SEA-FISHERIES LABORATORY. 185 



occasional and scattered observations ; and although 

 all observations have their value, and occasional records 

 mount up and may eventually enable us to draw 

 conclusions, still it takes time to accumulate the necessary 

 mass of statistics, and in a district like ours conditions 

 may change so that records are no longer comparable. 



Mr. Johnstone gives an account of the marking of 

 living plaice and soles in different parts of the district. 

 The fish are marked with numbers, measured and re- 

 corded, so that when a marked individual is caught again 

 its locality and size can be compared with the former 

 record. 



It is too soon yet to draw any conclusions, and this 

 is the kind of enquiry in which one would desire to have 

 a considerable mass of statistics before attempting to 

 formulate views. The matter is reported on now simply 

 for the purpose of informing the Committee that the work 

 is in progress. 



The study of the parasites and diseases of fishes is a 

 subject of very great importance, which, notwithstanding 

 a certain amount of work during recent years, must still 

 be regarded as in its infancy as an investigation. In our 

 district it was commenced several years ago by Mr. Scott, 

 who reported on the parasites he found in fishes at Piel. 

 Last year we had two valuable papers in the Report by 

 Mr. H. M. Woodcock, of University College, London; 

 and now the subject has passed into the hands of Mr. 

 Johnstone, who treats, in his paper below, of various 

 internal parasites and the abnormal conditions they give 

 rise to. Excepting the Copepoda, which affect the exterior 

 of the body, parasites of fishes may be grouped into three 

 great sections: (lj the Bacteria, which are microscopic 

 plants; (2) the Protozoa, which are minute and very 

 lowly organised animals, and (3) the Worm Parasites 



