Hair in its Microscopical and Medico-Legal Aspects. 167 



Actinocyclus spinosus, in the ' Quarterly Journal of Microscopical 

 Science,' vol. viii., p. 93, and the Mexillones guano. Aulacodiscus 

 crux of the Virginian deposit I have not seen in Captain Perry's 

 gatherings ; but A. scaler (which Ehrenherg also called A. crux) 

 does occur in these gatherings. Diatomists may perhaps be 

 interested in knowing that a Diatomaceous deposit (? sub-peat) has 

 been discovered in Talbot, Victoria, Australia, and my correspon- 

 dent (Mr. F. Barnard, of Kew, Victoria, to whom I am indebted 

 for a sample of it) writes me that the deposit is " twelve feet deep, 

 and covers acres." The prevailing form is Synedra amphirynchus, 

 Kiitzing. A few small Navicula and Cccconeis pediculus occur in 

 it, but at least 90 per cent, consists of the Synedra. 



VI. — Hair in its Microscopical and Medico-Legal Aspects. 



By Dr. E. Hofmann. 



The examination of the hair in its medico-legal relations is a 

 subject hitherto but little noticed, except superficially in tha 

 " Year-book of Legal Medicine." Yet many cases might be men- 

 tioned in which the microscopic examination of the hair was of 

 great importance. 



In the medico-legal examination of hair, two questions are met : 



1. Are the hairs from animals or from men ? 



2. In the latter case from whom do they come ? From what 

 portion of the body ? 



Of course, if the hairs belong to a beast, that may be sufficient 

 to settle the question at issue ; but the difference between such and 

 human hair has been too little noticed. A human hair under the 

 microscope shows three distinct layers : the outer, cuticula, or the 

 superficial covering, formed of epithelial cells, with rounded con- 

 tour, lying over each other like tiles, which clothes the surface of 

 the hair from its exit from the skin to its end. The ends of the 

 scale stand out somewhat from the shaft, and give the outer cir- 

 cumference of the hair a more or less jagged appearance. Seen 

 sideways, the cuticula appears as an undulatory design, more pro- 

 minent if the hair is treated for a short time with concentrated acid. 

 The scales have their points directed toward the free end of the hair ; 

 hence the latter can be easily distinguished from the other broken 

 end. 



The cortical substance forms the principal part, and often the 

 whole of the shaft. It consists of a system of closely-packed cells 

 in rows lying nearly parallel to the long axis of the hair, giving 

 the cortical substance an appearance as if striped lengthwise. 

 These cells are so intimately united that without reagents this 



