332 



Cheng, Thomas C, Carl N. Shuster, Jr., and Alan H. Anderson. 1966. 



A comparative study of the susceptibility and response of eight species of 

 marine pelecypods to the trematode Himasthla quissetensis . Trans. Am. Micr. 

 Soc. 85(2): 284-295. 



Experiments were conducted on 10 hard clams raised from laboratory-fertilized 

 eggs. A small hole was drilled in the left valve of each and 150 cercariae 

 were introduced. The hole was sealed with paraffin and the animals held in 

 seawater for 32 to 34 hrs . Soft tissues then were serially cross-sectioned 

 after fixation, staining and embedding in paraffin. Two Meraenaria' meraenaria 

 had one metacercariae in the stomach. Other metacercariae of the trematode 

 were in the process of penetrating stomach epithelium. Three quahaugs had 

 encysted metacercariae in the heart, each encapsulated within an inner cyst 

 wall. A number of leucocytes had adhered to the outer surface of the inner 

 wall of the cysts, forming an outer wall. Unencysted metacercariae also were 

 found in the space between palps and gills. No host leucocytes were seen in 

 their vicinity. Penetration through external body surfaces probably is the 

 primary method of infection. Observations of M. meraenaria showed that 

 metacercariae also can be carried by ciliary activity of gills and be ingested 

 with food organisms, then penetrating stomach wall. Where the post-cercarial 

 form had penetrated the stomach wall of the clam, leucocytes were present, 

 but not in appreciably greater numbers than usually found at this site. - J.L.M. 



333 



Cheng, Thomas C, Carl N. Shuster, Jr., and Alan H. Anderson. 1966. 



Effects of plasma and tissue extracts of marine pelecypods on the cercaria 

 of Himasthla quissetensis. Exper. Parasitol. 19(1): 9-14. 



Plasma of 7 species of marine pelecypod, including Meraenaria meraenaria , 

 stimulated cercarial encystment, but rapidity of encystation varied with 

 type of serum. The stimulatory component of sera was heat labile. All 

 tissue extracts killed cercariae, and time of death varied with type of 

 extract. Longevity of treated cercariae was much less than that of those 

 held in seawater. - modified authors' abstract - J.L.M. 



334 



Cheng, Thomas C, Amar S. Thakur, and Erik Rifkin. 1968. 



Phagocytosis as an internal defense mechanism in the Mollusca: with an 

 experimental study of the role of leucocytes in the removal of ink particles- 

 in Littorina scabra Linn. In Proc. Symp. Mollusca, Pt. II. Mar. Biol. 

 Assn. India, Mandapam Camp: 546-563. 



Comments on lipase activity .in leucocytes, and dehydrogenase and cholines- 

 terase in amoebocytes of Meraenaria meraenaria are given in more detail 

 elsewhere in this bibliography, in abstracts of papers in which original 

 data appeared. - J.L.M. 



335 



Cheng, Thomas C. , Gary E. Rodrick, David A. Foley, and Sherry A. Koehler. 1975. 



Release of lysozyme from hemolymph cells of Meraenaria meraenaria during 

 phagocytosis. J. Invert. Pathol. 25(2): 261-265. 



Quahaugs studied came from N.J. waters. Lysozyme activity was detected in 

 serum and cells of hemolymph of M. meraenaria which had been exposed to 

 Bacillus megaterium and in clams which had not been exposed to bacteria. It 

 is now known that lysozyme is released from hemolymph cells of hard clam 

 into serum during phagocytosis. This release is concurrent with phagocytosis 

 of bacteria and not a delayed effect. Release is not the result of destruc- 

 tion of the plasma membrane of hemolymph cells. What has been commonly 

 called "degranulation" in molluscan granulocytes, i.e., explosive discharge 

 of contents of cytoplasmic granules through cell surfaces, is in fact a 



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