27 
whicli reinforce the epidermis of most Y\itar\ca\ Tlie stomata are 
flush witli the STirfacc and sliow a remarkable devolopmont of the knife- 
like ridge of entrance which is characteristic of iloating plants. ^^ The 
large, respiratory chaiuher underlies guard cells and hyaline subsidiary 
cells. The stomata are enormous, 108 /t by 54 p., sometimes even 114 /i 
long, with the rift correspondingly large. I'be apex of the pendent 
fronds is abru])tly acuminate — that is, caudate. The stipes are fleshy, 
7 millimeters in diameter near the base. The sori are superficial and 
protected by numerous paraphj'ses with oleaginous heads, 100 ^ I'^'ng, 
70 fx broad. 
In spite of such examples as are given by these two ferns, the terrestrial 
vegetation of the rain forest as a A\hole reflects its environment in stature 
only, not in stmeturo. It has already been pointed out that great size 
is made possible by moist air, and that under no actual atniosj)heric cun- 
di lions can a very large fern be as hydrophytic in structure as a small 
one. This will explain the thicker epidermal walls possessed by such 
ferns than are encountered in those of the more hydrophytic plants of the 
high forest. However, the greater average thickness of frond is largely 
due to the considerable number of decidedly fleshy species, the largest 
fronds {A-^pidium, Donnstaedtia) being thinner than the average. Tiie 
only completely dimorphous species is the single pronounced xerophyte, 
Chclroplcuria. Blccliniun egregiunt and NepJtrodium ccuicscens are ^ub- 
dimorphous. 
Floristically, the rain forest is well marked by the presence of Didij- 
niocJdcena, Coniogramme and Schtzostege. 
The size of epiphytes is in general fixed by their position under not 
very elastic limits. Not merely is a large size unsuitable to plants 
the water supply of which is limited and uncertain, but, still more, the 
necessity of maintaining the plant's attachment to its support usually 
makes much weight or much area of exposure to the wind perilous. 
Therefore, the epiphytes of the rain forest, unable to respond to the 
nioister environment by a much greatcj: stature of frond, as is the case 
with the terrestrial ferns, differ from the epiphytes of the high forest 
in being distinctly less xerophytic in structure. In spite of the presence 
of some fleshy species as Scolopendrium scldzocarpum, the fronds of the 
rain forest are on the a\erage less thick. They also ha\c thinner epi- 
dernuil walls and in harmonv with the much denser ve^rotation on and 
near the ground, the nether epidermis is considerably thinner than the 
upper, as it is in terrestrial plants everywhere. Seventy-six per cent of 
the species have chlorophyll in the epidermis, as against 40 per cent of 
the high forest species; while less than 10 per cent, as against 39 per 
cent in the high forest, have any hyaline layer beneath the upper 
epidermis. 
"U.Tl>orI<imlt: Flora (1887). 70: !)'. Copeland: Ann, of Hot. (1902), 16: 349. 
