96 MALARIA 



for the removal of excess and seepage, and wherever 

 such provision is not made, standing water will ac- 

 cumulate in the low spots, not only causing unhealthy 

 conditions, but in some cases impairing the value of 

 the land by flooding on the deposit of alkali, as may be 

 seen in the San Joaquin Valley. 



Permanent control of malaria in the vicinity of 

 Penryn therefore depends on the control of waste 

 irrigation water by means of efficient drainage, the 

 provision of overflows and waterways from main ditches 

 and laterals, and the prevention of leaks and seepage 

 from the ditches. The Sacramento Valley Irrigation 

 Company, known as the Kuhn or Pittsburg Project, 

 at Willow, California, realizes this so thoroughly that 

 they are spending nearly as much money on drainage 

 works as on irrigation ditches. 



There are few places in the vicinity of Penryn where 

 the land is naturally swampy, and these places can be 

 cheaply remedied by assisting the natural drainage, 

 or in the case of the small pools, by filling. 



The work of the Field Agents in the past year has 

 been confined to temporary work almost exclusively, 

 as the funds available were not sufficient to do extensive 

 permanent work . Oiling methods have been employed 

 and some experiments were made with nicotine sul- 

 phate, a quantity of which was kindly donated by the 

 Kentucky Tobacco Products Company. While ef- 

 fective, the nicotine was found to be impracticable, 

 on account of expense, and it does not kill the larvae 



