26 



BULLETIN OF THE BUREAU OF FISHERIES 

 Table 1. ^Effect of low temperature on the ciliary activity of frontal and lateral cells 



The experiment shows that the frontal cilia can produce mechanical work and 

 transport the particles along the surface of the gill at 3° while the current is pro- 

 duced by the lateral cUia only at temperatures above 5°. This undoubtedly is due 

 to the fact that for the production of a current a coordinated ciliary motion along 

 the whole surface of the gill is essential, while the transport of particles along the 

 surface is accomphshed by the coordinated beats of frontal cilia on one or several 

 filaments only. If, for instance, the ciliary motion stops on one of the filaments 

 (which often happens at low temperatures), it would not affect the mechanical 

 activity of frontal cilise on the other filaments; as long as a sufficient ratio between 

 the progressive and regressive strokes is maintained, the frontal cilia are pushing 

 the particles toward the distal end of the gill, and the absence of ciliary motion in 

 some of the filaments does not interfere with the transport of the particles by the 

 others although the cessation of motion of lateral cilia in one of the filament inter- 

 feres with the running of current through the gilis. 



In connection with these experiments it is interesting to mention the results of 

 the observations that show that when the shell of the oyster is closed at low tempera- 

 ture the ciliary motion may be inhibited completely. The following experiments 

 supply evidence for this statement: On February 15, 1927, six oysters were taken 

 from the shallow water of the harbor; the temperature of the water was 0.8 ° and that 

 of the air 1.7°. The shells were forced apart slightly and a small thermometer was 

 thrust into the oyster meats. It registered the following temperatures: 1.4°, 1.2°, 

 1.3°, 1.2°, 1.4°, 1.4°. Then the oysters were opened and small pieces of gill epithe- 

 lium were put in sea water immediately and examined under the microscope. The 

 examination was made on the deck of a boat anchored in the harbor. Air tempera- 

 ture during the examination varied from 1.6° to 1.7°. In all the pieces of epithelium 

 cut from the gills and placed in sea water at 1.4° there was no ciliary motion. Ten 

 minutes later, however, the ciliary motion was active in all of them. The same 

 experiment was repeated next day with six oysters that were taken from the harbor 

 and left for two hours exposed to direct sunlight. The air temperature was 3.8°. 

 When the oysters were opened the temperature of theh' meats was as follows: 8.6°, 

 8.5°, 9.6°, 10.1°, 10°, and 10°. In all of them the ciliary motion observed on the 

 excised pieces of the gill epithelium was slow and irregular but became normal in a 



