EFFECT OF DIPLOID ON HAPLOID MYCELIA 209 



the periphery of the large and originally haploid myceUum {ab). The 

 radial distance of the periphery of the originally haploid myceUum 

 (ab) from the diploid inoculum {AB)+{ab) at the end of the experi- 

 ment was about 4-5 cm. (Fig. 121). 



From the result of this experiment it is clear that a diploid 

 myceUum (AB)+(a6) is able to diploidise a haploid mycehum {ab) 

 when it has come in contact with only the oldest part of the haploid 

 mycehum ; and from the results of the experiments (1), (2), and (3) 

 we may conclude that a diploid mycehum {AB)+{ab) can diploidise 

 a haploid mycelium (ab) if it comes into contact with the latter at 

 any point whatsoever. 



(4) Action of a diploid mycelium on both the kinds of haploid 

 myceliafrom which it was derived. The experiments described under 

 (1), (2), and (3) have shown that a diploid mycehum {AB)^{ab) 

 is able to diploidise a haploid mycehum {ab). Whether or not 

 such a diploid mycelium can also diploidise the haploid mycehum 

 {AB) was settled in the affirmative by means of another set of 

 experiments which will now be described. 



Three haploid myceha No. 10 {AB) were grown separately on 

 dung-agar in three small Petri dishes. When they had attained 

 a diameter of about 3-3 cm., each of them was inoculated at its 

 periphery with a tiny mass of the aerial hyphae of the diploid 

 mycelium No. 10 X No. 5, {AB)+{ab). 



At the end of five days after the diploid mycelium had been 

 added to the dishes, clamp-connexions were present all the way 

 around each of the three originally haploid myceha {AB). These 

 three myceha, therefore, had been diploidised by the diploid 

 mycelium. 



Having found that the diploid mycelium {AB)-\-{ab) can 

 diploidise each of the haploid myceha {AB) and {ab) separately, it 

 seemed of interest to determine whether or not the diploid mycelia 

 can convert both the haploid mycelia simultaneously into diploids. 

 Accordingly, on one and the same plate of dung-agar there were set 

 in a row three small pieces of dung-agar, the central piece containing 

 the diploid mycehum {AB)-^{ab) and the two outside pieces, each 

 1 cm. distant from the edge of the central piece, containing respect- 

 tively the haploid mycelia {AB) and {ab) {cf. Fig. 122). 



VOL. IV. P 



