PHYSIOLOGICAL OBSERVATIONS ON STARVATION AND DESICCATION OF THE SNAIL AUSTRALORBIS GLABRATUS

¹ U. S. Department of Health, Education, and Welfare, Public Health Service, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland

1. Decreasing humidity leads to a progressively more rapid decline of survival time, body weight and rate of oxygen consumption. Snails starving in air of high humidity survive longer than snails starving in water, but their final weight is lower.

2. The heart rate of snails starving in water or desiccating at 96 per cent relative humidity decreases. At all lower humidities a transitory phase of increased heart rate and many irregularities in heart action occurs.

3. During starvation in water and during desiccation, polysaccharide and lipid stores become depleted. Lactic acid disappears completely from the tissues during desiccation and volatile acids diminish.

4. It is concluded that the decrease in oxygen consumption is largely due to desiccation proper but that at high humidity starvation is a contributing factor.

5. Snails desiccating at high humidity have a purely aerobic metabolism. The relationship between the oxygen required for oxidation of polysaccharides and lipids and the total oxygen consumed indicates that protein may be the main substrate during prolonged periods of starvation in water or of desiccation.

6. The percentage of total body water lost and the percentage of water in the tissues do not decrease at the same rate during desiccation, tissue hydration declining at a slower rate. If marked tissue losses occur during long periods of desiccation, the over-all tissue hydration may remain unchanged even if the total water loss is very pronounced.