INTEODUCTION TO CRYPTOGAMIC BOTANY. 7 



definition are the main or subordinate divisions of any one 

 great class, or even, taking nature as a whole, when the 

 question regards the highest divisions into which her pro- 

 ductions are evidently distributed. In all these cases, defini- 

 tions can only be assigned with that degree of limitation which 

 is admissible where the exception may reasonably be held to 

 prove the rule ; or in other words, we must be content with 

 pointing out some grand and leading marks of distinction, 

 aware all the time that cases will occur in" which these 

 generally decisive tests will fail, so that it will be necessary 

 to recur to other characters to prove the real systematic 

 position of such organisms. 



4. The first grand distinction of Cryptogamic plants is that, 

 in contradistinction to Exogens and Endogens, they consist 

 of cells only, insomuch that these higher orders have been 

 denominated vascular plants, while Cryptogams are called 

 cellular. Now, though the distinction holds good of a very 

 large number of Cryptogams, yet two undoubted divisions, 

 at least, the Ferns and Club-mosses, exhibit decided vascular 

 bundles, nor, even were these excluded from Cryptogams, by 

 assigning to them a distinct class, would our definition be more 

 safe ; for even supposing nothing like vascidar bundles should 

 occur elsewhere, or though it should be denied that true 

 vascular tissue occurs in ferns, we shall stUl have true spiral cells 

 amongst mosses, as in the leaves of Sphagnum, and the elaters 

 of Hepaticce; and even should the true nature of the elaters in 

 Trichia be denied, a point which there will be occasion to 

 consider hereafter, we shall have as true vascular tissue in 

 Batarrea (Fig. 5) as in any Endogen or Exogen. 



We cannot, therefore, say that the absence of vascular 

 tissue is the universal character of Cryptogams, nor, on the 

 other hand, can an organism which does not contain such 

 tissue be pronounced at once a Cryptogam. Podostemads 

 may be found in certain states void of any appearance of 

 vessels, and so may some other aquatics, but in some particular 

 stage of growth spiral tissue will be found ; and it must be 

 recollected, in taking a view of such matters, that in all plants 

 the early embryonic state consists of cellular tissue only, and 



