536 E. I. WERBER 



not deny the possibility of such small size in synophthalmic 

 cyclopia, I would not leave unmentioned the fact that in my 

 observations made on a great number of sectioned teratoph- 

 thalmic embryos I have not yet had occasion to record a single 

 such case. Examination of the figures in Stockard's ('09, '10 a) 

 papers also very forcibly suggests that all cases of small 

 Cyclopean eyes which he pictures, represent perfect cyclopia, 

 i.e. a condition of median, genetically single, one-eyedness, where 

 a fragment of ophthalmoblastic material of one side developed 

 into a small, but whole, eye in the median position, which it 

 secondarily has come to occupy. 



On the basis of our conception of the morphogenesis of oph- 

 thalmic terata, namely that the latter are due to a defect it is 

 easy to account for the unquestionable fact that neither the 

 perfectly cyclopean nor the synophthalmic eyes (cyclopia synoph- 

 thalmica, synophthalmia unilentica et bilentica) are double the 

 size of one normal eye, as Stockard ('13, p. 270) postulates they 

 would have to be, if the fusion theory be regarded as correct. 

 Such eyes simply cannot be "equal in mass to the two normal 

 eyes fused" because the fusion in the synophthalmic eyes is due 

 to destruction of a part of the eye forming material. This, how- 

 ever, meets an important and justified objection which Stockard 

 has raised against the fusion theory of 'cyclopia.' 



It is, no doubt, true that, while sny ophthalmic deformities 

 can be accounted for on the basis of this fusion theory, it would 

 fail if extended to other ophthalmic terata. For, perfect cyclopia 

 cannot, as was pointed out above, be regarded as due to fusion. 

 Nor can it be denied that, as Stockard ('13, p. 278) remarks, 

 the genesis of asymmetric monophthalmia and microphthalmia 

 have yet to be accounted for. But while we admit these limita- 

 tions of the fusion theory, it must be borne in mind that its 

 most fundamental element — the exceedingly suggestive defect 

 hypothesis of Lewis and Spemann will alone account for asym- 

 metric monophthalmia and microphthalmia as well, as for per- 

 fect cyclopia. 



The defect which in synophthalmia we have assumed to con- 

 sist in a blastolytic elimination of a fragment of tissue from the 



