PLATE IV. 



Figs. 1-18.— AMCEBA RADIOSA. 



Figs. 1-4. Four views of the same individual, exhibiting the successive changes of shape ■within 

 a few minutes. From a pool at Fort Bridger, Wyoming, August, 1877. The pink globule within repre- 

 sents the contractile vesicle. Of the other globules two were ibod-balls ami the remaining one probably 

 the nucleus, though it was not very distinct. COO diameters. 



Fig. 5. Individual with globular body and long nearly linear rays, as seen floating. It contained 

 a large clear globule and a smaller one. The contractile vesicle absent or collapsed. The animal sub- 

 sequently assumed a more stellate, appearance. 



FIG. 0. Another individual accompanying the former. At first stellate it then assumed I he 

 tripod form, with central contractile vesicle as represented. In neither this nor the former specimen 

 was a nucleus detected. From a spring on Darby Creek, April, 1875. 



Fig. 7. Individual of globular form and long linear rays, with contractile vesicle, but no nucleus. 

 From the gutter at the fountain on Market street, in front of the City Hall, Philadelphia, August, 1876. 

 It subsequently assumed a more stellate appearance, with shorter, thicker, and more conical rays. 



Fig. H. Individual with globular body and comparatively short conical p-eudopodal rays. It con- 

 tains two contractile vesicles, which afterwards united in one. It also contains a diatom and a large 

 globule, with apparently a central, darkly-defined corpuscle. The creature subsequently became more 

 stellate and with longer arms. From a springy place on Darby Creek, Delaware County, Pennsylvania, 

 May, 1875. 



Figs. 9-11. Three views of the same individual, from China Lake, Uinta Mountains, Wyoming, 

 August, 1877. Figs. 9, 10, as seen floating. Fig. 11, as seen creeping, with numerous long digitate 

 pseudopods diverging in advance. The nucleus is seen in front with a clear surrounding zoue; the 

 contractile vesicle central. 



Fig. 12. An individual, resembling the former, as observed floating. From a ditch, among Duck- 

 meat, below Philadelphia, September, 1874. 



Fig. 13. An individual which, when first noticed, had a more stellate appearance, as in figure 4, 

 but afterwards applying itself to the surface of the object-glass it retracted its pseudopods and slowly 

 spread out so as to appear as in the present figure. At first it contained but few conspicuous globules, 

 but a multitude were subsequently developed, and one among them becoming much enlarged finally 

 collapsed. From the same locality as that of figure s. 



Figs. 14-10. Three views of the same individual, exhibiting the successive changes of shape 

 within a few minutes. From a dish of water with algie and other aquatic plants, preserved during the 

 winter. March, 1874. 3:!:! diameters. 



Figs. 17, 18. Two individuals from mud collected at the month of Cooper's Creek, near Camden, 

 New Jersey, May, 1874. 500 diameters. These in creeping on the object-glass extended a pair of broad, 

 thin lateral expansions, from which radiated narrow pointed pseudopods. From time to time one or 

 more of the. latter would slowly vibrate from side to side. One of the specimens (fig. IS) dragged after 

 it a large particle of quartz sand. 



Figs 19-21. SPONGILLA AMCEBOIDS. Obtained from the yellowish fresh-water sponge (Sponr 

 tjilla fragilis) attached to the under surface of rocks below Fairmount dam, in the Schuylkill River, 

 Philadelphia. 500 diameters. Figs. 19,20 are undistiuguishable from Amoeba radiosa ; tig. 21 resembles 

 A.rerracosa. Each contained a nucleus and from one to three contractile vesicles, together with color- 

 less or yellowish granular balls, which in true Amojbas would lie viewed as food-balls. 



Figs. 22-24. An Amcebaof uncertain reference, but probably a variety of Amoeba proteus. 



Fig. 22. An individual, as seen creeping from left to right, projecting in advance broad, clear lobu- 

 lar pseudopods. From the sides and at the posterior extremity there projected a variable number of 

 incessantly changing pointed conical pseudopods. The interior exhibits, from behind forward, a large 

 contractile vesicle, a multitude of minute desmids, a nucleus, and a number of clear globules. 250 

 diameters. From the soft ooze in the Lehigh River, near Fasten, Pennsylvania, June, 1874. 



Fig. 23. An Amoeba, with many conical pseudopods, mostly acute and divergent from the part of 

 the body in advance, the posterior extremity ending in mammillary processes. 500 diameters. 



Fig. 24. Another and larger individual of the same kind as the preceding, with many pointed 

 conical pseudopods; the posterior extremity of the body ending in mammillary processes. The interior 

 containing a multitude of pinkish globules, incessantly changing in number and size, together with a 

 loug doubled filament of Oscillaria and other alga}. From the posterior end of the body, as seen in the 

 figure, a discharge of etiele mailers occurred. 



The individuals of figs. 23 and 24, together with many similar ones of various sizes and inter- 

 mediate forms, occurred in water from Absecom pond, New Jersey, collected in the autumn of 1875 and 

 preserved during the winter until March, 1871). 



Fig. 25. AMffiBA PROTEUS. An individual from Absecom pond, New Jersey, November, 1874. 

 250 diameters. Besides the usual granular protoplasm, the contents consisted of brownish-yellow and 

 green food-balls, many crystals, several large clear globules, a uniformly granular nucleus (seen to the 

 right of the centre), and a large contractile vesicle (seen to the left). Around the latter may be ob- 

 served half a dozen darkly granular balls, the contends of which exhibited lively swarming movement. 



Fig. 26. An amoeboid animal, probably of the same character as those of figs. 23 and 24, and found 

 with them. It moved slowly and contained a multitude of scattered chlorophyl grains of nearly uni- 

 form size. These were first supposed to be a constituent element of the structure, as in some of the 

 Difflugias and in Hyalosphenia papilio. 500 diameters. 



A similar specimen was observed occupying a space of 0.18 by 0.1 mm., with nucleus and con- 

 tractile vesicle. Later, March, 1876, other specimens were observed, from the same locality, apparently 

 merging into forms like those of figs. 23 and 24. 



