576 WESTON 



ing heterothallism through involving self-sterility and cross-fertility to com- 

 patible opposites. 



In the case of the Basidiomycetes, a long and fruitful sequence of investiga- 

 tions from the pioneer work of Buller, Bensaude, Kniep, Vandendries, and 

 others, to the more recent investigations of J. R. Raper and his associates, 

 has revealed the interesting intricacies of the distinctive sexual reproduction 

 in this group, especially the notable migration of nuclei to achieve an extension 

 of diploidization, the frequency of occurrence of tetrapolar sexuality, and the 

 significant complications of heterokaryosis. Even the Fungi Imperfecti, whose 

 very status and existence as a classificational group implies the lack of sexual 

 reproduction, have been revealed by the work of Pontecorvo, of Roper, and of 

 K. B. Raper to possess the complicated mechanisms of heterokaryosis as a 

 substitute for sex. 



In general the fungi, with potentialities little suspected previously, have 

 been found during the past fifty years to be highly advantageous material 

 for the study of many significant aspects involved in the problems of sex and 

 have revealed complexities of behavior beside which the human patterns re- 

 ported by Kinsey, Havelock Ellis, Krafft-Ebing, Malinowski, and others show 

 a limited and naive simplicity. 



The third example is inherent in the marked success with which the exploita- 

 tion of mycological material has contributed to rapid and significant advances 

 in Genetics. In the early years of this half century, there was in this field 

 but little work with fungi. In the early 1920s, however, the pioneer work of 

 B. O. Dodge discovered Neurospora, the ascomycetous perfect phase of the 

 red bread molds, worked out the development and reproduction of the 

 eight- and four-spored species of this genus and pointed out their exciting 

 potentialities for genetic investigation. The geneticists, always ready to explore 

 and to exploit the possibilities of advantageous material, took up the study 

 of this easily manipulated mold and notable contributions such as those of 

 Beadle and his associates, showed that in addition to the rapid life cycle, 

 the ease of manipulation, the precision of the sequence of successive nuclear 

 divisions which led to the definite positional alignment of the spores in the 

 ascus, there were the additional advantageous features of hereditable and 

 readily assayed biochemical differences in the resulting strains. Thus, in the 

 case of this fungus, there was achieved a crossing over from Mycology to 

 Genetics and a change in its position from a recessive obscurity to a dominant 

 prominence. In a field which had been dominated by animals, by flitting fruit 

 flies, and hovering Habrobrachon, redolent with rats, squeaking with mice, 

 and twittering with guinea pigs, a field only sparsely garnished here and 

 there with plant material, such as primroses or corn, this colorful and catalytic 

 mold assumed a place of prominence. As a natural extension from this stimulus, 

 interest was aroused in other fungi with features advantageous for such in- 

 vestigation and work such as that of Edgerton and his students on Glomerella, 



