ANATOMY AND PHYSIOLOGY TT 
extend through a pore canal into the interior of the hair (Fig. 
QI); sometimes, to be sure, as in glandular or sensory hairs, 
the hair cell is multinucleate, rep- 
resenting, therefore, as many cells 
as there are nuclei. The wall of 
a hair is continuous with the gen- 
eral cuticula and at moulting each 
hair is stripped off with the rest 
of the cuticula, leaving in its place 
a new hair, which has been form- 
> 
ing inside the old one. 
Scales. — Besides occurring 
throughout the order Lepidoptera 
ssl 
Sar a 
and in numerous. Trichoptera, 
scales are found in many Thys- | 
anura and Collembola, several 
families of Coleoptera (including 
Dermestidze and Curculionide), a 
few Diptera and a few Psocide. 
Though diverse in form (Ig. 
E : Various forms’ of _— scales. 
> are A A are a r © ay a 
O2), scales arevessentially fattened , 5 iiysanuran, Maciilics B, 
sacs having at one end a short beetle, Anthrenus; C, butterfly, 
3 ae . Pieris; D, moth, Limacodes. 
pedicel for attachment to the 1n- 
tegument. The scales usually bear markings, which are 
more or less characteristic of the species; these markings, 
always minute, are in some species so exquisitely fine as 
to test the highest powers of the microscope; the scales 
of certain Collembola (Lepi- 
ee docyrtus, etc.) have long been 
used, under the name _ of 
‘“ Podura’”’ scales, to test the 
Cross section of scale of Anosia.— resi ving power of objec- 
After Mayer. ; A A 
tives, for which purpose they 
are excelled only by some of the diatoms. Butterfly scales 
are marked with parallel longitudinal ridges (Fig. 92, ©), 
which are confined almost entirely to the upper, or ex- 
