9 8 



lobular connective tissue. The intralobular vein is quite 

 easily made out in the center of each lobule ; from this the 

 cords of liver cells radiate in the form of irregular anasto- 

 mosing columns, between which the open capillaries, often 

 containing a few red blood cells deeply stained in eosin, 

 can be seen. Here and there a bile duct, lined by a single 

 la}^er of cubical or short columnar cells, will be seen in the 

 interlobular connective tissue. Sketch a portion of the 

 section, including a bile duct, as seen under high power. 



(d) Liver with Bile Capillaries Stained According 



to Oppel's Method. 



Small pieces of the liver were hardened in a solution of potas- 

 sium bichromate and osmic acid (Ramon y Cajal) for three days, 

 then transferred to a % % solution of silver nitrate, in which they 

 remained for several days. The sections are in turpentine ; mount 

 in hard balsam. 



The bile capillaries are stained black. Two sections 

 are given, one from the liver of an embryo rat, in this the 

 compound tubular character of the gland is easily made 

 out ; the second from the liver of a young kitten, showing 

 an apparent network of bile capillaries between the liver 

 cells. Sketch a portion of each section as seen under high 

 power. 



(e) Trachea. 



Small pieces from the trachea of a young cat were hardened in 

 mercuric chloride, stained in Delafield's haematoxvlin, embedded 

 in paraffin, and sectioned. Fix and mount in balsam. 



Study under high power. The trachea is lined by strati- 

 fied ciliated columnar epithelium resting on a mucosa of 

 loose fibre-elastic tissue, in the outer portion of which the 

 elastic fibres form a well-marked layer. The fibrous sub- 

 mucosa contains the mucous tracheal glands. In the 

 external fibrous coat is found the hoop of hyaline cartilage. 

 Between the ends of the cartilage the outer layer is com- 

 posed of fibrous and non-striped muscle tissue. Sketch a 

 segment of the trachea as seen under high power. 



(f) Lung. 



The lung of a cat was distended with absolute alcohol before 

 opening the chest cavity ; after ligating the trachea the lung was 



