GENUS AMCEBA— AMCEBA VEEEUCOSA. 53 



a^th of a millimetre in diameter. The granules of the nucleus were coarse 

 and uniform. In some specimens, the nucleus was simple, but in others 

 presented a tripartite division, as represented in figs 27, 28. I failed to 

 trace the further history of these Auicebas. 



Rarely have I had the opportunity of seeing Amoeba proteus,- or any 

 other species, multiplying by division. On one occasion, in the month of 

 February, while examining some material collected the previous autumn, I 

 observed a pair of small Amcebae connected by a narrow isthmus in the 

 manner represented in fig. 30. Each individual was of oval form, and 

 measured about ^th of a millimetre long by ^th of a millimetre wide. Each 

 contained a contractile vesicle and two large globules looking like oil, but 

 apparently no nucleus. The endosarc presented the usual character of 

 that of Amoeba proteus, and contained, besides minute crystals, a number of 

 alga?, some of which were green, and others, changed by digestion, were 

 brown. After about ten minutes from the time the Amoebae were first seen 

 they separated by rupture of the isthmus. Subsequently, one individual 

 became constricted transversely across its middle, and in the mean time, 

 while watching it, the other individual moved away and was lost to 

 view. The individual under observation became gradually more con- 

 stricted, and finally divided, as in the former case, into two. One division, 

 larsrer than the other, retained the contractile vesicle and both oil-like 

 globules. The smaller division, of rounded form, measured ^th of a milli- 

 metre ; but after a short interval a contractile vesicle appeared within it, 

 and the little creature assumed a clavate shape and moved out of the field 

 of vision. The larger division likewise assumed a clavate shape, and as it 

 moved away it measured ^th of a millimetre long. 



AMCEBA VERRUCOSA. 



Plate III. 



Amccha verrucosa. Ehrenberg: Infusionsthierchen, 1838, 126, Taf. viii, Fig. xi.— Dujardin : Infueoires, 

 1841,236. — Perty: Kennt. kleinst. Lebensfornien, 1852, 188. — Carter: An. Mag. Nat. Hist. 

 1857, xx, 37, pi. i, figs. 12, 13.-Leidy : Pr. Ac. Nat. Sc. 1876, 198; 1878, 158. 



Amoeba nutans. Perty: Kennt. kleinst. Lebensformen, 1852, 188, Taf. viii, Fig. 14. 



Amaba quadrilineata. Carter: An. Mag. Nat.. Hist. 1856, xviii, 243, pi. v, fig. 3; 248, pi. vii, fig. 81.— 

 Barker: Quart. Jour. Mic. Sc. ix, 1869, 94.— Leidy: Pr. Ac. Nat. Sc. 1874, 107. 



Tliecamocba quadripartita. Frouicntel: fitudes Microzoaires, 346, pi. xxviii, fig. 3. 



Animal in the maturer stages, as ordinarily observed, more or less 

 sluggish, and often nearly motionless, commonly appearing of an irregularly 

 oval, round, or quadrately rounded form, with wart-like expansions and a 



