49 
'■ r A •'yi rt -^r 'T 
LECTtJllE' YlII. 
tirely destitute, the particular kind of stridulous 
sound which some kinds are ohserved to produce 
■ . f : ■. ' r- \ •; 1 * / . ■- ■ 
on being first taken out of the water, being en- 
tirely owing to the sudden expulsion of air from 
their internal cavities, as in the Gurnards or Pi- 
pers, and some other fishes. 
By far the greater number of fishes are ovipa- 
rous, producing soft eggs, nsnally known by the 
name of spawn. Some fishes are however vivi- 
parous, the eggs first hatching internally. Fishes 
may certainly be considered as the most prolific 
of all animals : many millions often proceeding 
from a single individual. The gradual evolution 
■'Inc 34 ’* . . . 
of the young from the egg is highly curious. In 
the spawn of the Barbel and some others, which.'* 
usu^-Iy hatches in the space of about nine or tbh 
days, on the second day may be perceived in each 
egg a small dusky speck between the white and 
the yolk ; on the third day the motion or pulsa- 
tion of the heart becomes visible, and the body 
may be perceived, adhering laterally to the yolk: 
on the 6th day the back-bone and ribs are percep- 
tible ; on the 7th day the eyes ; and the animal 
begins to mcwe itself briskly from time to time, 
till at length, on the 9th or l Oth day it bursts from 
-"p -' J tf'- : 
LECT, IT. E 
