HISTORICAL. O 



detail. The following accounts are of these researches in which the term 

 indicator is actually employed or in which the use of instrument, quadrat, or 

 sucessional methods gives them distinct indicator objectives. 



AGRICULTURAL INDICATORS. 



Hilgard, 1860. The following excerpt will serve to show that Hilgard was 

 the first investigator to recognize clearly the importance of indicators in soil 

 studies and to make actual use of them in determining the agricultural possi- 

 bilities of new lands. A further account of his views and results is given on 

 a later page. 



"Judging of land by its natural vegetation. The distinction just men- 

 tioned, so far from being of merely theoretical value, is one of the highest 

 practical importance. Agriculturists are accustomed to judge of the quaUty 

 of lands by the natural vegetation which they find upon it; and they rarely 

 direct their attention to anything but the forest trees. Yet these are, for the 

 most part, indicative rather of what, in the agricultural sense is termed the 

 subsoil, than that of the surface stratum usually turned by the plow, in the 

 shallow tillage prevaiUng at present, which may be of a totally different 

 character. 



"As a general thing, the forest growth when considered not only with regard 

 to the kind (species), but also to the form and size of the trees, is a very safe 

 guide in judging of the quahty of land, and the systematic study of the subject 

 in connection with analyses of soils, promises results of a highly practical 

 importance, which it is intended to communicate more fully in a future report. 

 But this criterion may not infrequently lead to grave mistakes unless a proper 

 examination of the soil and subsoil be made at the same time. 



"These examples may suffice to show that while in the forest trees we possess 

 trustworthy guides to a knowledge of the character of the material in which 

 their roots are buried, it is quite essential to determine at the same time, by 

 inspection, that it is the arable soil itself, and not merely the subsoil, which is 

 thus characterized ; and we should especially make sure that the smaller plants, 

 viz, the shrubs and perennials, corroborate the evidence of the trees. Annuals 

 are less reliable in their indications because their development is to a greater 

 extent influenced by the accidental circumstances of the seasons." 



Chamberlin, 1877. Chamberlin shares with Hilgard the honor of being a 

 pioneer in the use of native plants to indicate the agricultural possibihties of 

 a region (1877 : 176). He deserves especial credit for being the first to recog- 

 nize that the community was a better indicator than the species, and for classi- 

 fying the vegetation of Wisconsin into communities with more or less definite 

 indicator value. Several of ChamberUn's associates on the Geological Survey 

 of Wisconsin made more or less use of his system of indicators (Woo'ster, 1882: 

 146; King, 1882: 614; Irving, 1880: 89), though it unfortunately appears to 

 have remained unknown to botanists, and consequently led to no further work 

 in this field. 



"The most reliable natural indications of the agricultural capabiUties of a 

 district are to be found in its native vegetation. The natural flora may be 

 regarded as the result of nature's experiments in crop raising through the 

 thousands of years that have elapsed since the region became covered with 

 vegetation. If we set aside the inherent nature of the several plants, the 

 native vegetation may be regarded as a natural correlation of the combined 

 agricultural influences of soil, climate, topography, drainage and underlying 



