472 



SCIENCE. 



[N. S. Vol. XVIII. No. 458. 



cates. As the same state of affairs exists in 

 many other libraries, it seemed to me that it 

 would be of mutual advantage to ourselves 

 and others to prepare a list giving the names 

 of both our own ' wants ' and of the publica- 

 tions we could supply to others, to assist them 

 in completing their files. This was done, 

 and mimeograph copies of the list were dis- 

 tributed to our correspondents and exchanges 

 during the latter part of 1901. The success 

 of the plan was marked, and for some of the 

 volumes on our list more inquiries and re- 

 quests were received than we could at that time 

 satisfy. In my annual report for that year 

 (1901, p. 13) I suggested that it might be of 

 value to develop this plan of mutual ex- 

 changes into a more comprehensive scheme, 

 having for its basis some large central ex- 

 change or ' clearing house ' to which all astro- 

 nomical and scientific libraries might send 

 their duplicate papers and publications, and 

 from which they might in return be able to 

 obtain the volumes or numbers of other pub- 

 lications required to complete their own sets. 

 The suggestion has met with favor- from many 

 scientific men, and it is hoped that some 

 arrangement may be made for carrying it 

 into effect at an early date. Some expense 

 is of course involved for correspondence and 

 the publication of exchange lists, but a large 

 part of this could be met by the payment of 

 a small annual fee, if a sufficient number of 

 societies and institutions would join in the 

 development of the plan. 



Since the publication of our first exchange 

 list two years ago, we have ourselves re- 

 ceived a large number of additional dupli- 

 cates, partly in exchange, and partly by pres- 

 entation. The most important gift of the 

 latter class was the one from Miss M. W. 

 Br\ice, whose valuable donation of her sister's 

 library to our collection was noted and ac- 

 knowledged in Science (Vol. XV., p. 758, 

 May 9, 1902) and more fully in my annual 

 report for the same year (' Miscellaneous Sci- 

 entific Papers of the Allegheny Observatory,' 

 No. 12, p. 9). In order to render these addi- 

 tional duplicates available for distribution we 

 have prepared a new exchange list which will 



be distributed to our regular correspondents, 

 and will also be sent on request to all inter- 

 ested. Correspondents desiring any of the 

 volumes on this list will kindly indicate the 

 titles of publications they are prepared to 

 offer in return, particularly any of those in- 

 cluded in our ' wants,' and we will accept all 

 equitable proposals for such exchanges and 

 fill them in the order in which they are re- 

 ceived. It is hardly necessary to state that 

 none of the volumes of this list are for sale, 

 but are only offered in exchange. 



In order to determine more fully the pos- 

 sible scope and usefulness of the general plan 

 of a central exchange bureau such as has been 

 proposed above, correspondents are requested 

 to give also a list of the publications which 

 they desire to obtain which are not included 

 in our present catalogue, together with a 

 list of all the duplicates in their own library 

 which they would be willing to send to this 

 bureau if it should be established for the pur- 

 poses indicated. If sufficient interest is mani- 

 fested and sufficient material offered to meet 

 the mutual ' wants ' of those willing to co- 

 operate in this plan, the Allegheny Observa- 

 tory wni undertake to furnish the requisite 

 facilities in the way of storage and packing 

 rooms, and will attend to the assorting, pack- 

 ing and correspondence necessary to effect 

 the exchanges desired on an equitable basis 

 to all parties concerned. 



F. L. O. Wadsworth. 



AlXEGHENT ObSEEVATORY, 



September, 1903. 



TOXIC EFFECT OF AND OH IONS ON SEEDLINGS 

 OF INDIAN CORN. 



In a recent article in these columns* on 

 'The Toxic Effect of H and OH Ions on 

 Seedlings of Indian Corn,' the author has 

 apparently overlooked my investigations pub- 

 lished some seven years ago.f In the part of 

 the article dealing with the effect of H ions 

 upon the seedlings of Indian corn the reader 

 is led to infer that the author is a pioneer. 



In my work I tested the effect not only of 



* Science, 18: 304. 1903. 



t' Toxic Effect of Dilute Solutions of Acids 

 and Salts on Plants,' Bot. Gaz., 22: 125. 1896. 



