222 



THE AMEEICAN MONTHLY 



[December, 



where a single one is drawn. The little unhatched creatures will continually 

 glide round and round within the imprisoning egg, often turning about to 

 travel in the opposite direction, and sometimes rolling completely over. The 

 sight is, indeed, as Leeuwenhoek said about the young Ufiio, ' one of the 

 most delightful things that could be exhibited.' 



Fig. 3.— Egg Mass. 



is--"^^::^^--^ 



Fig. 4.— Embryo of Snail. 



Fig. 5. — Spider's Foot. 



Many of Leeuwenhoek's discoveries are interesting to scientific people only, 

 anatomists caring for some, botanists for others (for he studied plants as well 

 as animals), but there is one that is pleasing to all. This refers to the scales 

 on the wings of butterflies and moths. The fine dust that clings to the fin- 

 gers when the delicate wings of these insects are touched is formed of in- 

 numerable scales, whose shape varies in different butterflies, and whose color 

 is the cause of those charming tints which ornament the filmy wings of the 

 airy creatures. A little piece of a wing snipped olT and examined as an 

 opaque object will show these beautifully formed and gorgeously colored 

 scales lying over the whole svu-face like the shingles on a roof, one row slightly 

 overlapping the row below it ; and a little of the dust scraped away and placed 

 on a glass slip will, under a low magnifying power, be revealed as separate 

 forms of wondrous beauty. Often the wings of the same butterfly, or moth, 

 will bear scales of several difterent shapes, while the forms obtainable from 

 butterflies of difterent kinds vary greatly in outline. In the plate seventeen forms 

 of scales are shown, including some from the common gnat, and the too com- 

 mon clothes-moth. Their exquisite color cannot be shown in a black-and- 

 white engraving, but the peculiar shapes are faithfully preserved. Curious 

 as these seem, some are from butterflies that flit abundantly through the sum- 

 mer air, others are from rarer specimens. 



Leeuwenhoek also first saw the very minute scales on the common gnat. 

 In the plate two of these are shown, marked a, a. These, in their natural 

 state, have very little color, scarcely more than a silvery sheen. The same 

 plate includes three scales, two marked 6, one c, both of which are 

 from the clothes-moth, the almost circular one, c, being from the under sur- 

 face of the wing. The one marked d, with its curiously elongated heart- 

 shaped outline, the fringe on the upper margin, and the stem with its ter- 

 minal bulb on the opposite end, is from the common cabbage butterfly, 

 w^hile sketch marked e shows how these scales are attached to the wing, the 

 little bulb on each one snugly fitting into a cup made to receive it. Notice 

 that there are two kinds of cups. This is explained by the fact that there 

 are two forms of scales on the same vs^ing, which necessarily call for two 

 kinds of cups to hold them in place. 



Leeuwenhoek did much work among insects, dissecting them to study 

 their microscopic anatomy. He discovered that insects' eyes are not simple 

 or single, but that each is composed of many, like the eye of the house-fly. 

 While examining spiders he was the first to see the Qi^gans called the spin- 



