262 RESEARCHES ON FUNGI 



differs from the two haploid mycelia from which it has been derived 

 in that, as a rule, when used as an inoculum, it is able to diploidise 

 a large haploid mycehum, whereas, as a rule, when they are used 

 as inocula, they are not able to do so. 



Unfortunately, owing to the fact that the writer was leaving his 

 laboratory for eight months, it was impossible for him to analyse 

 the diploidised haploid mycelia produced in the experiments 

 recorded in Tables VIII and IX for their sex-factors. Some of 

 these mycelia were transferred to sterilised horse dung and spore- 

 deposits were obtained from the fruit-bodies which they produced ; 

 but the work had to be stopped at this point. It was therefore 

 not possible to germinate the spores, to obtain monosporous mycelia, 

 and to pair these mycelia with one another and with the primary 

 mycelia (AB), (ab), {Ab), and (aB). Work of this kind is required 

 to inform us whether the diploidised haploid mycelia were normal 

 diploid myceha of the types {AB)-\-{ab) and {Ab)+{aB) or whether 

 they were abnormal mycelia of the types {AB)-\-{aB), {AB)-\-{Ab), 

 {ab)-^{aB), and {ab) + {Ab). It is true that the analysis (p. 251) 

 of the diploid mycelium produced on a mycelium (^6) by a diploid 

 inoculum {AB)-\-{ab) in Experiment No. 3 of Table V indicated 

 that the diploidised mycelium had the constitution {Ab)-\-{aB) and 

 not {Ab)+{AB) or {Ab)+{ab); but this analysis, unfortunately, 

 stands alone, and it is possible that other similar analyses, yet to 

 be made, may not yield the same kind of result. In illegitimate 

 combinations of a haploid and a diploid mycehum, it is therefore 

 still an open question whether the diploidisation of the haploid 

 mycelium is due simply to " Durchbrechungskopulationen " of the 

 kind already discussed earher in this Section or is due to the pro- 

 duction by the diploid, mycehum of one or more nuclei of a sex 

 opposite to that of the nuclei of the haploid mycehum. As a 

 concrete example of this question, we desire to know whether, in 

 the combination (AB) X {Ab)+{aB), when the mycelium (AB) 

 becomes diploidised, does the diploid mycehum send one or more 

 (Ab) or one or more (aB) nuclei into the (AB) mycehum so that the 

 pairs of nuclei in each cell of the diploidised (AB) mycehum are 

 {AB)-[-{Ab) or {AB)+{aB), or do the (^6) and (aB) nuclei of the 

 diploid mycehum when stimulated by the {AB) mycehum interact 



