284 THE AMERICAN MONTHLY [Oct., 



In the gathering from the Phipp Conservatory before men- 

 tioned, the host of Amoebas there found were associated with 

 Euglena, Coleps, Closterium, Trachelomonas and several other 

 genera of Infusoria and microphytes. One slide under exami- 

 nation contained nearly fifty Amoebas and several Stentors. 

 The last, Stentor polymorphus, while equaling the Amoeba in size 

 and strength is far more active. When viewing the objects on 

 this slide, attention was arrested by the sight of an Amoeba 

 partly enveloping the foot of a Stentor. The attacked animal- 

 cule, though in evident alarm, had not sense enough to loosen 

 its foot from the glass slide, but tore off and left a part behind 

 for the Ama?ba to make a meal of. So curious a sight natur- 

 ally excited much interest, and led to a search for more inci- 

 dents of the same kind of which quite an unexpected number 

 soon turned up. 



Presently another Stentor appeared in the field having the 

 middle part of its body enclosed by an Amoeba and rather se- 

 verely pinched at two points. With more judgment than the 

 first one, this Stentor, though in a worse plight, drew itself out 

 of the deadly cavity and swam away leaving nothing behind to 

 satisfy its hungry captor. This incident is shown in Figure 8. 



The cavity formed to enclose its prey has smooth walls which 

 appear somewhat darker than the remaining portions of the 

 Amoeba's body. So peculiar and characteristic is the appear- 

 ance of this cavity, that one finding it vacant may always be 

 sure some prey has just escaped. When an animalcule is inside 

 and sufficient time allowed, the opposite margins fuse together 

 forming a closed chamber from which there is no escape unless 

 the captive is strong enough to rupture the Amoeba. If left 

 empty, the cavity quickly collapses and disappears. 



Further search next brought into view the unexpected spec- 

 tacle of two Amoebas attacking one Stentor. The latter was 

 half enveloped by one Amoeba while its foot was partly seized 

 by the other, but an escape was easily effected without injury. 

 Figure 4 represents this. 



Ere long a solitary Amoeba and Stentor were found engaged 

 in a struggle which continued for some time with varying suc- 

 cess, finally ending in the escape of the latter. At one tiraetheii 

 Stentor was almost entirely within the cavity, and had time 

 been allowed for fusion of the edges, escape would have been 



