GENERAL SUMMARY 303 



spoken of as illegitimate combinations of a haploid mycelium with a 

 diploid mycelium. 



In what follows it has been assumed that a large haploid mycelium is 

 becoming diploidised when clamp-connexions appear on, and a change 

 from the wide-angled to the narrow-angled mode of branching is shown 

 by, all its peripheral hyphae progressively proceeding away from, and 

 on both sides of, the inoculum. 



In legitimate combinations, a diploid inoculum can convert a large 

 haploid mycelium into a diploid myceUum as smoothly, rapidly, and 

 completely as a haploid inoculum. 



In two legitimate combinations {Ab) x (Ab) + {aB) and (AB) x {AB) 

 + {ab), the large haploid mycelia {Ab) and (AB) became diploidised by 

 the diploid inoculum. A factorial analysis of the two diploidised haploid 

 myceha showed that they must have had the composition {Ab) + {aB) 

 and {AB) + {ab) respectively. 



In a legitimate combination between a large haploid mycehum and a 

 small diploid inoculum, the large haploid mycelium can be diploidised 

 by the diploid mycelium (1) when the inoculum is set at the periphery 

 of the haploid mycelium, or (2) when the inoculum is set at the centre of 

 the haploid mycelium. 



In a legitimate combination, when a diploid mycelium is set between 

 two haploid mycelia resembHng those which combined to form the 

 diploid mycelium, e.g. {AB) + {ab) between {AB) and {ab), the diploid 

 mycelium diploidises the two haploid mycelia simultaneously. 



In legitimate combinations, as the mycelia grow older under cultiva- 

 tion, the diploidisation of a large haploid mycelium by a haploid or 

 diploid inoculum takes place less rapidly and sometimes incompletely. 



In eight legitimate combinations of all possible kinds, a haploid or 

 diploid inoculum converted a large haploid mycelium, 5- 5-6-0 cm. in 

 diameter when just inoculated, into a diploid mycelium in 3-4 days. 



Since the development of a clamp-connexion on a haploid hypha is 

 an indication that pairs of conjugate nuclei have just been established 

 in the cells adjacent to the clamp-connexion, the rate of movement of 

 nuclei derived from an inoculum through a large haploid mycelium can 

 be calculated as soon as the time which has elapsed between the inocula- 

 tion of the large haploid mycehum and the first appearance of clamp- 

 connexions at the periphery of the large haploid mycelium at a measured 

 distance from the inoculum has been determined. 



In eight legitimate combinations of all possible kinds, the average 

 speed with which nuclei derived from the inoculum moved through a 

 large haploid mycehum (5- 5-6-0 cm. in diameter when inoculated) from 

 one side to the other was found to be : (1) with four haploid inocula {ab), 

 {AB), {aB) and {Ab), set on four large haploid myceha {AB), {ab), {Ab), 

 and {aB) respectively, 0-93 mm. per hour; and (2) with four diploid 

 inocula {AB)+{ab), {AB) + {ab), {Ab) + {aB), and {Ab)-\-{aB), set on four 



