MELANIC VARIATION IN LEPIDOPTERA, J 27 



he attributed the increase of heat to the more rapid respiration 

 of the insect, through an accession of vital energy. His conclu- 

 sion was that chemical changes in the air during respiration are 

 immediate sources of animal heat. It is also worthy of notice 

 that he found carbonic acid distinctly present in the gaseous ex- 

 penditure of the bodies of insects in different stages when ex- 

 posed to heat. 



Mr. M'Munn proves the existence in animals of true 

 chlorophyll not derived from vegetable substances.* 



This in the case of plants has been held to be produced by 

 the vibratory influence of light, and the consequent oxidization 

 of protoplasm. 



Mr. Charles Morris writes ' Every vibration, even of the 

 slightest, from whatever source, which enters into and acts upon 

 protoplasm apparently induces combination with oxygen (if this 

 element be present) with a consequent freeing of motor-energy 

 and production of change.' f 



And, again, ' Oxidation yields a quantity of free energy. 

 The sunlight which instigates oxidation also yields, perhaps as 

 vibration of the cell-contents, a quantity of free energy. The 

 energy thus set free does not manifest itself as mass-motion or 

 as temperature. It is undoubtedly consumed in the formation 

 of the starch molecules, and is one of the most important 

 requisites to carbon assimilation.' J 



If this is so in plants is it unreasonable to suppose that a 

 certain proportion of freed energy, not required as motion or 

 temperature, may in insects also be consumed in the formation 

 of molecular substances, affecting in a greater or less degree the 

 colour of their wings ? 



* Journal of Royal Microscopical Society, 1883. 

 t 'American Naturalist,' xvii, p. 141. 

 J Tom, cit., p. 264. 



