ORIGIX OF MONSTERS 511 



The microscopic examination of the sectioned embryo con- 

 fii-ms the macroscopic appearance. The whole eye appears in 

 forty-nine sections of 6/x thickness. Up to the twenty-second 

 section no trace of a lens is seen, and in these anterior sections 

 the condition is presented which normally obtains for posterior 

 sections, i.e. the view is one of the base of an eye where it is 

 entirely encircled by the pigment layer. In the section illus- 

 trated by figure 68 of Plate 1 the retinal layers are defectiA'e and 

 the brain, while being bilobed, yet appears to be greatly dis- 

 torted. Following the sections posteriorwards we see in the 

 twenty-second section (fig. 69) the beginning of the lens in its 

 abnormal position. It extends up to the forty-seventh section 

 inclusively and it is thus seen to occupy about the posterior nine- 

 sixteenth of the eye. No optic nerve can be found, although 

 the fibrous la^'er of the retina is fairly well developed. The 

 mouth is absent in this embryo and the pharynx comes into view 

 in the last sections through the eye, which is seen to be partly 

 enclosed by the defective mandibular arches and projecting for 

 the greater part into the distended pericardial vesicle. 



The optic cup is C-shaped; it strikingly suggests the simi- 

 larity to a component of a synophthalmic eye and points to the 

 morphogenesis of this monstrosity. Owing to blastolysis the 

 future interocular area of the early embryo, the entire ophthal- 

 moblastic material of one side and a part of it of the other side 

 were destroyed as well as also the earliest anlage of one olfactory 

 pit. The subsequent approximation of the wound surfaces has 

 moved the remainder of the one uninjured oplithalmic anlage 

 out of its original position so that the incomplete optic cup which 

 has developed from it, has turned at an angle of about 90° in 

 relation to its axis. The apparent heterotopia of the lens and 

 the pigment-enclosed front of the eye are evidently due solely 

 to this secondary change in position of the remaining part of 

 one optic anlage. No traces of a fusion could be found any- 

 where, and the presence of a single (non-fused) olfactory pit 

 (fig. 68) would seem to strengthen the evidence that the cyclo- 

 pean eye of this embryo has developed from the ophthalmo- 

 blastic material of one side only. 



