AMCEBA 141 



highly refractive, round or oval, vesicular nuclei were present. 

 The cyst-wall did not share in the rotation but gradually 

 became thicker by the addition of new layers to its inner 

 surface. By the fifth day the rotatory movement had ceased, 

 and shortly afterwards some thirty nuclei were counted, and 

 the cytoplasm was full of refractive albuminous spherules. 

 The nuclei apparently consisted of corpuscles of plastin 

 encased in chromatin, and in division they simply became 

 elongated and. dumbbell-shaped, and divided into two. The 

 albuminous spherules persisted in cysts in which some 300 

 nuclei were present, but then began to disappear, and were 

 no longer to be seen in cysts containing from 500 to 600 

 nuclei. Throughout these phases the dividing nuclei had no 

 membrane, but when about 600 were formed they acquired 

 membranes and passed to the periphery of the encysted 

 Amoeba. At the same time each nucleus became round 

 and vesicular and the chromatin was collected into its centre. 

 The cytoplasm surrounding each nucleus was then segmented 

 off as a minute corpuscle which presently began to put forth 

 pseudopodia and escaped through the cyst-wall which was 

 now in a state of disintegration. The segmentation did not 

 extend to the centre of the encysted animal, which was left 

 behind a sa mass of residual protoplasm. The young forms 

 or spores on escaping from the cyst appeared as perfect 

 amcebulse j they were transparent, contained very few granules, 

 put forth many pointed pseudopodia, and measured from 

 ten to fourteen thousandths of a millimetre in diameter. 

 Though very different from the adult form at the time of 

 their emergence, these amcebulae, when supplied with ap- 

 propriate food, could be reared into the adult A. proteus. 

 The cysts were either single, or several of them were 

 aggregated together and invested by a common gelatinoid 

 mass, derived from the outer walls of the cysts.' No con- 

 jugation was observed, either between the Amoebae prior to 

 encystment or between the amcebulse liberated from the 

 cysts, and it is noticeable that the young forms were 

 amoeboid from first to last, and never showed any trace 

 of a flagellate condition. Minute amoeboid reproductive 

 bodies such as these are often spoken of as pseudo- 

 podiospores. 



Several other Rhizopods allied to Amoeba have been 



