106 PHYSIOLOGY OF NUTRITION. 



secretion has an acid reaction. It is often still found in moderate 

 quantities on the surface of leaves which have been fed with meat, 

 and in course of time have opened again. Non-nitrogenous bodies 

 do not induce the production of a glandular secretion when placed 

 on a Dionsea leaf ; the upper surface of the leaf wings, in the 

 absence 'of proteid substances, remains dry. 3 



1 A peptonising ferment has been isolated from Drosera leaves by Reess and 

 Will. See Botan. Zeitung, 1876, Nr. 44. 



2 Literature. Darwin, Insectivorous Plants, 1876 ; Schimper, Z>oa?i. Zeitung, 

 1882 ; H. de Vries, Botan. Zeitung, 1886 ; Klemm, Flora, 1892. 



3 For a detailed account of the behaviour of these plants, see Darwin, Insec- 

 tivorous Plants. For a general view of the subject, consult Detmer, Lehrbuch 

 der Pjtanzenphysiologie, 1883, pp. 65 and 282. 



