120 Morphology BOOK i 



In that year, however, Bower advanced reasons for the 

 view that that position must be assigned to the Eusporan- 

 giate forms, and the opinion obtained general acceptance. 



The position of Isoetes as closely allied to Selaginella, 

 and properly included with the latter in the Ligulatae, 

 was challenged by Vines in 1888. He pointed out that the 

 chief resemblance is the development of the ligule, and 

 that the general features of its embryogeny especially 

 the absence of a suspensor, its general habit, the absence 

 of any cone-like fructification, the form of its antherozoids, 

 and some of its anatomical features, indicate a relationship 

 to the Ferns. Vines's view was endorsed by Campbell in 

 1895, although with a certain amount of reserve. Opinion 

 in Germany continued in favour of regarding it as akin 

 to the Lycopodiaceae, though apparently but little evidence 

 was forthcoming in favour of such position. 



The propriety of grouping together the Salviniaceae and 

 the Marsiliaceae was called into question by Campbell, who 

 pointed out that, regarding them as Ferns, the two groups 

 have little in common but their heterospory. The Salvini- 

 aceae show certain resemblances to the Hymenophyllaceae, 

 while the Marsiliaceae are more like the Polypodiaceae. 



Several objections were raised with regard to the position 

 of Ophioglossaceae among the more primitive Ferns, and 

 many botanists towards the end of the century were inclined 

 to place the group near, if not among, the Lycopodinae. 

 Celakowsky, in 1884, held that some ancestral form gave 

 rise to both the Ophioglossaceae and the Lycopodiaceae, 

 and that it probably possessed the simple sporophylls of 

 the latter ; he therefore considered that of all living plants 

 they were the nearest prototypes of the Ophioglossaceae. 

 From a comparison of their respective sporangia, Bower, 

 in 1891, and again in 1895, concluded that the two groups 

 are closely allied, and that the Psilotaceae are inter- 

 mediate between them. 



