XIV. OUTLINE OF THE HISTORY OF LEGU- 

 MINOUS ROOT NODULES AND RHIZOBIA 

 WITH TITLES OF LITERATURE CON- 

 CERNING THE FIXATION OF FREE 

 NITROGEN BY PLANTS. III. 



ALBERT SCHNEIDER. 



The first and by far the greatest installment of titles was col- 

 lected by Dr. D. T. MacDougal and appeared in the MINNE- 

 SOTA BOTANICAL STUDIES, issue of September 27, 1894. The 

 second installment, by the writer, appeared in the same jour- 

 nal, issue of May 31, 1897. In all about 780 titles are given. 

 It is not intended to imply that the list of titles is complete. 

 There are undoubtedly numerous omissions and many of them 

 very important. The writer would be very grateful if those 

 interested would supply from time to time titles not already 

 given. 



At some future time it is intended to prepare a fairly com- 

 plete history of the study of leguminous root nodules, and rhi- 

 zobia, accompanied by a citation up to date of the more impor- 

 tant titles on the subject, giving the titles in alphabetical as well 

 as in chronological order. Such a record is intended for the 

 benefit of future investigators. The following preliminary out- 

 line is intended to indicate the plan which is to be followed and 

 suggestions and criticisms would be highly appreciated. 



FIRST PERIOD : INITIAL STUDY OF LEGUMINOUS ROOT TUBER- 

 CLES FROM CLOS (1848) TO LAWES AND GILBERT (1860). 

 During this period nothing of marked scientific value was 

 done regarding the root tubercles of leguminous plants. Occa- 

 sional attention was called to their presence and theoretical or 

 hypothetical assumptions were made regarding their function 

 and structural nature. Clos was among the first to make more 

 extended observations and call especial attention to them, ex- 

 pressing it as his opinion that they were lenticular outgrowths 

 of the roots. Malpighi was perhaps the first author of note to 



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