72 PRACTICAL HISTOLOGY. 



as the fluid appears turbid it ought to be changed. The hardening will be completed in two 

 to three weeks. Wash the tissues well, and transfer them to spirit until they are required. 



B. Miiller's Fluid. Larger pieces of the liver may be hardened in this way, as this fluid 

 penetrates organs more readily than A. It takes, however, longer to harden (four to six 

 weeks). 



C. Two per cent. Potassic Bichromate, which acts in the same way, and in the same time, as 

 Miiller's fluid. 



Make sections of the liver of pig, rabbit, cat or dog, and man, by means of a freezing 

 microtome, and see that the sections are thin and made through the fibrous capsule. Some of 

 them are to be stained, and, for non-stained preparations, place the sections in one per cent, 

 osmic acid for four or five hours. This is an excellent method, and sharpens the outlines of 

 all the tissues. 



i. LIVER OF A PIG. 



EXAMINATION (L). Stain a section with logwood, and mount it in dammar. Observe 

 the fibrous capsule, and note the processes it sends into the organ, where they become 

 continuous with the fibrous sheath which surrounds each lobule. Note that the section is 

 mapped out into a number of distinct, more or less polygonal areas of nearly equal size 

 by bands of connective tissue stained blue ; these areas are the lobules, and each one is com- 

 pletely invested by a fibrous sheath a continuation of Glisson's capsule. Within each of these 

 areas is the true gland-substance, which will be considered in other preparations. This pre- 

 paration gives the student an excellent idea of the lobular character of the liver. {Indicate the 

 lobules in PI. XV., Fig. i.) 



2. LIVER OF A RABBIT. 



Logwood and dammar. Note that the liver-lobules are not nearly so accurately mapped 

 off from each other, but still polygonal areas sections of the lobules can be seen mapped 

 off here and there from each other by a very small quantity of connective tissue intcrlobular 

 connective tissue, or Glisson's capsule stained blue. {Indicate these appearances in PI. XV., 

 Fig. 2.) 



3. THE LIVER OF A DOG AND OF MAN. 



These ought to be prepared and studied in the same way. In them the outlines of the 

 lobules are even less distinct, owing to the lobules being more or less confluent, due to the small 

 amount of interlobular connective tissue. It is, therefore, the amount of interlobular con- 

 nective tissue which determines the mapping out of one lobule from another. Note 

 particularly the thickness of the fibrous capsule, and the small amount of interlobular 

 connective tissue in a normal human liver. This is essential, as in some diseases e.g. cirrhosis 

 it is increased in amount, and it is necessary to accustom the eye to the normal amount. 

 Continue the examination of the human liver with (L). Observe the capsule, and note its 

 thickness, and that it consists of two layers ; the lower one sends very fine processes into 

 the organ between the lobules. These processes are better seen in a section where the 

 liver-cells have been pencilled or shaken out, as directed for adenoid tissue (p. 29). Study a 

 lobule. In its centre, if it be cut transversely, observe the hepatic or intra-lobularvein, and note 

 its size ; for it is sometimes dilated in diseased conditions, especially where there is congestion 

 of the lungs and right side of the heart. Radiating outwards from this, observe the columns 

 of nucleated liver-cells, united at the outer part of the lobule by transverse branches to form a 



