INTRODUCTION. 31 



Long had they been regarded as within the domain of the 

 botanist. He laid claim to them as his subjects on various 

 grounds. They often had the external appearance of little 

 shrubs ; — they did not^like animals^ move from place to place, 

 but remained permanently in the same situation, attached to 

 other objects by fibres much resembling roots of sea-plants. 

 Some, from their hard and stony nature, were disposed to 

 place them in the mineral kingdom, alleging that they either 

 were crystallizations formed from calcareous sediment, or by 

 some natural incrustation of seaweeds. In support of these 

 theories more might have been adduced than at that time 

 they were able to do. It is now found that what were called 

 lithophytes, nullipores, and corallines, do really belong to 

 the vegetable kingdom, — such as Jania ruhens, Corcdlina 

 officinalis, and the various Melohesim ; and as such they are 

 figured and described in Harvey^s magnificent ' Phycologia.^ 

 How they contrive to clothe themselves in these stony habi- 

 liments, is one of the secrets of Nature known only to Him 

 who can mix flint with the green integument of Equisetum, 

 and iron in the stems of some of our cereal grasses. Tliat 

 Jania ruhens and the other nullipores, however, are of vege- 

 table growth is no longer matter of conjecture, for on the 

 application of a powerful acid their calcareous clothing is 



