102 R. H. A. PLIMMER. 



EXP. X. 120 c.c. toluol water extract of mucous membrane of intestine of kitten 

 passed through Berkfeld filter. 



(100 c.c. 5/ lactose solution, 50 c.c. extract, 2 c.c. toluol | Incubated at 38C. 



(100 c.c. 5/ lactose solution, 50 c.c boiled extract, 2 c.c. toluol \ for 72 hours. 

 To each added 10 c.c. mercuric nitrate solution. Filtered. 150 c.c. filtrate neutralised 

 with 7-5 c.c. 10 % NaOH and filtered. 140 c.c. filtrate treated with H 2 S. Excess of H 2 S 

 removed with CuS0 4 . Made up to 250 c.c. Filtered; and filtrate used for rotation, 

 reduction, and osazones, after neutralising and again filtering. 



The osazone of the experiment was completely soluble in boiling water except for 

 a very small quantity. 



The osazone of the control was completely soluble in boiling water. 



EXP. XL 210 c.c. toluol water extract of mucous membrane of intestine of dog. 

 (100 c.c. 5 % lactose solution, 100 c.c. extract, 2 c.c. toluol 1 Incubated at 38 C. 



[100 c.c. 5 / lactose solution, 100 c.c. boiled extract, 2 c.c. toluol ) for 72 hours. 

 To each added 10 c.c. mercuric nitrate solution. Filtered. 170 c.c. filtrate neutralised 

 with 5-5 c.c. 10 / NaOH and filtered. 150 c.c. filtrate treated with H 2 S. Excess of H a S 

 removed with CuS0 4 . Made up to 250 c.c. Filtered; and filtrate used for rotation 

 and redaction. 



The osazone of the experiment was not soluble in boiling water. 

 ' The rtsa'zone Of the control was completely soluble in boiling water. 



The table of results clearly shows that neither the pancreatic juice 

 nor the extracts of pancreas of milk and lactose-fed dogs contain lactase. 

 Except in Exps. VI and VII, the difference in reducing power is always 

 less than 1 mgm. glucose, but here it was about 2 mgin. This is no doubt 

 due to experimental error, since, where inversion has certainly occurred 

 there is a difference varying from 7 mgm. to 66 mgm. which represents 

 changes of 7 83 per cent., whereas in the above experiments the dif- 

 ference only represents a change of about 2'5 per cent. 



Exp. X clearly shows that the reduction method of determining the 

 presence of lactase is by far the most delicate. A difference of 6'6 mgm. 

 glucose or 7 per cent, inversion could be determined, whereas only a very 

 small quantity of glucosazone could be obtained. This by itself would 

 be insufficient to definitely show the presence of lactose. Bierry's 

 statement that a change of less than 20 per cent, cannot be detected with 

 certainty by the osazone method is thus confirmed. 



The melting points of the glucosazone obtained in Exps. IV and IX 

 are too low. This can easily be accounted for by the presence of galact- 

 osazone, which would also be formed and which would lower the melting 

 point considerably. As has been frequently shown the melting points 

 of osazones when impure are no criterion of their composition, so that 

 no stress can be laid upon these data. The estimation of nitrogen 

 by Dumas' method, however, definitely shows whether the osazone of a 

 monosaccharide or a disaccharide is present, since glucosazone contains 



