756 LIGHT AND LIFE 



ILLUSTRATIONS 



All figures are median sagittal sections modified and simplified from the orig- 

 inals. Magnifications were usually not indicated by the original authors, but 

 most of the organs are of the order of millimeters in diameter. No figure is given 

 of the squid camera eye, since it is, except for its inverted retina, topographically 

 identical with the vertebrate eye. 



Code: CL, corneagenous layer; COR, cornea (cuticle in arthropods); EP, epi- 

 dermis or hypodermis; IR, "iris"; L, lens; LAM, lamellated ring; N, nucleus; NV, 

 nerve; PH, photogenic cell or layer; PIG, pigment; RET, retinal cell or layer; 

 REL, reflector; RFR, refractor (Stabchen" or "rod mass" in case of eye); T.AP, 

 tapetum. 



Fig. 1. Mantle photophore of scjuid Abraliopsis. After Chun (fi). 

 Fig. 2. Squid cutaneous photophore. Composite of those figured from Histio- 

 teuthis by Joubin (19), from Pterygoteuthis by Hoyle (17), and from Pyroteuthis 

 by Mortara (22). 



Fig. 3. Thoracic photophore of schizopod shrimp. Composite of those figured 

 by Chun (4, 5) in several species, especially Neinatoscelis and Eupliausia, and by 

 several workers (7, 28, 29) in Nyctiphanes. 



Fig. 4. Diagram of ocellus of pseudoscorpions or lateral ocellus of pedipalps. .\fter 

 Demoll (8). This eye has an inverted retina (refractor element behind sensory), 

 but Demoll finds transition stages between it and the conventional type. 



Fig. 5. One stemma-like unit of the eye of Xet^os (Strepsiptera), after Strohm 

 from Demoll (8). In addition to the "Stabchen" (RFR), note the elongated lens 

 of the type which, in other stemmata, has apparently pinched off a separate in- 

 ternal "crystalline lens" from the cornea. 



Fig. 6. Ocellus of larval wasp (Cimbex), after Redikorzew (25). In general 

 (compare also Fig. 8) the "corneagenous" layer of the hypodermis hypertrophies 

 to greater or less extent or cuts off cells to form a refractile "Glaskorper" (crystal- 

 line cone), while the sense cells of the more proximal layer may develop distal 

 processes ("Stabchen"), also refractile. The two dioptric structures together are 

 the equivalent of cone and rod areas of an ommatidium. Ihe sensory element 

 (relinula) may consist of two to several cells, as in the compound eye. 



Fig. 7. Type of eyestalk and gill-chamber photophore of decapod shrimp Sergestes. 

 Composite from drawings of Hansen (12), Kemp (20), and Terao (27). 

 Fig. 8. Lateral ocellus of butterfly Zygnena. after Link (21). 



Fig. 9. Pleopod ocellus of decapod shrimp Acanthephyra, after Kemp (20). Ac- 

 cording to Dennell (9), the granular zone formed by the basal ends of the photo- 

 genic cells acts as a reflector. 



Fig. 10. Evcstalk section of shrimp Acniilhcpliyra, showing part of rom|)()uiid eye 

 and a pliolopiiorc of the Fig. 7 ty|)c. After Kemp (20). 



Fig. II. Single photogenic unit of uropod photophore of decapod shrimp Sys- 

 tcUdspis afjinis, after Dennell (9). The distal, sublenticular end is to the right 

 and the proximal end, which participates in forming the granular, nerve-con- 

 nected zone (Fig. 9) is to the left. Dennell has given the different regions de- 

 scriptive names, only assigning function to those indicated. He states that the 

 ])hot()gcni< luiil in this species has lost the cell nucleus which he figures for the 

 (orrespoiuling structure of fioj>l(>l)linnis lypus and which Kemp saw in Acanthe- 

 phyra (now Systellaspis) debilis (Fig. 9). 



