NOTES ON THE PHOTOPHORES OF SERGESTES PREHENSILTS BATE. 3 1 3 



although the presence of the membrane was given by him neither in the 

 text nor in the diagrammatic figure (pl. LIV, fig. 1). 



5) The reflector. — A body, which is regarded as the reflector, is 

 usualh", though not always, present in the photophores of S. prehensilis 

 (fig. I, r). It represents a plano-convex or a somewhat hemispherical 

 body, standing with its plane surface in direct contact with the basement 

 membrane and with its sharply defined arched surface in apposition to the 

 pigment mantle. Its diameter is somewhat shorter than that of the 

 photogenous layer. Observed in sections of well preserved material, the 

 reflector consists of a small-meshed and dense network of protoplasm, 

 which contains some small nuclei in irregularly scattered distribution. The 

 mesh spaces arc of a flattened shape, compressed in the direction vertical 

 to the plane surface of the body. In fact, the reflector may be regarded 

 as being made up of branching and anastomosing cells, with horizontally 

 extended slit-like interspaces. The protoplasmic reticulum is homogenous 

 and agrees in its reactions towards staining reagents perfectly with the 

 homogeneous contents of the photogenous cells at a stage just before they 

 be<jin to disintegrate. 



Kemp (/. c, p. 642) has attributed to the reflector of J>. challenge ri a 

 faintly striated appearance. I have found that to be also the case in 

 6". prehensilis, but only in those specimens which were preserved in formalin, 

 as were also Kemp's specimens. Moreover, it was given by the same 

 author that the reflector, in the species studied by him, contains numerous 

 pear-shaped nuclei which are very regularly arranged with their apices 

 directed towards the lens (p. 642). Such a condition of the nuclei in the 

 reflector, I have entirely failed to observe in .S". prehensilis. 



As to the origin of the reflector, I have arrived at no definite view. 

 Its histological character is so very different from those of the connective 

 tissue that it seems scarcely justifiable, in the absence of convincing proofs, 

 to assume its derivation from the latter. Possibly it is of hypodermal 

 origin. In its reactions towards stains, the reflector reticulum exhibits 



