2. TABULATION OF DATA 



a. Crosses between species of the same genus 



TABLE 1 



Cumparing the hybrids from F. diaphanus 9 X F. heteroclitus d^ with pure bred 



F. diaphanus 



2 hours 

 6 hours 



20 hours 



2d£ 



3 davs 



4 davs 



PURE F. DIAPHANUS (CONTROL) 



First cleavage 

 Advanced cleavage 



Blastoderm with germ ring 

 faintly defined, embryonic 

 shield barely visible (fig. 10) 



Germ ring halfway around the 

 yolk, embryonic axis well de- 

 fined, no neural tube (fig. 13) 



Blastopore closed, embryo with 

 short tail, lenses of eyes len- 

 ticular in form, mid-brain 

 broadly open, no heart-beat 

 or circulation, first chromato- 

 phores under hind-brain and 

 on adjacent yolk , 



Heart-beat beginning to be 

 established in nearly all em- 

 bryos, no circulation, scatter- 

 ing stellate dark chromato- 

 phores on top and sides of 

 brain, black j'^olk chromato- 

 phores scattered over whole 

 yolk, a few small red yolk 

 chromatophores of dull orange 

 color (fig. 16) 



Embryos about like those of 

 pure F. heteroclitus at 4 days, 

 heart-beat strong, circulation 

 well established, head chro- 

 matophores all brownish and 

 small, large black yolk chro- 

 matophores arranged along 

 the principal vitelline vessels, 

 red yolk chromatophores 

 large, stellate, and dull red- 

 dish brown 



459 



F. DIAPHANUS 9 X F. HETEROCLITUS c^ 



Same 



A larger proportion in more ad- 

 vanced stages than in control 



Germ ring well defined and well 

 established embryonic shield 

 (fig. 11) 



Germ ring nearly around yolk, 

 embryo long and with brain 

 and optic vesicles well defined 

 (fig. 14) 



Blastopore closed, tail long, 

 lenses spherical and partially 

 enclosed in optic cup, entire 

 brain closed, heart beating in 

 majority of embryos, much 

 more numerous and better de- 

 fined chromatophores on brain 

 and yolk 



Heart beating strongly, yolk and 

 body circulation well estab- 

 lished, pigmentation much 

 more advanced in every partic- 

 ular than in control, red j'olk 

 chromatophores redder than in 

 control (fig. 17) 



Embryos less markedly in ad- 

 vance of control than at 4 days, 

 a few large black head chroma- 

 tophores of the F. heteroclitus 

 type have appeared along with 

 numerous small brownish head 

 chromatophores of the F. dia- 

 phanus type, red yolk chro- 

 matophores intermediate in 

 color between the red-brown 

 of the maternal and the brick 

 red of the paternal species 



