'^ Issued Deqeaibet 6, 1908. 



United States Department of Agriculture, 



OFFICE OF EXPERIMENT STATIONS-Circular 47 (Rev,). 

 A. C. Tkue, Director. 



THE CARD INDEX OF EXPERIMENT STATION LITERATURE. 



It is the purpose of this circular to outline briefly the general plan 

 of the subject index of experiment sLalion literature regularly issued 

 in card form by this Office, and to state the conditions governing the 

 distribution and sale of the index. 



The index at the present time covers only the publications of the 

 agricultural experiment stations in the United States, Alaska, Hawaii, 

 and Porto Rico. Of these publications the index includes all regular, 

 special, and technical bulletins and the reports, but not such publica- 

 tions as circulars and press bulletins, except as these are reprinted in 

 the other publications mentioned. Publications of this Department 

 and of State boards or departments of agricultxu-e are therefore not 

 included. The index begins with the publications of the stations for 

 the year 1888, and is kept as nearly up to date as is practicable. 



The index comprises thirteen primary divisions, as follows: (1) 

 General sciences, (2) air and water, (3) soils, (4) fertilizers, (5) plants, 

 (6) foods, (7) animals, (8) entomology, (9) dairying, (10) technology, 

 (11) agricultural engineering, (12) statistics, and (13) miscellaneous. 

 These subjects have been divided and subdivided only so far as seemed 

 necessarj' to facilitate reference to the individual entries of the index. 

 Under general sciences are placed only such entries as relate to the 

 general principles of the various sciences which lie at the foundation of 

 experimental investigations in agriculture. Under statistics are in- 

 cluded the entries relating to the organization, equipment, and general 

 operations of the stations. The other primary divisions provide for the 

 articles relating more directly to the agricultural and economic investi- 

 gations. The plan of the index permits the addition of references to any 

 literature relating to agriculture, and also affords a wide opportunity 

 for the extension of the index by individual students for their own 

 special purposes. 



Each of the divisions, as a rule, contains entries for all the important 

 articles on the subject. In some cases, however, an article, especially 

 of a popular nature, may deal with- several subjects and be indexed 

 only under the most important phase of the work. As an illustration 

 of this point, an article dealing with the use of fertilizers for field crops 

 on certain soils may appear only under one of the headings — Fertilizers, 

 Field Crops, or Soils. This has been necessary in order to keep the 



