6 



on. The vrater lost by the surface evaporation is replaced by moisture 

 drawn up from below by capillary action. The water coming from be- 

 low contains a certain quantity of the soluble salts of the soil which it 

 has taken up on its way : as the water evaporates at the surface the 

 salts must be left behind, and a constant accumulation of the salt takes 

 place on the evaporating surface. Where such efflorescence takes place 

 at a disk nee from a canal, and where no free percolation takes place 

 it rxay possibly be explained by the action of an impervious stratum 

 of clay (or kunkur) at some depth below the surface, which arrests the 

 descent of water derived from the fall of rain (or irrigation), and accu- 

 mulated from a large area into some natural depression, and held as it 

 were, in a basin, though of ccurse diffused in the subsoil from which 

 the great summer heats at length extract the whole of it with the same 

 result as before suggested. — Prom " The Progress and Position of Ir- 

 rigation in New South Wales," by PL. G. McKinney. 



HEALTH AND IRRIGATION. 



The notion that iriigated rice fields are unhealthy has led to the 

 abandonment of rice-growing in France and Portugal. But it is only 

 when thela}er of water is exceptionally shallow or discontinuous as well 

 as stagnant, that bad effects on the health of the district have followed. 

 It is at the clcse of the growing season, when during very hot weather 

 the vater no longer covers 1 he soil, and also in the case of badly-planned 

 ard badly- managed rice fields, that there is danger from the rapid de- 

 composition of organic matters in the earth. — (Encyclopaedia Britannica.) 



DISEASED LEMON TREES. 



From Professor Pr. D. T. MacPougal to Director of Public Gardens, 



New York Botanical Garden, Bnnx Park, 

 New York City. 



Dear Mr. Fawcett, 



Your letter with the diseased specimen of lemon tree came duly to 

 hand. I have submitted the specimen to Professor Underwood, and 

 several of his men, and none of them can tell me anything about it. 

 As a last lesource I sent it over to Washington to be examined by Mr. 

 Webber who tnews mere about the diseases of the citrus trees than 

 any one else in the country. His letter is enclosed herewith, and 

 yeu v> ill see tl at it has not appeared in this country sufficiently toen able 

 him to find out anything about it. 



Cur failure to give you anjthirg definite abeut the various diseased 

 specimens you have sent me from time to time, impi esses me with the 

 necessity cf havirg seme one actually on the gronnd to work on your 

 plants, and I wish veiy much we could co-ojerate in getting a rrycolo- 

 gist to woik over Jamaica for a season or two. I have no definite pro- 

 position to mi;ke, however, as our exploration fund has already been 

 planned for the present year. 



Meanwhile I hope you will continue to send us anything you wish 

 examined, and we will do our best. Jamaica seems to have a series of 

 plant ailments quite different from those of Florida. 



D. T. MacDougal. 



