542 E. I. WERBER 



an eye (figs. 38-41) which may be single or composite (synoph- 

 thahnia, fig. 39). In the fragment of nervous tissue from which 

 such an eye arises the form relations of a brain do not exist, nor 

 is it possible to recognize what parts of the brain are represented 

 by the fragment. 



One of such eggs with a 'solitary eye' has been briefly de- 

 scribed in a previous paper (Werber '15 c). The significance of 

 such formations being obvious, it seems desirable to give at this 

 time a fuller description of it as well, as of two more eggs with 

 solitary eyes which have been studied in sections. 



In figure 40 is seen an egg without an embryo but with several 

 tissue fragments on the yolk, distant from each other, one of 

 which has given rise to a small eye discernible in toto. 



The sections into which this egg has been cut, run parallel 

 with the vertical axis of the solitary eye. Examination of the 

 entire series (only one section missing) discloses the following 

 conditions. 



Nothing can be found in the yolk in any of the sections. Thus 

 the possibility is entirely eliminated that the embryo had sunken 

 into the yolk lea\dng one of its eyes (constricted off) on the 

 surface. Several blood lacunae can be seen on the yolk-sac, 

 some filled with erythrocytes, while others are densely packed 

 with large cells of the appearance of leucocytes. The sections 

 through the tissue fragment from which the eye arose, present 

 a view somewhat similar to a transverse section of a rudimentary 

 spinal cord (fig. 53). In further sections, proximal to the eye, 

 this fragment of nervous tissue increases in volume so much 

 (fig. 54) that it seems safe to regard it as a — malformed, highly 

 defective — brain. Partially in contact with the latter is the 

 lens, which appears in further sections, after part of the optic 

 cup has already come into view. The whole eye is very small 

 and is rather deeply imbedded in the yolk (fig. 55). Of its 

 component parts the retina, and the lens are best developed. 

 No iris is present, and the cells of the cornea are poorly differen- 

 tiated. The space relations of the eye to the 'brain' which has 

 given rise to it are much distorted, the brain enclosing part of 

 the eye. 



