LACTASE IN INTESTINE. 21 



Besides these experiments on the adaptation of the pancreas and 

 intestine, a paper by Neilson and Terry (6) on the adaptation of the 

 salivary glands of dogs to amylase has recently appeared. The results 

 obtained by these authors, however, are not very conclusive and further 

 experiments on this point would be of great interest. 



Our present knowledge of the presence of lactase in the intestines 

 of animals rests chiefly upon the experiments by Weinland. The 

 earlier work by Dastre' 7 ', Rohmann arid Lappe (8) and E. Fischer 

 and Niebel was limited to the dog, calf, ox and horse. More extended 

 observations were made by Portier* 9 ', who examined, in addition to 

 the above animals, the rabbit, the pig and birds. Lactase was found in 

 the intestine of the old rabbit, but not in that of tbe pig and birds. 

 Then, a year later, Weinland took up the subject and examined the 

 intestines of young and old dogs, young and old rabbits, young and old 

 pigs, young and old oxen, young and old sheep, old horse, young goat, 

 new-born child and fowl. Lactase was found to be present in all except 

 the old rubbit, old ox, old sheep and fowl. His results, in the main, 

 confirm those of the previous observers, of whom in this connection 

 must also be mentioned Pantz and Vogl (10) with regard to the 

 new-born child. The recent work of Langstein and Stein itz (u) on 

 the presence of lactase in the excreta of children suffering from gastro- 

 enteritis is a confirmation of this. Porcher (12) has also found lactase 

 in the excreta of young mammals. The experiments of Bierry and 

 Gmo-Salazar< 13) upon animal lactase were rather in respect to its 

 localisation than to its presence in young and old animals. Finally, 

 a recent note by Mendel (14) , who found lactase present in the 

 alimentary tract of the embyro and suckling pig, but not in the adult 

 pig, completes the observations on the presence of lactase in the 

 intestines of animals. The net result of the work of these observers 

 is, that lactase is present in the intestines of all young animals but is 

 not found in all old animals. Doubt still remains with regard to the 

 old rabbit and old pig; the former having been found by Portier 

 but not by Weinland to contain lactase; the latter, according to 

 Weinland, contained lactase, but according to Portier and to Mendel 

 it is not present. 



It is necessary here to call attention to the methods which have 

 been employed for the detection of the lactase. Portier used the 

 osazone method, which has been shown lay Bierry to be incapable of 

 detecting a change of less than 20 per cent., and consequently, if less 

 hydrolysis had occurred, the possibility of detecting it would be excluded. 



12 



