DEVELOPMENT OF LOBULE OF PIG’S LIVER 321 
TABLE 1 
Table showing the average diameters of some of the larger lobules of the pig’s liver 
at various stages of the development 
AGE DIAMETER AGE DIAMETER 
2.1) CHT A ee a eae 0.33 S GRYGE. 4i3é:. Jon Gee 0.54 
fe mm Ee ike eh. nie. 0.33 3 weekstai hs see . aie 0.49 
DAMM ese phen eteye oe tic ole 0.33 AC WEEKSER Ne cotich oranda ee 0.51 
DOORN Ae ea sheets os ac 0.35 Per seVGualrlovere ay Seer Pees aber 0.59 
NT ee Meee San, ee 0.43 DNC (LGU rat Ae eS be eM ee a 1.2) 
1 The diameter of the lobules of the adult pig as given here (1.2 mm.) is the 
same as that given previously (Johnson, 7184). Mall (’06) gives it as 1.4 mm. 
There can be no question that Mall obtained his figures as I did, by averaging 
only the diameters of large lobules as seen in sections of the liver. The actual 
‘average diameter’ of the liver lobule is an altogether different thing, one difficult 
to calculate. It must be pointed out, as I have recently shown (’18a), that 
the hepatic lobules of the pig vary greatly in size within a single liver, and also 
that the average size varies for different adult livers. Reference to the table 
given in my former paper will show how I obtained the ‘average weights per 
lobule’ given in the table. From an average of these ‘average weights per 
lobule,’ I have attempted to calculate the average diameter, assuming a spherical 
form for the lobule. This gives 0.8 mm. Since, however, the lobules are not 
spherical, the diameter would in reality be less than0.8 mm. With regard to the 
relatively average diameter of the lobules in the young stages, I am confident that 
there is less variation in size than in the adult, and that the average diameter 
of the lobules of the stages 80 to 154 mm. is only slightly less than 0.33 mm. 
branch has formed for each hepatic branch present. These 
observations, however, I have been unable to confirm. 
The growth of the lobules likewise takes place in two ways: 
first, by an increase in the numbers of the hepatic cells and sinu- 
soids; second, as has been pointed out by Toldt and Zuckerkandl 
(75) and by Illing (’05), by an actual increase in the size of the 
hepatic cells. The latter, however, is counterbalanced to a cer- 
tain degree by a decrease in the diameter of the sinusoids. The 
rate of increase in size of the cells and sinusoids, and numbers of 
the cells, is shown in table 2. 
The formation of lobules begins at an early stage (Mall’s one- 
lobule stage), and, I believe, continues throughout all stages to the 
adult. This is in agreement with the statement of Lewis (’12), 
