270 



RESEARCHES ON FUNGI 



may have only two kinds of spores, {A) and (a), as in Coprinus 

 Rostrupianus ^ and Fomes pinicola,^ or it may have 

 four kinds of spores, (AB), (ab), (Ab), and (aB), as 

 in Coprinus lagopus,^ Armillaria mucida,^ Schizo- 

 commune,^ and Aleurodiscus polygonius.^ 

 The spores of any heterothallic species are haploid 



and give rise to haploid 

 myceUa (Fig. 140), the 

 nuclei of which we may 

 suppose contain n chromo- 

 somes ; and, when two hap- 

 loid myceha of opposite sex 

 come into contact, they 

 unite with one another by 

 means of hyphal fusions 

 and convert one another 

 into diploid myceUa (Figs. 

 141, 142, and 145; also 

 Plates I-II). The diploid 

 myceha thus produced al- 

 ways contain conjugate 



Fig. 141. — Coprinus lagopus. Diagram showing 

 two haploid myoelia of opposite sex, (AB) 

 on right (black nuclei), (ab) on left (white 

 nuclei), each derived from a single basidio- 

 spore. Note the simple septa, the wide- 

 angled mode of branching, the oidiophores 

 with their groups of oidia, and the isolated 

 nuclei. The two mycelia have just effected 



a hyphal fusion and, in the fusion cell, an 



(AB) nucleus and an (ab) nucleus have . 1 • / \ 1/ \ A 



become associated as a pair of conjugate pairs 01 nuclei (n)-f-(n) and. 



",wt!- The diploid cell is able to diploidise never isolated (2n) nuclei. 



all the other cells of both mycelia by a ^ ' 



process illustrated in Fig. 145. Highly The number of pairs of 



magnified. . , 1 • • • n 



conjugate nuclei originally 



formed in a hymenomycetous haploid mycehum during the 



1 Dorothy E. Newton, "The Bisexuality of Individual Strains of Coprinus 

 Rostrupianus,'''' Annals of Botany, vol. xl, 1926, pp. 105-128. 



2 Irene Mounce, " Studies in Forest Pathology. II. The Biology of Fomes 

 pinicola," Dominion of Canada, Dept. of Agric, Bull. Ill, 1929, pp. 1-74. 



3 W. F. Hanna, " The Problem of Sex in Coprinus lagopus,'" Annuls of Botany, 

 vol. xxxix, 1925, pp. 431-457. 



* Hans Kniep, " Uber morphologische und physiologische Geschlechts- 

 dififerenzierung (Untersuchungen an Basidiomyceten)," Verh. Physik.-mediz. Ges. 

 Wurzburg, Bd. XLVI, 1920, pp. 1-18. 



^ Hans Kniep, ibid. ; also Die Sezualitdt der niederen Pflanzen, Jena, 1928, 

 pp. 1-544. 



^ Hans Kniep, " tjber Geschlechtsbestimmung und Reduktionsteilung," Verh. 

 Physik.-mediz. Ges. Wurzburg, Bd. XLVII, 1922, pp. 1-28. 



