



Mi lllmeters 



0.5 



Figure 238. — Transverse section of the accessory heart of C. virginica preserved in widely expanded state. Kahle, 



hemato.xyhn-eosin. 



cells the sample may be placed in a moist chamber 

 or a small quantity of blood may be dropped in 

 a glass dish with sea water of the same salinity 

 from which the oysters were taken. Under these 

 conditions the cells of C. virginica may remain 

 alive for about 6 daj^s and can be used for studies 

 or classroom demonstration (Breder and Nigi-elli, 

 1933). 



For smear preparations drops of blood should be 

 left on slides until the cells begin to expand. 

 When a desired state of expansion has been at- 

 tained, the preparation is fixed in Bouin III for a 

 few minutes or in chromic or osmic acid (liquid or 

 fumes). Satisfactory preparations may be ob- 

 tained by using Romanowsky's, Leishmann's, 

 Giemsa's, and McNeal's tetrachrome stains made 

 in a solution of absolute methyl alcohol. These 

 reagents fix and stain the cells in one operation. 



COLOR OF BLOOD 



The blood of the oyster is colorless alid contains 

 no respiratory pigments such as the hemoglobin 

 in vertebrates or hemocyanin found in snails and 

 cephalopods. In semipopular books on oysters a 

 statement is sometimes found about the presence 

 of hemocyanin in oyster blood. To clarifj' this 

 question, a composite sample of blood and peri- 

 cardial fluid was collected from six adult C. 

 virginica and submitted for spectrophotometrical 

 analysis, which was kindly performed in George 

 Wald's laboratory at Woods Hole. The following 

 is the report received from Wald: 



"The pH (of the sample) was 7.33. The ab- 

 sorption spectrum showed specific absorption in 

 the visible region corresponding to the hemocyanin 

 band at about 570 ni/z. Hemocyanin possesses 

 also a very high, sharp absorption peak at about 

 340 m/j., some 20 to 30 times as intense as the 

 absorption in the visible spectrum. This therefore 

 constitutes a very delicate test for the molecule. 

 This also did not appear in the spectrum though 

 a small band was found at lower wavelengths, at 

 about 327 m^. 



"The 570 and 340 m^. absorptions are found in 

 oxyhemocyanin; both are abolished in the reduced 

 condition. As an added test therefore this sample 

 of oyster blood was reduced with sodium hydro- 

 sulfite. The ultraviolet absorption at about 327 

 ii\fi. instead of being depressed, rose greatly. I 

 do not know what this substance is, but quite 

 certainly it is not hemocyanin." 



THE HYALINE CELLS 



These cells with clear cytoplasm containing but 

 few granules are of uniform shape, varying only in 

 size from 5 to 15 ti. When examined alive they 

 are usually spherical (fig. 239), have a distinct 

 cell membrane, and are of pale yellow-green color. 

 Because of their high refractive quality they stand 

 out sharply in the field of view of the microscope. 

 The slow movenaent of the cells can be noticed if 

 the preparation is watched intently for 30 minutes 

 or longer. One of these cells, under continuous 

 observation in the Woods Hole laboratory for 45 



CIRCULATORY SYSTEM AND BLOOD 



261 



