RESEARCHES OX THE CARBONIFEROUS FLORA. 269 



guage and published in the Annates des Sciences Natureties, 

 1882 (28), "a bomb thrown into the enemy's camp," as 

 Williamson was fond of calling it. This paper certainly 

 produced, its effect, though it was not till a little later that 

 conviction was brought home to most of the opponents. 

 Ultimately our author was fully justified in saying as he 

 does in his autobiographical notes : " The contest, so far as 

 this great question of the existence of an active cambium- 

 zone producing secondary wood in the stems of Cryptogams 

 is concerned, was settled for ever ". 



No one who has studied the anatomy of carboniferous 

 plants at first hand can fail to be struck, not so much by the 

 mere occurrence of secondary growth in these ancient Cryp- 

 togams as by the close resemblance of the process, in most 

 cases, to that which goes on in normal Gymnosperms and 

 Dicotyledons. This is a remarkable fact, for we know that 

 secondary growth may also take place in totally different 

 ways, as in certain Monocotyledons. 



We may be allowed to quote a few words from Count 

 Solms-Lau bach's obituary notice of Williamson in Nature 

 (32), which places the importance of his results in a clear 

 light : " It was thus made evident by Williamson that cam- 

 bial 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." 



Williamson's last paper on the Lepidodendrese (26) has 

 a somewhat melancholy interest. It cost him a vast amount 

 of labour, quite at the close of his life, when he should 

 rather have been enjoying his well-earned rest. His toil, 

 however, was not thrown away, for by means of it he at 

 last convinced himself that his long-cherished views as to 

 the growth of the medulla and primary wood were mistaken. 

 After giving the full details of his elaborate numerations 

 and measurements, he says (p. 59) : " Anyhow, it is ob- 

 vious that my original hypothesis of an enlargement of the 



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