J. M. Macfarlane. — Nepenthaceae. 21 



cells of the detentive region may be slightly to greatly indurated, and in Üie former 

 cuticularized. The cuticularization and induration may be so extensive as almost to 

 obliterate the lumen of the epidermal cells as in N. Edwardsiana. But the proto- 

 plasm of the gland cells, and of the surrounding epidermal cells is placed in living 

 and direct continuity with the more deeply-placed tissue of the mesophyll, by fine canals 

 that traverse the thickened walls, and which contain fine intercellular protoplasmic threads. 

 As in all of the glands already described, each detentive gland is directly in connection 

 with a vascular bundle-termination. 



Biological Relations of the Leaf. The general morphology and alike the 

 histology of Nepenthes leaves suggest a carnivorous and particularly an insectivorous 

 habit. Observation of the relation between insects and pitchers clearly demonstrates 

 this, while all travellers agree in describing the abundance of insect remains in the 

 pitchers. While some of the caught insects in herbarium specimens from the East are 

 winged, it seems largely true that running insects such as ants and cockroaches form 

 the principal prey of the group. Such is typically the case in conservatories, where 

 the writer'a experience is that ants and cockroaches are almost invariably the victims. 

 Running up the stem such insects turn to right and left in quest of food ; a globular 

 drop exuded from an alluring stem-gland may arrest them for a time. Reaching the 

 base of a leaf they may pass along it, attracted by the frequent presence of honey- 

 drops there. They almost invariably run along its under side, to shelter themselves 

 from enemies and bot suns. Moving on restlessly, and sipping from glands as they 

 proceed, they reach the tendril which in some species offers considerable attraction. 

 The ventral wings and the areas between are more beset with alluring glands than is 

 the outer or dorsal part of the pitcher, and along this they often run tili they reach the 

 orifice or the lid. The lid-glands of the inner surface prove a great attraction, specially 

 in such species as N. khasiana, N. maxima and N. sanguinea, but their secretion does 

 not compare with that from the marginal glands. Straining to reach the orifices of the 

 glands the insect visitors often over-reach themselves after a few efforts, tumble into 

 the pitcher cavity, and in rare cases is escape again possible. Where a definite con- 

 ducting surface is developed, the irregulär tottering and struggling efforts made by 

 insects on it, demonstrate how effective it is for the work in band. 



The presence of liquid in the pitcher-cavities early attracted the attention of bo- 

 tanists. Thus Grimm in 1682 spoke of the native Ceylon species, N. distillatoria as 

 "planta inhabilis destillatoria". Later observers like Rumph and Loureiro spoke of 

 the varying amount of the secretion during day and night, while Korthals stated that 

 the fluid was more abundant in plants that grew in the sun, than in those that grew 

 in the shade. As already stated, a considerable quantity of liquid accumulates in the 

 young pitcher cavily, while it is still air-tight, and hermetically closed by the lid. This 

 liquid is clear and slightly viscous. According to the original statement of Hooker 

 it "is always acid and effects digestion of proteinaceous substances". He further noted 

 that when the fluid was emptied out of a fully formed pitcher that had not received 

 or been in contact with animal matter, the liquid again collected in small quantity, 

 and further that placing of inorganic substances in the fluid, did not apparently cause 

 increased secretion, though animal matter did. Gorup-Besanez extended Hooker's 

 observations, and further stated that acidification of the liquid in young pitchers with 

 dilute hydrochloric acid, increased the digestive action. Vines and Clautriau have 

 supplied more exact informalion, and they both oppose the views of Dubois and 

 Tischutkin, who contendcd lhal iligestion of animal prey or of other proteinaceous 

 substances is effected by bacteria in the pitcher cavity. Vines and Clautriau agree 

 that a specific ferment is excreted, which the former has named Nepenthin. From 

 experiments conducted on N. melamphora at a high elevation in Java, supplemented 

 later by experiments in greenhouses at a warmer temperature, Clautriau concluded 

 that the liquid of the unopcncd pitcher was at first neutral. After mechanical Irrita- 

 tion or shaking of the pitcher, the liquid became acid and a digestive ferment was 



