1895-] ENTOMOLOGICAL NEWS. 97 



another near clypeus; sutures and jaws black. Body flesh-brown, densely 

 covered with small, rounded, purplish black, confluent spots', almost cov- 

 ering the surface. Feet, cervical shield and venter entirely purplish black; 

 on joints 3 and 4 a broad dorsal and narrow subdorsal bright brown band. 

 Lateral oblique lines indicated by heavier mottlings above and predomi- 

 nence of the ground color below; spiracles black, with orange-red and 

 central line, surrounded by black. 



Pupa. Tongue case large, distant from the body, extending to near 

 the middle of the cases then recurved along the body to near its origin, 

 rounded and a little enlarged at the end; cremaster broad, flat, narrowing 

 laterally and ending in four short spines ; color bright mahogany-red, 

 darker on tongue case, cremaster nearly black. Length 64 mm.; width 

 of thorax 15 mm.; length of tongue case about 47 mm.; distance from 

 origin to joint of recurvature 21 mm.; diameter of tongue case 2.5 mm. 



-o- 



THE COMPOUND EYE. 



By E. BRENDEL. 



The anatomical and physiological comparison of the organ of vision is 

 certainly a most difficult undertaking. Though the study of the eye of 

 the vertebrate animals has progressed during the last century in an ad- 

 mirable way, notwithstanding there are left many obscure points which 

 will perhaps never be elucidated. We do not know anything concerning 

 the reversion of the image, nor the physiology of the cones, or bacillse. 

 The art of photography has helped us considerably in proving the law of 

 vision. The momentary retension of an image by the exposure to the 

 eye of a living vertebrate animal for the reception of the projection of an 

 object on the retina has been proved in a chemical way by developing 

 and fixing the image on the retina, demonstrating a physiological analogy 

 of the photographic camera and the eye. 



The image in the camera appears to us not convex, but as a geometrical 

 projection, if the object is in all its parts equally illuminated, that is, shade- 

 less. The presence of light and shade with its delicate gradation alone 

 produce the imagination of rotundity in a rather defective way. 



In the human eye the image is also plain when we use only one eye, 

 but there are other additional factors than the shades of the object pro- 

 ducing the perception of rotundity. There is our experience by touch 

 assisting our eye then the very defect of our vision, seeing sharply only 

 such parts of the object which lie nearest to the optical axis is partly cor- 

 rected by the combined use of our two eyes as each one receives an image 

 from a different standpoint. The axes of vision of our eyes are conver- 

 gent and adjustable. One eye sees parts of the object which the other 

 cannot see; but the congruity of the images makes us in reality see more 

 than the geometrical projection of the object on the single retina and cor- 

 rects the flatness of the image. The photographer imitates nature by 



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