Of a Gnaf. 
they gradually increafe towards their more perfect Hate, 
when they become like the old ones. 
Mr. Derham has plainly {hewn, that their ticking 
noife is a wooing a£t, and that it is commonly about 
July 55 ; he never found them in coitu, till about a week 
or a fortnight after their ticking; though it is probable 
they copulate at that very time. He has feen the old 
death-Vatches feed upon dead infedts, as the young ones 
do, and alfo upon bifkets, tallow. Sec. nay dull: itfelf, 
and hath obferved them through a microfcope to felect 
feme grains thereof, and rej e£t others. 
Of a gnat. 
H E firft obfervable in the generation of this infedb, 
A is its vaft fpawn, fame of them being one inch and 
half long, and one eighth of an inch broad, floating in 
the water, but being made faft to fomething to prevent its 
being wafhed away ; in this tranfparent fpawn the eggs are 
neatly depofited, in fome a Angle, in others a double fpiral 
line a , running from end to end, as in fig. 125 and 126. 
and in fome tranfverfly, as in fig. 127. 
When the eggs are by the heat of the fun, and warmth 
of the feafon, hatched into fmall maggots, thefe maggots 
defeend to the bottom ; and by means of fome cf the 
gelatine matter of the fpawn, which they take along 
with them, they (lick to ftones, and other bodies at the 
bottom, and there make ihemfelves little cafes or cells, 
which they creep into, and out of at pleafure, till they 
arrive at a more mature nymph Hate, and can Iwim 
japout here and there in queif of food j at which time 
a Phy, Theo. p» 39 4* 
* Phil. Tranf. No. 271. 
