Frank W. Weymouth

Relationship between body size and metabolism.

Recently Kleiber has studied the relation in liver slices of oxygen consumption to body weight in rats, rabbits, and sheep. 1 It was shown that the Q02 was inversely proportional to a fractional power of the body weight, so that plotted on a log log grid the data gave a straight line represented by the formula where Q02 is in mm3/mg dry tissue/hour and W is the body weight in kilos. It was concluded that “the factors which determine the metabolic level in vivo seem still to be present in the surviving tissues cut out of the organism.” Subsequent determinations of tissue respiration and observations on the relation of total metabolism to body size justify an additional note on this subject. A recalculation of values from the original individual records of Kleiber gives a coefficient of correlation between log Q02 and log body weight of -0.783 and a coefficient of regression of -0.228 with a standard error of ±0.017. The formula thus becomes. Field has since obtained data on respiration in kidney and brain slices for the rat and rabbit. Although covering only two species, the regression obtained is very similar, the average being -0.199. A value as low as this might be expected to occur by random sampling in data similar to Kleibers about once in 10 times so that the difference can hardly be considered as significant. It is thus apparent that other tissues behave in a manner very similar to liver slices. This strengthens the view previously expressed by Kleiber. On the other hand it is interesting to compare the exponent with that required by the surface area “law”, 0.333.

The Metabolism of the Excised Brain of the Largemouthed Bass (Huro Salmoides) at Graded Temperature Levels

consumption of frog brain and of Palladin and Rashba (1935) on oxygen consumption and ammonia content of frog, toad, and lizard brain appear to be the chief relevant material. This investigation of fish-brain metabolism was undertaken to extend a general study of the effects of temperature on the metabolism of isolated tissues and to provide additional data on the tissue metabolism of groups other than the Mammalia. Furthermore, the reports that the metabolism of intact fish, unlike that of intact mammals, is not augmented by administration of desiccated thyroid (Etkin, Root, and Mofshin, 1940) or of epinephrine (Smith and Matthews, 1942) warrant investigation of fish-tissue metabolism. The black bass was chosen because it was a readily available vertebrate heterotherm with a brain large enough to permit measurement of metabolism in vitro by standard methods.

Refractive Differences in Foveal and Parafoveal Vision

Abstract A report of experimental studies made in the Laboratory of Physiology, Leland Stanford University, comparing foveal and parafoveal vision by strong or feeble light, with a discussion of the causes of the phenomena observed, including nine tables, with bibliography.

Growth Rate and Variance in the Razor Clam

In discussing the growth of the razor clam (Siliqua patula, Dixon) we have pointed out a correlation between the absolute growth rate and the variability as measured by “D”, the interdecile range. 1 In this work we used samples of clams representing the normal population of the respective beds. For this reason the numbers in the older age groups were small, and it was not possible to determine the presence or extent of selective mortality which might greatly affect the relation between growth and variance. Recently we have selected 2 samples of clams, one from Little River, Humboldt County, California, containing 300 specimens, all 7 years of age, and one from Hallo Bay on the Alaskan Peninsula, containing 76 specimens 13 years old. A complete growth record was obtained for each individual by measuring the consecutive annual rings. The mean length and the variance were calculated for each year for the 2 localities, and the tenth, the fiftieth (median), and the ninetieth percentiles were determined for the distribution of sizes at each age. We have, therefore, by this means obtained data which is obviously unaffected by selective mortality. The absolute growth rate (annual increments) shows a high positive correlation with the variance. During the period preceding the inflection of the growth curve both the growth rate and the variance is increasing, and the point of maximum absolute growth occurs at the same time as that of the maximum variance. As the growth rate declines the variability also declines. As the animals approach final adult size they tend to reach a uniform length. During the time the growth rate is increasing the successive annual increments are apparently mutually independent. The variability increases with time, in such a manner that we might consider it to be due to chance.

The regression of age with size, a neglected aspect of growth.

Growth, always an attractive study, has of recent years received the attention of several distinct types of workers who have amassed much data for man, for some domesticated animals of economic importance, for the ever-useful white rat and guinea pig, and for a very few invertebrates. Almost invariably the results have been presented as average weights or lengths at stated ages. Thus presented, the growth data of most animals agree in certain general features. There is an early period of rapid growth which gradually slackens with age. In some forms growth continues, though at a very reduced rate, throughout life; in others, notably in man and birds, growth completely ceases for a long period of adult life. This is followed by a period of declining size. A graph constructed from these values shows the average length (or weight) for any age. Recently while working on the growth of the razor clam, a bivalve of considerable commercial value, which is in need of protective legislation, a growth curve of this kind was used in studying the possible effects of different proposed legal sizes, and, as often happens in work of this sort, it became desirable to determine the average age of clams of different lengths. At first it would appear that the same graph contained these values if the process of reading were merely reversed. Is such a process correct? The correlation between age and weight or length is nonlinear; the correlation ratio, as usually calculated, is very high, often exceeding 0.9. As is well known in ordinary linear correlations, the line of regression of x on y is not the same as that of y on x, though with correlations above 0.9 the difference is not great.