357 



Table 1. 



Time of Observation. 



Fund. X Fund. 



Fund. X Men. 



9.10 p. M. 



, June 26.' 



In 2 cells. 



In 2 cells. 



9.40 P. M. 



June 26. 



Beginning 4 cells. 



Beginning 4 cells. 



10.00 p. M. 



June 26. 



Completion 4 cells. 



Completion 4 cells. 



10.15 p. M. 



June 26. 



Beginning 8 cells. 



Beginning 8 cells. 



10.20 p. M. 



June 26. 



Well begun on 8 cells. 



Well begun on 8 cells. 



10.30 p. M. 



June 26. 



In 8 cells. 



In 8 cells. 



11.00 p. M. 



June 26. 



Beginning 16 cells. 



Beginning 16 cells. 



9.00 a.m. 



June 27. 



Well along in segmentation. 



Well along in segmentation. 



9.00 P. M. 



June 27. 



Well begun on gastrulation. 



First trace of gastrulation. 



9.00 A. M. 



June 28. 



l+over the yolk. 



i or less over the yolk. 



3.00 p.m. 



, June 28. 



Blastopore closed. 



1 over the yolk. 



5.30 p. M. 



June 28. 



Blastopore closed, the embryo 



Blastoporeclosingornearly losed; 







long and narrow. 



embryo much shorter than nor- 

 mal. 



9.00 a.m. 



, June 29. 



Embryo with optic vesicle. 



Blastopore closed, embryo short, 

 no optic vesicle; apparently 









dead. 



'Eggs fertilized at 7 p. m., June 26. 



From this table it will be seen that the hybrids fall behind the nor- 

 mals in their development. This becomes apparent only in the later stages. 

 In the latter stages considerable irregularity in the rate -of development 

 obtains. Usually in a lot of eggs most of v\^hich have the blastopore just 

 closed, some eggs may be found that have just entered upon the germ-ring 

 stage. Others may be variously further along. The number of such tardy 

 eggs is usually small. These eggs may stop their development at various 

 stages with consequent shortened embryos and incomplete blastopore closure. 

 In this aborted condition they may live for days, forming pigment both in 

 the embryo and in the yolk. This mass of cells may even develop a heart 

 and ear vesicles. The heart beats for days without, however, handling any 

 blood. From such condition to one where the embryo seems at first to be 

 practically normal there are all stages. The great majority of the embryos 

 die at a co)idition where the blastopore is closed, the embryo is laid down, 

 though somewhat short, with pigment developed but no heart, eyes, etc. 



Some of the embryos, under favorable conditions, develop considerably 

 further. In the more successful of these the yolk becomes highly pigmented 

 with both kinds of chromatophores. The same is true of the embryo. There 

 is an attempt at pattern formation, showing bilateral symmetry but lacking 



