254 WILLIAM CRAWFORD WILLIAMSON 



The first memoir was on the Calamites, and controversy at 

 once broke out. Williamson was from the first impressed by the 

 manifest occurrence of exogenous, or, as we should now call it, 

 secondary growth, both in the Calamites and the Lepidodendreae, 

 groups which he was convinced were cryptogamic. The con- 

 troversy with the great French school, headed by the illustrious 

 Brongniart, is well known. As Williamson put it: "The fight 

 was always the same; was Brongniart right or wrong when he 

 uttered his dogma, that if the stem of a fossil plant contained 

 a secondary growth of wood, the product of a cambium layer, it 

 could not possibly belong to the cryptogamic division of the 

 vegetable kingdom.''^" 



In England, however, the dispute was on different lines, 

 " In August of 1 87 1," says Williamson, "the British Association 

 met at Edinburgh. At that meeting I brought forward the 

 subject of cambiums and secondary woods in Cryptogams, with 

 the result that my views were rejected by every botanist in the 

 room." There followed a controversy in the pages of Nature, 

 which is of some interest, as showing the state of opinion in 

 England at that time. Williamson tells us in his autobiography 

 the principle by which he was guided in his work: " I determined 

 not to look at the writings of any other observer until I had 

 studied every specimen in my cabinet, and arrived at my own 

 conclusions as to what they taught." In spite of this excellent 

 rule it is probable that he was at first unconsciously influenced 

 by the views of Brongniart, which may have led him to attach 

 too much systematic importance to the occurrence of secondary 

 growth. At any rate he proposed at the Edinburgh meeting 

 " to separate the vascular Cryptogams into two groups, the one 

 comprehending Equisetaceae, Lycopodiaceae and Isoetaceae, 

 to be termed the Cryptogamiae Exogenae, linking the Crypto- 

 gams with the true exogens through the Cycads; the other 

 called the Cryptogamiae Endogenae, to comprehend the Ferns, 

 which will unite the Cryptogams with the Endogens through the 

 Palmaceae'*'." 



It is curious to note in passing that his main divisions, so 

 far as vascular Cryptogams are concerned, correspond to the 



^ Rmiiniscencesy p. 203. "^ Nature^ Vol. iv., 1871, p. 357. 



