276 FRANKLIN PARADISE JOHNSON 



the lobules separate by gentle shaking. Care should be taken 

 not to allow the maceration to proceed too far, yet it should 

 not be stopped before all the connective tissue is destroyed. 

 The blocks can be tested from time to time by gently pressing 

 them with a dissecting needle. When the maceration is com- 

 plete, the acid should be diluted four or five times with cold 

 water and the lobules studied in this solution. (When placed in 

 either water or alcohol the lobules disintegrate inside of a day or 

 two.) If dissections of the liver lobules and vessels are desired, 

 such as are shown in figures 11 and 12, maceration should be 

 stopped when the lobules can be torn apart easily with dissecting 

 needles. I have been unable to obtain good results in the isola- 

 tion of lobules following hardening in either Zenker's or Bouin's 

 fluid or in alcohol, and have been entirely unsuccessful in macer- 

 ating fresh unfixed liver. 



THE SHAPE OF THE LIVER LOBULES 



The form of liver lobules is so variable that it is impossible 

 to describe them in terms of any familiar solid. In general, it 

 may be said that they are irregular polyhedrons of a varying 

 number of sides, borders and angles. The surfaces may be 

 plane, convex or concave, and may vary from as few as four or 

 five in some of the smaller lobules to fifteen or more in some of 

 the larger ones. The borders may be either sharply marked or 

 rounded, while the angles formed by the union of the borders 

 may vary from sharply acute to greatly obtuse. 



So far as shape alone is concerned I have found no way of 

 determining on which surface the hepatic vein leaves the lobule, 

 the surface which Kiernan ('33) describes as the base. Its point 

 of exit may be either a small or large surface, plane, convex or 

 concave, or it may even proceed from one of the borders or angles 

 of the lobule (figs. 5, 6, 9 and 10). 



The surface lobules (figs. 1, 5, 9 and 11) are in many instances 

 distinguishable from the deeper lobules in that they are often 

 irregularly prismatic in shape, their external surfaces are usually 

 slightly convex and the shape of a four, five or six-sided polygon ; 

 the sides are plane or only slightly curving and more or less rec- 



