STUDIES ON THE ANAEROBIC METABOLISM AND THE AEROBIC CARBOHYDRATE CONSUMPTION OF SOME FRESH WATER SNAILS

¹ Laboratory of Tropical Diseases, National Institutes of Health, Bethesda, Maryland

1. Lymnaeidae and Physidae tolerated complete lack of oxygen less well than Planorbidae or operculates belonging to different families.

2. All species consumed carbohydrate under anaerobic conditions and produced carbon dioxide and lactic acid. While in several species the lactic acid produced was sufficient to account for all or a large part of the carbon dioxide as liberated from bicarbonate, this was not the case in other species.

3. The anaerobic metabolic level as measured by carbon dioxide production and carbohydrate consumption of the resistant species was, on an average, lower than that of the nonresistant ones. The former did not accumulate lactic acid within their tissues during an anaerobic period, while the latter did so to a marked degree.

4. In most species the anaerobic carbohydrate consumption was only slightly higher than the aerobic rate. One of the reasons for this may be the probable occurrence of aerobic fermentations in these species.

5. Lactic acid was quantitatively a major end product of the anaerobic carbohydrate consumption only in Lymnaea stagnalis and Lymnaea natalensis; in all other species unidentified end products must have prevailed.

6. The anaerobic carbon dioxide production followed the surface law in intraspecific comparisons in pulmonates rather closely, but definitely not in all cases of interspecific comparisons.