O0() E. I. WERBER 



})undles of fibers and to enter the opposite sides of the brain 

 after having formed an indistinct cross (fig. 46). 



The incompleteness of the fused optic cups and the other 

 abnormaUties exhibited by this eye are- probably due to the 

 circumstance that at a very early stage of development a large 

 part of the ophthalmoblastic material had undergone destructive 

 changes and has suffered partial elimination owing to the chemi- 

 cal action of the toxic solution and physical action (increased 

 osmotic pressure) due to subsequent transfer to pure sea-water. 

 The injury sustained by the embryo has apparently been the 

 severest at the most anterior point of the chief body axis, dimin- 

 ishing gradually posteriorly. The following data would seem to 

 substantiate this interpretation. The malformation is restricted 

 mainly to the eyes and the anterior part of the head. For, 

 examination of sections shows that the fore-brain of this embryo 

 is unpaired and otherwise defective, while the rest of the brain 

 is, when followed in sections posteriorwards, seen to gradually 

 present more and more distinctly the condition of bilateral 

 symmetry. The mid-brain and hind-brain while being bilateral, 

 exhibit, however, a certain other abnormality. The injury here 

 was apparently restricted to the blood and lymph vessels, the 

 earliest anlagen of which seem to have been arrested in their 

 development. This conditiori can be recognized by the great 

 number of large, clear and empty spaces (figs. 45 and 46) in the 

 tissues of the posterior parts of the brain which in the living 

 embryo have apparently been filled with fluid owing to the 

 existing imperfection in the circulation. A condition of oedema 

 has thus apparently resulted from lack of drainage, an analogue 

 of which is also represented by the oedematous distension of the 

 cranial ca^'ity in the region of the fore-brain and mid-brain. No 

 other abnoi-malities of the posterior parts of the brain or any 

 other part of the embryo can be noted, which suggests the con- 

 clusion that the anterior part of the embryo's body is the most 

 sensitive one and thus subject to the highest degree of injury. 



c. Cyclopia synophthahnica. The distinction between this de- 

 formity and the preceding one is based on morphological differ- 

 ences existing between the two types of a genetically similar 



