NOTES. 447 



ence of the forest to be equal in value to five or six inches 

 of rainfall, this amount of moisture being saved by its 

 presence. 



Among recent papers which possess the highest value in 

 describing the movements of water in the ground, and thus 

 throw light on a most important phase of the whole subject. 

 Bulletin 32 of the Experiment Station, Fort Collins, Colo., by 

 Professor L. G. Carpenter, is noteworthy. Professor Carpen- 

 ter shows that it is possible by mechanical means (ditches in 

 this case) to prevent the rapid run-off in high-water time and 

 thus produce a steadier flow of a stream and also raise the 

 level of the ground water, as well as saturate large areas of 

 otherwise arid land. In other words, he shows that in Colo- 

 rado the work of irrigation has resulted in a rise in the level 

 of the ground water, changing deep wells into shallow ones ; 

 that it has taken water out of the Platte and Cache la Poudre 

 rivers, and saturated thousands of acres of formerly arid land, 

 the seepage of which has changed dry branches into steady 

 rivulets, and supplies already a steady inflow into the rivers, 

 from which the water is taken above the fields. This inflow 

 tends to make these rivers steady and uniform sources of 

 water supply, and makes irrigation possible at points below 

 where in former times such irrigation would have been out of 

 the question. 



P. 78. Sanitary Influence. — The theories of the develop- 

 ment of the various pathogenic bacilli in the soil which were 

 based on Pettenkoffer's authority have lately been discarded, 

 and the origin of malaria has also experienced a different ex- 

 planation by some authorities. The general statement that 

 the forest soils, being removed from the contact with man's 

 occupations, is usually less favorable to the propagation of 

 pathogenic microbes remains true, and at least this indirect 

 relation of soil conditions to malaria exists, namely, that the 

 mosquito, which is considered the direct breeder of the disease, 

 is dependent for its development on swampy conditions of 

 soU, stagnant water, pools, etc. 



