The Mosquitoes of New Jersey 



79 



tide-water with its supply of killifish can be brought into the area 

 and caused to circulate (without overflowing the ditches) through- 

 out the system and again escape from the area. Experience has 

 clearly shown that failure to provide for this circulation is followed 

 by breeding in stagnant water in the ditches requiring the extensive 

 use of oil which can not usually be made sufficiently complete to 

 prevent the emergence of all of the mosquitoes. The circulatory 

 feature of the drainage system on the enclosed, non-shrunken, non- 



Fig. 44. Drainage system on an enclosed, sunken and sewage-charged marsh. 



polluted marsh is just now in process of being worked out. As the 

 matter now stands it seems best to bring the water in through a large 

 channel and to provide for its passage along the foot of the upland 

 and its escape through the narrow trenches into the main outlets. 

 Such a scheme is now in partial operation on the North Elizabeth 



meadow. 



At this point the danger which marsh enclosure involves should 



