256 Transactions British Mycological Society. 
I desire to express my thanks to Miss G. Lister, F.L.S., for 
examining and identifying many of the specimens, for much 
kindly help in the preparation of the paper and for seeing it 
through the printer’s hands. I am indebted to Mr F. T. Chipp, 
F.L.S., for reading over part of the original rough notes and for 
supplying me with information as regards previous records of 
Malayan Mycetozoa. 
HOMOTHALLISM AND HETEROTHALLISM 
IN THE GENUS COPRINUS. 
By Irene Mounce, M.A. (British Columbia), Hudson’s Bay 
Company Research Fellow, University of Manitoba. 
I. INTRODUCTION. 
In 1918 Mlle Bensaude* brought forward experimental and 
cytological evidence which appeared to prove that Coprinus 
fimetarius is heterothallic; and in 1919 Hans Kniepf, after 
making a similar investigation, came to the conclusion that 
heterothallism is characteristic of Schizophyllum commune and 
of a number of other Hymenomycetes. 
In 1921, in a paper published in these Transactions, I recorded 
that clamp-connections had regularly appeared in mycelia of 
monosporous origin in Coprinus sterquilinus, C. stercorarius, 
C. lagopus and C. niveus, and that I had therefore come to the 
conclusion that all these four species are homothallicf. This 
paper was sent to England for publication in May 1921. The 
following autumn, on resuming my investigations, I made a 
large number of monosporous cultures of Coprinus lagopus but 
found to my surprise that in not a single one of them did any 
clamp-connections make their appearance. The spore-deposits 
used for making the cultures described in my previous paper 
had been destroyed, so that it was unfortunately impossible to 
investigate them again. The spores in my new cultures, there- 
fore, had a different origin from those previously employed. 
Suspecting that the strains of the fungus used in my new in- 
vestigation were heterothallic, I tried the effect of pairing the 
mycelia. The results of this operation were similar to those 
* Mathilde Bensaude, Recherches sur le cycle évolutif et la sexualité chez 
les Basidiomycétes, Nemours, 1918, pp. 1-156. 
+ Hans Kniep, Uber morphologische und physiologische Geschlechtsdifferen- 
zierung, Verhandl. der Physikal.-med. Gesells. zu Wurzburg, 1919, pp. I-18. 
t Irene Mounce, Homothallism and the Production of Fruit-bodies by 
Monosporous Mycelia in the Genus Coprinus, Trans. Brit. Mycolog. Soc. vi, 
1921, pp. 198-217. 
