No. li.T)] 



THE HAIR OF MAMMALS 



519 



piece, and the 4 mm. objective with transmitted light, 

 preferably from a blued glass, or better, daylight glass, 

 gives the best results. Indirect lighting, with the mirror 

 swung to one side, may be used where the scale edges are 

 not easily seen. Keflected light lias been found excellent, 

 but only in a very few cases. 



With hairs like those of the rabbits and hares, shrews, 

 moles, the fur hair of bats, and the like other manipula- 

 tions of the hair must be brought into requisition. One 

 of the most generally useful of the various staining 

 preparations consists in immersing the hair, after its 

 ether-alcohol bath, in a solution of gentian violet, methyl 

 blue, methyl green, or safranin, in 95 per cent, alcohol. 

 The stain is prepared by making up a saturated solu- 

 tion of the stains enumerated, and then diluting each 

 with 95 per cent, alcohol to the desired degree of 

 color depth, which must be empirically determined 

 for each different species 7 of hair. The evaporation 

 of the alcohol, which must be accomplished rapidly in a 

 warm current of air from a bunsen flame, deposits in the 

 depressions just ectad of each cuticular scale edge, a 

 tiny bit of the stain, which therefore clearly outlines the 

 contour of each individual scale. This method is diffi- 

 cult, and the writer has found that repeated trials with 

 the same hairs were frequently necessary before satis- 

 factory results were secured. In working with hairs it is 

 better to use a tuft of 25 or 50, rather than try to work 

 with but a few. 



The preparation of the hair, is, however, of but slight 

 importance compared with the manipulation of the 

 proper lighting and the proper combination of objective 

 and ocular. Where the cuticular scales remain obstin- 

 ately invisible, or only faintly seen, various sorts of il- 



