CIRCULATION OF THE CCELOMIC FLUID. 187 



of time. It is doubtful whether careful or extensive work would 

 prove this imperviousness to be as general or as great as it is 

 sometimes thought to be. 



The fact that the coelomic fluid is red points suggestively to 

 an oxydizing function. In other nematodes having red ccelomic 

 fluid the color is said to be due to the presence of haemoglobin 

 and this is therefore probably the condition in these worms. 

 Since their host is an aquatic animal and since they live rather 

 near the anus, it would be a comparatively easy matter for a 

 certain amount of oxygenated water to come in contact with 

 them. This being true, haemoglobin in the coelomic fluid could 

 take up any available oxygen. 



In dissolving any doubt regarding the function of circulation 

 in these worms it would be materially helpful to learn how 

 extensive the process may be among nematodes in general and 

 under what conditions it occurs. There is so little color dif- 

 ferentiation in the fluid of most nematodes that possibly circula- 

 tion may have been overlooked in species where it does actually 

 take place. In the present case the redness of the fluid in 

 contrast with the light background of the tissues made move- 

 ments of the fluid noticeable and easy to follow. If the process is 

 primarily an oxygenating one it might be found more frequently 

 among species internally parasitic or otherwise living where 

 thorough distribution of a small supply of oxygen would be a 

 matter of importance. 



LAKE LABORATORY, 



OHIO STATE UNIVERSITY. 



