HOUSE-FLIES. PONDS 251 



" All stalls in which animals are kept shall have the surface of the 

 ground covered with a water-tight floor. Every person occupying a 

 building where domestic animals are kept shall maintain, in connection 

 therewith, a bin or pit for the reception of manure, and, pending the 

 removal from the premises of the manure from the animal or animals, 

 shall place such manure in said bin or pit. This bin shall be so con- 

 structed as to exclude rain water, and shall in all other respects be water- 

 tight, except as it may be connected with the public sewer. It shall 

 be provided with a suitable cover, and' constructed so as to prevent the 

 ingress and egress of ffies. No person owning a stable shall keep any 

 manure or permit any manure to be kept in or upon any portion of the 

 premises other than the bin or pit described, nor shall he allow any such 

 bin or pit to be overfilled or needlessly uncovered. Horse manure 

 may be kept tightly rammed into well-covered barrels for the purpose 

 of removal in such barrels. Every person keeping manure in any of the 

 more densely populated parts of the District shall cause all such manure 

 to be removed from the premises at least twice every week between 

 June 1 and October 31, and at least once every week between Novem- 

 ber 1 and May 31 of the following year. No person shall remove or 

 transport any manure over any public highway in any of the more 

 densely populated parts of the District, except in a tight vehicle which, 

 if not inclosed, must be effectually covered with canvas, so as to prevent 

 the manure from being dropped. No person shall deposit manure 

 removed from the bins or pits within any of the more densely populated 

 parts of the District without a permit from the health officer. Any 

 person violating any of the provisions shall, upon conviction thereof, 

 be punished by a fine not more than $40 for each offense." 



Slime on Ponds 



The slime, or algaB, on ponds may be destroyed by copper sulfate. 

 The common spirogyra is dispatched by 1 part of the sulfate to 

 25,000,000 parts of water, and other forms by a stronger solution. 

 These weak solutions are little injurious to the higher plants and not 

 much so to any animals. A better way is to keep the toads and to 

 let their tadpoles eat the algae. Red-bellied minnows would also 

 help. 



