I KAXSPlKAl ION AND WATKR Sr()RA(iK. 17I 



with Sli'lis at mid-heights, while the associates of Guzmania 

 on the highest Hmhs are other non-storing types. 



The meteorological records for Cinchona show that 

 there are rare occasions during the relatively dry seasons in 

 early spring or mid-summer when no rain falls for several 

 days, or even in very rare cases for several weeks. During 

 these periods the atmospheric conditions would favor a much 

 more rapid desiccation than that which took place in the 

 ahove tests, a fact that would be partially offset i)y the avail- 

 ability of water from the substratum during the earHer 

 part of such unusual dry spells. Gnzmanla, under these same 

 conditions, would soon lose all the water held externally by 

 its rosette of leaves, and in default of the power to absorb 

 further water from the substratum it would suffer drought 

 comparable to that of the experiment, or even more severe 

 in view of its exposure to insolation. 



In the savannas of the south coast of Jamaica there 

 are very many epiphytes of the non-storing type which are 

 without provision for the external retention of w^ater, as 

 Tillandsia nsiwoides L. and T. reciirvcitd L. The ability 

 of these forms to withstand prolonged periods of drought 

 is too well known from common observation to need ex- 

 perimental proof, although it must not be forgotten that the 

 copious dew of the savanna regions forms an additional sup- 

 ply of water for these forms, and they are also able to 

 avail themselves of the humidity of the air. 



The water storing epiphytes are restricted in their dis- 

 tribution not only by the climatic conditions themselves, but 

 by the occurence of fa\'orable water-holding substrata on the 

 limbs of trees. Tn the rain forests the deep mats of mosses 

 and such hepatics as Plil'idiiiui and Tr'uhocolt'ci, with their 

 finelv dissected leaves, serve to retain a reserve of water 

 from which the orchids are able to absorb slowly for the 

 replenishing of their storage tissues. Tn the savanna regions 

 water storing forms are confined to the lower and larger 

 limbs of \ery large trees where there are accumulated 



