X. CONTRIBUTION TO THE LIFE-HISTORY OF 



RUMEX. 



Bruce Fink. 



Introduction. — The preliminary work leading to the present 

 paper was nearly all done in the botanical laboratories of the 

 University of Minnesota during the summers of 1896 and 1897. 

 This work included a study of the macrosporangia and their con- 

 tents in Bursa bursa-pastorts (L.) Britten, Stlene antirrhina 

 L., Polygonum erectum L., Rumcx acctosclla L., Rumex salici- 

 folius Weinm., and Rumcx vcrticillatus L. 



At the close of the season of 1897, I had about an equal num- 

 ber of good preparations of the last two species and had learned 

 that Rumex vcrticillatus is a much more favorable plant for 

 study than Rumcx salicifolius because of the larger size of the 

 structures to be investigated. Consequently, during the latter 

 part of x\ugust, 1897, after previous study of the former plant 

 had enabled me to select methods which seemed best adapted to 

 my purpose, a large number of flowers and buds, selected to 

 represent various stages of development of the gametophyte, 

 were preserved for future study. During the summer of 1898 

 over three thousand macrosporangia were sectioned, and the 

 drawings presented with this paper were reproduced from the 

 preparations that gave the best results. Rumcx salicifolius 

 was also further studied in 1898, and the series of slides of this 

 plant is nearly as complete as that for Rumex vcrticillatus. As 

 the two plants gave very similar results, except for size of 

 structures, I have not thought it necessary to multiply figures by 

 giving a full series for both plants. The figures then are, in 

 the main, drawn from preparations from the latter plant ; those 

 from the former being introduced only when the equivalent 

 phases of development were not found in the other plant, or 

 were poorly exhibited in the preparations. 



The plants of the genus studied are not well adapted to the 



