Abstract
An effort was made to determine observationally the various interrelationships of physiological manifestations of ameba at varying high pH concentrations in celery infusions. All the cultures were kept under the same temperature and light conditions, the temperatures varying between 21 and 25°C. The same temperature and light conditions prevailed throughout the period of observation. Efforts were made to maintain uniform concentration by the use of like containers and by the addition of 5 cc. of distilled water and infusion every three or four days to each of the cultures. All detailed miscroscopic observations were made with Zeiss Apchromat Lens 3 mm. n.a. 1.4.
In determining pH, the colorimetric drop method of LaMotte with Clark and Lubs' standards was employed.
Quantitative studies on population density at different pH were attempted for the first time. The limits of pH tolerance as stated by Hopkins 1 were extended. 15 of the 22 cultures had a maximum population density at pH 7.8-8.4. A maximum population density-occurred in one culture at pH 8.4. Only cultures in which 10 adult ameba in 0.05 cc. of medium occurred were used in the averages. The average density at different pH was as follows:
Hopkins has reported a relationship between pH and size, decrease in size occurring at pH 7.8 and higher. In our cultures maximum average size occurred at pH 8.0 and 8.2 (330-405 microns). Larger sizes (600 microns frequently and occasionally 700-900 microns) were found under these alkaline conditions when food supply was abundant.
The average rate of movement of A. proteus from reports of other workers is 0.1400 mm. per minute. Edwards 2 found a maximum of 0.2880 mm. per minute. In our cultures movements between 0.2-0.4 mm∗ were found in 50.5% of 2,300 records.
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