328 
EFFECT OF DARKNESS ON ANIMALS. 
IV. The skin of the animal (very probably the colour of the 
skin) appears to have a determining influence on the pre- 
ceding results. Example : place under a green glass a certain 
number of frogs weighing the same as the preceding; esti- 
mate the quantity of carbonic acid produced after twenty- 
four or forty-eight hours. The excess will be in favour of the 
frogs placed under the green ray, as w r e have said ; afterwards 
remove the skins of the frogs and replace them in the same 
conditions* The result will be changed : the quantity of 
carbonic acid produced by the skinned frogk will be more 
considerable in the red ray that in the green ray. 
V* The influence of the coloured rays of the spectrum on 
the proportions of carbonic acid exhaled in a given time by 
a living animal is continued for some time with the dead 
animal (muscular respiration), and ceases as soon as putre- 
faction commences, that is to say'; after the disappearance of 
the stiffness of death. Butcher’s meat, taken the day after 
or two days after the death of the animal, always gave an 
equal proportion of carbonic acid when placed simultaneously 
under the various coloured rays. 
VI. A small number of experiments tried on the cutaneous 
exhalation of the vapour of water, showed that in darkness 
(with the same temperature and weight) frogs lose by evapo- 
ration a quantity of water half or a third less than in white 
light (ordinary diffused light). In the violet ray the quantity 
of water lost by the animal ih a given time is distinctly the 
same as in white light. 
Comptes Rendus ; No. 9, March 1st, 1858, and Chemist, 
LIGHT. 
Light,, it has been justly said, is the great painter of 
Nature, giving to the dome of heaven Hope’s own colour, 
blue; to the rainbow its vivid tints; to the morning and 
evening clouds their glowing livery of ruby, sapphire, and 
gold ; to the flowers all their beauteous hues ; and to grass, 
the earth’s best vest, that green which, above all other 
colours, is most grateful to the eye* All these phenomena 
depend solely upon the regular appearance of the orb of day; 
yet man is so accustomed to the regular course of Nature 
that he is less aroused by the grandeur of the sun rising in 
pomp and might, filling the world with beauty, and diffusing 
gladness everywhere, than he is by a momentary meteor of 
the night. 
