698 William Patten 



confined to one crystalline cone, but to several; (2) the retinidium is 

 formed by a set of nerves supplying not only one ommatidium, but 

 several, so that a single Impression produced in one would be liable 

 to cause, by sympathy, an Impression in the next. 



An important, but fallacious argument in favor of Müller's theory 

 was elucidated by him, and strangely enough has been sufficient to 

 Support it until the present day. This argument is, briefly, the follow- 

 ing: there appear to be but two suppositions possible: either the Insect 

 must see an upright «mosaie image«, or a multitude of inverted ones ; 

 but it would be impossible for the animai to rectify ali these inverted 

 images in order to see well , therefore the former supposition must be 

 the correct one! Müller seems to bave forgotten that according to bis 

 adopted theory there is no neeessity of invertiug the images; because, 

 surely, if the insect could not invert the images, it would stili beable 

 to see infinitely better than one , which , according to bis theory, was 

 only able to distinguish the amount of light! 



Müller also ignored the fact that some Insects are provided 

 with as many as forty simple eyes, the images formed by which must 

 be inverted. Neglecting the last named fact, to which Grenacher has 

 also called attention, Müller preferred to consider that ali Insects, some 

 of which he must bave known were notoriously sharp-sighted, are only 

 capable of distinguishing light from darkness, rather than suppose that 

 they could rectify numerous inverted images ! But it seems to me that 

 a little consideration will show that there is no more difficulty in this 

 process, than in that performed by Vertebrates. It is a great mistake to 

 suppose that ali animals with compound eyes see equally well , or that 

 it is necessary for them to form an idea of a landscape. There is a great 

 difference between the structure of an eye like that of an Ant and that 

 of a Dragonfly, and there is undoubtedly as wide a gulf between their 

 visual powers. But a landscape even could be seen and recognized by 

 means of a compound eye , provided the inverted images were small 

 and very numerous; it would consist of an upright picture, with its 

 general features unchanged, composed of innumerable inverted images. 

 But most of the objects brought into daily relation with insects are small, 

 therefore their images would be formed only on one, or a very few 

 crystalline cones , so that the erection of their inverted images would 

 not present any physiological difficulties. 



It would be absurd to assert that Insects or Crustacea could see in 

 this or in that manner without giving specific cases. That, however, 

 we are not prepared to do. But we may say with safety that there is 



