Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange
Abstract
The study of metabolism in the higher forms of life has been carried on for many year and much has been found out that has been of great importance in understanding the way things live and grow. It has been only in the last few years that attention has been given to this phase of the work in insects. The extensive work that has been carried on concerning metabolism in men and animals is the basis for the more recent researches on the lower forms including the microorganisms. Before this work could be carried out on the small forms it was first necessary to develop special technique and instruments which would accurately measure their respiration. The basis of metabolism is the chemical break down of food material by the body and the use of the food in carrying on body activity. Most organisms have adjusted their mode of living to the extent that their diet is confined to a rather restricted food range. Such is the case in the animals concerned in this paper. In the selection of honey bees as subject for metabolism studies, the selection was made in light of their economic importance and not because of the fact that bees would be good material on which to work. Actually, bees, due to their gregarious instincts, are unusually difficult to handle in the manner called for in this type of research. Since this work is some of the first along this line, the results and conclusions can not be taken as at all conclusive but rather as a basis for future study as better technique is developed. The greater part of this study has been carried on in a micro-respirometer modified after Thunberg 1905 and Trendlenburg 1909. The apparatus was designed for the study of tissue respiration and can be equally adapted for work with small organisms. The instrument is volumetric in nature and consists of two small respiratory chambers of equal capacity connected together thru stop-cocks by a fine capillary tube. In the capillary is placed a drop of oil and any change in the capacity of either chamber is read on a scale along the length of the capillary tube by observing the movement of the oil drop. In metabolism studies we are interested in the use of food and the elimination of body wastes. These wastes are carbon dioxide, water and nitrogenous products. In the study of the bees, we need consider only the carbon dioxide and water because the honey bee subsists as a diet almost exclusively of honey. Honey is a mixture of the simple sugars of the formula C6H12O5. One gram molecule of this sugar requires 6 molecules of oxygen for its combustion and in metabolism gives off 6 molecules of carbon dioxide and 6 parts of water. Since a molecule of one gas is equivalent to a molecule of any other gas, both taken at the same temperature and pressure, in the burning of honey equal volumes of oxygen and of carbon dioxide are involved. In the light of this chemically established fact, a metabolic relationship has been established between the oxygen intake and the carbon dioxide outgo. This relationship is the value of carbon dioxide, divided by the value for oxygen, the resulting ratio being called the respiratory quotient or R.Q. Theoretically this can be calculated for the metabolism of carbohydrates, fats and proteins. The R.Q. of carbohydrates should be (1), protein (0.8), and fats (0.7). These ratios have been borne out in experiments on men and animals and have established the fact that nothing is gained or lost in the body without a compensating force of energy to balance. The measurement of oxygen consumption was done by absorbing the CO2 in KOH and recording the loss in volume. Carbon dioxide is measured by using sulphuric acid in the chambers and observing the difference between oxygen used and carbon dioxide given off. For good readings with the volumetric apparatus a water bath was constructed which held constant temperature thruout [sic] the experiments. The instruments required about one hour to adjust for temperature; therefore, all readings were begun at the end of one hour. Bees differ from other insects in that they do not hibernate during cold weather but instead form a cluster within their hive. The temperature of this cluster never falls below 14° C, any time during the year. Sufficient host is generated within the cluster to maintain this temperature by the consumption of honey and by body activity. In view of this fact several temperatures for experiments were selected that would correspond with known hive temperatures. The following temperatures were used, 0° C; 14° C cluster temperatures; 21° C room temperature; 25° C; 34° C breed rearing temperature
