Separate Finger Research Articles

Genetics of dermal ridges; the relation between total ridge-count and the variability of counts from finger to finger.

SummaryPart 1Frequency distributions for the finger ridge‐count on each of the ten digits in a population sample of 825 males and 825 females are given, together with their respective means and standard deviations.The highest means are those for digit I, followed in order by those for digits IV, V, III and II.The mean ridge‐count is significantly greater on each digit in males, the difference being greatest on digit I of both hands.The mean ridge‐count on the right hand is significantly greater than that on the left on digit I in both sexes and on digit II in females.Digit II shows the greatest variability in ridge‐count and digit V the least. Part 2A value S2, the sum of squares of deviations of the ten separate finger ridge‐counts from their mean, has been used as a measure of the variability between the digits of an individual.The joint distribution of this variable with the total finger ridge‐count, Q, is given for 825 males and 825 females, respectively.In both sexes the distribution is arch‐shaped, with entries decreasing from the base to the apex, while the regression of S2 on Q is a curved line. In each case there are signs of trimodality.The joint distribution of (S/√ 10) and Q is also given for each sex.The correlation between S2 and Q is negative in both sexes: r=–0–195 ± 0–03 for males and r=—0–12 + 0–03 for females. These values are significant.The characteristic features of the joint distribution of S2 and Q are discussed with a view to their possible genetic significance.The data used for this paper are filed in the archives at the Galton Laboratory.

Recovery of Radium Tubes from Sewer

A search for three tubes of radium which had been lost in a sewer, and the recovery of the last of these tubes fifty-four days after it disappeared, involved the use and consideration for use of some equipment which it is believed had not previously been employed for such work. The successful conclusion of this search was due to the suggestions and cooperation received from the hospital authorities, employees of the city engineer's department, members of the biophysics laboratory section, representatives of the insurance company, Prof. J. W. Buchta of the University of Minnesota, and numerous others whom we may have inconvenienced. The tubes each contained approximately 50 mg. of radium, sealed inside a glass tube, which in turn was sealed inside a tube of Monel metal whose outside dimensions were 27 mm. (1 1/16 inches) in length and 5.6 mm. (a little less than 1/4 inch) in diameter, with a wall thickness of 1.5 mm. At the time the tubes were lost, each was tied in a separate finger cot and had small pieces of gauze bandage adhering to it because of clotted blood. When they were recovered, the finger cots were still attached to the tubes: one cot was still intact, one was slit part way down the side, and one was attached to the tube only by the string; all the gauze had been washed away. The tubes were removed from a patient about 8:30 p.m. on Sept. 3 and presumably left in a tray, which also contained some instruments and dressings. That the radium was lost was discovered about 9:30 p.m. In the intervening hour the tray had been taken from the patient's room to a utility room, the instruments had been cleaned, and the hopper had been flushed. A few minutes after 10 p.m. a search was started with a portable Geiger-Müller counter. As no indication of the radium was found on the floor of the hospital on which the loss had occurred, a rough check of the sewer line was immediately made from the utility room to its point of emergence from the hospital. Tests with a similar tube of radium made at a later date showed that the counter would have indicated the presence of any one of the three tubes if it had been in the hospital sewer line at that time. The wastepaper rooms, the linen rooms, and the incinerator were then checked. All wastepaper and linens were ordered held on the hospital floor until checked with the counter.

Effect of Maximal Feeding on Metamorphosis in Amblystoma

Twitty and Schwind have shown that in heteroplastic grafting between the 2 species Amblystoma tigrinum and A. punctatum, comparable results with respect to growth are obtained only when the hosts are all maintained at the same nutritional level, an effect obtained by maximal feeding, thus insuring the rapidly growing voracius tigrinum larvae opportunity to realize their full capacity for growth. The effect of maximal feeding upon the more slowly growing species has not been emphasized, although various workers have noted that along with the spectacular acceleration of the growth rate, and a consequently earlier metamorphosis, there is a high mortality during the metamorphic period in maximally fed groups of A. punctatum, regardless of the type of diet. The present experiments were undertaken in order to show the results of quantitative variation in a single diet upon the developmental rate and viability of A. punctatum from the earliest feeding stage through metamorphosis. Two hundred animals, taken from several bunches of eggs all at approximately the same stage of development, were reared from stage 39 onward in separate finger bowls. At the feeding stage the animals were divided into 4 groups of 50 each. The first 50 animals were starved, the second group given one feeding weekly, the third fed 3 times a week, and the fourth fed maximally. Enchytraeus, a small white worm, was used as the sole diet. All animals were measured at approximately 2-week intervals, the total length being recorded.