above the ground. It has already been mentioned that Achrostichum 
aureum sometimes has pnenmathode-roots which are not greatly differ- 
entiated. 
HUMUS COLLECTORS. 
The amount of study which has already been devoted to two of the 
most extraordinary specializations of ferns, those for collecting humus 
and for association with ants, spare me the necessity of entering into the 
details of either. Of humus-collectors, we have at San Eamon the nest- 
builders, Asplenium musaefolium, A. Phyllitidis and Drynaria rigidula; 
Polypodium punctatum, which makes brackets of leaf-bases interlaid 
and overlaid with humus and detritus which are sometimes 15 centi- 
meters broad and almost as deep, but which does not normally form 
round nests; P. heracleum and Drynaria quercifolia, which, in their best 
development, form spiral brackets, the supporting leaves being in a single 
series, but imbricate; and Thayeria., which makes a most perfect, inde- 
pendent receptacle with each leaf. Other Philippine humus-collectors 
are Dryostachyum splendens in Mindanao and Luzon, and " Polypodium ” 
meyenianum in Luzon. This character of D. splendens is not generally 
recognized and my determination might be in error, but it is based on 
a comparison with a plant of the type number of Cuming’s collection. 
Thayeria is so remarkable and recent a discovery that I take the 
liberty of repeating a part of the description, from this Journal 
(Volume I Suppl. (1906) page 165). “Fronde solitaria in ramo laterale 
rhizomatis endogena, cornucopiseforme ; ramo in fundo cornucopia: in 
radiculas multas dissipato.” “In its humus-collecting structures Thay- 
eria is wholly unlike any other known plant, the specialization having 
gone beyond the frond to the rhizome. Each leaf is a unit, a complete 
receptacle, wholly out of contact with the main rhizome. It is the 
most perfect of the humus-collecting organs developed in its group, 
the material collected being inclosed on all sides and protected against 
desiccation with a throughness not attained even by Asplenium Nid'us. 
The specialization of the branch end as a root'bearef in the bottom of 
the cornucopia is a very novel feature.” 
MYRMECOPHILY. 
Our two remarkable myrmecophilous ferns, Polypodium sinuosum and 
Lecanopteris, have recently been thoroughly studied by Yapp, 27 in whose 
paper the previous literature is summarized. With regard to the anat- 
omy, there is nothing essential to add ; but with regard to the signif- 
icance of the bizarre form and structure of these and other myrmecoph- 
ilous plants of this region, Yapp followed Treub and Goebel in a 
puzzling- oversight of the service rendered the plant by the ants, which 
insects furnish their hosts with mineral food. 
17 Ann. of Bot. (1902) 16, 185. 
