EFFECT OF DIPLOID ON HAPLOID MYCELIA 259 



the haploid inoculum caused clamp-connexions to appear on a few 

 hyphae situated at the junction between itself and the large haploid 

 mycelium ; but the diploidisation did not spread laterally farther, 

 so that the large haploid mycelium remained almost completely 

 haploid. It is therefore clear that the haploid inocula diploidised 

 the large haploid mycelium either not at all or to an extremely 

 slight degree. The diploid inocula exerted a far more powerful 

 effect on the large haploid mycelium than the haploid inocula ; for, 

 in each of the four combinations in which a diploid inoculum was 

 employed, Nos. 3, C, 9, and 12, the diploid inoculum converted the 

 haploid mycelium into a diploid mycehum, although slowly and 

 patchily as compared with what happens in a legitimate combina- 

 tion of a large haploid mycehum and a diploid inoculum (c/. Nos. 2, 

 4, 6, and 8 in Table VII). 



The twelve experiments of Table VIII are set out in four series 

 of three each. In each series of three are shown the results 

 obtained by subjecting one kind of large haploid mycehum first to 

 one haploid inoculum, then to another haploid inoculum of oppo- 

 site sex, and then to a diploid inoculum which originated by the 

 interaction of two myceUa like the two haploid inocula. Thus, for 

 example, in the first three experiments set out in the Table, we can 

 compare the effect on a large haploid mycelium {AB) of a diploid 

 inoculum {Ab)-\-{aB) with the effect of its two components, the 

 haploid inocula (^6) and (aB) employed separately. 



The conclusion to which a study of the results shown in 

 Table VIII points is that, in illegitimate combinations, as a rule, 

 a large haploid mycelium can be converted into a diploid mycelium 

 by a diploid inoculum, but not by either of two haploid inocula 

 taken from the two haploid mycelia which were mated to provide 

 the diploid inoculum. 



That a diploid inoculum is far more active in diploidising a large 

 haploid mycelium than either of its two haploid components is 

 again shown by a study of the four experiments recorded in 

 Table IX. The diploidisation process in each of the four experi- 

 ments (c/. Fig. 137) took place in three steps : (1) first, the two 

 bits of haploid myceha set side by side quickly diploidised one 

 another and thus formed a diploid inoculum for the large haploid 



