THE PHYSIOLOGY OF PITCHER-PLANTS. 



107 



downwardly directed hairs arranged in a succession of rings, 

 amongst which a number of stalked two -celled glands are 

 scattered. The neck opens below into a small cavity, the inter- 

 nal surface of which is destitute of hairs, but which bears a 

 number of scattered two-celled glands, as well as two rows of 

 four-celled glands situated in two rows, one on each side, each 

 corresponding with the longitudinal course of a vascular bundle 

 with which the glands are in close relation. The arrangements 

 here somewhat recall those in Sarracenia. The glands in the 

 neck pour out a secretion which attracts minute animals to 

 enter, and to creep further and further along it, the chevaux 

 defrise of hairs preventing any return, until at length they 

 reach the dilated glandular chamber at the extremity of the 

 neck. What takes place there is not known ; but whether the 

 insects are digested or decomposed, the organic products are 

 absorbed by the plant. Our knowledge of these pitchers is due 

 to Darwin (" Insectivorous Plants ") and to Goebel (" Pflanzenbio- 

 logische Schilderungen," II., 1891, p. 121; also "Biologie von 

 Genlisea," Flora, 1893). 



We come now to Lathrasa, the last of our series of plants 

 having subterranean pitchers. Attention was first directed 

 to the peculiar cavities in the subterranean scale-leaves of 

 this plant by J. E. Bowman (" Trans. Linn. Soc," xvi., 1829). 

 He detected the numerous glands which are borne on 

 the surface of the labyrinthine cavity ; and he suggested 

 that, inasmuch as the scales have no stomata, these cavities 

 might serve a respiratory function, opening as they do by 

 an orifice just below the insertion of each scale. Shortly 

 afterwards Meyen (" Phytotomie," 1830) distinguished the 

 two kinds of glands — the sessile multicellular glands, the 

 shortly stalked two-celled glands — and regarded the whole as 

 an apparatus for the excretion of carbonate of lime. Various 

 observers published observations on these structures during suc- 

 ceeding years without, however, making any striking sugges- 

 tions as to their function, until Cohn, in 1877 (" Jahresb. d. Schl. 

 Ges. fiir vaterl. Kultur") suggested that they might be traps to 

 catch animals ; but as he failed to find animal remains as a 

 rule in the cavities, he relinquished this view in favour of 

 another, that, namely, the glands secrete a liquid which renders 

 it possible for the plant to absorb certain humus-constituents 



