44 1 min and measuring the timefor the skin fold to retract to the surrounding skin surface. The exact end point was sometimesdifficult to measure in older people, and if the fold had not retracted completely in 90 sec, this time measurement was used at the maximum. (3) Graying of the Hair. The degree of graying was expressed on a 0 to 4+ scale as follows: 0, no graying; 1+, slight “‘salt and pepper” graying; 2+, moderate “salt and pepper” graying; 3+, nearly complete graying; 4+, complete graying. Special Senses.* (1) Eyes. All ophthalmologi- cal values were obtained during the 1964 survey. (a) Accommodation was measuredin diopters by use of the Prince refracting rule. The average reading of the two eyes was used. (b) Visual acutty was measured by Snellen’s test. It was found that by taking the squareroot of the average visual acuity (denominator) of the two eyes the scale was more linear. Thus the best vision, 20/10, was repre- sented as 3.2 (the square root of 10), the worst reading, 20/200, was represented as 14.1 (the square root of 200), and intermediate readings were similarly recorded. (c) Arcus sentlis wasestimated on a 0 to 4+ scale. Only slight limbic clouding was considered as 1 + with increasing clouding as 2+ or 3+ and marked cloudingas 4+. (2) Ears (Hearing). Audiometric examinations were carried out in a special cubicle lined with acoustic tile. A rugged screening type of audiometer was used.** Impairmentof hearing was aver- aged for the two ears as follows: the decibelloss for each of the 6 frequencies (200, 500, 1000, 2000, 4000, 7000) for each ear was averaged, and a mean frequency loss in decibels for the two ears wasobtained. Cardiovascular Changes. Systolic Blood Pressure. Two readings were obtained with the standard aeronoid cuff-type sphygmomanometer, and the Figure 33. Marshallese subject taking light-extinguishing test of neuromuscular and mental ability as part of the aging study, adjusted level of physical activity such as resting for a standardperiod of time prior to the readings. Pressures were taken from theleft arm with the subject supine during the course of the physical examination. Neyrological and Neuromuscular Function. (1) under more desirable conditions. Vibratory Sense. Vibratory perception was measured over the head of the left tibia by an electric vibrometerset at a standard frequency of 120/‘sec at 20 V. The end point was the voltage intensity required for perception of the vibration. (2) Neuromuscular Functton. This was measured by having the subject depress the key of a hand-taily type of blood celi counter as many timesas possible in the period of one minute (1964 data). The total number of depressions represented the score. (3) Light Extinction Time.* A battery of lights were connected in random series, and the subject extinguished curement Agency, Fort Totten, New York, for loan of the audiometer. for information on the construction and use of this instrument. average of the two was used. There was no basic or “With regard to the reliability of determinations using the Prince refracting rule, Snellen’s test, and hearing acuity, it should be pointed out that these tests were carried out under standardized conditions; but, in view of the necessity of using an interpreter underfield conditions, it was not feasible to have the test repeated by more than one examiner. The data from these tests are believed to be sufficiently reproducible to be of relative value, although not so accurate perhaps as might be obtained **The authors are grateful to the Armed Services Medical Pro- *Weare grateful to Dr. J.W. Hollingsworth ofYale University