segmentation cavity and the blastopore are equally diminished in 



size and similarly acquiring an eccentrical position. 

 Fig. 31. — Left side view of Egg C, sketched at 11:27 a.m. of the third day. 

 Fig. 32. — Left side view of Egg C, sketched at 0:50 p.m. of the third day. 

 Fig. 33. — Left side view of Egg C, sketched at 5:14 p.m. of the third day. 

 Fig. 34. — Left side view of Egg C, sketched at 3:30 p.m. of the third day. 

 Fig. 35. — Left side view of Egg C, sketched at 4:50 p.m. of the third day. 

 Fig. 36. — Left side view of Egg C, sketched at 10:37 a.m. of the fourth day, 



when the blastopore has nearly closed, and the general outline as well 



as the location of the embryonic body become equally well recognisable. 



Fig. 37. — Posterior view of Egg C, sketched at 10:50 a.m. of the fourth day. 



Fig. 38. — Left side view of Egg 0, sketched at 8:30 a.m. of the fifth day. 



Figs. 39-42. Selected to show successive stages of a Rana 



egg (R. japonicd) observed in the same way as Egg C, Zeiss 



Oc. 1 x Obj. a\ 



Fig. 39. — Lower view of the Rana egg sketched at 4:30 p.m. of the first 



day, after being fixed on the " Prismen -Rotator." 

 Fig. 40. — Lower view of the same egg sketched at 7:40 a.m. of the fourth 



day, after being fixed on the " Prismen-Rotator." 

 Fig. 41. — Right side view of the same egg sketched at 3:32 p.m. of the 



fifth day, after being fixed on the " Prismen-Rotator." 

 Fig. 42. — Right side view sketched at 3:00 p.m. of the sixth day. 



Figs. 43-49. selected to represent successive stages of a Bufo 

 egg (B. japonica) No. 1. Observed in the same way as Egg C. 

 Pio-, 43. — Upper view of the egg at the first appearance of the second 



cleavage line. 

 Fig. 44. — Frontal view of the first cleavage line, corresponding to the later 



left side view of the egg. 

 Fig. 45. — Left side view of the egg sketched at 8:30 a.m. of the third day 



after deposition. 

 Fig. 46. — Left side view of the egg sketched at 8:20 a.m. of the fourth day. 

 Fig. 47. — Left side view sketched at 1:30 p.m. of the fourth day, when the 



egg has rotated around its transverse horizontal axis about 30°-35°. 

 Fig. 48. — Posterior view of the egg, sketched at 4:00 p.m. of the fourth day. 

 Fig. 49. — Posterior view of the egg, sketched at 8:30 a.m. of the fifth day. 

 Fig. 50. — Anterior view of a Bufo egg No. 3 in its peculiar rotatory 



motion. The arrows show the direction of the rotation, and the 



meridional lines represent successive positions of the neural groove 



in the moving egg. The dots made between the thick lines indicate 



different positions which the anterior extremity of the neural groove 



assumes by oscillation in every turn of the egg. 



