250 RESEARCHES ON FUNGI 



did the diploid inoculum manage partially to diploidise the large 

 haploid myceUum ? Let us consider the diploidisation of the 

 haploid myceUum (Ab) by the diploid inoculum {AB)+{ab). It 

 seemed possible that the union which had taken place was essen- 

 tially of the same nature as the " Durchbrechungskopulationen " 

 recorded as sometimes occurring in haploid combinations such as 

 (Ab) X {AB) or (aB) X {ab) hyBTimswik'^ in C oprinus picaceus and, 

 more recently, by Oort - in Coprinus fimetarius (the G. lagopus of 

 this chapter). In certain of these combinations Oort found that 

 patches in the united myceha could be observed in which clamp- 

 connexions were present, but that this apparently normal diploid 

 mycelium, when transferred to a new culture medium, produced 

 haploid and not diploid fruit-bodies. He states that some of the 

 basidia produced from a combination {AB) X {Ab) bore four spores 

 {AB), {AB), {AB), and {AB) and other basidia four spores {Ab), 

 {Ab), {Ab), and {Ab), so that there were only two kinds of spores. 

 On this account he is inclined to regard the fruit-body which pro- 

 duced these two kinds of spores as built up of two kinds of hyphae, 

 {AB) and (^6), and the pilei as " haploid chimaerae." 



In view of Oort's investigation of " Durchbrechungskopula- 

 tionen," which has just been recorded, it seemed possible, in the 

 combination {Ab) X {AB)^{ab) of Table V, that either a nucleus 

 {AB) or a nucleus {ab) had, at the beginning of the diploidisation 

 process, moved out of the diploid inoculum into the large haploid 

 mycelium (^6) and that its progeny had associated themselves with 

 (^6) nuclei, so as to form a mycehum producing clamp-connexions 

 and having the constitution {Ab)+{AB) or {Ab)+{ab). An analysis 

 of the sex-factors of the mycelium in question was therefore 

 undertaken. 



A piece of the clamp-connexion-bearing mycelium produced on 

 the large {Ab) mycelium (Experiment No. 3 of Table V) at a place 

 5 • 5 cm. distant from the inoculum was removed from the dung-agar 

 Petri dish and placed on sterilised horse dung in a wide test-tube 



1 H. Brunswik, " Untersuchungen iiber die Geschlechts- und Kernverhaltnisse 

 bei der Hymenomyzetengattung Coprinus,'" Botanische Abhandlungen herausgeg. 

 V. Goebel, Heft V, 1924, pp. 85-90. 



2 A. J. P. Oort, " The Sexuality of Coprinus fimetarius,'' Proceedings of the 

 Koninkiijke Academie van Wetenschappen te Amsterdam, vol. xxxii, 1929, pp. 1-6. 



