OF THE WOODY ZONE IN CALAMITE. 179 



unquestionably true. So far I agree with the opinion 

 always held by M. Adolphe Brongniart respecting the 

 stems of his genus C alamo dendr on. But that distinguished 

 botanist has further held that these plants were Gymno- 

 spermous Exogens,, which of course involved reproduction 

 by means of stamens and pistils ; but this, as I have just 

 shown, is not the case. The cone to which I have referred 

 is unmistakably Cryptogamic in its type. The same 

 remark applies to the cones described by Mr. Binney. 

 The conclusion, therefore, at which I arrive is, that the 

 Calamites constitute essentially one large group of plants, 

 with some considerable range of variation in the details of 

 their internal organization, but not more than exists in 

 many well-defined family groups of living plants (as, for 

 example, the Equisetaceae) , and that their stems were exo- 

 genous, so far as the woody cylinder was concerned, and 

 closely related to those of the Dadoxylons. But, on the 

 other hand, their fructification was Cryptogamic, but not 

 necessarily Equisetiform, though not Avithout some fea- 

 tures of resemblance to that type of recent Cryptogams. 

 Thus we have in the Calamite a combination that appears 

 to have no living representative. Mr. Darwin may fairly 

 point to these plants as indicating a generalized structure 

 which at some later period became dififerentiated, through 

 the Dadoxylons of the carboniferous rocks and the true 

 Equiseta of the Oolites, into the modern types of Conife- 

 rous and Equisetiform plants. It must be remembered, 

 however, that these Dadoxylons are not ail true Conifers 

 like the living types. We have not yet found in them 

 (with one exception) the peculiar glandular disk, with its 

 central spot, which occurs in all the modern Coniferse, 

 even in the Cycadese. Consequently these supposed Coni- 

 fers themselves may ultimately be shown to constitute 

 an additional connecting link between the ancient and 

 modern types of gymnospermous vegetation. Every ad- 



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