304 RESEARCHES ON FUNGI 



large haploid mycelia {AB), {ah), {Ah), and {aB) respectively, 0-89 mm. 



per hour. 



When a large haploid mycelium {AB) was inoculated with a haploid 

 mycelium of opposite sex {ah), the {ah) nuclei travelled through the 

 haploid mycelium a distance of 6-0 cm. in 40 hours or at the rate of 

 1 -5 mm. per hour. This was the maximum rate of movement observed 

 in a combination of two haploid mycelia. 



When a large haploid mycelium {AB) was inoculated with a diploid 

 mycelium {AB)+{ah), the {ah) nuclei travelled through the haploid 

 mycelium a distance of 7-7 cm. in 64 hours or at the rate of 1-2 mm. 

 per hour. This was the maximum rate of movement observed in a 

 combination of a haploid and a diploid mycelium. 



A haploid mycelium of Coprinus lagopus, like the haploid mycelia 

 of Hymenomycetes in general, is a three-dimensional network of hjrphae. 

 Hence, nuclei cannot travel from an inoculum through a large haploid 

 mycelium in straight-line courses which are radial in respect to the 

 inoculum, but must travel through the large haploid mycehum in very 

 zig-zag courses. Hence, in the experiment already cited in which the 

 nuclei travelled through a large haploid mycelium a distance of 6-0 cm. 

 from the inoculum in 40 hours or at the rate of 1 -5 mm. per hour, the 

 speed of the nuclei in passing along the hyphae of the mycelial network 

 probably attained at least 2-0 mm. per hour and may have been 

 2- 0-3-0 mm. per hour. 



The nuclei derived from a tiny mycelial inoculum, when advancing 

 through a large haploid mycelium which they are diploidising, can 

 travel through any part of the haploid mycelium, old or young, but they 

 move more readily through a younger part than an older part. 



At the periphery of a large haploid mycelium which had been inocu- 

 lated with a haploid mycelium of opposite sex, the conversion of haploid 

 into diploid hyphae, as indicated by the development of clamp- 

 connexions and a change from the wide-angled to the narrow-angled 

 mode of branching, was directly observed under the microscope as a 

 result of continuous watching. 



The number of nuclei of opposite sex required to diploidise all the 

 hyphae which come to contain conjugate nuclei in a large haploid 

 mycelium 6-0 cm. in diameter may well exceed 250,000. 



On a diploid hypha fourteen successive clamp-connexions were, 

 formed in the course of twelve hours. Therefore a clamp-connexion was 

 formed, and a conjugate nuclear division took place, every fifty minutes. 



In Coprinus lagopus any mycelium can form hyphal fusions with 

 any other mycelium. 



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 derived from the two haploid mycelia 

 which were mated to provide the diploid inoculum. Thus a large 



