256 WILLIAM CRAWFORD WILLIAMSON 



On the other hand it has been said by a distinguished botanist 

 that in the Fern-series secondary growth came in together with 

 the seed. This is not strictly correct, but it is true that the 

 plants such as Lyginodendron, which Williamson in his later 

 publications cited as Ferns with secondary growth, have turned 

 out to be seed-bearing. Even among the Lycopods a certain 

 proportion of the Lepidodendreae bore organs closely analogous 

 to seeds. These partial concessions, which may now gracefully 

 be made to the old Brongniartian creed, do not however really 

 affect the importance of Williamson's results, which Count 

 Solms-Laubach has well summed up in the following words: 

 "It was thus made evident by Williamson that cambial growth 

 in thickness is a character which has appeared repeatedly in the 

 most various families of the vegetable kingdom, and was by no 

 means acquired for the first time by the Phanerogamic stock. 

 This is a general botanical result of the greatest importance and 

 the widest bearing. In this conclusion Palaeontology has, for 

 the first time, spoken the decisive word in a purely botanical 

 question 1 ." 



To attempt a review of Williamson's work in fossil botany 

 would be to write a treatise on the Carboniferous Flora. In 

 every group Calamites, Sphenophylls, Lycopods, Ferns, Pteri- 

 dosperms, Gymnosperms his researches are among the most 

 important documents of the palaeobotanist, and to a great 

 extent constitute the basis of our present knowledge. At 

 the time he wrote, the wealth of his material was absolutely 

 unrivalled, and its abundance was only equalled by the astonish- 

 ing energy and skill with which he worked it out. 



As regards the Calamites, he demonstrated, to use his own 

 words, "the unity of type existing among the British Calamites," 

 abolishing the false distinction between Calamiteae and Cala- 

 modendreae. 



Among the Sphenophyllums (although there was at first 

 some confusion in his nomenclature) he gave the first correct 

 account of the anatomy, and of the organization of the cone. 



Concerning the Lycopods, the greater part of our knowledge 

 is due to him. He described the structure in ten species referred 



1 Nature, Vol. LII. 1895, p. 441. 



