Franklin P. Mall 231 
In all other glands we make the duct the center of the structural unit. 
From this center often the artery and the framework radiate. In the 
liver everything radiates from the so-called interlobular space,—arterial 
and portal blood yessels, bile duct, lymphatics, nerves and connective 
tissue ; the liver develops from this point; physiologically everything cen- 
ters there. So, viewed from any standpoint, it is the center of the struc- 
tural unit. 
Throughout my description I shall use the term portal structural unit, 
portal unit, structural unit, or unit, for the clump of tissue which sur- 
rounds each terminal branch of the portal vein. In order to avoid con- 
fusion I shall use the term lobule in its old sense,—as the hepatic lobule,— 
for after much discussion carried on during two centuries, it has become 
well established. The old idea, the idea of Wepfer, Malpighi, Ferrein, 
Kiernan, and J. Miiller should be marked with the word lobule; the new 
idea, associated with the unity of structure, should be called the unit. 
VASCULAR PROPORTION. 
Roux has stated in one of the theses in his Habilitationsschrift* that 
the lobular subdivisions of the liver are due, in their arrangement and 
form, to the vascular system. This same idea is again brought forth 
several years later in the Introduction to his Archiv.’ In this he says, 
on page 17, “ Die Gliederung der gewohnlichen, baumartig veristelten 
Driisen in Liappchen erscheint durch die gestaltenden Wirkungen der 
Epithelien, also der specifischen Teile, bedingt und ist, so weit dies 
richtig ist, Selbstdifferenzierung der Driisensubstanz. Bei der Leber 
dagegen, einer Netzdriise, erscheint die normale Grosse und Gestalt der 
Lappchen und auch die lobulire Gliederung selber durch die Blutgefasse 
bedingt, und zwar einmal durch die geeignete Kapillarlange wie zweitens 
durch die Eigenschaft der letzten Veristelungen der Vena porte, beim 
Wachsthum des Kapillarnetzes dichotomische Verzweigungen in letz- 
terem auszubilden. Die acindse Gliederung des Leberparenchyms stellt 
somit eine von dem Blutgefisssystem. abhingige Differenzierung der 
Driisensubstanz dar.” 
A much more extended discussion of the growth and proportion of the 
vascular system is given by Thoma in his numerous papers, but that 
’ Roux, Ueber die Leistungsfahigkeit der Principien der Descendenzlehre 
zur Erklarung der Zweckmassigkeiten des thierischen Organismus, Breslau, 
1880, and Gesammelte Abhandlungen, I, 1895, p. 134. 
®° Roux, Einleitung zum Archiy fiir Entwickelungsmechanic der Organismen. 
Leipzig, 1894, p. 17. 
