INFLUENCE OF ENVIRONMENT 



333 



bifida) ; or the brain may be forced outside of 

 the head or may be lacking altogether (anen- 

 cephaly) . In some cases eyes are wholly lack- 

 ing, in others the two eyes fuse together into a 

 single one as in the fabled Cyclops (Fig. 78). 

 Practically all such cases of monstrous devel- 

 opment are due to abnormal environmental 

 conditions in early stages of development. 



In addition to such monsters, which are in- 

 capable of long life, many peculiar if not ab- 

 normal types of animals are produced by the 



I 



Fig. 78. Young fish; on the right a normal individual with 

 two eyes; on the left cyclopean monsters with one eye; 

 produced by treatment with magnesium solutions. (From 

 Stockard.) 



