LIFE-HISTORY OF XENOPUS LAEVIS, DAUD. 821 
Fig. 3a. Seen from below. 
Fig. 4. Early blastula stage. 
Fig. 5. Late blastula stage. 
Fig. 6. Egg with early stage in the formation of the blastopore. The egg is in its natural position, and 
is seen from the right side. 
Fig. 64. The same stage seen from below. 
Fig. 7, Stage showing circular blastopore with large yolk plug. 
Fig. 8. Stage with open medullary groove, seen from behind, 
Fig, 8a. The same stage seen from before. 
Fig, 9, Stage after closure of medullary groove. 
Fig. 10. Embryo, 3 mm. long, taken out of egg. (x 25.) 
Fig. 104. Anterior end of the same embryo viewed in the direction of the arrow in fig. 10. (x 48.) 
Puate II. 
Fig. 11. Ege deposited on a leaf of Myriophyllum proserpinnacoides. ( x 6.) 
Fig. 12. Embryo, 3°2 mm. long, in vitelline membrane ; the jelly surrounding this has been stripped off. 
Drawn from life. (x 25.) 
Fig. 13. Embryo, 3°8 mm. long, taken from egg. Drawn from life. (x 25.) 
Fig. 14. Embryo, 5 mm. long, taken from egg. Drawn from life. (x 25.) 
Puate III. 
Vig. 15. Head of larva just hatched, seen from before, in the direction of the arrow in fig. 15a. (x 60.) 
Fig. 15a. Outline of larva, 5 mm, long, just hatched, seen from side, ( x 15.) 
Fig. 16. Larva, 4°5 mm. long, lying in the egg attached to the vitelline membrane by the cement organ 
before hatching commences ; the larva is seen from the ventral side. The layer of jelly outside the vitelline 
membrane is omitted. (x 11.) 
Fig. 17. A, B and C, Head of larva during process of hatching, to show the yielding vitelline 
membrane. A., 8’ 15” before hatching. B., 3’ 15” before hatching. C., 15” before hatching. (x 12.) 
Fig. 18. The position of the same larva when it emerged from the egg. The vitelline membrane has 
shrunk and caught the tip of the tail. (x 10.) 
Fig. 19. The same larva as in figs. 17 and 18, as seen a few seconds later, hanging by a thread of 
mucus to the further shrunken vitelline membrane. ( x 10.) 
Fig. 20. Portion of the skin of the tail-fin of a tadpole, 62 mm. in length, killed during the daytime: 
from the middle of the length of the tail. (x 170.) 
Fig. 21. A corresponding portion of the tail-fin of the tadpole drawn in fig. 24, which was killed at 
night. (x 170.) 
Puate LV. 
Fig. 22. Anterior view of the head of a larva 10 mm. long. The stage reached is a few hours earlier 
than that at which the animal begins to feed. (x 33.) 
Fig. 22a, Outline sketch of the same larva as fig. 22 in side view. (x12.) (From a formalin 
specimen. ) 
Fig. 23. Side view of a tadpole 12°4 mm. long, which has fed for two days. (*11.) (From a 
formalin specimen.) 
Fig. 24. Side view of a tadpole, 60 mm. long, with the arm not yet extruded. Drawn in the position 
in which the rapid ascent to the surface is made to obtain air, (x 3.) (From a specimen killed at night 
and preserved in alcohol-formalin-acetic acid mixture.) 
Fig. 25. The left pectoral region of a tadpole, 62 mm. long, slightly older than that shown in fig, 24, 
to show the extruded arm and the spiracle into which a style has been passed. (x 13.) (Preservation as 
described above, fig. 24; killed at nightfall.) 
TRANS. ROY. SOC. EDIN., VOL. XLI. PART III. (NO. 31). 120 
