138 The Microscope. 



are curved gracefully toward the shaft till their bifurcated tips 

 impinge upon the external curvature of each preceeding barbule. 

 A feather from the crown of a Great-crested Flycatcher (M. crinitus} 

 presents still narrower barbs with rib-like superior, and expanded^ 

 thickened border of shaft inferiorly, with an ovate, inter portion 

 filled with pith-cells. The lower barbules are very thin, wide,, 

 granulated and closely set at the base, with one to two dentate 

 spines along the superior border, changing gradually to a round 

 shaft with four-spined knobs, dividing it into joints, a single 

 inner spine of which becoming more prominent successively 

 until the apex is reached, where it is so marked as to be a specific 

 character. Ascending the barb serially, this form of barbule is 

 replaced by those with the flattened portion of the anterior series 

 followed by tapering shafts without knobs, but with a few hook- 

 lets beyond which are occasional spines along the inferior border 

 to the extremity, which is also divided but into spines of equal 

 length. The posterior series of barbules, like the former at the 

 base, pass gradually into rounded, unmarked shafts, except that 

 they are also apically bifurcated. 



There may be seen another example of these modifications of 

 structure, in the familiar plumage of the peacock's tail. It may 

 be trite to say of it, " How resplendant ! How magnificent, how 

 transcendantly beautiful ! " yet, however frequently seen we 

 never cease to think of it in these or kindred expressions, even 

 if we do not utter them with our lips ; but when with only the 

 lower powers of the microscope we enter upon the analysis of 

 one of these gorgeous feathers, a painful revulsion from our en- 

 chantment makes us ready to consign that unsympathetic, un- 

 sentimental instrument to the shades of irreclaimable oblivion.. 



Pluck off from the shaft an isolated barb, long and drooping,, 

 or a shorter one from the heart of the " eye-spot " at the extremity,, 

 and with only our unaided vision we behold a myriapod with 

 its thousand legs protruding stiffly from each border apparently 

 ready to crawl away from under our eyes. 



If the barb has been taken from the upper part of the plume 

 where the iridescence is greatest, a short section under about 

 120 diameters will show a deep, thin, angulated shaft of pith- 

 cells, thickly studded on either side with club-like opaque seg- 

 mented barbules terminating in a few digitate, claw-like appen- 

 dages resembling a magnified spider's foot. Fig. 8 gives a good' 



