426 STUDIES IN GENERAL PHYSIOLOGY 
It is not to be wondered at that the various investigators 
arrived at diametrically opposite results. 
Edwards states that frogs’ eggs do not develop and soon 
die when inclosed in a dark box, while the development 
takes place in an open box which is exposed to the light. 
According to Edwards, even the young larve require a longer 
time to develop in the dark than in the light. Edwards’s 
statements are based on very few experiments. Dutrochet 
repeated the experiments of Edwards, and found that 
where the supply of oxygen was sufficient and the tempera- 
ture was the same in the two boxes, the eggs of Batrachians 
developed as well and as rapidly in the dark as in the 
light. These facts indicate that in Edwards’s experiments 
the eggs suffered from lack of oxygen and exposure to a low 
temperature. 
Béclard published a short communication on the influence 
of light on the development of the eggs and the larve of 
flies. He placed the eggs under colored bell-jars, and found 
that after four or five days development was most advanced 
under the violet and blue jars, and least under the green. I 
cannot understand the experiments of Béclard, as fly larve 
hatch in about two days in summer, and up to this time their 
size depends on the size of the eggs, since further growth 
takes place only when the larve find food in which to bury 
themselves. The statements of Béclard regarding the influ- 
ence of light on the production of carbon dioxide in animals 
are also doubtful. 
It is rather strange, though characteristic, that in the 
scientific literature of our subject one frequently finds serious 
mention of the investigations of General Pleasanton, made 
on six pigs. The general put three pigs into a stall with 
violet windows, and three into a stall with ordinary windows. 
While the three pigs exposed to violet light gained 398 
pounds in four months, the others gained during the same 
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