NOTES ON THE PHOTOPHORES OF SERGESTES PKEHENSILIS BATE. 2>°7 



belonging to it did not remain unobserved by him ; but these were regarded 

 by him to be those of the underlying photogenous cells, the true nuclei of 

 which apparently remained unrecognized by him. In passing it may be 

 remarked that the epithelially arranged cells, described by Kemp and 

 situated under the lens in the photophores of Acanthephyra debil is, probably 

 represent the lens epithelium under consideration. 



The lens epithelium in 6". prchensilis is of much the same appearance 

 as the general hypodermis. But there are in it some special features which 

 deserve specially noting, as being of some significance as regards the genetic 

 relation of the photogenous layer to the epithelium. While the majority of 

 the nuclei in the epithelium lie flattened against the lens surface, exactly as 

 do those of the hypodermis against the cuticula, a good many others are 

 seen to more or less stand out inwards at certain angles from the level of 

 the epithelium. The projecting nuclei, which appear to be mostly of an 

 elongate ovoid shape, are generally so disposed with their long axes that 

 imaginary outward prolongations of these converge towards the axis of the 

 internal lens body. Cell-bodies to the projecting nuclei could scarcely ever 

 be made out with definiteness. Instead of resting nuclei, karyokinetic 

 figures occur not unfrequently in the lens epithelium ; they are mostly 

 found in positions which indicate their origin from the projecting nuclei, the 

 spindle axis being directed in the same way as the long axis of the latter. 

 It may be that the multiplication of the epithelial cells, especially of those 

 projecting inwards, stands in relation to the regeneration of photogenous 

 cells, which not unlikely takes place at certain period or under certain 

 circumstances. 



3) The phofofjenoits layer. — Directly inside of the lens epi- 

 thelium is a relatively thick layer, the photogenous layer, the main 

 constituents of which are the photogenous cells {ph.). The layer is seen 

 to cover the somewhat flattened central parts of the internal lens surface, 

 without extending into the periphery of the latter. The photogenous cells 

 are of a bulky size and of an approximately pyramidal shape, being broadest 



