208 A YORKSHIRE NATURALIST 



question of the existence of an active cambium zone 

 producing secondary wood in the stem of the Crypto- 

 gams is concerned, was settled for ever. 



My chief remaining opponent the Marquis de 

 Saporta, having relied upon men like Grand* Eury 

 for his facts in this controversy, gave way at once 

 when these supports were withdrawn. 



For many years I failed to discover any plants of 

 the class of Ferns that possessed this exogenous 

 organisation, though I had in my cabinet specimens 

 of the genus Lyginodendron, which I strongly 

 suspected of belonging to that group. It required 

 twenty years of vigilant research before I obtained, 

 in 1892, unquestionable proof that my suspicions 

 were correct, and that my plant, which, along with 

 two or three congeners, exhibits some of the finest 

 exogenous structures that I have found in these 

 ancient beds, really belongs to the Ferns of that 

 primeval age.* 



* Dr. Williamson had always intended writing some 

 account of the men to whose untiring zeal and keen 

 observation he was indebted for the material which gave 

 rise to his long series of Memoirs on Fossil Plants. He 

 was prevented by failing health from doing what he 

 wished ; but after his death, I found a paper, the last he 

 touched, with the following names in pencil : " Butter- 

 worth, Whitaker, Binns, G. Wilde, Earnshaw, Spencer, 

 Nield, Hemmingway, Lomax." Excepting a few speci- 

 mens given to him by friends and fellow- workers, these men 

 furnished all he possessed. The cabinet containing them 

 has been purchased by the British Museum, and is now in 

 the Natural History Department, South Kensington. 



