164 MULLEE'S THEORY OF MOSAIC VISION. 



This theory was at first received with much favour. 

 In 1852, however, Gottsche * attacked Miiller's view, 

 pointing out that each separate cornea of a compound 

 eye can, and in fact does, give a separate and distinct 

 image. This had, indeed, long previously been ob- 

 served by Leeuwenhoek, who said, " When I removed 

 the tunica cornea a little from the focus of the micro- 

 scope, and placed a lighted candle at a short distance, 

 so that the light of it must pass through the tunica 

 cornea, I then saw through it the flame of the candle 

 inverted, and not a single one, but some hundreds of 

 flames appeared to me, and these so distinctly (though 

 wonderfully minute) that I could discern the motion of 

 trembliug in each of them." t 



Of this, indeed, it is easy to satisfy one's self. It is 

 only necessary to look at a candle through the cornea 

 of an insect, and then slightly draw back the micro- 

 scope, when a thousand small images of the candle, 

 each formed by one of the lenses, will be plainly seen. 

 If, then, in such cases there was a retina placed at the 

 proper distance, a true image would be formed, as on 

 the retina in our own eyes. This paper of Gottsche's 

 threw great douht on Miiller's explanation, which, 

 indeed, was, in Dors's words, " abandonnee par tout le 

 monde." | 



It is one thing, however, to see that the lenses throw 

 distin 't picturfS, but quite aQother to understand how 

 such pictures could be received on the retina, or com- 

 bined into one distinct image. 



* "Beit, zur Anat. und Phys. der Fliegen und Krebse," Miiller's 

 Arch., 1852. 



t A. Van Leeuwenhoek, " Select Works,'' translated by S. Hoole. 



X " De la Tision chez las Arthropodes," Ar. des Sci. Phys. et Nat. 

 Geneva: ISGJ. 



