512 E. I. WERBER 



The injury sustained by the embryo was a severe one, much 

 severer than is usually found in either synophthalmia or synoph- 

 thalmia cyclopia. This is evidenced by the defective and oedem- 

 atous condition of the brain (fig. 69), and the curving of the 

 head, to which is due the appearance in one section of the eye, 

 medulla, and semicircular canals. Yet the morphogenetic fac- 

 tor which brought about the embryo's deformity was, no doubt, 

 the same as in synophthalmic monsters. 



A case of perfect cyclopia, where the malformation is far more 

 extreme than in the preceding one is presented in figure 8 (p. 

 488). The embryo is seen to be extremely deformed. It has a 

 single, median, unusually small eye, and greatly distended ear 

 vesicles (cf. fig. 71); the entire body is oedematous, all fins are 

 lacking and the tail is club-shaped. 



On microscopic examination (fig. 70) the eye is seen to be 

 genetically single, there being no indication whatever of its 

 having been formed out of optic anlagen of both sides. It is 

 very rudimentary in structure, the pigment layer and the rela- 

 tively very large lens being its best developed parts, while the 

 retina is very defective, the optic nerve, the iris, anterior chamber 

 and the vitreous body lacking altogether. The brain is lateral 

 to the optic cup of this minute eye instead of being dorsal as 

 should be expected from the position of a cyclopean eye. • This 

 distortion of the relation between the eye and the brain, the 

 defective and unpaired condition of the latter throughout (cf. 

 fig. 70) and the deformities of the rest of the body suggest that 

 a severe injury was sustained by the entire embryo. However, 

 the defects are most extreme at the embryo's anterior end, 

 which again points to the conclusion that in this case, too, the 

 degree of injury was the highest at the most anterior part of the 

 early embryonic anlage, diminishing posteriorly along the chief 

 body axis. The eye arose from a fragment of one potential 

 optic anlage, the remainder of which and the entire other poten- 

 tial optic anlage as well as a part of the future brain and the 

 potential olfactory pits having suffered destruction. Owing to 

 subsequent processes of regulation the surviving ophthalmo- 

 blastic fragment has come to occupy the median position in the 

 defective head where it developed into the rudimentary eye. 



