TERMINALS OF HUMAN BRONCHIOLE 269 
or less spherical form with numerous alveoli on its walls and 
giving origin to from two to five air-sacs. The lung of the dog 
was used in Miller’s first investigation; but in 1900 and again in 
1913 he published accounts of further researches, and maintained 
that his description held good for lung of cat, ox, child, and 
adult man. 
In his article of 1900 he gives the following table of nomencla- 
ture for the air-spaces of the lung: 
W.S8S. MILLER B.N.A. SCHAFER SCHULZE KOLLIKER 
Bronchus Bronchiolus Bronchial Alveolengang | Alveolengang 
respiratorius tube 
Terminal Ductuli Lobular 
bronchiole alveolares bronchus 
Atrium 
Air-sac Air-sac Infundibu- Infundibu- 
Tumi lum 
Air-cell Alveolus Air-cell Alveolus Alveolus 
pulmonis 
But at the same time he revised his own earlier terminology, 
substituting the B. N. A. terms for ‘Bronchus’ and ‘Terminal 
bronchiole.’ In his investigations Miller used the method of 
wax reconstruction. His results have found wide acceptance 
by the authors of text-books, in spite of several dissenting voices. 
In 1900 Justesen gave an account of his investigations of the 
structure of the lung in oxen. He used corrosion preparations 
and also serial sections, drawings of which were made on trans- 
parent paper, so that by superposing the drawings, successive 
sections might be compared. He finds that each ‘bronchiolus 
simplex’ forms dichotomously two respiratory bronchioles, each 
of which again divides dichotomously, each of the branches so 
formed ending in a large cavity which he identifies with the 
atrium of Miller. His atria are variable in size, sometimes quite 
distinct, and sometimes only slight enlargements of the bron- 
chioles, and while Miller finds two to five air-sacs on each atrium, 
and Waters six to ten, Justesen believes that there are normally 
four. Two first bud out and these then divide, so that each of 
the four occupies a position corresponding to one of the angles 
