540 ME. A, LISTER ON THE DIVISION OF 



* 



than on the first day, possibly from the absence of nutritive 

 matter; dividing-cells were observed, showing, as before, darkly- 

 stained karyokinetic figures. There could be little doubt from 

 their size that some at least of the dividing-cells were the offspring 



of a former division. 



Spores from another gathering of Reticularia* collected nearly 

 two years ago, germinated as quickly and showed the same karyo- 

 kinetic process in the nuclei as in the former case. 



Amaurochcete atra, collected last summer, produced swarm-cells 

 a few hours after the spores had been placed in water : division 

 begansooner in these than in Seticularia^wiihihe same appearance 

 of karyokinesis, the dividing nuclei taking a deep stain as before 

 described. Although the swarm-ceils of this species are much 

 larger than those of Heticularia, they are not so favourable for 

 observation, because the greater depth of granular protoplasm 

 obscures the definition in gentian-violet stainings, at the same 

 time the spindle-threads connecting the separated halves of the 

 nuclear plate were clearly indicated in some instances. 



Numerous experiments were made with the spores of Chondrio- 

 derma difforme ; those cultivated in a hanging drop and supplied 

 with a thin section of the testa of a cress seed gave the best 

 result. Three days after having been wetted and when the 

 swarm-cells were very numerous and chiefly in the amoeboid 

 form, they were killed with osmic vapour and stained with acetic 

 gentian-violet. The nucleoli alone in the active cells took a deep 

 stain, the rest of the nucleus being scarcely more coloured than 

 the body of the swarm-cell ; but when karyokinesis took place 

 the stages were strongly marked, as in the other species. 



Stainings were made with acetic methyl green, picrocarmine, 

 and mauvine, but none of them answered so well as acetic gentian- 

 violet; for, although it is unsuitable for permanent mountings, 

 the deep colour which it immediately gives to the dividing nucleus, 

 in strong contrast with those of the active cells, allows several 

 hours of favourable observation before the preparation becomes 

 obscured by the concentration of the stain. 



In making smears of the sporangia of Comatricha for prepara- 

 tion in Flemming's solution, the stage of development was ascer- 

 tained by staining the remainder with dilute gentian-violet, and 

 it was interesting to observe how precisely the deep colouring of 

 the dividing nucleus corresponded with the same stage of karyo- 

 t kinesis in the swarm-cells. Although the definition was not so 



