I Pitcher Plants 17 



Scraping our microscopic preparations as before, we 

 may rapidly note the nectar-glands of the attractive lid, 

 the flask - shaped marginal glands just referred to, the 

 smooth internal conductive surface, and below this the 

 secreting surface. The former often shows small down- 

 ward-directed crescentic ledges, while when we come to 

 the secreting surface we find these suddenly becoming 

 better developed and crowded, each ridge bearing below 

 it a well -developed gland, which projects slightly, like a 

 watch just beginning to slip out of an inverted watch- 

 pocket. 



The fluid of the pitcher stands at a tolerably regular 

 level, and so far as the insect visitors are concerned re- 

 places the detentive surface of Sarracenia. That it is a 

 normal and genuine secretion, and not mere collected rain, 

 is evident from its development before the young pitcher 

 has opened ; while its analysis by Voelcker shows the 

 presence of oxalic and citric acids, of chloride of potassium, 

 and of carbonate of soda, magnesia, and lime. Lawson Tait 

 again denies the presence of acid in the fluid of a young 

 pitcher. Of much greater importance, however, is the 

 interpretation of its nature and uses first promulgated by 

 Sir Joseph Hooker in a memorable address to the British 

 Association in 1874, in which he gave full details of his 

 experiments on the digestive properties of the fluid, which 

 he tested not only upon insects, morsels of beef, egg, etc., 

 but even upon substances so resisting as cartilage. Lawson 

 Tait in 1875, an ^ subsequently Rees and Will of Erlangen 

 in 1876; Gorup - Besanez, the well-known physiological 

 chemist of Strasburg, in 1877; Vines, and others, con- 

 firmed these results, and extended them by the separation 

 of a digestive ferment, apparently identical with the pepsin 

 of the animal stomach. Rees and Will actually found that 

 fibrin was dissolved even more rapidly by the secretion of 



