10 J. M. Macfarlane. — Gephalotaceae. 



Biological Relations of the Leaves (Blattbiologische Verhältnisse). 

 Robert Brown seems to have been the first to note that the pitchers trapped 

 insects. He says (Bot. Terr. Aust. p. 68) "The-ascidia or pitchers of C. were observed 

 to be generally nearly half filled with a watery fluid, in which great numbers of a 

 small species of Ant were frequently found drowned. This fluid, which had a slightly 

 sweet taste, may possibly be in part a secretion of the pitcher itself, but more probably 

 consists merely of rain water received and preserved in it." But Hamilton first gave 

 detailed information, from study of the plant in its native home. He says "the mature 

 pitchers contain liquid up to the lower edge of the glandulär surface." The quantity 

 naturally varies with the size of the pitcher". . . . "The liquid is greenish black in 

 color, from the large quantity of animal remains contained in it, but occasionally one 

 finds a pitcher with only a few victims, and then it is quite clear. Among the debris 

 in the pitchers I recognised wings of various insects, legs, chitinous plates from the 

 thorax and abdomen, balancers of mosquitoes, scales of moths, the claws of a chelifer, 

 living larvae of a fly, and large numbers of unicellular Algae, consisting of a green 

 cell with a gelatinous envelope; it is probably a Protococcus, and certainly lives and 

 multiplies in the liquid." From such accounts, and from the histological similarity of 

 the pitchers to those of the Sarracenioids, it is evident that elaborate contrivances have 

 here been evoked for capture of insects. Further as in the Sarracenioids and in Ne- 

 penthes, we can appropriately designate the pitcher areas as (a) the alluring surface 

 that includes the entire pitcher exterior, (b) the attractive surface that includes the 

 inner lid surface, the peristome, and the posterior upper part of the ledge or collar, 

 (c) the conducting surface that includes the whole of the ledge and of its lower 

 infolded area except the posterior upper part just noted, (d) the digestive and de- 

 -tentive surface, that includes all below the collar. We may now consider each of 

 these shortly. 



That the pitcher exterior functions as an alluring surface is strongly suggested by 

 the abundance of glands over it, and by the statement of Hamilton that "the glands 

 on the outer surface certainly secrete a fluid, and although I have not been able to 

 detect any taste in it, yet I think we are justified in concluding that it is attractive 

 to insects, as they certainly visit and lick the exterior of pitchers". Tempted by this 

 secretion then, they move toward the pitcher mouth, and approach the cavity either 

 by stepping on the inner lid-surface, or more directly by mounting over the corrugated 

 rim, both being richly provided with glands. Regarding the latter also Hamilton says 

 "insects visiting the pitchers delay a long time licking the surface of the collar before 

 proeeeding lower". Both areas therefore may well be designated, as in Nepenthes, the 

 "attractive surface". The area of the ledge or collar is so strikingly like the conduct- 

 ing surface in the Sarracenioids, that though we by no means regard the two groups 

 •of plants as systematically related (vide p. \ 3), the same physiological and environ- 

 mental actions and reactions have here called forth like morphological details. It forms 

 therefore an efficient barrier against escape of those smaller insects that would be an 

 appropriate prey for the plant, and even more conduets them into the lower part where 

 they are retained and drowned. In treating finally of the physiological relation of the 

 lower pitcher cavity it should be remembered that we deal with a region into which rain- 

 water or even dew might fall, and that at least two groups of glands line the cavity, 

 viz the medium-sized glands of the upper detentive area, and the huge glands of the 

 lateral patches. Direct proof has not yet been furnished that the pitcher liquid is 

 digestive. But in Lawson Tait's paper (op. cit.) he distinctly states that the pitcher 

 liquid of Cephalotus is digestive like that of Nepenthes. His results for the latter so 

 closely agree with recent studies, that we may well aeeept it as likely that digestive 

 liquids are exereted, though by which type of gland, we cannot yet affirm experimen- 

 tally. It is even possible that Fenner's Suggestion for Nepenthes etc. may be true here, 

 namely that distinet sets of glands may exist, in one case for the exeretion of a 

 digestive ferment, in another for the absorption of the digested material. Tait further 



