152 HISTORY OF BOTANY 



tissue, the first beginnings of a vascular system and 

 almost the initials of sporangial regions. Be3'0nd the 

 extension of the haustoria into roots, all that is wanted 

 is the enlargement of parts of the axis into photosynthetic 

 areas and the association of definite sporogenous tissue 

 with these extensions. We should thus obtain a structure 

 not unhke an Ophioglossum or a Plwlloglossum. Campbell 

 is responsible for the suggestion that the former genus 

 might represent the nearest living descendant of an 

 Anthoceros-hke ancestor, while Bower at one time favoured 

 Phylloglossum, and figured the primitive Pteridophyte 

 as a plant with a simple erect reproductive axis bearing 

 sporophylls, each with an axillary sporogenous region, 

 a sporangium or sporangiophore. 



It would be most misleading, however, were I to leave 

 you with the impression that the main line of evolution 

 of the Pteridophyta had now been definitely estabhshed, 

 and that all that was left for the future to accomphsh 

 was the elaboration of details. How far we are from 

 having reached such a consummation I must now 

 endeavour to prove to you. In 19 16 there appeared a 

 notable memoir by Dr. T. G. Halle, on certain fossil 

 plants from Roragen in Norway, and in it an account is 

 given of a remarkable type which he named Sporogonites. 

 In the following year Kidston and Lang published a 

 monograph on a fossil plant to which they gave the 

 name of Rhynia, from the Old Red Sandstone of Rhynie, 

 Aberdeenshire. In May 1917 Bower contributed an 

 account of these two discoveries to the Glasgow Herald, 

 and I cannot do better than quote from his article : 

 " But the real novelty of Dr. Halle's memoir," he says, 

 " lies in the discovery of a new fossil which he describes 

 as Sporogonites. It consists of a simple stalk, bearing 

 a terminal capsule containing spores. Though relatively 

 large. Dr. Halle regards it as a structure closely agreeing 

 with the sporogonium, or capsule of the Mosses, of which 

 it may be a generahsed type. He justly remarks that 



