ORIGIN" OF THE ANIMATED TRIBES. 



113 



and depends on the fictitious aid of a visionary force, should 

 continue to exist a system which at the outset ought to have 

 broken down by the most common considerations, such as those 

 connected with the mechanical principles involved in the bony 

 skeleton, the optical principles in the construction of the eye, 

 or the hydraulic action of the valves of the heart." 1 



So much for the combinations concerned in living bodies ; 

 but how shall we hope to see their forms brought under any 

 relation to physical laws ? On this point we have some illus- 

 trations in the phenomena attending the production of crystals, 

 a class of bodies which has been said to stand between the 

 inorganic and the organic. From the agency which has been 

 employed by Mr. Crosse in making crystals formerly supposed 

 to be of Nature's production alone, it is now incontestable that 

 crystallization is dependent in some degree on electric agency, 

 the special forms being the result of the peculiar nature of the 

 constituent substance and the conditions under which the im- 

 ponderable is applied. Here are obviously natural means 

 concerned in producing forms almost as various as those of 

 living beings, and equally determinate and regular. A certain 

 community of cause in the two instances is indicated by the 

 surprising resemblance which some examples of crystallization 

 bear to vegetable forms. In some, the mimicry is beautiful 

 and complete ; for example, 

 in the well-known one called 

 the Arbor Diance. An amal- 

 gam of four parts of silver 

 and two of mercury being 

 dissolved in nitric acid, and 

 water equal to thirty weights 

 of the metals being added, a 

 small piece of soft amalgam 

 of silver, suspended in the 

 solution, quickly gathers to 

 itself the particles of the sil- 

 ver of the amalgam, which 

 form upon it a crystallization 

 precisely resembling a shrub. 

 Vegetable figures are also 

 presented in some of the 

 most ordinary appearances Crystallized Silver. 



Treatise on the Forces which produce the organization of Plants 

 -New York, 1844. 



FIG. 71. 



