of the Fishery Board for Scotland. 



331 



APPENDIX F. — No. XII. 



FURTHER REPORT ON THE EXAMINATION OF RIVER 

 WATERS FOR MICRO-ORGANISMS. By W. S. Greenfield, 

 M.D., Professor of General Pathology in the University of Edin- 

 burgh, and John Gibson, M.B. 



During the past year the investigation supon the subject of the presence 

 and relations of the lower fungi, and especially of bacteria, in the water of 

 large rivers, have been continued without intermission. A very large 

 amount of valuable information has been thus obtained, to which it is 

 hardly possible to do justice in a report, as it is to a large extent pioneer 

 work in a new field. 



It has been already pointed out in a previous report by Dr Woodhead 

 and myself (Appendix F, No. XI. p. 176), that the object in view is 

 to determine the nature of the bacteria and other low fungi commonly 

 present in river water, the conditions of their prevalence, and the effects 

 which they may produce in relation to the life or health of fishes. At 

 the outset our inquiries were limited to the question of the conditions 

 under which salmon disease occurred, and we had in view the possibility 

 of readily detecting the Saprolegnia in any sample of river water, and 

 determining the conditions favourable to its occurrence and spread. We 

 have steadily kept this object in view, and although we have not attained 

 the end, we have worked through a large number of complex difficulties 

 which must necessarily present themselves to any one who attempts to 

 solve the problem. 



The work done may be divided into four distinct branches — 1. The 

 enumeration of the number of organisms in river water in different rivers 

 and under various conditions; 2. The study and identification of the 

 bacteria and closely allied organisms present; 3. The study of higher 

 microscopic fungi; 4. Observations upon the mode of growth, and culti- 

 vation of the Saprolegnia, and the manner in which it invades and affects 

 salmon. 



In the present report we have been obliged owing to want of time to 

 take up only the first and second of these subjects, and we hope to com- 

 municate the others in a further Report. 



Section I. Enumeration of Micro-Organisms. 



We need to inquire what is the proportional abundance of 

 fungoid life in river water under various conditions. The mere enumer- 

 ation of the actual number of organisms present in a given bulk of 

 water is now regarded as one of the most important elements in any 

 analysis of water, and in recent Health Reports special attention is 

 always given to this point. We have already indicated some of the 

 bearings of this subject. The presence of a large number of bacteria in 

 a sample of water is usually an indication of an excess of organic refuse, 

 which, in the case of drinking water, frequently implies sewage contamin- 

 ation. In relation to fish disease, we have observed that, in like manner, 

 excessive number of bacteria may indicate a favourable condition for 

 the prevalence and spread of salmon disease. It is not, however, neces- 



