226 RESEARCHES ON FUNGI 



reasons already discussed in connexion with Experiment No. 1, 

 the average rate of movement of the nuclei just calculated, namely, 

 1 -2 mm. per hour, must be regarded as an under-estimate. 



(5) Comparison of the rate of movement of nuclei through (1) a 

 haploid mycelium being diploidised by another haploid mycelium 

 with the rate through (2) a haploid mycelium being diploidised by 

 a diploid mycelium. As will be seen by reference to Table II, the 

 average rate of movement of the nuclei right across four haploid 

 mycelia being diploidised by haploid mycelia (Experiments Nos. 1, 

 3, 5, and 7) was 0-93 mm. per hours whereas the comparable 

 average rate right across four haploid mycelia being diploidised by 

 diploid mycelia (Experiments Nos. 2, 4, 6, and 8) was • 89 mm. per 

 hour. The difference between these two average rates scarcely 

 exceeds 4 per cent. , and therefore comes within what may be regarded 

 as the limits of experimental error. Hence it appears that the 

 diploidisation of a haploid mycelium can be effected as rapidly by 

 a diploid mycelium as by a haploid mycelium. 



In Experiment No. 1, in which a haploid mycehum was inocu- 

 lated with another haploid mycelium, (AB) with (ab), the maximum 

 speed of movement of the nuclei, calculated on a direct path for 

 40 hours, was 1-5 mm. per hour ; whereas in Experiment No. 2, 

 the maximum speed of movement of the nuclei, calculated on a 

 direct path for 64 hours, was 1-2 mm. per hour. These were the 

 two maximum speeds observed for any period of time in the eight 

 experiments recorded in Table II. In view of the comparison of 

 average speeds discussed in the preceding paragraph, it seems not 

 unlikely that further work might show that the maximum speed of 

 movement of nuclei through a haploid mycelium is often just as 

 great when a haploid mycelium is being diploidised by a diploid 

 mycelium as when a haploid mycelium is being diploidised by a 

 haploid mycelium. 



(6) Time taken by a nucleus in travelling a distance equal to its 

 own width. Another aspect of the movement of nuclei through a 

 haploid mycehum which is becoming diploidised may now be 

 briefly considered. The haploid hyphae of Coprinus lagopus, as 

 observed growing on dung-agar in Petri dishes, have a diameter of 

 about 5 fj,. In Experiment No. 1, described earlier in this Section 



