Talk:Book - The Frog Its Reproduction and Development 2
The rate of development of the egg and embryo will depend upon the temperature at which they are kept. The approximate schedule of development at two different temperatures is given below.
Stage At 18
Fertilization
Gray crescent 1
Rotation li/^
Two cells 3V2
Four cells 4V2
Eight cells 5V^
Blastula 18
Gastrula 34
Yolk plug 42
Neural plate 50
Neural folds 62
Ciliary movement 67
Neural tube 72
Tail bud 84
= c.
At 25"
C.
hrs. . . .
hrs.
1/2-1
1
. 21/2 '
" 31/2 '
41/2 '
12
20
32
40
48
52
56
66
Stage Atl8°C. At25°C.
Muscular movement 96 hrs 76 hrs.
Heart beat 5 days 4 days
Gill circulation 6 " 5
Tail fin circulation 8 " 6V^
Internal gills, operculum 9 " IV2
Operculum complete 12 " 10
Metamorphosis 3 mos IVi mos.