292 Charles R. Stockard, 



CYCLOCEPHALI AND "mONSTRA MONOPHTHALMICA ASYMMETRICa" 



The magnesium solutions induce the formation of two distinct 

 types of eye monstrosities. The first type is the typical cyclopean 

 monsters, which exhibits a series of individuals showing various 

 degrees of cyclopia. Beginning with a normal individual having 

 eyes in their usual position, w^e find others in which the eyes are 

 slightly inclined forward and somewhat closer together than 

 usual; or the eyes are still more approximated and occupy an 

 unusually anterior position. (See the diagram. Fig. i). Next 

 in the series are individuals with their eyes approximated but 

 still distinctly separate, having two optic nerves and two eyeballs 

 with their choroid coats in intimate approximation. We next 

 find the true cyclopean eye which still shows a double nature 

 having two optic nerves; the retina has a paired arrangement and 

 either one or two lenses may occur, depending upon the degree of 

 distinctness of the two components. This eye generally occupies 

 a ventro-median position and looks forward, inclining slightly 

 downward. The eye in others is completely single, showing no 

 indication of a compound structure; it has one optic nerve, a 

 single retinal arrangement, one lens and one pupil. This is the 

 perfection of cyclopia and many embryos possessing such an eye 

 are apparently normal in other respects, except the mouth and 

 nose. They have a typically bilateral brain and are perfectly 

 capable of free-swimming movements. Passing beyond this 

 stage of cyclopia, we find embryos which have gone to the extreme 

 and show" only a defective antero-median eye. In some indi- 

 viduals the eye is represented merely by a choroid vesicle. The 

 step beyond this is the entire absence of the eye. Diagram Fig. i 

 gives a schematic illustration of the various degrees in the cyclo- 

 pean series thus outlined. The histological conditions shown 

 by such a series will be considered beyond. It is important to 

 understand that this series is made up of different individuals 

 showing various degrees of cyclopia and that a cyclopean monster 

 does not pass through these steps in its development. The 

 cyclopean defect is foreshadowed in its final condition when the 

 optic vesicle first separates itself from the brain. 



