BIOCHEMICAL STUDIES OF THE PITCHER LIQUOR OF 



NEPENTHES. 



By JOSEPH SAMUEL HEPBURN, A.M., M.S., Ph.D. 

 {Read April 14, 19 17.) 



As the pitcher of Nepenthes gradually develops, a liquor is 

 secreted and occupies the lower portion of its cavity. After the 

 operculum, or lid, has opened, insects are attracted by the nectar 

 which is secreted by glands. The nectar glands are found on the 

 outer surface of the pitcher, more abundantly on the inner surface of 

 the lid, and on the inner edge of the corrugated rim that surrounds 

 the margin of the pitcher. The insects, thus attracted, are tempted 

 down into the pitcher, and pass to a richly glandular zone with a 

 smooth surface — the so-called detentive surface — on which they lose 

 their footing, and are precipitated into the liquor. The insects are 

 then digested by the liquor. 



Two theories exist as to the manner in which digestion occurs ; 

 each theory is supported by experimental evidence. Hooker,^ Tait,- 

 von Gorup and Will,^ Vines,'' Goebel," Clautriau,'' and Fenner' con- 

 cluded from their researches that the digestion is due to an enzyme 



1 Hooker, Nature, 1874, X., 366-372. Report of the Forty-fourth Meeting 

 of the British Association for the Advancement of Science, i8v'4; Notes and 

 Abstracts of Miscellaneous Communications to the Sections, 1875, pp. 102-116. 



2Tait, Nature, 1875, XH., 251-252. 



3 von Gorup and Will, Sitzungsberichtc dcr physikalisch->nedicinischen 

 Socictdt cu Erlangcn, 1875-6, VHI., 152-158. Ber. dcr dent. chem. Gescll, 

 1876, IX., 673-678. 



4 Vines, //. of Linnean Society, Botany, 1877, XV., 427-431. Annals of 

 Botany, 1897, XL, 563-584; 1898, XH., 545-555; 1901, XV., 563-573- 



^ Goebel, Pflanzenbiologische Schilderimgen, 1893, H., 186-193. 



" Clautriau, Memoirs couronnes et aiitrcs ;«^;not>^.y, publics par I'Academie 

 Royale des Sciences, des Lettres et des Beaux Arts de Belgique, Collection 

 in 8°, 1899-1900, LIX., third memoir, 56 pages. 



"' Fenner, Flora odcr alUjemeinc botanische Zeitung, 1904, XCHL, 335- 

 434 (especially pp. 358-363)- 



112 



