ON MICROSCOPIC DISCOVERY. 



615 



they are divided into a number of hexagonal 

 cells, each of which forms a complete eye. 

 The external parts of these eyes aro so perfectly 

 smooth, and so well polished, that, when 

 viewed as opaque objects, they will, like so 

 many mirrors, reflect the images of all the 

 surrounding objects. The figure of a candle 

 may be seen on their surface multiplied almost 

 to infinity, shifting its beam to each eye, ac- 

 cording to the motion given to it by the hands 

 of the observer. Other creatures are obliged 

 to turn their eyes towards the object, but 

 insects have eyes directed thereto, on whatso- 

 ever side it may appear : they more than 

 realize the wonderful accounts of fabulous 

 history : poets gave to Argus an hundred eyes ; 

 insects are furnished with thousands, having 

 the benefit of vision on every side with the 

 utmost ease and speed, though without any 

 motion of the eye or flexion of the neck." 



The reticulated eyes in someof the fly class are 

 not inferior in appearance to the richest gems : 

 they exhibit nearly every variety of colour 

 under a brilliant and surpassing lustre. In con- 

 nection with the general description, we have 

 only to add that the number of separate lenses 

 in the hemispherical reticulations of some 

 insects are almost beyond belief: the agrion 

 lias no fewer than 12,000 distinct lenses, or 

 separate eyes, the common house fly 8,000, 

 the hawk moth 20,000, the libellula 12,544, 

 the melolontha 8,820, the mordella 25,088, 

 papilio 17,008, phaslana cossus 11,300, the 

 scarabaeus 3,180. We in vain attempt to 

 reason regarding these lucid points, each of 

 which is a meniscus lens of several layers, con- 

 nected with a pyramid of fibres and pulmon- 

 ary tubes whose uses we cannot deter- 

 mine. 



The tongue or proboscis of insects is a taper 

 and compact instrument, by which they obtain 

 the juices of plants or other nutriment requisite 

 for them. Some creatures can contract or 

 expand it, others roll it up with dexterity ; in 

 some it is inclosed within a sheath. It is 

 taper and spiral in the butterfly, tubular and 

 fleshy in the fly ; in all affording agreeable 

 amusement for the microscope. 



The following represents the tongue of the 



riohurticce taken out and unrolled, displaying 

 two segments, as united with the rugae of which 



they are composed, and the papillae or absor- 

 bents towards the end. 



The following figure on the left hand gives 

 a front view of the mouth without the palpi, 

 the clipeus being raised to show the opening 

 of the mouth and insertion of the tongue. 



The right hand figure shows the manner in 

 which the tongue, after the extremity has been 

 applied to the nectary of a flower and has 

 absorbed the juices, is conveyed to the mouth, 

 and the papillae cleansed by scraping on the 

 under part of it. 



Above is represented the under part of the 

 mouth and tongue, with the articulations of the 

 palpi. 



"The bee's tongue, for its complex yet fin- 

 ished structure, and the trunk of the common 

 house-fly, with the spiral fibres of the muscles 

 which surround its termination, will amply re- 

 pay the pains of an attentive and minute ex- 

 amination." These two objects form the prin- 

 cipal subjects of our illustrations on this head ; 

 and the brief descriptions we are enabled to 

 give of them, will convey a general idea of the 

 wonderful structure and admirable adaptation 

 of parts by which these insect organs are dis- 

 tinguished. 



Plate 34, fig. 32, exhibits the tongue or 

 trunk of the common house-fly, as it appears 

 under a considerable magnifying power. This 

 is one of the most interesting and beautiful 

 objects that can be submitted to the microscope, 

 especially when it is mounted in Canada bal- 

 sam and viewed by transmitted light. Baker 

 thus describes it : " It consists of two parts 

 folding over one another and sheathed in the 

 mouth. The extremity thereof is sharp like a 

 knife, for the separation of any thing. The 

 two parts can also be formed, occasionally, into 

 a pair of lips for taking up proper quantities 

 of food, and by the fly's sucking in the air, 

 they become a kind of pump to draw up the 

 juices of fruits or other liquors." We call 

 particular attention to the serrations of the 

 tongue ; these are separate and perfect teeth, 



