AMOEBA PROTEUS 51 



believing that Amoeba does anything intentionally or wilfully 

 but all of its activities can be explained on the ground of re- 

 sponses to environmental stimuli. An interesting analogy to 

 vital processes in Amoeba is shown by the rolling up of a fila- 

 ment of shellac in a drop of chloroform. Another species of 

 Amoeba, A. verrucosa, captures and rolls up a filament of 

 Oscillaria in exactly the same way and the inference is that both 

 processes are due to the same fundamental physical laws. 



Reproduction. In all forms of life the process of reproduction 

 when reduced to its simplest terms is the same viz. cell division, 



FIG. 20. Amoeba during division stages of the nucleus. From preparations. 



and the young forms invariably begin life as single cells which 

 after the stimulus of fertilization or its equivalent begin to 

 divide. The products of this continued division soon begin to 

 differentiate into tissues and organs, the various phenomena 

 constituting the subject matter of the science Embryology. 

 In Amoeba proteus, however, the cell is never more than a single 

 unit and might at all times be considered the equivalent of an 

 egg. There is evidence, although proof is not certain, that only 

 at definite periods is Amoeba really similar to an egg cell, and 

 requiring fertilization for its continued activities. At other 

 times the cell divides as does the fertilized egg of other animals, 

 but unlike the products of cleavage of the egg the daughter cells 

 of Amoeba do not remain attached to one another but separate 

 and live as independent organisms similar to the parent.. Here 



