CALCIFICATION IN MARINE MOLLUSCS * GERRIT BEVELANDER AND PAUL BENZER The Bermuda Biolor/ical Station for Research and the Department of Histology, College of Dentistry, New York University INTRODUCTION The correlation between mantle activity and the production of shells in molluscs has been of interest for a considerable time. Studies by Rawitz (1888, 1890) have shown in considerable detail the histological structure of the mantle tissues of a number of species. Biederman (1914) and Schmidt (1923) described the morphological aspects of shell formation with particular reference to the pattern and arrangement of the various components. The reports of Moynier de Villepoix (1892), Brooks (1905). Hass (1935), Bourne (1943) and others too numerous to mention have also added considerably to our understanding of the structure, com-position, crystalline pattern and in some degree to the detailed mechanism involved in the calcification of the shell. Despite a voluminous literature (see Hass, 1935) which has appeared in con-nection with calcification in molluscs, several phases of this problem still await further study and clarification. By means of methods to be described in the fol-lowing paragraphs we have examined in detail a number of aspects of shell forma-tion and in so doing have utilized several different methods of attack upon the problem. MATERIAL AND METHODS The species of molluscs vised in this investigation consisted of Atrina rigida (Pinna), Pedalion alatitin, Codokia orbicularis, Pinctata radlata, and Venus nicrccnaria. For studies in a closed system the young spat of Pedalion proved to be most successful. For rapid regeneration studies in which a glass cover slip was placed in the mantle cavity (Brooks. 1905) Pinna proved to be efficacious. Codokia and 1'cnits were better suited for histological and histochemical studies than other forms examined due to the relative lack of pigment in the mantle tissues. Standard techniques and procedures were used for histological studies. Mucin was localized by Hoyer's thionin method, phosphatase, pre-formed phosphate and reticulum according to the methods of Gomori (1937. 1941), and calcium accord-ing to the method of Feigl (1943). The artificial sea water media used in our experiments was made up according to the formula of McClendon (Rogers, 1927). In this study we were concerned with various factors relating to calcification. It was therefore necessary to choose a number of different test animals in order that different aspects of the problem could be investigated. For certain phases of the study, histological and histochemical observations were made, for others a change in the environment of the animal was initiated, in a third set of observa-'* This work was supported in part by a grant-in-aid contributed by Dr. Harry Seldin. 176
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