84 Frederick H. Krecker, 



movement presses in to fill the depression above the latter. The series 

 of transformations liere described is shown in figures 5 and 6. 



The corneal hypodermis, when finally in place, is composed of 

 extremely large, relatively tall cells. In median longisections of the 

 eye one sees the boundaries of these indestinctly so that the layer in 

 this region appears to consist of a homogeneous granulär substance 

 in which lie enormous nuclei. Their number averages 4 — 5 for each 

 section; two smaller ones lying between two that are larger. One's 

 attention is straightway attracted by their gigantic size which is en- 

 tirely out of proportion to that of the layer (Fig. 6). They are oval, 

 oecupy most of the basal half of the layer and show the characteristics 

 of nuclei present in cells actively engaged in secretion. Those cells near 

 the periphery have distinct outlines and are somewhat more slender. 



In addition to the cells just described there are on each side of 

 them especially large and interesting cells which give a characteristic 

 appearance to this stage of the development. These are the iris cells. 

 Their origin and composition is like that of the corneal hypodermis. 

 In form they are long and tapering; their broad base with the large 

 circular nucleus lies, as in the adult, below the groove which now first 

 appears surrounding the lens, and their distal end extends to that of 

 corneal hypodermis but is not in contact with the latter (Fig. 7). In- 

 stead they bulge outward crescent-like, leaving a space between them- 

 selves and the corneal hypodermis. I am inclined to think that the 

 Separation of these two is due to artificial causes during the prepara- 

 tion of the tissue. Nevertheless, the fact that there is no sign of tear- 

 ing; that in other respects the tissue showed no tendency to part and 

 that, finally, in everyone of the sections of this stage the structures 

 concerned maintain the same relative positions might point to a natural 

 condition. 



Immediately after the formation of the corneal hypodermis it 

 begins to secrete the lens. The supposition by Redikokzew (00), that 

 in the ocellus of Apis mellifica the cells composing the iris perform a 

 double function in that they aid in the formation of the lens is borne 

 out by the action of the iris cells in this case. In fact they appear to 

 be primarily cells of the corneal hypodermis which later act as iris. Thus 

 far there has been no indication of a lens, but from this time on it grows 

 rapidly at the expense of both iris and corneal hypodermis. In some 

 of the preparations there could be seen bands of secreted matter between 

 the corneal hypodermis and the already more or less firm portion 

 of the lens. 



