The pattern of branching and distribution of the segmental bronchi in the rightlower lobe of 50 adult Chinese lungs were studied and the following results were ob-tained. 1. In 98% of the cases the superior segmental bronchus (B~6) arises as a single stem,which is either divided into 2 branches (86%) or 3 branches (12%). In the formercase, the prevailing pattern (68%) has the formula B_(a+b)~6 and B_6c. In 22% of the cases, the superior segment is obliquely fitted to the basal segmentsof the lower lobe, and in the remaining 76% it caps the basal segments horizontally. Only in one instance (2%), B~6 arises as two separate stems. In 38% of the cases the subsuperior bronchus proper (B~*) is present. In some cases(6%) of this group there are two B~* in the same lobe. The accessory subsuperior bronchus (BX_(10)~*) is found in 86% of the cases. It maybe represented by 1--3 stems. The B~x or BX_(10)~* almost always distributes to at least the posterior section of thelung but it may spread medially to the paravertebral area or laterally to the postero-lateral zone. 2. The percentages of occurrence of types Ⅰ, Ⅱ, Ⅲ and Ⅳ of the medial basal bron-chus (B~7) are 38%, 30%, 16% and 16% respectively. The anterior basal bronchus (B~8) is remarkably constant in occurrence and pattern,80% of B~8 bifurcated into B_a~8 and B_b~8, 18% is expanded by the inclusion of the sub-segmental bronchus of adjoining segments, and 2% is defective. The lateral basal bronchus (B~9) divides typically into B_a~9 and B_b~9 in 82% of thecases. Only 2% of B~9 is expanded, this is due to the inclusion of the displaced B_b~8. Inthe remaining 16%, B~9 is defective. In such instances its two subsegmental bronchiarise independently, one has developed at the usual site of B~9, the other arises as a dis-placed branch usually from main trunk of B~(10). In all specimens, the posterior basal bronchi (B~(10)) divides into B_a~(10) and B_b~(10). Onlyin two specimens, B_b~(10). is expanded by inclusion of the displaced B_b~7. 3. The lengths and the relative levels of the segmental bronchi of the right lowerlobes were measured.

The lengths and diameters of the trachea and bronchi, the angle formed at the bi-furcation of the trachea were measured in 141 Chinese adult cadavers. The length of the trachea measured in 141 specimens was 71--134 mm with110.77?9.94 mm as an average. The internal transverse diameter of the trachea was9.5--22.0 mm, having an average of 16.17?2.61 mm. The internal sagittal diametervaried from 8 to 22.5 mm, with 14.73?2.68 mm as the average. The transverse dia-meter is greater than sagittal. The angle formed at the bifurcation of the trachea variedfrom 35?--92?, averaged 68.09??11.82?. The angle is greater in female than in the malefor about 5?. The left bronchus had a length of 42--63 mm (average, 51.89?4.18 mm),doubled that of the right one (15--36 mm average, 26.18?4.05 mm).

The pattern of branching and distribution of the blood vessels in the right lowerlobe of 50 adult Chinese lungs were studied and the following results were obtained. 1. In 68% of the specimens, the A~6 arose as a single branch, which bifurcated intotwo (50%) or three rami (18%). In 30% of the cases there were two separate A~6arteries and in 2% there were three. 2. The subsuperior bronchus (B~*) might be supplied with 1--3 arteries. Twenty-seven arteries to 22 subsuperior bronchi were found in 19 cases whereas fifty nine arteriesto 57 accessory subsuperior bronchi (BX_(10)~*) occurred in 43 cases. 3. A~7 occurred in 78% as a single branch, among which 34% were branched offfrom the basal artery and the remaining arose in combination with other arteries. A~7occurred in two branches in 22%. A~8 arose as a single branch in 22% and in com-bination with other arteries in 44%. 34% of A~8 was present in two branches, thereforethe variations of A~8 are far greater than that of B~8. The arteries to the lateral basalsegment (A~9) arose as a single branch of the basal artery in 44% of the specimens. Inanother 38% A~9 was of two branches. In the remaining 16%, it was associated withbranches to the neighboring segments. In 98% of the specimens, the artery to the pos-terior basal (A~(10)) divided into A~(10) a and A~(10)b. 4. The veins from the different segments of the right lower lobe were drained intotwo principal pulmonary veins. A superior vein (V~6), which is usually a single branch,occasionally two branches (18%), drained the vein from the superior segment, and alower vein (common basal vein) draining the veins from the basal segments. The com-mon basal vein formed by the union of a superior and an inferior basal veins was foundin 90% of the specimens. The basal veins may be classified into three types; the un-complicated type is the prevailing pattern which occurs in 52%.