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JAMES ROLLIN SLONAKER 



changes. This increase in thickness is thus caused mainly by 

 the proHferation of cells in the substantia propria. As these 

 cells become differentiated into the thin lamellar-like bands, they 

 occupy less space thus reducing the thickness. 



By the eighth day the projection from the mesenchyme (fig. 

 37, 1), destined to become the iris, extends almost to the lens. A 

 space, bounded by the cornea in front and partially by the iris 

 and the lens behind, is the beginning of the true aqueous chamber. 



TABLE 1 



Showing the thickness of the different layers of the cornea in the developing eye and 

 the adult. Also the axial and equatorial diameters of the whole eye at different 

 ages. All measurements are in millimeters. H-2 and H-4, hatched two and 

 four days; H-fl, the age of leaving the nest, or the first flight 



At this age, however, it is confined to this limited region and 

 does not extend across the front of the lens. The cornea is in 

 direct contact with the lens over most of its anterior surface. 



At the ninth day (fig. 38) the iris (7) has grown until it is 

 applied closely to the surface of the lens for some distance. It 

 still consists of a thin free margin and the whole is composed of 

 undifferentiated mesenchyme cells. This corresponds well with 

 the condition found in the young albino mouse at the age of two 

 days as described by Nussbaum ('12). The aqueous chamber 



