76 PttOCEEBINGS OF THE 



sense. The comparison between the sporangiophores of Spheno- 

 phi/Uum and the fertile pinnules of the Devonian " Fern " 

 ArcluFopteris * does not seem to me very helpful, for Arclufopteris 

 can scarcely be regarded as one of the Primofilices, but appears 

 to have been a very advanced type, possibly, as Mr, Kidstou has 

 suggested, a Pteridosperm rather than a true Fern, 



With reference to the seed-bearing plants, however, I find myself 

 in agreement with Prof. Lignier as to their ultimate origin from an 

 early Filicinean stock. This is an opinion which has been very 

 generally adopted, during the last few years, either for the whole 

 or at least for a large part of the Seed-plants ; formerly the 

 Lycopods were in favour as the probable ancestral group, though 

 the origin of the Cycads from Marattiaceous Ferns was taught by 

 Sachs about the year 1880, It may be worth while to point out, 

 in a few words, the grounds on which the modern view is held. 



For nearly 30 years the existence of a considerable group of 

 Palaeozoic Fern-like plants allied to the Cycads has been 

 recognized by some ])alsBobotanists, though at first only on 

 negative grounds, the plants in question showing no evidence of 

 Filicinean fructification. Then came the discoveries of Williamson, 

 Solms-Laubach and others, proving that many of these Fern-like 

 plants had an anatomical structure intermediate between that 

 of Ferns and Cycads, These observations strongly conlirmed the 

 opinion that the latter plants were derived from, or had a common 

 origin with, the former ; this stage in the development of our 

 knowledge may be called the " Cycadofilices " phase. The dis- 

 covery of the multieiliate spermatozoids of living Cycads, in 

 1896, further strengthened tlieir affinities with Ferns, 



Then in 1903 began the series of discoveries, led by Oliver and 

 Kidston, proving that certain of the Cycadofilices bore seeds of a 

 Cycadeau type, and establishing a strong probability that this 

 applied to the whole group, a group outnumbering the true Ferns 

 of the period. The name Pteridospermese marks this important 

 step in advance. That the Cycads sprang from a Fern-like ancestry 

 was now established beyond reasonable doubt. The Cycads, 

 however, were not merely the little isolated family that now bears 

 the name — in Mesozoic times they were a vast and varied class of 

 plants, for which Xathorst's wider name Cycadophyta is appro- 

 priate ; for long ages they were a dominant race throughout the 

 whole world. Thus the proof of the Fern-ancestry of this great 

 class was already a serious matter. But the theory could not stop 

 here. It had always been recognized, since the first recognition 

 of the Cordaitefe as a separate class, that these plants had a strong 

 Cycadean affinity. It now further appeared that the seeds of the 

 Preridosperms were organized just on the same lines as those of 

 the Cordaiteae, while anatomically an almost unbroken series of 

 transitions between the two groups has been traced. Hence it 

 became evident that the Cordaitese — the most specialized of the 



* Ligiiier, " Sur I'Origine des Sphenophyllees," Bull. Soc. Bot. de France, 

 si-r. 4, t. viii. p. 278 (1908). 



