28 ACTION OF AUXETICS AND KINETICS 



and dark, suggestive of internal movements (the 

 nucleus being stationary and always in focus), and 

 on one occasion a spherical granule was noticed to 

 leave the nucleus, and was lost to view in the 

 cytoplasm (fig. 7). 1 The nuclei of the cysts are 

 also usually single, but there may be two, three, 

 or even four present. The contractile vacuole is 

 a prominent feature in every cell and completes 

 a pulsation once in about forty seconds when the 

 amoeba is in an active, healthy condition. The 

 food vacuoles are of no particular interest ; they 

 contain bacteria, etc., in all states of digestion, 

 and may be scanty or so numerous as to occupy 

 almost the whole of the cell. The granules of the 

 endoplasm are usually small, but in some cultures 

 many of the amoeba* contained large ones only 

 (fig. 8). These are distinguishable by their faint 

 staining reaction with polychrome methylene blue 

 from the volutin granules which accumulate in 

 many amcebse prior to encystment, and which 

 take up an intense blue colour with the dye. The 

 amoebae encyst at intervals to protect themselves 

 from so-called ad verse conditions of the surroundings. 

 During cultivation through several generations it 

 is interesting to observe that the characters of the 

 amoeba have changed slightly from those which were 

 present in the original growth in the citrate solution. 

 The pseudopodia were then markedly lobose ; when 

 the cells moved, the ectoplasm, followed by a small 

 portion of the granular part, sluggishly flowed round 

 the main body of the organism, another portion of 

 the periphery subsequently resuming and continuing 



1 Intranuclear changes in the so-called resting nucleus have also 

 been observed by Leger and Duboscq, and others in various organisms. 



