. Animal aggregations, a study in general Animal ecology. COMMUNAL ACTIVITY OF BACTERIA 255 agar, and inspection of the figure shows that a fair growth resulted. This growth was not due to an accHmatization to the dye, because all experiments made looking directly toward such acclimatization have been unsuccessful. Further, attempts to reinoculate gentian- violet agar from this growth failed, at least insofar as the first smears were concerned. In discussing these re- sults. Churchman sug- gests four possibilities: The original transplants, though not surviving, may live long enoug
. Animal aggregations, a study in general Animal ecology. COMMUNAL ACTIVITY OF BACTERIA 255 agar, and inspection of the figure shows that a fair growth resulted. This growth was not due to an accHmatization to the dye, because all experiments made looking directly toward such acclimatization have been unsuccessful. Further, attempts to reinoculate gentian- violet agar from this growth failed, at least insofar as the first smears were concerned. In discussing these re- sults. Churchman sug- gests four possibilities: The original transplants, though not surviving, may live long enough to effect some change in the dye such that subse- quent transplants can survive. Or, the result may be due to some pro- tective barrier laid down by the dead bodies of the bacteria. Or, nutri- tional or growth-promot- ing substance may be provided by these same dead bodies. Or, finally, the results may be due to communal activity of the living bacteria, a possibility which will be examined later. We have already discussed possible causes of survival and growth in such cases in preceding chapters. In experimenting to find which of these possibilities actually obtained, Churchman grew B. suhtilis on medium containing only distilled water and agar, in order that the cells might contain a minimum of nutritive material. These bacteria were washed six times with distilled water and were killed. In order to test whether food material was present under these conditions, these dead bacte- ria were smeared over a Petri dish bottom which was then dried,. Fig. 22.—Showing the effect of reinoculations on a divided agar plate. The upper part contains gen- tian violet; the lower part is plain agar. Two initial strokes of Bacillus suhtilis were made. On the right side, nothing further was done. On the left, reinocu- lations were made on the gentian-violet agar. (From Churchman.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for
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