144 



HATCH EXPERIMENT STATION. [,hin. 



the copper. Daphna,, a form of Crustacea, was also plenti- 

 ful, and experienced no ill effects from the copper treat- 

 ment. 



From day to day the bacterial contents of the water were 

 determined, with the results shown in the following table : — 



Copper Sulfide Test on MassaclmsetU Agricultural College Pond Water. 



Date op taking Sample. 



Number of Bacteria 



per Cubic Centimeter 



of Water. 



1903. 



June 17 (one hour after treatment) , 



June 19, 



June 20 



June 21 



June 22 



June 23 



June 24, 



June 25 



June 26 



June 27 



June 28, 



June 29, 



June 30 



July 1, 



July 3, 



Sept. 16 



Sept. 17, 



Sept. 18, 



Sept. 19, 



6.224 



3,463 



219 



336 



1,583 



1,187 



538 



1,144 



1,399 



1,144 



616 



763 



1,145 



1,078 



1,078 



990 



1,017 



990 



636 



From this table it will be seen that the bacteria decreased 

 very rapidly for the first few days after treatment, and, while 

 they slowly increased again, they never reached their former 

 numbers. The results obtained on June 24, 28 and 29 may 

 be attributed to an unusually clear or settled state of the water 

 on those days, while when the other samples were taken the 

 water was considerably agitated, either from the effects of 

 rain or wind. 



A second treatment was contemplated in September foi- the 



