4 PRELIMINARY. 



character of metal, which is a child of darkness." (Natur- 

 philosophie, 1040, ed. 3.) 



Scarcely less objectionable is the assertion of Dr. D. P. 

 Gardner, who declares (Philosophical Magazine and Journal 

 of Science, vol. xxviii., p. 432) "the physical structure of 

 plants to be that of a porous system subject to the laws of 

 the diffusion of gases and endowed with no vitality other 

 than the power of forming cytoblasts and arranging cellules 

 after a definite type." So that it would seem as if the 

 singular phenomenon of impregnation, the invariable direc- 

 tions assumed by organs, the infinite diversity of forms, 

 colours, and attributes belonging to plants, their irritability, 

 their locomotion, such as it is, all which are inexplicable 

 by the laws of chemistry, electricity, or physics, were mere 

 phenomena belonging to a "porous system" of any sort. If 

 this were so, Dr. Gardner should be able to make a plant 

 and set it in action. Can he do that? 



Upon the whole, it seems impossible to define a plant with- 

 out taking into account the power which all vegetables 

 possess of secreting starch, a power unknown in the animal 

 kingdom. This property has been shown by M. Pay en to 

 exist in those heretofore doubtful bodies, which former 

 naturalists referred to Corallines, but which M. Decaisne 

 has proved to be truly plants. 



The former observes (Ann. des Sciences Nat., 2d ser., xx. 67), 

 " that although the results at which he had arrived seemed 

 perfectly conclusive as to the vegetable nature of calciferous 

 Corallines, he nevertheless thought it would be as well to seek 

 in the tissues of Corallina the properties which, in addition 

 to its elementary composition, characterise cellulose, the 

 immediate principle that binds together every vegetable 

 structure, and is the chief constituent of the membranes of 

 plants. For this purpose he took a piece of Corallina offici- 

 nalis, treated it with dilute muriatic acid to get rid of the 

 incrustations, washed it, then treated it with ammonia, again 

 washed it and placed it with a little tincture of iodine between 

 two plates of glass under the microscope ; all the quaternary 

 substances contained in the cells or which had penetrated 

 their sides immediately became tinged orange-yellow. After 



