288 The Plant World. 



ready established in businesses equally legitimate and necessary- 

 It has been suggested that one way to avoid trouble which 

 the unrestricted operation of manufacturing plants of certain 

 sorts has produced, is for the owners of these works to buy up 

 surrounding country. In such a proposal as this the nation, as 

 well as the individual owner has an interest; for as the nation is 

 interested, as a consumer of food, in the production of food in 

 sufficient quantity, at a sufficiently low price to insure its being 

 obtainable by all, so the nation is directly concerned in anything 

 which may interfere with the production of food. When land 

 which is best suited to the production of food is bought by a 

 manufacturing concern and made idle by the operation of the 

 works, the food supply of the nation is correspondingly decreased. 

 If the principle of buying out producers who might otherwise 

 interfere with or make trouble for the owners of manufacturing 

 works is indefinitely extended, we shall find the area from which 

 food can be supplied correspondingly decreasing. In this there 

 seems to be a principle to be very carefully considered before 

 the practice is allowed to extend. 

 Stanford University, California. 



THE EFFECT OF CEMENT DUST ON CITRUS TREES. 



By S. B. P.\rish. 



Slover Mountain is an isolated upheaval of limestone, rising 

 abruptly from the fertile mesa lands of the San Bernardino 

 Valley. Its altitude is perhaps 500 feet, and its circumference 

 is some two miles. From its very base, mile after mile, extends 

 an almost uninterrupted succession of orange and lemon or- 

 chards. Some years ago a small cement mill was built at the 

 northern foot of the mountain, and it has grown, with the in- 

 creasing demand for its product, to be an establishment of con- 

 siderable size; and now a still larger mill has been built on the 

 southern side of the mountain. From these mills dust is poured 

 forth in vast clouds, which is carried by the winds over the sur- 

 rounding country, and settles down over everything therein 

 situated. The presence of this dust can be readily detected at 

 distances of three miles, but its seriously injurious effects are 



