The physiological reactions of two subjects were investigated in air at a temperature of 70–100° F., and of 40–96 per cent. relative humidity. The experiments lasted 3 hours, and one of the subjects performed mechanical work (step climbing) at the rate of 14,000 kg. m. per hour.The pulse rate was about 10 beats greater in dry air than in moist air of the same wet-bulb temperature. The winter observations agreed well with the effective temperature scale, but did not agree with the wet bulb, the dry-bulb or the kata-thermometer scales.Acclimatisation effects showed themselves in experiments made at a dry-bulb temperature of 87° F. or more, but only very slightly in those made at 81° or less. Acclimatisation was fairly well marked in the summer, the pulse rate being 5 to 10 beats less than in the winter, and no longer agreeing with the effective temperature scale.The body temperature corresponded with the pulse rate, for it was 0·3–0·6° F. higher in dry air than in moist air of the same wet-bulb temperature, and was 0·15° lower in summer than in winter. The winter observations agreed well with the effective temperature scale.The skin temperature of the face was found to depend on the dry-bulb temperature of the air, but that of the trunk showed no agreement with any of the scales. In moist air it was 1° F. lower than that of the face, and in dry air, 6° lower, owing to the cooling effect of increased sweating.The gross mechanical efficiency fell off slightly at temperatures above 70 or 75° F. It was affected by the dry-bulb temperature of the air as well as the wet bulb, but not to the extent indicated by the effective temperature scale.The weight of moisture lost by sweating corresponded well with the effective temperature scale. It increased gradually in consecutive experiments made in dry air, and diminished in those made in moist air.The degree of fatigue experienced in dry air was considerably greater than in moist air of the same wet-bulb temperature, and it corresponded with the effective temperature scale.Acknowledgments. We wish, to express our indebtedness to the authorities at the London School of Hygiene and Tropical Medicine, and especially to Dr G. P. Crowden, for the facilities offered to us in our work.
No abstract
(From the Zoological Station, Naples.) IN a former paper upon the subject of Heat Rigor in various inivertebrate and cold-blooded vertebrate animals', it was shown that the various temperatures of loss of excitability could not be accounted for by supposing them directly related to the proportion of water present in the tissues. This was somewhat unexpected, for it was found that if water were added to or subtracted from muscles by previously soaking them in hyp-and hlyperisotonic salt solutions, the ternperature of loss of excitability was most distinctly diminished in the one case, and somewhat increased in the other.
THE subject of the respiratory exchange of the lower marine animals has an interest quite apart from the mere measurement of the exchange of material taking place in particular individual animals, because of the comparatively slight differentiation the tissues have in many of them undergone. In the higher animals the respiratory exchange is the sum of the changes taking place in various tissues, which differ considerably from each other both in their structure and chemical nature. Also the respiration is as a rtule largely influenced and governed by stimulation and inhibition from nervous centres. In animals such as Beroe and Cestus, however, the nervous system is exceedingly primitive, so that we are probably justified in looking upon the respiratory exchange as almost entirely a pure tissue metabolism phenomenon, uncomplicated by nervous influence. Now in the transparent pelagic animals such as Medusaw, Ctenophora and Salpa, there appears to external observation but slight differentiation of the viscid protoplasmic tissue, and so it seemed of interest to determine whether, within the limits of experimental error, unit weight of such animals has at the same temperature the same respiratory exchange, and whether the relation of the respiratory activity totemperature is in the different animals constant. The respiratory exchange of marine animals has hitherto been studied almost exclusively by Jolyet and Regnard'. Their method of experiment is a modification of that used by Regnault and Reiset for measuring the respiration of air breathing animals. As it necessitates the constant bubbling of a stream of air through the water in which the animal under examination is placed, it is quite impossible to use it for measurements of the respiration of delicate pelagic animals, and so another method had to be devised. The method adopted is 1 Archives de Physiologie, 2 Sr. 4. 44, 584.
As is now well known, the very varied symptoms produced by rapid decompression from high atmospheric pressures, and popularly known as “ caisson disease” or “ diver’s palsy,” are due to liberation of bubbles of gas—chiefly nitrogen—in the blood and tissues. In the course of a recently published investigation, I found that air is much more soluble in certain oils than in water. Dr. J. S. Haldane pointed out to me the interest of this fact in connection with the causation of caisson disease, and at his suggestion I have repeated and extended my observations. The fats experimented with were olive oil, cod liver oil and lard. In the case of the first two, the solubility was measured at 15° and at 37° C., whilst for lard it was determined at 45° C. In the observations made at room temperature, the oil was shaken violently with air in a bottle for several minutes, and was allowed to stand for 1 to 1½ hours till all the air bubbles had risen to the surface. It was then weighed, and about 40 to 50 grammes of it were sucked up into the vacuous flask of a Geissler’s mercury pump. This flask contained 70 to 100 c. c. of 0·5 per cent, sulphuric acid which had previously been well boiled for an hour so as to get rid of all traces of air. The mixture of oil and water was now boiled for half an hour, the oil breaking up into a very fine emulsion and giving up practically all of its gas in the first few minutes. This gas was pumped off and analysed with Haldane’s gas analysis apparatus. The oil was boiled with dilute acid instead of water, so as to obtain the whole of the carbon dioxide present, both combined and in solution. In determining the solubility at 37°, the oil, previously saturated at room temperature, was warmed to about 38° to 39°, and was shaken vigorously with air for about two minutes. At the end of this time its temperature had fallen to about 36°·5. It was warmed up a second time and the shaking repeated, and was then kept in a water bath at 37° for about half an hour in the case of the cod liver oil, and an hour in the case of the olive oil, these being the times required for all the bubbles of air to rise to the surface. The gaseous content of a weighed amount of the oil was then determined as before. The results obtained are given in the tables. They represent the volumes of gas, reduced to 0° and 760 mm., contained in 100 c. c. of the oil at the temperature recbrded, when saturated with air at a pressure of 760 mm. To calculate these values, it was assumed that the specific gravity of olive oil at 15° is 0·917, and at 37°, 0·902. The specific gravity of cod liver oil, compared with that of water at 15°, was found by direct experiment to be 0·928 at 15°, and 0*914 at 37°.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.