4 8 



AN INTRODUCTION TO ZOOLOGY 



tact and engulf solid particles of various kinds. One of the most 

 ingenious of these imitations is that reported by Rhumbler of 

 the ingestion of a filament of Oscillaria (44). A thread of shellac 

 is brought into contact with a drop of chloroform in a watch 

 glass of water. The drop adheres to the filament, lengthens 

 along it, and, because of its tendency to again become spherical, 

 succeeds in bending the now softened thread. The tension of the 

 surface film gradually draws in more of the filament, until finally 



FIG. 15. Ameba vcrrucosa devouring a filament of Oscillaria. (From Rhum- 

 bler in Archiv f. Entwick.-mech.) 



the whole thread is embedded in a complicated coil within the 

 drop. The ingestion of Oscillaria by Ameba is quite similar 



(Fig. 15). 



Choice of food may also be imitated with inorganic substances. 

 For example, a drop of chloroform in a watch glass of water will 

 take in shellac, paraffin and other substances, and will reject 

 sand, wood, glass, etc. (40). The substances accepted are those 

 which adhere to the drop of chloroform. Since in the majority 

 of cases food particles do not stick to the surface of the 



