30 J Scientific Proceedings^ Royal Dublin Soci,et>j. 



the pitcher. During the dry season, when tlie plant is most in want of water, 

 the pitchers contain no water. Finally, quoting Scott and Sargant, " the 

 inner surface of the pitcher is characterized by its structure as the transpiring 

 surface par excellence of the plant, this being indicated both by the presence of 

 spongy parenchyma in this region only, and by the relatively large number 

 of its stomata." It is obvious that this surface could not so function in a 

 pitcher containing liquid water. 



Taking all these points into consideration, together with my observations 

 on the plants growing in situ, I am strongly of the opinion that tlie storage 

 of liquid water is not a function of the pitchers, the presence of such water in 

 them being accidental. 



These objections do not apply to the view that the pitchers are organs for 

 economizing the water- vapour given off in transpiration. The main transpiring- 

 surface of the plant is the inner surface of the pitcher ; and as most of the 

 absorbing surface of the roots is contained within the pitchers, there can be 

 no doubt that the great part of the water- vapour of transpiration is condensed on 

 these roots, or the nest-material, and directly or indirectly absorbed by them. 



Scott and Sargant have pointed out that the development of the purple 

 coloration turns the pitcher into a dark chamber, into whicli the negatively 

 heliotropic roots are attracted.' I came across an interesting confirmation of 

 this in one of the intermediate forms between foliage leaf and pitcher. This 

 was an almost perfect pitcher in shape, but having no purple pigment ; the 

 dorsal root was well developed, but instead of entering the pitcher it had 

 grown round the stem, and become an attaching root. Supporting this is 

 also tiie fact that the dorsal roots do not, iu normal pitchers, make their 

 appearance till some time after tiie ventral roots, when the pitcher is almost 

 fully developed, and the purple pigment has appeared. 



The view that the pitchers act as receptacles for storing humus, 

 detritus, &c., and that which regards them as ant-shelters, must be considered 

 together, for they are closely connected. Groom thinks that " the solids iu 

 the pitchers are partly derived from detritus washed down the stem and 

 branches of the host by the rain ; but they are also, and perhaps chiefly, 

 brought by ants which nest iu the pitchers." I think that the fact of 

 these solids being found iu both pendent and upright pitchers, not lying iu 

 their lowest parts, but built up around the roots, and being of the same 

 material as the ant-runs, leaves no doubt that they have been brought there 

 altogether by ants and not washed in by rain. That they are constantly 

 inhabited by ants I have already shown. 



' Scott aud Sargant, loc. cit. 



