Regeneration in Couipoiuid Eyes of Crustacea 177 



corneal hypodermal cells in situ that are engaged in the secretion 

 of the new cuticle. In the normal adult condition the pair of 

 corneal hypodermal cells that belong to each ommatidium appears 

 as much flattened cells crowded between the distal ends of the 

 cones and the corneal facets. Their nuclei stain faintly and 

 appear to be slender oval bodies lying flat against the cuticle. As 

 the distal ends of the cones in an injured eye break down the 

 nuclei of the corneal hypodermal cells enlarge, become rounded, 

 stain deeply and in every way show signs of increased activity- 

 Fig. 52 includes a series of figures showing the transformation of 

 the corneal hypodermal nuclei into the larger, more deeply staining 

 type seen in the regenerating eye. a and b in this figure represent 

 the corneal hypodermal cells as they appear in the normal omma- 

 tidia. The other figures of this series, c, c',^ and ^, show corneal 

 hypodermal cells, belonging to ommatidia that have degenerated 

 either wholly or partially. In c, c', e the distal ends of the cones 

 still remain almost intact and in c the nuclei of the corneal hypo- 

 dermal cells appear but little larger than those associated with nor- 

 mal ommatidia. In c' and ^, however, the nuclei of the corneal 

 hypodermal cells are much enlarged, stain deeply and the cyto- 

 plasm surrounding them appears granular and loosely reticular. 

 One nucleus to the left of the figure in d appears to be preparing to 

 divide amitotically. That the nuclei shown in d are the trans- 

 formed nuclei of the original corneal hypodermal cells is deter- 

 mined by the fact that on either side of these nuclei are others still 

 associated with partially disintegrated cones. Their original 

 character is also suggested by the fact that they are groliped in 

 pairs. A regenerated, rather than a transformed, hypodermis 

 over the ommatidial region never shows the nuclei arranged in 

 pairs in the early regenerative stages. That the new cuticle has 

 been secreted by these transformed hypodermal cells is shown by 

 the relations of the two structures. The cytoplasmic strands of 

 the hypodermis are continuous with the inner layers of the cuticle 

 (Fig. 52^). 



Of course it is not absolutely proved that the transformed 

 hypodermal cells take part in the later regenerative processes. 

 This could not be done without examining a very great number of 



