ARTIFICIAL PARTHENOGENESIS AND HEREDITY 297 
the closure of the blastopore.’”’ I have been able to raise the 
hybrid between Fundulus heteroclitus 2 and Menidia, Cteno- 
labrus, and Stenotomus ¢ in large numbers beyond this stage. 
These hybrids lived a month or longer, formed hearts, blood 
vessels, eyes, and fins, but never hatched. With a few excep- 
tions no circulation was ever established although the heart 
beat for weeks. 
Fic. 87.—Hybrid between Fundulus heteroclitus 2 and Menidia 6, twenty 
days old, showing purely maternal characters. 
Fig. 87 shows a three-weeks-old hybrid of Fundulus hetero- 
clitus 2 and Menidia ¢. The pure breed of Fundulus hetero- 
clitus, of the same age, were already hatching. The hybrid 
embryos had formed the pigment characteristic for the pure 
breed of Fundulus heteroclitus. But the anomalies of the em- 
bryo are very obvious. The embryo is rather small, owing to 
the slowness with which these hybrids digest the yolk. Its 
eyes are abnormal and approach the cyclopean condition. In 
many specimens only irregular masses of pigment indicate 
where the eyes should be. The head is comparatively small 
and not bent as is characteristic for the pure breed. The heart 
is developed but corresponds to an early stage in the develop- 
ment. It beats regularly and at an almost normal rate. The 
