a cost of less than one cent per page, since more than 300 pages are furnished 

 per volume. The average number of entries per page is now 6.76. 



Statements to cover volumes V and VI will be rendered on the basis of 

 $6.00 for the United States and dependencies; $6.25 for Canada; and $6.50 

 for other countries. 



AUTHOR INDEXES 



The author index for volume II was sent out with the July (1920) issue. 

 Author indexes for volumes III and IV are in preparation, and they will be 

 sent to subscribers as rapidly as possible. It is planned to improve the 

 author index, for volume III and thereafter, by inserting abbreviated and 

 distinctive titles, so that these indexes together with the tables of contents for 

 the several volumes, may partially take the place of annual subject indexes. 



SUBJECT INDEXES 



The important problem of subject-indexing botanical and other scientific 

 literature is receiving much serious attention in many quarters and it is 

 hoped that a satisfactory and feasible system for this indexing may be 

 worked out in the near future. While it has been disappointing not to be 

 able to publish a subject index for volumes I and II together, as was origi- 

 nally planned, various difficulties and bibliographic considerations have ren- 

 dered the decision necessary not to issue any subject index until after six 

 volumes have appeared. When issued, the subject index will be sold by 

 subscription. The first subject index will be announced in due time. 



PLANS FOR 1921 



Beginning with January, 1921, subscribers will be rendered statements 

 to cover Volumes VII and Mil (averaging 300 text pages each). It is 

 now hoped that 650 pages will be sufficient to carry the 1921 material. 

 The subscribers, however, should be prepared for a larger or smaller 

 number of pages, as this matter of pages to be published will be deter- 

 mined by the amount of literature to be cared for. 



THE PUBLISHERS. 



