278 FRANKLIN PARADISE JOHNSON 



The clumps, therefore, must be considered as ''compound lobules" 

 (Kiernan) and are due to incomplete connective tissue septa. 

 They undoubtedly are the result of the failure of the septa to 

 grow completely across the lobules in the developing liver, at 

 the time when the lobules are dividing to form additional ones. 

 The evidence of incomplete septa can often be seen in ordinary 

 sections of the adult pig's liver. 



THE SIZE AND NUMBER OF THE LIVER LOBULES * . 



The size of the lobule of the adult pig's liver is very variable, 

 great differences existing within any individual liver. The small- 

 est lobules may be no larger than 0.5 mm. in diameter; the larg- 

 est ones may be 2 mm. or over. Assuming that the shapes of 

 the large and small lobules are approximately similar, it is evident 

 that the largest lobules must be as much as 64 times greater by 

 volume than the smallest ones. 



The average volume of the liver lobule is dependent to a cer- 

 tain degree upon the size of the liver, thus in small livers the 

 average volume is less than in large ones. This is shown in the 

 accompanying table. 



The total number of lobules in the pig's liver is also quite 

 variable. This can be readily observed with the naked eye when 

 examining isolated lobules of different livers of approximately 

 the same weight — in some the majority of lobules are large while 

 in others they are decidedly smaller. 



The method of calculating the average size and number of 

 hepatic lobules, which I have found most satisfactory, is as fol- 

 lows : Rectangular blocks of formalin-fixed liver, with dimensions 

 between 1 and 2 cm., were taken from a liver of known weight. 

 ■Each block was carefully weighed, placed in a separate dish in 

 50 per cent hydrochloric acid over night, and then in an oven 

 at a temperature of from 50° to 60 °C. After about an hour the 

 surface lobules become swollen and each projects slightly from 

 the surface. The surface lobules now being definitely marked 

 off from one another, were counted under a hand-lens, care being 

 taken not to count twice those lobules on the borders and cor- 

 ners of the block. The block was again placed in the oven and 



