18, 6 Nafiagas: Position and Size of Kidneys 703 
3. The upper pole of both male kidneys was generally found 
at the lower half of the twelfth dorsal vertebra, and in the 
case of the left often at the level of the disk above it, with a 
tendency in both sides to be higher. In females it is also found 
at the level of the twelfth dorsal vertebra, though apparently 
not so frequently as in males, with a tendency to occupy lower 
levels. 
4. The right kidney is found farther from the median line 
of the back than the left, regardless of sex, and in correspond- 
ing sides it is found farther from that point in males than in 
females. 
5. In general the left kidney is larger than the right. 
6. The female kidneys, considered either in general or by 
corresponding sides, were larger than those in the males. 
7. There is a gradual increase in size of both kidneys with age, 
up to a certain maximum, attained in males between 30 and 40 
years, and in females up to the age of 30 with a gradual decline 
thereafter. 
I wish to thank Dr. Arturo Garcia for helpful suggestions in 
the preparation of this paper. 
REFERENCES 
1. ADDISON, CHRISTOPHER. Journ. of Anat. and Phys. 35 (1901) 294. 
2. CUNNINGHAM. Text book of Human Anatomy, 5th ed. Wm. Wood & Co. 
(1918) 1425. 
3. PrersoL. Text book of Human Anatomy, 1st ed. Lippincott & Co. (1907) 
1870. 
4, RAuBer-KopscH. Lehrbuch der Anat. des Menschen 4 (1909) 241. ' 
