laboratory at Woods Hole using adult virginica 

 showed that 5 ml. of 1 percent solution of chloral 

 hydrate applied to the mantle cavity of an oyster 

 kept in a 4 1. tank of slowly changing water de- 

 pressed the beating of the lateral cilia by 50 to 

 87 percent. Twenty-five minutes after the re- 

 moval of the drug the effect disappeared and 

 normal (i.e., preceding) rate of ciliary motion was 

 reestablished. Application of 1 ml. of 0.1 per- 

 cent chloral hydrate to the mantle and gills had 

 no visible effect, but 4 ml. of the same concentra- 

 tion injected in the vicinity of the gills increased 

 the ciliary motion by 15 percent. The effect 

 lasted only a few minutes. 



In the above e.xperiments the duration of the 

 drug action was brief since the oysters were kept 

 in running sea water. Different results were ob- 

 tained when the test oysters were left in stagnant 

 water. No appreciable effect was noticed in 

 0.015 percent solution of chloral hj^drate, a slight 

 decrease (about 12 percent) was recorded in 0.019 

 percent, and the ciliary action stopped in 0.03 per- 

 cent solution. 



Slight depression of cihary motion (from 11 to 

 13 percent) was obtained by a single 1 ml. dose of 

 nembutal solution (concentration 0.02 g. per 1.) 

 injected directly into the mantle caWty. No 

 decrease in ciliary motion appeared in the control 

 tests in which 1 ml. of sea water was injected. 

 Ciliary activity in all these tests was measured 

 by determining the velocity of the cloacal current. 



Introduction of 3 ml. of digitalin (1:500) into 

 the pallial cavity results in an immediate, 90 per- 

 cent depression of ciliary activity. Figure 136 

 represents part of the record obtained by using 

 the electric drop counting method described in 

 chapter IX, p. 190. The effect is dissipated in 

 about 2 minutes. 



A solution of pilocarpine of 1:10,000 in sea water 

 applied directly to the excised pieces of C. virginica 

 gills has no effect on lateral cilia. In the test 

 made in the Woods Hole laboratory the frequency 

 of beat in natural sea water varied in this experi- 

 ment from 10.5 to 11.4 per second, and from 10.3 

 to 10.9 per second after addition of the drug. Tlie 

 concentration of 0.5 percent slowed down the 

 frequency by approximately 40 percent (6.5 to 

 6.8 per second). All observations were made at 

 23.5° C. Atropine sulfate solution of 1:1,000 had 

 only a slight effect on the frequency of beat of the 

 lateral cilia, reducing it by about 17 percent at 

 22.3° C 



THE GILLS 



733-851 — 64 10 



_KJvlLJu^_J^_^_^Ju^LJ^_^_^_^_^_rouu^JvAJvAAAJlJu^JLJ^_I^JL 

 J 1 1 



time jntervol - I second 



Figure 136. — Kymograph record of the effect of digitalin 

 (1:500) on the rate of ciliary activity of the gill of C. 

 virginica. Electric drop counting method. First and 

 third line indicate time intervals of 1 second; dotted 

 line marks the 2 minute interruption in recording. Second 

 and fourth lines show the contacts made by each drop 

 of water discharged through the cloaca. Two ml. of 

 digitalin solution were injected into the pallial cavity in 

 5 seconds, which are indicated at the top by the straight 

 line which interrupts the beat recording. A signal key 

 was depressed for 6 seconds (upper line) when the 

 digitalin was being added. 



The effects of acetylcholine and eserine are of 

 particular interest because of their importance to 

 the functioning of the neuromuscular mechanism. 

 Eserine inhibits the action of choline esterase, 

 the enzyme which hydrolizes acetylcholine and 

 prevents its accumulation. The latter would 

 cause an excessive neuromuscular activity. 

 Nomura and Kagawa (1950) found that at concen- 

 trations higher than 10"" both acetylcholine 

 chloride and eserine inhibit ciliary movement of 

 the gills of C. gigas. These investigators deduced 

 from their observations and from the experiments 

 of Nomura (1937) that acetylcholine and adrena- 

 line, while inhibiting ciliary motion in tlie oyster, 

 have the opposite effect on the lieart of this 

 mollusk. 



INHIBITION OF CILIARY MOVEMENT 

 BY ANTISERUM 



Antiserum produced in rabbits by the injection 

 of minced gill tissue of Anodonta inhibits ciliary 

 motion of the gills of this species. This observa- 

 tion of GaUi-Valerio (1916) was confirmed by 

 Makino (1934) for C. gigas, Meretrix, and other 

 bivalves. 



The problem was furtlier studied by Tomita 

 (1954, 1955), who improved the technique of 

 preparation of the antisera by eliminating the 

 preservatives (merthiolate and phenol) which are 

 known to depress the ciliary motion in the con- 

 centrations commonly used for this purpose. 



141 



