326 
INFLUENCE OF LIGHT ON ANIMALS. 
interesting fact he communicated to us the other day. Being 
required judicially to decide, in concert with Professor 
Brand, as to whether the lead-compound which had been the 
cause of the death of many animals feeding in the neighbour- 
hood of lead works, was deposited on the herbage or existed 
in the soil, he took home to London with him a small 
quantity of the latter, and in it sowed some mustard seed. 
The plants grew luxuriantly, and from them he obtained 
abundant indications of the presence of lead.] 
ON THE INFLUENCE OF LIGHT ON ANIMALS. 
By M. J. Beclard. 
The action of light on the phenomena of vegetable life 
has long since attracted the attention of observers. The 
works of Ingenhousz, Sennebier, de Condolle, Knight, Payer, 
Macaire of Geneva, &c., have shown that the luminous solar 
radiation exercises an incontestable influence on the respira- 
tion, absorption, and exhalation of plants, and consequently 
on their general or local nutrition, on the direction of the 
stalks and on that of various parts of the vegetable. 
Science is much less advanced as to what concerns the 
action of light on the animal organisation. The experiments 
of W. Edwards on the development of frogs 5 eggs, and on 
the metamorphosis of the tadpole, (development and meta- 
morphosis which, according to his investigations, are not 
accomplished in the dark, but only in daylight) ; the works 
of M. Morren on the animalcules developed in stagnant 
waters ; finally, those of M. Moleschott (which show that 
the respiration of frogs, measured by the quantity of carbonic 
acid exhaled, is more active in the light than in the shade) ; 
such are the only positive notions which science possesses on 
this point. 
About four years ago we commenced, in the laboratory of 
the Faculle de Medecine , a series of experiments relative to the 
influence of ordinary light (white light), and also the influ- 
ence, not yet studied, of the various coloured rays of the 
spectrum on the principal functions of nutrition. The object 
of the present note is to present, by anticipation and in a 
concise form, some of the more important results of these 
experiments. 
I. The nutrition and development of animals which have 
neither lungs nor branchia, and which respire by the skin, 
