28 



R H. A. PLIMMER. 



Another experiment was made with the intestine of the dog, but 

 here two scrapings of the same length of intestine were made, a surface 

 and a deep scraping, in order to determine, if possible, whether lactase, 

 like enterokinase, is localised in any particular layer of cells. Both 

 were well ground up and made up to the same volume with toluol water 

 (200 c.c.) and filtered ; 90 c.c. of each were incubated with 100 c.c. 

 lactose solution, 30 c.c. samples being removed at intervals and treated 

 in the usual manner. 



These results would seem to show that lactase is localised rather in 

 the deeper than in the surface layers of the mucous membrane, but it 

 must be remembered that the quantity of solid matter is much greater 

 in the former than in the latter and the volume of toluol water used to 

 make up to 200 c.c. is much less. The following experiment, however, 

 shows that more hydrolysis occurs with the surface scraping : 



1! 



J100 c.c. lactose sol., 100 c.c. extract surface scraping, 2 c.c. toluol 



(100 c.c. lactose sol., 100 c.c. boiled extract surface scraping, 2 c.c. toluol) [ 



1100 c.c. lactose sol., 100 c.c. extract deep scraping, 2 c.c. toluol I [ 



(100 c.c. lactose sol., 100 c.c. boiled extract deep scraping, 2 c.c. toluol J ) 



The four mixtures were then treated in precisely the same manner with Hg(N0 3 ) 2 &c. ; 

 and the following figures were obtained on reduction with 20 c.c. solution. 



Surface Scraping. 



Control 

 Grs. Cu 2 O = Mgm. glucose Grs. Cu 2 O 



0-5896 

 0-5922 



0-5754 

 0-5772 



5763 



250-6 



244-0 



0-41501 

 0-4172 j 



Deep Scraping. 

 0-4172 



,,,>, 

 4161 



0-4182J 



0-4177 



Mgm. glucose 

 185-0 



185-8 



Percentage of 

 hydrolysis 



82-7 



73-1 



The conclusion is from these experiments that lactase is distributed 

 fairly equally through the whole of the mucous membrane of the 

 intestine. 



