HAIRS OF INSECTS. 



659 



Fig. 337. 



VI 



resemble those of the Lepisma-scale in being due to a series 

 of toothed ridges, the profile of which resembles the edge of 

 a Saw.* 



514. The Hairs of many Insects, and still more of their Laivae, 

 are very interesting objects for the Microscope, on account of their 

 branched or tufted conformation ; this 

 being particularly remarkable in those 

 with which the common hairy Cater- 

 pillars are so abundantly beset. Some 

 of these afford very good tests for the 

 perfect correction of Objectives. Thus, 

 the hair of the Bee is pretty sure to 

 exhibit strong prismatic colours, if the 

 Chromatic Aberration should not have 

 been exactly neutralized ; and that of 

 the Larva of the Dermestes or ' Bacon- 

 beetle' was once thought a very good 

 test of defining power, and is still useful 

 for this purpose. It has a cylindrical 

 shaft (Fig. 337, b) with closely-set 

 whorls of spiny protuberances, four or 

 five in each whorl ; the highest of those 

 whorls is composed of more knobby 

 spines ; and the hair is surmounted by 

 a curious circle of six or seven large 

 filaments, attached by their pointed 

 ends to its shaft, whilst at their free 

 extremities they dilate into knobs. An 

 approach to this structure is seen in the 

 Hairs of certain Myriapods (Centipedes, 

 Gally-worms, &c. ), of which an example 

 is shown in Fig. 337, a ; and some 

 minute forms of this class are most 

 beautiful objects under the Binocular 

 Microscope, on account of the remark- 

 able structure and regular arrangement 

 of their hairs. 



A, Hair of Myriapod. 

 b, Hair of Dermestes. 



* See Mr. R. Beck ' On the Scales of Lepidocyrtus ? hitherto termed 



Podura-scales, and their value as Tests for the Microscope,' in " Trans, of 

 Microsc. Soc," N.S., Vol. x. (1862), p. 83.— The Author quite accords 

 with Mr. R. Beck in his interpretation of the appearances of the Podura- 

 scale. Mr. Beck gives the following as his mode of removing the scales : — 

 " Wherever practicable, I prefer taking the stone, piece of wood, or what- 

 ever the Insects may be on (if at all portable) into the house, where I 

 spread a large piece of paper on the table ; they are easily brushed-off on 

 to this, when they should be immediately covered over, before they have 

 time to hop, by some small thing, such as the top or bottom of a pill-box ; 

 if this be left over them for a minute or so, and then removed, they will 

 be found to be quite quiet, and a slide or a piece of thin glass may be 

 carefully pressed upon them, without squeezing out any of their juices, 



u u 2 



