parts of 1 percent chloral hydrate solution, and is 

 left in it for about 24 hours. The tissue is then 

 transferred into solution No. 3 consisting of 1 part 

 of Ehrlich acid heniato.xylin, 1 part of glycerol and 

 6 parts of 1 percent chloral hydrate solution. 

 After several days in this niixtm-e the preparation 

 is destained in the solution No. 2 for about 12 to 

 24 hours and cleared in glycerol. Time of staining 

 and destaining may be modified depending on 

 thickness and condition of tissues. In successful 

 preparations the dark purple nervous tissue is 



visible against the semitransparent visceral mass. 

 In my experience tlie method proved to be capri- 

 cious and not entirely reliable. 



In a live oyster the nerves appear as thin, white 

 threads which can be traced for some distance in 

 very thin oysters containing no glycogen. Oysters 

 starved for 4 to 6 weeks in filtered sea water were 

 found to be very suitable for nerve study. Dissec- 

 tion of the nervous system must be supplemented 

 by reconstruction of ganglia and nerves through 

 examination of serially sectioned material. 



/ D. n. 



^ Centimeters ^ 



Figure 253.- — Diagram of the nervous .sy.stem of C. virginica seen from the right side. Dorsal and ventral ends of the 

 gills are shown under the mantle; the middle portion of the gill has been cut off; the middle portion of the branchial 

 nerve is indicated by the dotted line. Ad.m. — adductor muscle; ad.n. — adductor muscle nerve; a.p.n. — anterior 

 pallial nerve; br.n. — branchial nerve; e.g. — cerebral ganglion; c.p.n. — circumpallial nerve; com.p.n. — common 

 pallial nerve; c.v.c. — cerebro-visceral connective; g. — gills; Ib.n. — labial nerve; lb. p. — labial palps; l.p.n. — lateral 

 pallial nerves; p.o. — pallial organ; p.p.n. — posterior pallial nerve; r. — rectum; v.g. — visceral ganglion. The 

 cerebral commissure is not visible. 



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