1917] DUNN—DUMONTIA 427 



fleisch 4). The next epoch making paper in the study of the red 

 algae was that by Oltmanns (9). Oltmanns worked out very 

 carefully and in much detail the nuclear and cell history during 

 fertilization and carpospore formation in Dudresnaya, Gloeosiphonia, 

 and Dasya. Oltmanns' chief contribution was the convincing 

 evidence that the nucleus functioning in the auxiliary cell at the 

 time of the formation of the carpospores is a descendant of the 

 fusion nucleus in the carpogonium, and that no other nuclear 

 fusion has occurred. Oltmanns' descriptions are detailed and his 

 illustrations are remarkably clear, but nevertheless some present 

 day botanists question his observations concerning the absence of 

 a fusion between the nucleus in the auxiliary cell and that nucleus 

 which enters it from the sporogenous filament. These botanists 

 are inclined to believe that in the members of the Crytonemiales, as 

 in certain of the Ascomycetes, there are two nuclear fusions at the 

 time of fertilization. Dumontia and Dudresnaya belong to the 

 same family, Dumontiaceae, and it is to be expected therefore 

 that the two genera will have similar reproductive organs. In 

 view of the fact that Oltmanns' results have been questioned by 

 some workers, the present investigation of Dumontia filiformis 

 was undertaken for the purpose of gaining all possible information 

 concerning the behavior of the nuclei during fertilization and the 

 formation of the carpospores. It was also desired to gain informa- 

 tion concerning the general structure of this alga, the cytology 

 of its tetraspores, and the structure of its male reproductive 

 organs. 



This study was begun in June 19 13, at the Harps well Labora- 

 tory, South Harpswell, Maine, where the plants were abundant. 

 It was continued during 1913, 1914, and 1915 at South Harpswell 

 and at Johns Hopkins University. 



The writer wishes to thank Professor J. S. Kingsley for the 

 privileges of the Harpswell Laboratory, and also Dr. M. A. Howe 

 and Mr. F. S. Collins for identifying this alga. This investigation 

 was undertaken at the suggestion of Professor D. S. Johnson, 

 under whose directions it has been carried out, and whose criticisms 

 have been a constant source of aid. Dr. W. D. Hoyt also has 

 kindly examined many of the preparations. 



