STUDIES ON THE ANAEROBIC METABOLISM AND THE AEROBIC CARBOHYDRATE CONSUMPTION OF SOME FRESH WATER SNAILS THEODOR VON BRAND, HARRY D. BAERNSTEIN, AND BENJAMIN MEHLMAN 1 Laboratory of Tropical Diseases, National Institutes of Health, Bcthcsda, Maryland Field work attempting the eradication of schistosome-transmitting snails in various parts of the world has demonstrated the inadequacy of the hitherto available molluscacides. If control of schistosomiasis is to be attempted by means of chemical compounds interfering with the metabolic pathways of the intermediate hosts of the flukes, the establishment of a theoretical basis for further evaluation of potential and actual molluscacides is urgently needed. In a previous paper by von Brand, Nolan, and Mann (1948), some data on the aerobic faculties of various species of snails are recorded. A detailed knowledge of the anaerobic metabolism of such snails is also necessary since, according to a per-sonal communication by Dr. W. H. Wright, some schistosome-transmitting snails have the ability to escape the action of poisons by burrowing into the mud, which is usually very poor in oxygen. In the present paper an attempt is made to answer some unsolved problems con-cerning the anaerobic metabolism of snails which, in fact, has so far never been studied. Specifically, the following points have been investigated : Anaerobic resistance of various species, the anaerobic carbohydrate consumption, carbon di-oxide and lactic acid production, and the quantitative relationships between anaerobic and aerobic carbohydrate consumption. MATERIAL AND METHODS The following species of snails were employed and where no further information is provided they were of the same derivation as those used in a previous study (von Brand, Nolan, and Mann, 1948). 1. Pulmonates PLANORBIDAE : Australorbis glabratus; Helisoma duryi; Helisoma trivolvis specimens collected near Brownsville, Texas ; Tropicorbis obstructus; Tropi-corbis donbilli; Planorbarius corneus, laboratory-reared ; Bioniphalaria boissyi, laboratory-reared from Egyptian specimens ; Biomphalaria pfcifferi, laboratory-reared from Liberian stock. LYMNAEIDAE: Lymnaca stagnalis and Lymnaca palitstris, both laboratory-reared from Douglas Lake, Michigan stock ; Lynmaea natalensis, laboratory-reared from Dharan, Saudi Arabia, specimens. 1 The authors wish to express their appreciation for the contribution of snails to Dr. E. G. Berry, Mrs. M. O. Nolan, Dr. L. Olivier, and Mr. W. B. DeWitt of this Laboratory and Dr. H. van der Schalie and Mr. E. Abdel-Malek of the University of Michigan. 266
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