Heterothallism and similar phenomena 13 
structures. The whole series of arguments may be profitably studied 
in his papers ( 29 , 30 , 31 ). 
The opinion of Maire and of Miss Nichols ( 36 ), it may be remem¬ 
bered, is that, in the forms investigated by them, the binucleate con¬ 
ditions arose by simple division from the uninucleate condition. This 
may well be in some forms. Kniep, some few years ago, showed 
that in Armillaria mellea, basidia can arise on a uninucleate mycelium, 
so that here the conjugate stage is entirely left out( 28 ). Miss 
Bensaude( 3 , 4 ), in a preliminary statement has briefly recorded her 
observations on an unnamed species of Coprinus , and her full thesis 
has since appeared: in this she describes the development of 
Armillaria mucida, Tricholoma nudum, and especially of Coprinus 
fimetarius. The hyphce of the mycelium formed from a single spore 
exhibited anastomoses, but no clamp-connections, and never gave 
rise to the binucleate condition nor did they form fruit bodies. With 
mixed sowings, however, migrations take place after cell-fusions, the 
fusions being between mycelium and oidium or another mycelium; 
and in this manner the binucleate condition is brought about. 
Miss Bensaude is therefore of the opinion that the species of Coprinus 
investigated by her is heterothallic like some of the Mucors. Brefeld 
was able to grow fruit bodies, of another species of Coprinus, from 
one spore, so that Miss Bensaude does not expect that the method 
discovered by her will be found to be general among the Higher 
Basidiomycetes. The way in which the nuclear association is brought 
about reminds one of the similar process in Humaria rutilans{%±) 
—except that here nuclear fusions immediately follow the binucleate 
condition—and more especially of the state of affairs in the Ure- 
dineae( 37 ) and in the Hemibasidii(2), in some of which the conju¬ 
gate condition continues for a considerable period. No phenomena 
suggesting the occurrence of heterothallism have been met with in 
the Uredineae, Bunts or Smuts. 
In one genus of the Ascomycetes a phenomenon that seems allied 
to heterothallism has been found by Edgerton(20, 21). Here what had 
been formerly regarded as two different species of Glomerella are 
found to produce a larger number of fruits than are formed by 
either mycelium alone and under conditions that do not seem to 
point to hybridization. 
This fungus forms but few ascocarps in the minus mycelium and 
the asci are small; a considerable number of asci are formed on the 
plus mycelium; at the junction of the two kinds of mycelium the 
perithecia form abundantly and contain large, well-developed asci, 
