522 E. I. WERBER 



main body axis, Spemann ('03, '04) concluded that the 'cyclo- 

 pean' deformity produced by him was due to a defect because 

 it resulted from the destruction of the area which would nor- 

 mally be the area between the eyes. While not inclined to 

 support unreservedly the hypothesis originally advanced by 

 Meckel ('26), namely that the synophthalmic or cyclopean con- 

 dition results from a secondary fusion of two originally separate 

 optic vesicles, Spemann leans very strongly ('04, pp. 440-441) 

 to the view advanced by Fischel ('03) according to which cyclopia 

 might result from a fusion at a very early stage of development of 

 two originally separate 7nasses of cells which were to form the eyes 

 hut had fused before they began to undergo the process of differen- 

 tiation into these organs. With this latter view agree well the 

 observations made by Stockard ('09) which I can confirm from 

 my own experience and which were confirmed also by Lewis 

 ('09), namely that the synophthalmic and monophthalmic de- 

 formities can be recognized as such already in the stage of the 

 optic vesicle, in other words that a 'twin optic vesicle' or 'cy- 

 clopean optic vesicle,' if these expressions be permitted, comes 

 off from the brain directly as such. 



The experiments of W. H. Lewis ('09) have also a very impor- 

 tant direct bearing on the subject of morphogenesis of terato- 

 phthalmia. This author employed the method of pricking the 

 anterior end of Fundulus eggs in the embryonic shield stage. 

 Various synophthalmic and one-eyed monsters resulted from these 

 operations, depending on the degree and exact localization of 

 the injury inflicted. 



From these results Lewis concluded that in the cases of 'cyclo- 

 pia' certain cells have been destroyed by pricking, which would 

 normally form the area between the eys. Owing to this elimi- 

 nation of tissue, "the repair, taking place after the operation, 

 consists of a closing together of the parts left behind .... 

 and rudiments are thus brought into contact that normally are 

 quite widely separated, those of the eyes, for example." This is 

 essentially an assumption of a fusion of early optic anlagen 

 before their differentiation into optic vesicles, as underlying the 

 morphogenesis of cyclopean and synophthalmic monsters. 



