- 

 nations of the viscosity of the liquid were made every five minutes during 

 nearly eight hours, with the exception of about one hour in the middle. The 

 variation of tlie viscosity with time is shown in curve No. 1. The time of 

 flow increased from 12'8 seconds to 108'6 seconds, and was still rising when 

 the experiment terminated. The slight irregularity which is observable in 

 the readings taken just after the interval, in which observations were not 

 made, is due to the fact that the mixture of ice and water had been left for 

 about an hour without being stirred, and therefore the liquid in the viseosi- 

 meter had become slightly warmer, with a consequent increase in the activity 

 of the enzyme. 



TIME IN HOURS 

 The curve obtained shows tliat the rise in viscosity, which occurs slowly 

 at first, gradually becomes more rapid. 



