230 A CENTURY OF PROGRESS IN WE NATURAL SCIENCES 



more than sixty years later that J. H. Craigie (1927a, 1927b) demonstrated that 

 the spermatia are really functional male cells. When De Bary sowed the telio- 

 spores upon the wheat plants, however, he obtained no infection, although ure- 

 diospores were effective. Eemembering the tradition among the peasants that 

 barberry {Berheris vulgaris L.) caused the "blasting" of nearby wheat, he placed 

 the teliospores from wheat upon the barberry leaves and obtained spermogonia 

 and aecia. The mystery was solved. He coined the two terms to be applied to 

 rusts: "heteroecious" for those that alternated on two kinds of not closely re- 

 lated hosts and "autoecious" for those that could develop aecia and telia upon 

 the same host. His study of other rusts demonstrated that there were some in 

 which certain stages were lacking (e.g., aeciospores or urediospores or both), 

 so that only spermogonia and telia occurred, whereas in Endophyllutn the ure- 

 dia and telia were lacking and the aeciospores took over the function of the 

 teliospores and germinated by means of a promycelium which bore sporidia. 



In his later studies De Bary sought for the sexual organs in the Ascomycetes, 

 Mucorales, etc. ,To accomplish this he developed methods of growing the fungus 

 from a single spore in pure culture on sterilized liquid or solid media. Oscar 

 Brefeld, one of his students, learned these methods from him and improved 

 upon his technique. He published a series of fifteen Hefte entitled Botanische 

 Untersuchungen . . . (1872-1912) on various fungi, from the Mucorales, yeasts, 

 various other Ascomycetes, smuts, various other Basidiomycetes, etc. These show 

 great mastery of the methods but reveal that he missed the basic underlying 

 principles taught by De Bary, viz., that these techniques were to be used to dis- 

 cover the facts from which the unbiased conclusions could be drawn. Thus De 

 Bary had clearly shown that sexual reproduction did occur in some Ascomy- 

 cetes, as he had also demonstrated it in various species of Saprolegniales, Pero- 

 nosporales, and Mucorales, although in many of these fungi he showed that there 

 was a tendency toward the occurrence of apogamy or parthenogenesis, with the 

 partial or complete loss of the sexual organs. He considered this a downward 

 modification. Brefeld, on the contrary, developed the hypothesis that there was 

 no sexuality in the Ascomycetes or Basidiomycetes. With this in mind he made 

 his cultures to prove the correctness of the hypothesis. When Brefeld did ob- 

 serve what De Bary considered to be sexual organs, he claimed that they had 

 no sexual functions. It must be said, in excuse for his error, that he was so suc- 

 cessful in growing his fungi from single spores that he missed the demonstration 

 that would have been convincing, had he mated his cultures of opposite sexual 

 phases. He claimed that there were two evolutionary tendencies that had led 

 from the Phycomycetes to the higher fungi. In both of the lines, sexuality was 

 supposed to have disappeared. The asci in the Ascomycetes were, in his opinion, 

 modifications of the sporangia or zoosporangia while the basidia of the Basidio- 

 mycetes were modifications of the conidiophores of those Phycomycetes that pro- 

 duced conidia instead of sporangia. In both these lines he postulated a reduc- 

 tion of the number of spores from indefinite to eight or four in the Ascomycetes 

 or from indefinite to four in the Basidiomycetes. The genera of the former class 

 in which the asci produce many spores, e.g., Ascoidea, Theleholus, and Monascus, 

 he placed in the intermediary group, Hemiasci. It must be noted that later 

 studies of Monascus demonstrated that this actually produces many eight-spored 

 asci, tlie dissolution of whose ascus walls sets the ascospores free within the peri- 



