Vital Physics. 5 



COLOUR. 



Although colours enter so largely into all things both 

 of the organic and inorganic worlds, yet the blending of 

 them in every variety of shade and hue, more particularly 

 pertains to the organic kingdom. But in relation to vital 

 force it is more a proof of exposure to air and light, and of 

 the healthy condition of an organism or otherwise, as it is 

 exposed to light or it is withdrawn from it, than an essential 

 part of life. We cannot treat of light in the organic 

 world in any different form to that in which it is viewed in 

 the inorganic world, namely, that all the permanent colours in 

 bodies are known to us by reflected light, and that it is owing 

 to some more finely elaborated mechanical property in mole- 

 cular arrangement than either the microscope, or the subtle 

 behaviour of matter under chemical changes and affinities 

 enables us to detect ; and whether the corpuscular or emis- 

 sional theory, or the more elegant theory of light, known as 

 the undulatory, be accepted, it matters little, as in reflected 

 light the result is pretty much the same ; namely, some 

 subtle molecular arrangement in the atoms of matter gives 

 the various shades and hues of light known under the general 

 term of colour. 



UPON ANIMAL DIFFERENTIATION AND 



METAMORPHOSIS. 



Leaving therefore, the subject of light and colour, which 

 refer only to reflected light in relation to organic nature, an 

 attempt is made to found a system of morphology and 



