338 



A. W. BELLAMY. 



gastrulse, for the reason that under the slightly more severe 

 inhibiting conditions where both dorsal and lateral lips are 

 inhibited, the blastopore forms, when about half completed, a 

 figure like a much flattened crescent. When such a blastopore 



B 



D 



FIG. 16. Inhibition of dorsal lip region. Eggs placed in m/io LiCl in late cleav- 

 age stages immediately before gastrulation. A and B after 18 hrs. in the solution; 

 C, D and E after 54 hrs. in the solution, d.l., dorsal lip region; y.p., yolk plug. 

 (Experiment IV 76.) 



is complete the yolk plug is always much larger than in the con- 

 trol. All stages exist between this flat crescent type and those 

 cases where the blastopore extends around the equator of the 

 egg (equatorial gastrulation). In these forms the cleavage ratio 



