6oo 



MORGAN AND HAZEN. 



EXPLANATION OF PLATE XXXIV. 



Figs. 11-16, and 19, 20, were drawn with Zeiss 4, oil immersion 2 mm. Figs. 17 

 and 18 were drawn with Zeiss 4 D. The figures on the plate were reduced one- 

 third. 



The embryo- from which Fig. 11 was drawn was killed in Flemming's solution 

 and was unstained. Figs. 16-18 were drawn from material killed in Flemming's 

 solution, the stronger formula, and stained in iron haematoxylin. The remaining 

 figures were drawn from material killed in corrosive acetic and stained with 

 lithium carmine. 



Fig. II 



Fig. 12 

 derm cells 



Fig. 13 



Fig. 14 



Fig. 15 



Fig. 16. 

 pore. 



Fig. 17 



Fig. 18 



Fig. 19 



Fig. 20 

 after division (at x). 



Blastopore drawn from a total mount at about 2 a.m. 

 Blastopore from a total mount at about 3 a.m., showing also endo- 

 through the blastopore opening. 



Blastopore from total mount at about 5 a.m. 

 Blastopore from total mount at about 6 a.m. 

 Optical section through an embryo at 2 a.m. 

 Embryo with endoderm cells turned outward around the vegetative 



Embryo with vegetative pore. 



Embryo with opening at animal pole. 



Embryo, showing vegetative pore at 6 a.m. 



Oblique section of an embryo at 4.30 a.m., showing cells during and 



