io RESEARCHES ON FUNGI 



undoubtedly complete, was also observed in mixed cultures of 

 Septoria apii and S. petroselini, but not in mixed cultures of other 

 Septoria species. In consequence of having made these observations 

 Laibach suggested that fusion phenomena may possibly be of 

 assistance in deciding upon the affinity of doubtful forms. 



In 1902, Arthur Meyer l gave a list of fungi in which hyphal 

 fusions had been found and discussed the physiological significance 

 of the channels which hyphal fusions provide. He illustrated a 

 tip-to-tip fusion of two hypliae of Hypomyces rosellus in a series of 

 four drawings much resembling similar drawings made by Marshall 

 Ward. He thought that a side-branch which took part in a fusion 

 was produced only after a younger hypha had touched the side of 

 an older hypha, but this may have been due to insufficiently close 

 observation at the moment when the side-branch first began to 

 appear. 



In 1924, Burgeff, 2 in an important paper, analysed the reactions 

 which take place between (+) and (— ) mycelia of the Mucorineae 

 at the time when the sexual process is initiated and zygophores 

 and zygospores are being formed. He confirmed Blakeslee's dis- 

 covery that (+) and (— ) zygophores grow toward one another 

 through the air (cf. Volume IV, Fig. 84, p. 153). Thus, in an experi- 

 ment with Mucor hiemalis, he 3 set two strips of agar, one containing 

 a ( + ) mycelium and the other a (— ) mycelium, 1- 5-2-0 mm. apart 

 and observed that the two mycelia produced ( + ) and (— ) zygo- 

 phores which grew toward one another through the air and across 

 the gap between the two pieces of agar until they met. In another 

 experiment with Mucor Mucedo he 4 separated two pieces of agar, 

 one containing a (+) mycelium and the other a (— ) mycelium, by a 

 celluloid membrane, and he observed that the mycelia mutually 

 stimulated one another through the membrane in such a way that 

 they both produced zygophores and so that the (-f ) and ( — ) zygo- 

 phores grew toward one another, although prevented by the 

 membrane from coming into contact. 



1 Arthur Meyer, " Die Plasmaverbindungen und die Fusionen der Pilze der 

 Florideenreihe," ~Bot. Zeit., Jahrg. LX, pp. 162-163, Taf. VI, Figs. 29-31. 



2 H. Burgeff, " Untersuchungen iiber Sexualitat und Parasitismus bei Mucorineen. 

 I," Goebel*s Botmiisch AbhandJungen, Heft IV, 1924, pp. 1-135. 



3 Ibid., pp. 14-15. 4 Ibid., pp. 20-23. 



