TERMINALS OF HUMAN BRONCHIOLE QE. 
indented, and a good deal depends on whether the subdivisions 
are considered as separate air-sacs or not. 
Calculating from the lengths of the tubes in the model the 
following are the actual lengths of these tubes in the adult lung. 
mm. 
INK SSS Ree oan AH RH Ciao Boks Pian ont bOI OREO NS Moca DER Ea IOe 1G 
INIG iS SEARS Tn 6 MERITS SGI ORO Gachc GEO IEe HERG Th OCR NES rep ROTERS retusa 0.8 
TSO) Te RR a aS, oO tee ee 0.5 
INO US aca oc era at rier ae to lar hrs teh a ea eae ea a 0.5 
INI OE Hens clo Sie CieEEsG Di GRRE SRIIEIG Gia Old Gk Atak BIS ORSLE EOE IGE? CoO Mncee Ears tat 0.5 
INO GRR Ceo ee ne ee rte ene ESE, OG SOOO. Ca OOS Sr semene 0.4 
ISON Gy Oe ee eee A 8 a a See Ne tS Oe he ie er eer 0.2 
The greatest and least diameters of the non-respiratory bron- 
chioles represented in the same model were estimated as follows: 
mm 
UNOS Blo islet CO Oh OC RCE AED CRETE IC ORT Eee One ee une ry Ah ean ae 0.3 x 0.40 
DIN eA a Per ale arene ps se kot ek ows rie teeter chem ceo tap eeneie aa eet OP3ec0825 
INGE CY Deas & GE OE Oe Ue IIE rN Seas rite irae the Baa oa) OMe 0e22 
Similar estimates in the case of the respiratory bronchioles 
were: 
mm. 
INGA DARREN SOO RR Se & cisR eter trek Ue eee cL ee a EE 0.4 x 0.30 
INIG)S EO Re crea 2 cic bo Dae AGE IIO ORE MES SRI tio co rR Rd Geto Gero ony 0.3 x 0.35 
INIGS GEE SB ES OB ET OOS o DOOD OG At OC ERE DE ACTE Sen SOM StT aean Doe One xa0E 30 
SINCE OID eveprcrcepetreae eves cr ean cree nia: «1 ncaa haat ore EN etots es wace ah opealars wore 0.4 x 0.30 
Measurements of the greatest and least diameters of those 
tubes into which the air-saes open gave the following results in 
three cases,—the figures indicating the actual dimensions in the 
lung: 
0.3 mm. x 0.2 mm. 
0.5 mm, x 0.3 mm. 
0.4 mm. x 0.3 mm. 
This gives an average of 0.4 mm. X 0.27 mm. 
Ogawa found the average diameter of an alveolar duct to be 
0.24 mm., and he quotes Kolliker’s estimate as 0.27 mm. and 
that of Schulze as from 0.4 to 0.2 mm. 
It will be seen from these measurements and from the illus- 
trations that the bronchial tree in its finer ramifications by no 
means shows a decrease in the diameter of successive branches 
