532 MR. A. LISTER OF THE DIVISION OF 



"I cut sections of each batch, staining with borax carmine 

 before embedding in paraffin. 



" The sporangia gathered on Oct. 15 show the nuclei in various 

 stages of division by karyokinesis. 



" In the sporangia of the later gatherings the karyokinetic 

 division of the nuclei occurred between the morning of Oct. 20 

 and that of Oct. 21. On Oct. 20 nuclei were scattered through 

 the undivided protoplasm, while twenty-four hours later ea?h 

 nucleus w y as the centre of a young spore, distinctly separated 

 from its neighbours, although no spore-wall could \et be seen. 



" On Oct. 28th 1 found a crop of young sporangia on a rotten 

 elm log, and brought it to the Laboratory to treat in the same 

 manner as the Trichia. Part of it was allowed to ripen and 

 was identified as Arcyria tncarnata, Pers. 



" At 2.40 p.m. development was progressing so rapidly that 

 from this time until 5.40 a small group of sporangia was pre- 

 served every hour, namely, at 2.40, 3.35, 4.40, and 5.40. On 

 cutting sections of this series, the division of the nuclei by 

 karyokinesis was found to be in full progress at 5.40, while the 

 sporangia preserved an hour earlier showed no sign of it. 



" On Nov. 5 the process was repeated with a fresh crop of 

 Arcyria tncarnata from the same stump. Sporangia were pre- 

 served at 9.18, 9.55, 10.45, 11.25, and 12 noon. 



" In this series karyokinesis was in progress at 10.45. The 

 nuclei at the 9.55 stage show some indication of change, but 



none of them have reached the metaphasis of the process of 

 division, while at 11.25 the metaphasis was finished and the 

 protoplasm already aggregated round the daughter nuclei." 



At Lyme Kegis similar experiments were then made with 

 Trichia fragilis, Trichia fallax, Comatricha Friesiana, and Phy- 

 sarum Jeucophceum ; but instead of hardening the sporangia and 

 cutting sections, the contents of the young sporangia were 

 smeared over thin cover-glass and then treated with Flemming's 

 fluid, stained with picrocarmine, and mounted in balsam. 



The following records show the period when karyokinesis 

 appeared : 



Nov. 13. A large growth of Comatricha Friesiana, just rising 

 from rotten wood, was brought indoors and placed under a bell-jar. 



12.45 p.m. The ovoid sporangia were nearly sessile, the dark 

 stalks just appearing at the base. The staining showed the nuclei 

 containing one to three nucleoli lying in a loose reticulum. 



