A LOG AND SOME MYCETOZOA. 133 



pinkish tinge. In less than twenty-four hours from the first 

 observation they were fully formed, and of a light salmon-pink 

 colour, vivid and arresting. Next day this had deepened, and 

 by the day following had changed to a light bufi. Two days 

 later they had finally dried off to a bufE colour with a greenish 

 brown tint. On each occasion the temperature was about 20° C. ; 

 the first group appeared on a showery day, after a spell of dry 

 weather which had become rather close ; and the other two 

 groups were formed a few days after there had been much rain 

 and occasional thunder. The plasmodia of Mycetozoa appear to 

 be very sensitive to electrical conditions, as I have several times 

 found that in wet and close or thundery weather they are apt 

 to pass into the sporangial stage. 



Now comes the remarkable part of my story. The first Lyco- 

 gala were quickly followed by other kinds of Mycetozoa ; and my 

 record shows that, on an average, from the last week in May 

 till the first week in October, plasm issued from the log on, ap- 

 proximately, two days out of every three. In July there was but 

 one day on which no new emergence could be found ; and the 

 longest break was towards the end of September, when there was 

 an interval of a week without any fresh developments ; but the 

 weather was then cooler, and after a last emergence of plasm 

 on October 4th, a rapid fall in temperature brought the series to 

 an end. 



The Mycetozoa included in these sequences were chiefly 

 Stemonitaceae • Stemonitis fusca, S. ferruginea, Lamproderma 

 columbinum and one- small group of Comatricha nigra. The re- 

 mainder consisted of the Lycogala already described, two small 

 clusters of the beautiful Arcyria denudata and four little patches 

 of Physarum nutans. 



A description of the formation of sporangia of Stemonitis was 

 given in a previous paper * and need not be repeated here ; but 

 one incident occurred which ought to be mentioned. On July 20th 

 three patches of white plasm, one to two inches in diameter, issued 

 from the log through crevices in the bark and proceeded to 

 develop in the normal manner ; but before the process was at 

 all complete, they were drenched by a heavy shower of rain. 

 The result of this disturbance and dilution was that instead of 

 forming tall and slender cylindrical sporangia elevated on stalks, 

 * Journ. Quekett Microscopical Club, April 1916. 



