18 5 
SECT. XX. 
ON DARKNESS AS FAVOURABLE TO GERMINATION. 
Even the weak Embryo, ere to life it breaks. 
From his high pow’r its slender texture takes ; 
While in his book the various parts inroll’d. 
Increasing, own eternal Wisdoms mould. 
Smart. 
That light and heat* are distinct bodies though often conjoined, was known 
to the Honourable and Illustrious Mr. Boyle. 
In general, a very considerable degree of heat is requisite to the emission of 
light from any body; but there are several exceptions to this, especially in 
light proceeding from putrescent substances and phosphorus, together with 
that of luminous animals, and other similar appearances. Light proceeding 
from putrescent animal and vegetable substances, as well as from glow-worms, 
is mentioned by Aristotle. Thomas Bartholin mentions four kinds of lumi¬ 
nous insects, two with wings, and two without; but in hot climates travellers 
say they are found in much greater numbers, and of different species. 
Columna, an industrious naturalist, observes, that their light is not extin¬ 
guished immediately upon the death of these animals. 
The first distinct account that we meet with of light proceeding from 
putrescent animal flesh is that which is given by Fabricius ab Aquapendente; 
who says, that when three Roman youths, residing at Padua, had bought a 
lamb, and had eaten part of it on Easter day 1502, several pieces of the 
remainder, which they kept till the day following, shone like so many candles 
when they were casually viewed in the dark. Part of this luminous flesh 
was immediately sent to Aquapendente, who was professor of anatomy in that 
city. He observed that both the lean and the fat of this meat shone with a 
whitish kind of light; and also took notice, that some pieces of kid’s flesh, 
which had happened to have lain in contact with it, was luminous, as well as 
3 A 
