588 BALDWIN SPENDER AND GEORGINA SWEET. 



Figs. 24 — 26. — Sections through the follicle and hair of an embryo of 

 Echidna of the same age as that represented in Fig. 22. They have been 

 stained with hsemalum, carmine and indigo, and subsequently treated with 

 picric acid to show the cornificatiou of the different structures and the con- 

 tinuity of the inner root-sheath with the stratum lucidum of the surface epi- 

 dermis. 



Pig. 24. — Longitudinal section through two follicles ; in the one on the 

 right side the hair has been torn away from the bulb. The inner root- 

 sheath is seen to run continuously along the whole . length of the 

 follicle. At its lower end in the bulb region it can be divided into an 

 outer («. r. s.^ and an inner part {i. r. s.^), the latter being less 

 cornified than the former. At ;r is a special collar arrangement where 

 the hair is most tightly grasped. The cuticle {c.i.r. s.) of the sheath 

 passes upwards, and is continuous with the stratum corneum. 

 Eig. 25. — More highly magnified part of the follicle shown in Fig. 24, to 

 show the special modification in the inner root-sheath to form a collar. 

 The face of the inner root-sheath on the side of the follicle is seen in 

 part. 

 Fig. 26. — Transverse section across the follicle. The strongly pigmented 

 medullary and cortical parts (m, and co. h.) are seen, the medulla not 

 being distinct from the cortex. The network of the inner root-sheath 

 is seen more cornified on its face next to the hair than on that next to 

 the well-marked outer root-sheath. 



