The Microscope. 23 1 



hothing was seen the least resembling it. Some weeks after, ex- 

 amining some more of this slimy matter, again the same kind of 

 insect made its appearance; after watching it for sometime, it 

 suddenly changed its form, — -it drew in its neck, and only the 

 body appeared; another change then quickly took place, — it thrust 

 out its head, as in fig. 20, with wheel-work machinery. 



The Monoculus, or Water-flea. So numerous is this 

 insect in the summer months, that the waters will appear tinged, 

 sometimes red and at others green, owing to myriads of these in- 

 sects upon the surface. It is the size of the common flea when 

 full grown, but is a much better object for the microscope when 

 young, as it is then not larger than a mite, but much more trans- 

 parent, and the motion of the inside is clearly visible. The pul- 

 sation of the heart may also be distinctly seen. Its head is ex- 

 tremely small, and the eye is situated on the trunk. It has two 

 arms, or legs, which it waves as a bird moves its wings, and, by 

 striking the water, it rises or descends with great rapidity. 



The Hydra, or Polype. The nature of this insect is ex- 

 tremely singular, and contrary to the general principle of life; for 

 if the polype be cut into any number of pieces, each piece will 

 become a perfect creature, having all the functions of animal life. 

 Hydra were first discovered by Mr. Trimley, who took them for 

 plants, and saw, as he imagined, young shoots or branches coming 

 out; at last he perceived them devour smaller insects; he cut one 

 of them in two, and, in a few days, new arms were growing out 

 of the part he had cut away; these insects have since been divid- 

 ed in every way with similar effect. The green polype, which 

 is most common in this country, is about half an inch in length, 

 and its arms are placed in a circle round its mouth. This kind is 

 found crawling on the ground in clear running water, or on water 

 plants, hanging by its tail, and extending its arms in search of 

 food. The hydra, or polype, (put into a glass vessel with other 

 water insects and a quantity of duck-weed,) maybe kept alive for 

 months. 



The Ephemera. This is another curious insect in the larva 

 state, and is found either in ponds, or among the aquatic weeds 

 that grow by their side. The ephemera, in its perfect state, 

 which is that of a fly, seldom exists more than one day; within 

 this short period it performs all the functions of other insects, and 

 then expires. There is a great variety of this tribe, all very beau- 

 tiful; the most common species is found in gardens, and is a slen- 

 der-bodied fly, of a grass-green color, with large bright gold eyes 

 and four wings. It is about the size of a large common gnat. 

 Great care is requisite in securing them, as they are extremely 



