AUTHOR’S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, APRIL 7 
THE DEVELOPMENT OF THE LOBULE OF THE PIG’S 
LIVER 
FRANKLIN PARADISE JOHNSON 
Department of Anatomy, University of Missouri 
TWENTY-EIGHT FIGURES 
CONTENTS 
LOSS TL Pe ghe B a SRS Sane een A ee ON Ree, rere ETO Tee a eee eee 299 
Development of the connective tissue septa...................0 2 eee eee ee 301 
CHEESES VES el See get a ae Neat nse dnd « bh DAEs Seay iat Ape ae at 2 lied 308 
HOLM GION OMmneWPLODULES Hs cine o.cteoeee aie ook oe eee elo ae ACs cae Sete 308 
Rilevof the/ connective tissue septa: :.:... 224 anh elas d. sie. ate 2 oda rinen 318 
PmeeaRMLRMRE TEI UOT Sikes oh ete sade Ova a Was dei nines DEA Ro alngn are 5 cue Sty ae 319 
UD TL SVE Cis ree ii inde as fe ec eee mete Mon op 1 bee onl cae), eda 325 
INTRODUCTION 
The development of the liver lobules offers a difficult problem 
owing to the fact that in most animals the lobules have no defi- 
nite boundaries, one running directly into the other without 
demarcation. In section, therefore, the livers appear to con- 
sist of solid masses of parenchyma, pierced at more or less reg- 
ular and alternating intervals by various-sized branches of the 
portal and hepatic veins. This lack of lobule definition is so 
great that one readily appreciates why Weber, in 1842, denied 
the presence of true lobules in the human liver, and one may 
himself doubt the appropriateness of the term ‘lobule’ for either 
the portal or hepatic units. 
Early recognizing this difficulty, I chose for material the 
liver of the pig, for I hoped that by using an animal in which 
the liver lobules are definitely marked out, this difficulty would 
be greatly overcome. I soon found that the pig’s liver does 
not show indications of dividing septa until about birth, and 
that the connective tissue septa are not definite until about 
the second month of postnatal life. Contrary to the state- 
299 
