I'EBKUABY 27, 1914] 



SCIENCE 



315 



Barker (1902), seemed to establish the 

 occurrence of a nuclear fusion in the oogo- 

 nium in these forms also. This, with 

 Harper's, work made it seem probable that 

 this fusion is a frequent phenomenon 

 throughout the aseomyeetes in general. 



The researches of certain other cyto- 

 logical workers, however, convinced them 

 "that no fusion of nuclei really occurs in the 

 ■oogonium of the aseomyeetes studied by 

 -them. Thus Dangeard (1897 and 1907), 

 working on SpJiwrotheca and Erysibe, 

 found no fusion except that in the ascus. 

 Claussen (1907) and Brown (1909) could 

 find no other in the varieties of Pyronema 

 studied by them. Both workers find paired 

 nuclei associated in the aseogenous hyphse 

 and finally in the young ascus. Claussen, 

 'therefore, regards the fusion in the young 

 ascus as a fusion of descendants of the sex- 

 ual nuclei that were brought together in the 

 oogonium but did not fuse there. In other 

 words, he thinks it a real sexual fusion which 

 has been deferred. Brown, on the other 

 hand, says that in his plant no antheridial 

 nuclei are concerned, since the antheridium 

 never reaches the oogonium. He therefore 

 regards the fusion of pairs of nuclei, de- 

 rived from the oogonium, which occurs in 

 the ascus, as one that serves as a substitute 

 for the sexual fusion that primitively 

 occurred in the oogonium. Brown's view 

 is supported further by his work on 

 Lachnea (1911), and by Faull's recent 

 work (1912) on certain Laboulbenias. 



If this view of Brown's be accepted it 

 implies that the original diploid condition 

 of the cells of the sporophyte has been al- 

 together eliminated, except for the brief 

 uninucleate stage of the ascus. In spite of 

 :this, however, the whole structure and devel- 

 opment of the original 2X generation, from 

 fertilized oogonium to mature fruit and 

 ascus, has been retained. This same normal 

 ;type of vegetative structure, in spite of an ab- 



normal chromosome number, has been demon- 

 strated in gametophyte and sporophyte 

 of aposporous and apogamous mosses and 

 ferns. It is implied also in Lewis's sug- 

 gestion that, in the red seaweeds, the reduc- 

 tion has been postponed from its original 

 location at carpospore-formation over into 

 the primitively haploid tetrasporic phase of 

 the next generation. 



Still other recent work on the aseomy- 

 eetes, however, supports Harper's view that 

 a double fusion frequently occurs in the 

 aseomyeetes. Thus Blaekman and Fraser 

 (1906), Fraser (1907-08) and Fraser and 

 Brooks (1909), find evidence of several 

 degrees of loss of function of the antheridia 

 in the different species of the cup fungi 

 Lachnea and Eumaria. In those cases 

 where no antheridial nuclei are discharged 

 into the oogonium, nuclei of this organ itself 

 are believed, by these workers, to fuse in 

 pairs within it. The later fusion in the 

 ascus, which they find in common with all 

 workers, they regard as a nutritive phe- 

 nomenon. 



Until toward the end of last century the 

 basidiomyeetes were generally assumed not 

 to be sexual. At least no sexual organs had 

 been described for them, with the exception 

 of the spermagonia and Eecidia of the plant 

 rusts. These had been called male and fe- 

 male organs, respectively, by Meyen, before 

 the middle of the century. The very first 

 nuclear studies of the rusts and toadstools, 

 however, revealed the occurrence of a nu- 

 clear fusion, and at another point in the life 

 history, indications of the complementary 

 process, a reduction, were discovered. 



In the case of the rusts Rosen (1892) 

 saw two nuclei in the agcidiospore of certain 

 species. Dangeard and Sapin-Trouffy 

 (1893) reported the occurrence of a nuclear 

 fusion in the teleutospore. Sapin-Trouffy 

 (1896) found that the cells of the Eeeidium- 

 bearing mycelium are uninucleate up to the 



