CHAPTER XVII. 

 SENSE ORGANS. 



Olfactory epithelium. Guinea pig. (p. 3, s. 11, 22 & 24, c. 

 P., m. B.) (Z/) The mucosa of the olfactory region is covered 

 with many layers of cells, fusiform and columnar in shape and 

 non-ciliated. Beneath this note the glandular masses (Bowman's 

 glands) and the numerous nerves making their way to the 

 surface, (//) In very thin sections it is possible to recognise 

 the two kinds of cells. The olfactory cells are thin, with a 

 swelling over the nucleus ; the end which reaches the surface is 

 provided with short bristle-like processes. The other cells are 

 columnar near the surface, fusiform and irregular further in. 



Isolated olfactory cells, (p. An exposure of the brown 

 membrane of the turbinated bone of a rabbit for 24 hours to 

 one-third alcohol, five minutes in l p - c - osmic acid, stain in 19 in 

 bulk ; dissociate and diffuse in glycerin jelly (after Stirling). 

 The thin olfactory cells can easily be recognised from the 

 columnar supporting cells. The latter are irregular and branched 

 at their attached extremities. 



Eye. "V.T.S. Head of mammalian foetus, for the general 

 structure and origin of its parts, (p. 16, s. 22 & 24, c. P., m. B.) 

 (L) Find the cornea, the part nearest the cutaneous surface, 

 and note its continuity with the external coat or sclerotic of the 

 eye-ball. Within this, in front, is the voluminous lens, the fibrous 

 nature of which is perceptible even with a low power ; note their 

 backward trend. On each side of the lens posteriorly find the 

 ciliary bodies, or what represents them at this stage, a slight 

 thickening, which trace into the thin choroid. The pigment will 



