340 THE AMERICAN MONTHLY [Nov. 



with a hot needle. Spread a piece of diachylon plaster 



the width of the slide at the opposite "end 



On the plaster place wax to hold each hair in place, fast- 

 ening it by a heated needle. Treat the hairs thus ex- 

 tended and fastened side by side, with absolute alcohol, 

 then by ether, taking care not to wet the diachylon. 

 This done, wet with collodion so as to engulf them in a 

 mass as the ether evaporates. Remove the layer of col- 

 lodion containing the hairs and harden in chloroform. 

 Imbed in paraffin. Make perpedicular sections. Avoid 

 the use of clove oil, which would dissoWe the collodion, 

 but clear with bergamot oil or by benzine. 



Epithelial sheaths of the hair follicles. — Take a piece 

 of hairy skin as fresh as possible from which the hairs 

 have been shaved. Treat with alcohol (24 hours), 

 gum (48 hours), alcohol (24 hours). 



Make two series of sections, some parallel with, others 

 perpendicular to the surface. It is necessary to observe 

 certain rules to obtain good longitudinal sections com- 

 prising the hair, the epithelial sheaths, and the papilla. 

 The hairs not being inserted vertically but more or less 

 obliquely, it is necessary to make the sections in the 

 proper direction, as can be done after some experiment- 

 ing. The best way is to make sections free hand and to 

 make a large number with the razor variously inclined. 

 Good sections should be stained by picro-carmine, and 

 mounted in glycerine. 



The nails ; dissociation. — Place a bit of the finger nail 

 in a drop of 40 per cent potash or of ordinary suljihuric 

 acid, and Avarm over the flame. Cover and compress 

 lightly. It is necessary to examine the preparation from 

 time to time to avoid too great heating. With potash 

 the horny cells swell up and show their nuclei. Macerate 

 a fragment for 24 hours in ammonia ; examine in the 

 same after pressing on the cover glass with a needle. 



Sections. — To be instructive these should include the 



