HAIRS OF MONOTREMES AND MARSUPIALS. 



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with a special and well-marked layer of nuclei continuous with 

 those in the layer, which traced upwards above the bulb is 

 seen to give rise to the hair cuticle. Further still, at the open 

 end of the follicle the cuticle of the root-sheath is directly 



Fig. a. — Longitudinal section through the hair, showing the relationship 



of the layers as indicated by Mertsching. 

 Fig. B. — Longitudinal section through the hair, showing the relationship of 



the layers in Monotremes. 



1. Cuticle of hair. 2. Cuticle of inner root-sheath. 3. Huxley's layer. 



4, Henle's layer. 5. Outer root-sheath. 



continuous with the outermost layer of the epidermis, and takes 

 the stain, in its course along the follicle, in precisely the same 

 way (figs. 24 and 25). 



If now we represent diagrammatically the relationship of the 

 various parts in the developing hair of a Monotreme, this can 

 only be done as represented in the accompanying Fig. C, which, 

 though diagrammatic, represents what is actually the relation- 

 ship of the hair and inner root-sheath. If we suppose the hair 



