100 FREDERICK ORPEN BOWER 



long stalk composed of a single row of cells — structurally so like 

 a hair bearing a terminal gland — seemed the natural predecessor 

 of the more massive, and short stalked, or even sunken sporangia 

 of the Marattiaceae or Ophioglossaceae. The analogy of the sim- 

 pler superior as compared with the more complex inferior ovary 

 of Flowering Plants doubtless lent colour to the conception that 

 this progression had been a real one. A further error was the 

 neglect of collateral checks upon the opinion thus assumed. If it 

 were true the Leptosporangiate Ferns should preponderate in 

 the Primary Rocks, and the Eusporangiate Ferns should be char- 

 acteristic of higher horizons. But the observations of Stur and 

 others showed that the converse was actually the case. The 

 revolt against the position thus based primarily on assumption, 

 and insufficiently checked by collateral lines of comparison, was 

 initiated by Campbell. 1 Probably no paper of like brevity has 

 ever had a more far-reaching effect than this in correcting erro- 

 neous views. Once the basal assumption is swept away, and the 

 eusporangiate sporangium accepted as relatively primitive, there 

 appears no need to refer the sporangia of the Equisetales or Lyco- 

 podiales to that simple origin typified by the Leptosporangiate 

 Ferns. In fact the way lies open to the polyphyletic origin of the 

 Pteridophyta which is now so generally recognised, and supported 

 on so many lines of more recently acquired evidence. 



A second view now discarded, which at the time received general 

 attention, though never a very general acceptance, was the phy- 

 letic origin of the Hymenophyllaceae, as the simplest Ferns, from 

 the higher Mosses. It was suggested by Prantl that the sorusof a 

 Trichomanes was the correlative of a moss sporogonium, that the 

 indusium represented the sporogonial wall, and the receptacle the 

 columella, while the spore-sac was the correlative of the sporangia 

 seated upon it. This hypothesis received an apparent support in 

 the delicacy of texture of the Hymenophyllaceae, which was held 

 as primitive, and in the filamentous prothallus of Trichoma?ies, 

 which appeared to correspond to the protonema of the Moss. 



The fallacies here involved are more complex than in the for- 

 mer case, but again assumption takes a prominent part. In the 



^ot. Gaz., January, 1890. 



