The antigens were prepared by Tomita in the 

 following manner. The gills of C. gigas, Anadara 

 inflata, and Pecten yessoensis were minced in 0.85 

 percent saline and homogenized in a blendor. The 

 protein content of the homogenate was estimated 

 from the determination of nitrogen made by 

 microKjeldahl method, and the preparation was 

 diluted with saline to give the final protein content 

 of 1 mg. per ml. Merthiolate in the concentration 

 of 1:10,000 was added as a preservative. On 

 alternate days a quantity of antigens containing 

 2.5, 5.0, and 7.5 mg. of protein per kg. of body 

 weight were injected into healthy rabbits. After 



2 weeks the animals were bled and the antisera 

 were placed aseptically in sterile ampules without 

 any preservatives and stored in a refrigerator. 



Small pieces of gill tissues, 3 to 4 mm. long and 



3 mm. wide were cut from the free margin of the 

 middle demibranch and placed in sea water in a 

 glass tubing about 12 mm. in diameter. The rela- 

 tive speed of crawling estimated by Nomura's 

 method (1937) was taken as a measure of ciliary 

 activity in normal sea water (100 percent effi- 

 ciency) and in various dilutions of the antiserum. 

 Complete stoppage of crawling was recorded in tlie 

 dilution 1:40 after 32 minutes. Considerable de- 

 pression of ciliary motion was noticed in the dilu- 

 tion 1:320 after 77 minutes of exposure. It is 

 regrettable that no observations were made on the 

 ciliary motion of an intact gill or that the frecjuency 

 of ciliary beat in the excised pieces was not meas- 

 ured by a stroboscope or by any other technique 

 more reliable than the "crawling" method. 



The antisera of the two other species of bivalves 

 (Anadara and Pecten) have an inhibitory effect on 

 the gills of Ostrea. The inhibition was, however, 

 less pronounced than that caused by the anti- 

 Ostrea serum. The anti-muscle serum tested on 

 the gills of all three species was less effective than 

 the anti-gill serum. The author deduced from 

 these observations that both "tissue-specificity" 

 and "species-specificity" are involved in the in- 

 hibitory effect of the antisera. 



EFFECT OF PRESSURE ON CILIARY 

 MOTION 



Observations of the effects of increased hydro- 

 static pressure on ciliary motion were made by 

 Pease and Kitciiing (1939) using the gills of 

 Mytilus edulifi. Part of an excised gill plate was 

 placed inside the glass chamber of a pressure bomb 

 designed by Marsland, and the surrounding sea 



water was saturated with veratrine, which accord- 

 ing to Gray (1928) considerably prolongs the 

 activity of the cilia. 



Under normal pressure the rate of beating, 

 measured stroboscopically, was about 9 to 10 times 

 per second, considerably slower than the normal 

 rate of 15 to 17 per second that one expects at the 

 temperatures of 21° to 24° C. at which the tests 

 were conducted. Apparently the use of veratrine 

 was unnecessary because the duration of the ex- 

 periments did not exceed 90 minutes and some of 

 them were completed within 8 to 16 minutes. 

 The tests show that a sudden increase in the hydro- 

 static pressure by 1,000 pounds per square inch or 

 more immediately increases the frequency of beat 

 of the lateral cilia. Decompression results in a 

 reduction in frequency below the normal level and 

 slow recovery. Pressure in excess of 5,000 pounds 

 per square incii decreases the frequency and causes 

 permanent injury. The authors claim that the 

 change in temperature due to compression or de- 

 compression is too small to account for the ob- 

 served effects, because, on theoretical grounds, it 

 may be expected that the temperature increases by 

 0.6° C. when the water is compressed adiabatically 

 to 5,000 pounds. The actual temperature in 

 chamber of the pressure bomb was not observed. 



It would be of interest to repeat these experi- 

 ments using pieces of gill epithelium kept in normal 

 sea water not poisoned by veratrine. 



CILIARY CURRENTS OF THE GILLS 



The ciliary currents at the surface of the gills 

 of an intact organ can be observed by dropping 

 small particles (carmine, carborundum, colloidal 

 carbon, and willemite) on the surface of the demi- 

 branchs and following under the binocular micro- 

 scope their movement and direction. The most 

 important contributions to the studies of this 

 subject were made by Wallengren (1905a), Orton 

 (1912), Kellogg (1900, 1915), Yonge (1926), and 

 Atkins (1937, 1938). 



There are five major tracts on the surface of the 

 gill fif C. virginica (fig. 137). The frontal cilia beat 

 parallel to the surface of the demibranch from the 

 base toward its free margin. This current, main- 

 tained along all ordinary filaments (or.f.), carries 

 the particles settled on the surface of the gill to the 

 terminal groove (tr.g.). This is lined with ciliated 

 cells that beat parallel to the edge of the gill and 

 push the particles entangled in mucus toward the 

 mouth. Between the plicae the current caused 



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