183 



to the signilicance of the peculiarities exhibited by the embryo 

 which shows only two organs, aside from the very poorly defined 

 foot, viz., the cotyledon and primary root; and these grow in 

 almost exactly opposite directions without any clear line of 

 demarcation between them. The writer (Mossfs and Ferns, 2d 

 edit., p. GOO) has ventured to draw a comparision between the 

 sporophyte of Ophioglossum and that of Anthoceros, assuming 

 that the former has arisen from some type not unlike Antho- 

 ceros, by the development of a root from tlie base of the 

 sporogonium and of a special foliar organ from the basal 

 meristem of such a sporogonium. This view was strengthened 

 by the discovery of the remarkable 0. simjjlex (see Bower, Ann. 

 of Bot., 205, 1904:) which nearly fulfilled the hypothetical form 

 suggested by the writer. The embryo of 0. moluccanum comes 

 still nearer this hypothetical form, as it consists only of leaf 

 and root and no stem apex is developed from it, its growth being 

 of limited duration. In this case the definitive sporophyte is a 

 secondary structure developed as a bud upon the primary root. 

 In 0. vulgatum, however, the definitive stem apex, although 

 of very late origin, is nevertheless a product of the original 

 embryonic tissue, although the first foliage leaf is of much 

 later origin. In 0. pendidum the formation of the leafy sporo- 

 phyte is secondary, as in 0. moluccanwn, but neither stem 

 apex nor leaf is produced from the embryo itself. 



If, as the writer believes, Ophioglossum represents the most 

 primitive type of the fern series of Pteridophytes, it is quite 

 conceivable that in 0. moluccanum and its allies the embryo 

 represents the condition existing in the ancestral type from 

 which these have sprung. On the supposition that the leafy 

 sporophyte is derived from a large bryophytic sporogonium 

 resembling that of Anthoceros, there must have been a stage 

 when the sporophyte consisted of two parts only, the upper 

 sporogenous portion, which developed into a sporophyll, as 

 represented in Ophioglossum, and the root. Of course it is 

 quite possible that the peculiar origin of the definitive sporo- 

 ph^^te in 0. moluccanum and 0. pedunculo.nim it secondary, but 



