174 EXPERIMEXT STATION. [Jan. 



The results slio-wn in this experiment coincide in a general 

 way with those of the previous one. They are, however, of 

 more value, since they show the bacterial flora of the normal 

 or untreated jDond water. 



It will be noted that the number of bacteria in the untrej^ted 

 pond water remained quite constant throughout the exj^eri- 

 ment, while the water treated with copper sulfate showed the 

 same general decrease in the nuiuber of bacteria. The sub- 

 sequent increase in the number of bacteria in the treated water 

 in the laboratory experiment was smaller than that shown by 

 the pond experiment. Furthermore, a comparison of the two 

 jars in the laboratorj^ experiments showed that the water in 

 the treated jar was much clearer, owing to the fact that most 

 of the. forms of living matter had been killed and had settled 

 to the bottom of the jar. This was proved by the much larger 

 amount of sediment in the bottom of the treated jar than in 

 the untreated. 



Large bodies of water can be successfully treated with cop- 

 per sulfate, and many undesirable forms of organisms elim- 

 inated. The copper sulfate treatment, moreover, appears to 

 exert an influence upon the bacterial flora for quite a length 

 of time ; but after a certain period has elapsed a body of water 

 may become as badly contaminated with various forms of 

 living matter as before, or even worse. 



The location of the college pond is such that no harm could 

 result in any way from a treatment with copper sulfate, even 

 though some of the copper escaped. Precautions, however, 

 must be exercised in treating bodies of water ; and the safest 

 method to follow, in case such treatment is necessary, would 

 be to consult our State Board of Health or others familiar 

 with this subject. 



Banding Substances for Tkees. 

 In connection with the rencAved warfare against the gyi^sy 

 and brown-tail moths, a number of new banding substances, 

 which are claimed to be effectual as insect barriers and harm- 

 less to trees, have been placed on the market within a year or 

 so. These substances are sold under various names and at 

 varying prices, and they are quite dissimilar in their eliomieal 



