I50 



SCIENCE. 



[Vol. XVI. No. 397 



fects of fatigue on the following day. Both practice and 

 fatigue are subject to large individual variations. Oehrn 

 lias studied the minor variations of practice and fatigue in a 

 session of two hours' work, finding first a stage in vrhich 

 practice outweighs fatigue, and then a stage in which the 

 reverse is true. 



(8) Miscellaneous and Individual Variations. The 

 complex re-actions, just as the simple ones are subject to the 

 influences of distraction, vary under the action of drugs, in 

 morbid conditions, and present large individual variations. 

 These points, though frequently noticed incidentally, have 

 not been subjected to special study, so that briefly citable 

 and conclusive figures are lacking. Regarding the action of 

 drugs, Kraepelin is inclined to believe that the distinction 

 is, under their influence, almost always rendered more difli- 

 cult, being only slightly subject to the period of shortened 

 times, while the choice factor very readily becomes shorter 

 than the normal. Marie Walitzkaja finds that the complex 

 re-actioi? times in the insane differ more from the normal 

 than do their simple times. An adaptive re-action for the 

 two hands which for the normal required 351-406(r, required 

 707-9430' in cases of general paralysis, and IjOSSff in a case 

 of mania. These should, however, be regarded as individ- 

 ual rather than general results. The individual variations 

 may be regarded as increasing with the complexity of the 

 re-action. Men differ more from one another in the time 

 needed for doing difficult things than in the time needed for 

 simple things. Systematic experimentation upon this point 

 is lacking: but a suggestion of the truth may be obtained by 

 calculating the average deviation from their mean, of Mer- 

 kel's ten subjects in their simple re-action times, their sub- 

 jective distinction times, and their adaptive re-action times; 

 the result being 2.23 per cent, 3.35 per cent, and 6.79 per 

 cent. Joseph Jasteow. 



[To be continued.] 



LETTERS TO THE EDITOR. 



*** Correspondents are requested to be as brief as possible. The writer's name 

 is in all cases required as proof of good faith. 



The editor will be glad to publish any queries consonant with the character 

 of the journal. 



On request, twenty copies of the number containing his communication will 

 i>e furnished free to any correspondejit. 



A Study of California Soils. 



The material greatness of California rests, in the last analysis, 

 Tipon the vast range and high native fertility of its soils. Cali- 

 fornia is a State with but few deposits of coal and iron, though 

 possessing almost every other kind of mineral. Its food-produ- 

 cing resources, as shown by the character and extent of its soils, 

 are very much beyond any thing that the Californians themselves 

 have ever claimed. 



The longest report on California soils that has ever appeared is 

 that in the "Tenth Census Report;" but the work of soil-analysis 

 ias been going on ever since, and the larger number of the State 

 University's agricultural bulletins are devoted to this and cognate 

 subjects. The agricultural subdivisions adopted are as follows: 

 the Sacramento valley; the San Joaquin valley; the Sierra foot- 

 hills; the southern or Los Angeles region; the coast region north 

 of San Francisco and San Pablo Bays; the coast region south of 

 those bajs. 



In all of these districts the variety of soils is very great. Only 

 a few especially representative soils can be tabulated at length in 

 this article. The Sacramento valley, for instance, contains a 

 great variety of rich sediment soils, gray or dun-colored, powdery 

 loam, very rich and easy of tillage; also dark adobe loams, mod- 



erately heavy, paler in color a foot below the surface; also clay 

 loams, brown-black when wet; also heavy, black adobes, the 

 strongest of wheat-lands; also light, grayish-yellow "slickens,'' 

 the mining debris deposit. All these soils have a sufficient and 

 often a very generous supply of lime. In all the alluvial soils the 

 amount of potash is large, sometimes very large. The supply of 

 phosphates is not large. Professor Hilgard sums up the Sacra- 

 mento valley lands by saying that the predominant soils are 

 "fine-grained alluvial loams, with extensive belts of heavy clay," 

 or, in the California phrase, ' ' adobe lands." The California adobe 

 is much like the black prairie soil of the Mississippi, but the 

 phosphoric acid supply is one-third higher. 



Sacramento Valley Soils. 



Insoluble matter, and silica 



Potash 



Soda.. 



Lime . . 



Magn 



Br. oxide of manganese 



Peroxide of iron 



Sulphuric acid 



Alumina 



Phosphoric acid 



Water and organic matter. . 



Total 



Elver 

 Alluvium. 



.077 

 1.444 

 8.877 



.015 



10.397 

 .C87 

 5.351 



Blacli 

 Lcam Sou. 



99.578 



Valley 

 Soil. 



Mining 

 Sediment. 



6 586 



.067 



14.889 



.078 



8.084 



In the great San Joaquin valley the prevailing character of the 

 soil is sandy, often very coarse. There are also black adobes in 

 narrow belts, near the rivers or sloughs, and hillocky plateau 

 lands, either loamy or of gravelly clay, with much hard-pan. 

 The "red soil" of the foot-hills shows many distinct sorts. 

 Orange-red is nearly the prevailing tint. Red loam, red gravel, 



Saw Joaquin Valley Soils. 



wire- 

 Grass 

 Laud. 



Insoluble matter and soluble silica 



Potash. 



Soda 



Lime 



Magnesia. 



Br. oxide of manganese 



Peroxide of iron 



Alumina 



Phosphoric acid 



Sulphuric acid 



Carbonic acid 



Water and organic matter .. 



Total 



red clay, and the red soil of the placer mines, filled with decom- 

 posed slate, are among the kinds of Sierra foot-hills soils. The 

 color comes from the presence of four to twelve per cent of iron 

 oxide. The average of phosphates is low, but in some districts 

 the supply is all that can be desired. These soils are eminently 

 well adapted to vines, fruit-trees, and vegetables. In the Coast 



