GENUS AMCEBA— AMCEBA VILLOSA. 65 



pressure by change of form (fig. 14), and also exhibit elasticity in the 

 return to the globular shape when the pressure was relieved. 



The individuals with the large granular nuclei usually contained little 

 food, though they were quite as active as the others. 



On one occasion, while observing an individual of the kind, in an ani- 

 malcula-cage, but not submitted to pressure, as it moved along in the usual 

 manner it suddenly assumed a spheroidal form. It contained two large 

 granular nuclei together with a large contractile vesicle and other ordinary 

 contents. After a brief interval, the contractile vesicle began to collapse, 

 when at the same moment one of the large nuclei burst, and in an instant 

 its coarse granular contents were expelled from the animal apparently 

 together with the liquid contents of the pulsating vesicle, as seen in fig. 15. 

 The scattered granules were minute globules, exhibiting only molecular 

 motion, and measuring about 0.002 mm. They were probably germs or 

 spores, but their destiny I failed to trace. The little Amoebae above de- 

 scribed, in the usual clavate form, measured from 0.08 mm. long by 0.024 

 mm. wide at the anterior or thicker end, to 0.14 mm. long by 0.04 mm. wide. 



An individual containing three large granular nuclei was 0.1 mm. long- 

 by 0.01 mm. wide; the nuclei, of uniform size, were 0.028 mm. in diameter. 

 An individual with six large granular nuclei was of the same length as 

 the preceding - , by 0.028 mm. wide ; the nuclei were 002 mm. in diameter. 

 The granules of the nuclei were about 002 mm. in diameter. 



Forms closely similar to the above, and containing the same kind of 

 large granular nuclei, are described and figured by Dr. Wallich in his 

 account of Amaba villosa* 



Several weeks subsequently to making the above observations, some 

 Amcebaj from the same water and apparently of the same kind, instead of 

 the ordinary minute crystals, contained minute concretionary bodies of 

 varied shape, as seen in figs. 34, a-l. These bodies measured from 0.001 

 to 0.004 mm. Under the action of acetic acid they slowty dissolved, but 

 without any visible evolution of gas. 



In some ooze, collected from a pond on Darby Creek, Delaware County, 

 Pennsylvania, in the month of March, there were a number of Amoebae 

 of the same character as the preceding, as seen in figs. 9, 10, pi. I. They 

 were usually clavate in form, reaching a length of about 0.1 mm. They 



*Aii. Mag. Nat. Hist. 1863, si, 365, pi. is. 



5 Rniz 



