The condition index has a practical use for 

 oyster growers. It gives an objective method 

 of comparing the quahty of oysters talcen from 

 difl'erent commercially exploited oyster beds, 

 but this comparison is valid only if oysters of the 

 same species and of approximately the same age 

 are used. Oysters from overcrowded natural 

 reefs and young oysters are usually Hat, witli very 

 little inner space between the valves; consequently 

 their condition factor will be relatively high 

 because the bodies occupy almost the enthe shell 

 cavity. 



Westley (1961) found that the condition index 

 of samples of C. gigas in Oakland Bay, Wash., in 

 1956 varied between 6.2 and 8.1. The condition 

 index of the oysters in North Bay, Wash., in 

 August 1957 was 12.3 to 15.0. 



Observations were made on 0. lurida in Oyster 

 Bay on July 11 and repeated on August S, 1957. 

 On the first date the range of condition index 

 varied from 6.6 to 7.2, while a month later it had 

 increased to 16.0 to 17.3. The improvement was 

 probably associated with an accumulation of 

 glycogen after discharge of the larvae. In this 

 case the volume of the oysters was measui'ed by 

 weighing them first in air and then in water, and 

 computing the volimie from the difference between 

 the weights. The removed meats were oven- 

 dried to constant weight (at 100° C). 



Although the condition index may be useful to 

 oyster growers as a measure of quahty of oyster 

 meats, it provides no advantages for physiological 

 studies, and cannot be used for the study of 

 growth. 



ANTIBACTERIAL AGENTS 



Antibacterial and antiviral agents were found 

 in the meat of the oyster {C. virginica), in abalone 

 (Haliotis rufescens), and in a number of other 

 mollusks. These substances have been isolated 

 in the laboratory of the U.S. Pubhc Health Service 

 and their activity tested in vitro on a number of 

 pathogenic bacteria (Li, Prescott, Jahnes, Martino, 

 1962), and on various strains of influenza and polio 

 viruses. In vitro tests were made by using cul- 

 tures of monkey kidney tissue; tests in vivo were 

 conducted by feeding white mice with the extracts 

 and recording the death rate after infection. 

 There are two differe'nt extracts which the authors 

 call Paolin 1 and Paolin 2 (according to Li, Paolin 

 is a Chinese word which means "abalone extract"). 

 Paolin 1 was found to inhibit the growth of 



Staphylococcus aureus, Streptococcus j)yogenes, Sal- 

 monella typhosa, Shizella dysenteriae, and others. 

 Paohn 2 fed to white mice decreased the death 

 rate of animals experimentally infected by virus. 

 The decrease was from 36 percent in the controls, 

 which received no extracts, to 10 percent in the 

 animals fed with oyster or abalone extracts before 

 infection (Li and Prescott, 1963). The discovery 

 by Li and his coworkers is of great practical sig- 

 nificance and opens a new chapter of research into 

 the role of antibacterial and antiviral agents in 

 the tissues of mollusks. 



BIBLIOGRAPHY 



Baird, R. H. 



1958. Measurement of condition in mussels and 

 oysters. Journal du Conseil, vol. 23, No. 2, pp. 

 249-257. 

 Bargeton, Marie. 



1945. Sur la teneur en glycogene des diverticules 

 digestifs de I'huttre. Comptes Rendus Hebdomad- 

 aire des Seances de I'.Vcademie des Sciences, tome 

 220, pp. 623-625. 

 Beard, Harry R. (Compiler). 



1926. Nutritive value of fish and shellfish. [U.S.] 

 Bureau of Fisheries, Report of the Commissioner 

 of Fisheries for the fiscal year 1925, appendix 10 

 (Document 1000), pp. 501-552. 

 Bergmann, Werner. 



1934. Contributions to the study of marine products. 

 III. The chemistry of ostreasterol. Journal of 

 Biological Chemistry, vol. 104, No. 3, pp. 55.3-557. 

 1962. Sterols: their structure and distribution. In 

 Marcel Florkin and Howard S. Mason (editors) , 

 Comparative biochemistry, a comprehensive 

 treatise, vol. 3, part A, Constituents of life, ch. 2, 

 pp. 103-162. Academic Press, New York. 

 BiERRY, Henki, Bernard, Gouzon, and Colette Magnan. 

 1937. Les variations de la teneur en glycogene des 

 Huitres de consommation. Comptes Rendus 

 Hebdomadaires des Seances de I'Academie des 

 Sciences, tome 204, pp. 1895-1897. 

 Birckner, Victor. 



1919. The zinc content of some food products. 

 Journal of Biological Chemistry, vol. 38, No. 2, 

 pp. 191-203. 

 Calderwood, H. N., and Alfred R. Arm.strong. 



1941. Determination of glycogen in oysters. 

 Journal of the Association of Official .Agricultural 

 Chemists, vol. 24, No. 1, pp. 1.54-165. 

 Calderwood, H. N., and R. J. Pieohowski. 



1937. Modified distillation method for moisture. 

 Industrial and Engineering Chemistry, analytical 

 edition, vol. 9, pp. 520-521. 

 Chipman, Walter A., Jr. 



1947. Seasonal changes in the fattening of oysters. 

 Addresses Delivered at the Convention of National 

 Shellfisheries Association, June 3-5, 1947, pp. 28-32. 



CHEMICAL COMPOSITION 



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