H2 PRACTICAL HISTOLOGY. 



182. It is advantageous to stain a section of cat's lung 

 with logwood for comparison with the foregoing. 



It is also advantageous to have a section of the lung of 

 a child, hardened as described in 6, cut in the freezing 

 microtome, and stained with logwood. Mount in Farrants' 

 solution. The important point of difference between the 

 cat's lung and this, is the small amount of interalveolar 

 fibrous tissue in the normal human lung. The logwood 

 brings out the nuclei of the alveolar epithelium clearly. 



183. Examine (L.) a section of lung with its blood- 

 vessels injected with gelatine and carmine and mounted in 

 dammar ( 180 e) ; also (H.) a section of silvered lung 

 showing the outlines of the alveolar epithelia. 



Regarding the lymphatics of the lung, Klein's memoir, Anatomy of 

 the Lymphatic System, Part ii., London, 1875, maybe advantageously 

 consulted by the advanced student. 



ALIMENTARY CANAL. 

 TONGUE. 



1 84. Method. The tongue, when cut into small pieces, 

 may be hardened in chromic acid and then in alcohol, as 

 mentioned in 7. Sections are best made in the freezing 

 microtome, but they may also be made from tongue 

 imbedded in paraffin. The sections may be preserved 

 unstained in Farrants' solution or glycerine, or they may be 

 stained with logwood and preserved in the same fluids or 

 in dammar. 



185. Structure. V. S. unstained chromic acid tongue, 

 made as above. Mount in Farrants' solution or glycerine, 

 and examine. 



(L.) The papilla. Unlike the filiform papilla? of the 

 human tongue, those that correspond to them in the cat are 

 short thick stumps. The muscular fibres are seen divided 

 longitudinally and transversely. The fasciculi of the latter 

 are well seen, also the general arrangement of the fibres 

 some passing transversely, others vertically, and others 

 longitudinally. 



