ON THE PRESENCE OF LACTASE IN THE INTES- 

 TINES OF ANIMALS AND ON THE ADAPTATION 

 OF THE INTESTINE TO LACTOSE. BY R. H. ADERS 

 PLIMMER, D.Sc. 



(From the Physiological Laboratory, University College, London.} 



IN a recent communication to this Journal^, I showed that neither the 

 pancreas nor the pancreatic juice of dogs, even when they were fed on 

 milk and lactose, contained the enzyme lactase. These results definitely 

 proved that there was no adaptation of this organ to a particular diet, 

 a result which might have been expected, as the intestines of dogs 

 contain the ferment in considerable quantity. 



Since, however, the pancreas never at any time in the life of an 

 animal contains lactase, whereas the intestines of, at any rate, young- 

 animals contain this ferment, while those of adult animals in many 

 cases have lost their power of hydrolysing lactose, adaptation of this 

 organ might be reasonably expected to occur, when the animals are 

 subjected to this stimulus by feeding, a supposition put forward by 

 Emil Fischer and W. Niebel* 2 ' in 1895. 



Experiments in this direction have already been carried out by 

 Weinland' 3 ' and by Portier and Bierry (4) . Weinland found that 

 the adult rabbit and the fowl (the intestines of which do not contain 

 lactase), when fed on milk and lactose produced this enzyme in their 

 intestines. Portier and Bierry, using the duck in their experiments, 

 in one case obtained no evidence of adaptation, but in another case found 

 that adaptation had occurred. In their communication they stated 

 that they would confirm this, but so far as I have been able to find out, 

 no confirmation has appeared. The same observers also made experi- 

 ments on the production of the ferment inulase, an enzyme not present 

 in the intestines of animals, by feeding animals on Jerusalem 

 artichokes, which contain inulin. The results were likewise negative 

 and they confirm those of Richaud' 5 ', who found that inulin was easily 

 hydrolysed by the acid of the gastric juice and thus converted into 

 laevulose which could be assimilated. 



