240 RESEARCHES ON FUNGI 



another haploid mycelium (AB) ; and, three days after inoculation, 

 the large mycehum {ab) was becoming progressively diploidised 

 around its periphery on both sides of the inoculum. At the peri- 

 phery of the mycelium (ab) a place was found, about 6 cm, from 

 the inoculum, where there was a transition from hyphae producing 

 clamp-connexions regularly and therefore completely diploid to 

 hjrphae not yet producing clamp-connexions and therefore completely 

 haploid. 



In the transition zone just described particular haploid hyphae 

 were watched with the microscope for several hours and their 

 conversion into diploid hyphae was actually observed, as will now 

 be recorded in a particular case. 



A leading hypha growing radially between diploid and haploid 

 hyphae at the periphery of the (ab) mycelium was branched in the 

 wide-angled haploid manner, and there were no clamp-connexions 

 on it or on its four youngest branches (Fig. 133, A, branches Nos. 5, 

 6, 7, and 8) ; but three of its older branches (Nos. 2, 3, and 4) each 

 bore a single clamp-connexion. It seemed very probable .that the 

 hjrpha in question was being converted from a haploid to a diploid 

 state ; and, therefore, it was kept under continuous observation 

 until, at the end of four hours and ten minutes, the change had 

 been completed. To observe the hypha, the cover of the Petri dish 

 was removed and then the low-power or the high-power of the 

 microscope (magnifications 132 and 500) was appHed to it. Between 

 observations the cover was set on the Petri dish to prevent undue 

 loss of moisture from the culture medium. The hypha under 

 observation was growing along the surface of the agar and therefore 

 did not dry up when exposed to the air. 



The first state of the haploid hypha in process of being converted 

 into a diploid hjrpha is shown in Fig. 133, A, where it will be seen 

 that the three lower branches of the hypha a, Nos. 2-4, bear clamp- 

 connexions, whereas the four upper branches, Nos. 5-8, have no 

 clamp-connexions whatever. The hypha with its branches was 

 sketched with the low-power of the microscope at 1.30 p.m. 



At 3.40 P.M., the hypha a, along with its branches, was sketched 

 again (Fig. 133, B) ; and a comparison of the drawings A and B 

 in Fig. 133 shows that, in the intervening two hours and ten 



