108 



THE FERN BULLETIN 



eria which makes a perfect independent receptacle of 

 each leaf. Other Philippine humus-collectors are 

 Dryostachyum splendens in Mindanao and Luzon and 

 "Poly podium" Meyerianum in Luzon. 



In its humus-collecting structures, Thayeria is 

 wholly unlike any other known plant, the specializa- 

 tion having gone beyond the frond to the rhizome. 

 Each leaf is a unit, a complete receptacle, wholly out 

 of contact with the main rhizone. It is the most per- 

 fect of the humus-collecting organs developed in its 

 group, the material being enclosed on all sides and pro- 

 tected from dessication with a thoroughness not at- 

 tained even by Aspleniitm nidus. The specialization 

 of the branch-end as a root-bearer in the bottom of 

 the cornucopia is a very novel feature. 



Our two remarkable myrmecophilous ferns, Poly po- 

 dium sinuosum and Lecanopteris have recently been 

 thoroughly studied by Yapp in which paper the pre- 

 vious literature is summarized. With regard to the 

 anatomy there is nothing essential to add; but with 

 regard to the significance of the bizarre form and 

 structure of these and other myrmecophilous plants of 

 this region, Yapp followed Treub and Goebel in a 

 puzzling over-sight of the service rendered the plant 

 by the ants, which insects furnish their hosts with 

 mineral food. 



Our myrmecophilous plants are, without exception, 

 epiphytes. As such they are exposed to dearth of 

 water and dearth of mineral food. When they protect 

 themselves against the former by using devices to re- 

 duce transpiration, they aggravate the latter difficulty. 

 Epiphytes have many ways of overcoming the diffi- 

 culty of obtaining their mineral food, such as the 

 maintenance of remote ground connections, the ac- 



