46 THE CHAIN OF NATURE. 



some other singular productions. As a whole, they are rarely green, 

 and never produce stem or leaves, consisting of little more than masses 

 of cellular matter, though the figures are often singularly beautiful 

 and symmetrical. An entirely new world is opened among them by 

 the microscope, which reveals shapes and phenomena of inexpressible 

 wonder. They are collectively called Thallogens. 



But while separated so decidedly in type or central plan, these four 

 great classes, Exogens, Endogens, Cormogens, and Thallogens, are not 

 exact and rigid in their boundaries. There are many curious plants 

 which stand intermediately between them, giving a hand to each, and 

 thus linking the whole into one grand confraternity. The Tamils, or 

 white bryony, which festoons the autumn hedges with vegetable coral, 

 unites the Exogens to the Endogens ; fir-trees touch both Exogens 

 and Cormogens ; and midway between the Exogens and the Thallogens 

 stands an extraordinary Bornean plant, having the substance and 

 general habit of a mushroom, but the configuration of a pentamerous 

 flower. Intermediates of similar nature connect every subordinate 

 class and family, locking all together in reciprocal aflSnity. 



These things plainly shew how futile must be attempts to put the 

 objects of the vegetable kingdom in a row, beginning with the noblest, 

 and ending with the humblest. And yet this has been the aim and 

 cherished fancy of many men who, captivated by the ancient and 

 sonorous suggestion of a universal " chain of nature," have thought 

 labour alone was necessary to arrange everything in exact sequence. 

 There is no such line in nature. It is easy to pick out plants that 

 can be placed in lineal order, but thrice as many must be omitted as 

 incompatible. The true relation which the four great primary classes 

 bear to one another is represented in the following diagram, wherein 

 are introduced also the names of the principal intermediates : — 



Endogens. 



Tamus. 



I 

 EXOGENS. 



Fir-trees. Rafflesia. 



CoBMOOENs. Thallogens, 



