622 



THE AMERICAN NATURALIST [Vol. XL 



la\er except for a sliglit decrease in thickne^^ from 65 ti to 44.2 a 

 The nuclei stain more deeply with the iron-alum h^ematoxylin, 

 and all are spherical except those of the supporting cells or fibers 

 of Mailer, while the nuclei of the horizontal cells are readily dis- 

 tinguished by their clearer texture. The cytoplasm of the layer 



The llKTici lak Layers 



The reticular layers are ])urely cytoi)lasinic in both origin and 

 structure, there being no evidence to the effect that ruiclei have 

 anything to do with their formation. Each retinal nucleus, ex- 

 cept in mitosis, is always enveloped in an intact nuclear mem- 

 V)rane, and there are never appearances that might suggest the 

 extrusion of nuclear substance or in the strict sen.e of the word 

 the protrusion of processes of an^ kin.l. To be sure, the cyto- 



