12 THE OPHIOGLOSSALES 



The gametophyte of 0. moluccanum shows a greater or less number of rhizoids 

 both at the base and along the fertile branch (plate i, fig. lo). In the more slender 

 forms, however, these rhizoids are few. They are in some cases two-celled, but more 

 commonly consist of a single elongated cell. It is not unusual to find withm this the 

 penetrating filament of the mycorrhiza, as has been described for other species 

 of Ophioglossum. The rhizoids are much longer relatively than in 0. pendulum. 

 According to Bruchmann, the rhizoids are quite absent from the prothalha of O. 

 vulgatum. 



Mettenius states that in O. pedunculosum the prothallia often appear above the 

 surface of the earth, and they then become somewhat flattened and sometimes 

 divided into several small lobes, and in such cases chlorophyll is developed. Met- 

 tenius, however, does not note any further development of these green lobes. 

 Bruchmann found that chlorophyll might also develop in 0. vulgatum, when the 

 prothallia were exposed to the light, but he did not find any flattening of the apex. 

 Owing to the very small number of growing prothallia found by me, I could not 

 test the power of developing chlorophyll in 0. moluccanum, but the occurrence of 

 chromatophores in the germinating spores makes it highly probable that chlorophyll 

 may be developed in the older prothallia under the stimulus of light. 



Fig. 2. 



Gametophytes, ftr, and young sporophytes of Ophioglossum mo/uccanum and allied species, slightly enlarged. C and F from 

 Hakgala, Ceylon; the others from Buitenzorg, Java; k, bud on primary root; /, primary leaf; /^, secondary leaf; ?, tuberous 

 enlargement at base of gametophyte. 



The small size of the prothallium in 0. moluccanum and the cessation of growth 

 after the sporophyte is formed indicate that the gametophyte lives only for one 

 season, and this is probably the case also in Helminthostachys. In this respect 

 O. moluccanum and its allies diff^er markedly from O. pendulum and O. vulgatum, 

 where the gametophyte lives for many years. 



At Hakgala, in Ceylon, an undetermined species of Ophioglossum of the type 

 of 0. reticulatum is common. After careful search, a few prothallia which closely 

 resembled those of 0. moluccanum were collected (fig. 2, C, F). The material was 

 too scanty to make a detailed study possible, but from the external appearance it is 

 likely that the structural details would closely resemble those of O. moluccanum. 



The prothallium of Ophioglossum vulgatum, according to Bruchmann (Bruch- 

 mann 1), closely resembles that of 0. moluccanum, but is very much larger, some- 

 times reaching a length of 6 centimeters, and it is not infrequently branched 



