326 Report S.A.A. Advancement of Science. 



the mechanical nature of the surface soil affords free aeration and 

 uninterrupted capillary movement, the plant will to a large extent 

 perpetuate itself by reseeding, always provided sufficient moisture is 

 available in the subsoil. Irrigation in a great measure assists self- 

 propagation, and counteracts the prejudicial effects of a heavy 

 surface soil, but it cannot altogether eliminate the disadvantages 

 arising from a close, heavy subsoil and a remote ground water level. 

 A study of the map throws considerable light on the peculiarity of these 

 water-carrying strata, for we notice at once the phenomenon that 

 characterises the rivers of what may be termed the " Central River 

 System." 



Commencing with the rivers flowing from the north, the Rio 

 Dulce starts in the Sierra de Aconquija in the Andes chain, traverses 

 the provinces of Tucuman and Santiago del Estero, and empties 

 itself into Lake Porongos on the northern border of Cordoba. The 

 Rios Catamarca and Fiambala cross Catamarca and disappear in the 

 sands of the province of Rioja. The Bermejo, El Zanjon, Castano, 

 and San Juan, the most important rivers of this system, are fed from 

 the snow-clad Cordillera de los Andes, and, flowing south-east, are 

 lost near Lake Huanacacho, in the province of San Juan. Further 

 south, the Mendoza, Tunuyan, Diamante, Atuel, and Desaguadero, 

 all of which take their rise in the Andes, flow east across Mendoza 

 into Mar Chiquita del Sur, in the territory of Pampa. The system 

 also includes the rivers Primero, Segundo, Tercero and Quarto, 

 starting in the Sierras de Achales, and the Quinto, whose source is 

 in the Sierra of San Luis, all of which disappear in the south-west 

 of the province of Cordoba. 



The regularity of the phenomenon is primarily owing to the 

 surface configuration, which is singularly level even up to the foot 

 of the Cordillera, and these, as is the case with the mountains already 

 mentioned, rise precipitously from the plains. I will not attempt to 

 formulate a precise dehnition of the relationship between these 

 rivers and the subterranean water found in the plains, but it seems 

 probable that from^ where they disappear, the water is conducted 

 through porous strata to the sand-beds, in which gravitation and 

 capillarity again bring it to the surface ; analogous facts on a smaller 

 scale have been observed in other parts of the world. 



It would not be possible in the time allowed me to enter at 

 length into the vast and manifold resources of the Argentine Repub- 

 lic. A few items must therefore suffice to show the strides that 

 have been made in population, enterprise, and wealth ; and of these 

 the pastoral and agricultural statistics are for the purpose of this 

 article particularly informing. 



The division of " Statistics and Rural Economies " has supplied 

 the following particulars :— The population in 1878 totalled 

 1,850,000; tliis had risen in 1895 to 4,094,911, and in 1901 to 

 5,026,913. Immigration between 1870 and 1880 was made up of 

 260,613, which increased in 1891 to 1900 to 648,326. The length 

 of railways open for traffic in the year 1880 was 1435 miles, a great 



