XIV] 



THE CORDATE TYPE 



277 



after the model o{ Phylloglossiim, and of Orcliis; but here it is carried out by 

 the gametophyte. The case is still more complicated in Anogravune lepto- 

 phylla, in which the sporophyte is annual, the species depending entirely 

 upon the gametophyte for perennation. The tuberous archegoniophore is 

 larger than in A. cJiaei'opJiylla, and the prothallial surfaces that nourish it 

 are more complicated, exposing a funnel-shaped expanse of photo-synthetic 

 tissue (see von Goebel, I.e. p. 967, Fig. 963). 



In addition to the rhizoids already mentioned, hairs are frequently 

 found on prothalli, usually borne in a marginal position, but sometimes also 

 superficially. They may be 

 either glandular, as in Dryo- 

 pteris (Iwg. 265) ; or less com- 

 monly they are stiff bristles, 

 as in Polypodium obliqitatuvi 

 (Fig. 268, a). Sometimes they 

 resemble very closely the 

 hairs borne upon the sporo- 

 phyte of the same plant. 

 This is particularly notice- 

 able in the glandular hairs of 

 Notholaena (Fig. 186, p. 199). 

 Occasionally more massive 

 appendages appear on pro- 

 thalli as they grow old. This 

 has been noted by von Goebel 

 in Ferns related to the Dick- 

 son ieae and Cyatheae {Flora, 

 Bd. X, 191 2, p. 36). For in- 

 stance in Loxsoma they, arise 

 on the under side of the old 

 prothalli, right and left of the 

 region where the archegonia 

 are borne. They consist of cell- 

 rows with transverse septa, but 

 with longitudinal walls added in the basal region, and they correspond in this 

 structure to the bristles of the sporophyte in Loxsoj/ia (Fig. 268, d, c). Similar 

 bristles have been found on prothalli of Hemitelia capensis, but here they 

 ultimately become flattened as scales (ramenta). As von Goebel himself 

 points out {I.e. p. 38), ''Loxsoma stops short at the stage of bristle-formation, 

 while this is only an intermediate stage in Hemitelia eapensis." Thus the 

 prothallus of Loxsoma shares in its appendages the characteristic feature 

 of the sporophyte of Dicksonioid Ferns, viz. that hairs or bristles, but no 



Fig. 268. Various hairs of the bristle-type, a, a bristle from 

 the margin of a prothalkis of Polypodium obliqnatiiin, 

 after von Goebel; b, \ia\rsoi Loxsoma, i, ii, on sporeling; 

 iii, on an old plant ; c, apical region of a prothallus of Lox- 

 soma with bristles : showing also archegonia and the young 

 sporophyte. After von Goebel. 



