PITCHER-PLANTS. 



379 



plants, and so to serve as a climbing organ. At the end of this tendril a peculiar 

 appendage is noticeable very early; this developes later into the pitcher, so remark- 

 able in every respect, and the common form of which is shown in Fig. 247. In the 

 majority of species the pitcher is only 4-10 cm. high, and 1-3 cm. broad; but there 

 are species with pitchers 30 cm. high and 

 of corresponding breadth. The pitcher is 

 provided with a lid, which, however, in 

 the developed condition never closes the 

 opening. The whole organisation of this 

 wonderful organ is calculated to allure 

 small animals, especially ants, &c., in such 

 a manner that they are guided by two 

 wings running outside the pitcher to the 

 margin dd, where an exudation of honey 

 invites them further. Immediately be- 

 neath this margin, and on the interior, 

 the pitcher is bright and smooth, so that 

 even the foot of an insect finds no hold : 

 the animals fall down to the bottom of 

 the pitcher, and are there received into 

 a copious fluid secretion. This secretion, 

 which may easily be poured out of large 

 pitchers in quantities amounting to several 

 or many cubic centimetres, is excreted by 

 some thousands of small epidermal glands 

 (at 5 in the figure). In the non-irritated con- 

 dition the liquid has a neutral reaction, but 

 even then contains a peptonising ferment, 

 as Gorup-Besanez and Vines have demon- 

 strated, since on adding an acid the se- 

 cretion is able to digest fibrin ^ Just as 

 in Drosera, the acid necessary for diges- 

 tion is only excreted after an insect has 



fallen into the abundant secretion. The great difficulties attending the culture of 

 Nepenthes in our hot-houses may depend chiefly upon the fact that this addition 

 of proteid substance in nutrition is mostly deficient. 



FIG. 247.— I eaf tendril a of hepeiithes Icevis with tlic 

 pitcher bisected longitud inlly (the interior of the posterior 

 lialf of the pitclier is shown) , * basal region with digestive 

 glands ; c upper smooth portion ; d margin of pitcher ; e lid 

 (nat. size). 



' S. II. Vines, 'On the Digestive Ferment of Nepenthes' (Linn. Soc. vol. xv. p. 427). E. v. 

 Goriip and II. Will, ' Fortgesetzte Beobachtungen über peptonbildende Fermente im Pflanzenreiche'' 

 (.^ Mitth.) in Berichten der deutsch, ehem. Gesellschaft (Berlin, 1S76). I mixed the secretion of 

 two pitchers oi Nepenthes Scdeni (amounting to about 12 c.c.) with three drops of hydrochloric acid 

 and, later, an equal volume of water. This fluid gradually digested enormous quantities of swollen 

 blood-fibrin, which I estimated at about 8 c.cm. 



