194 T HE BEHAVIOR OF LOWER ORGANISMS. 



the Amoeba ; on the contrary, it was pushed ahead as fast as the Amoeba 

 moved. The Amoeba now put out a pseudopodium on each side of the 

 cyst, while that part of the protoplasm immediately behind it stopped 

 moving. Thus the cyst was enclosed in a little bay. On bringing the 

 upper surface of the cyst into focus it could be seen that a thin layer of 

 protoplasm was also sent over the cyst. The two pseudopodia enclosing 

 the cyst now bent over at their free ends, so that the cyst could not be 

 pushed away by movement of the Amoeba. The two free ends finally 

 met, leaving only a sort of transparent seam to show the place of con- 

 tact. Later this disappeared, and the two pseudopodia fused completely. 

 At the end of two minutes from the time that the Amoeba first came in 

 contact with it the cyst was completely enclosed. The Amoeba now 

 remained perfectly quiet for one minute, then crept away, carrying the 

 cyst with it. With the cyst had been taken in some water, so that it 

 was enclosed in a vacuole a little larger than itself. The walls of the 

 vacuole had exactly the appearance of the ectosarc on the outer surface 

 of the Amoeba. 



This is essentially the method of food taking that I have observed in 

 a large number of cases in Amoeba proteus and its relatives. The 

 essential points are the sending out of pseudopodia on each side of 

 and above the food body and the fusion of these pseudopodia at their 

 free ends or edges, thus enclosing the food. In no case, in these species, 

 was there any evidence that the Amoeba was aided by the adherence 

 of the food body to its protoplasm. On the contrary, there was a 

 decided 'tendency for the food body to be pushed away, and an essential 

 part of the process is the overcoming of this mechanical difficulty by 

 sending out a pseudopodium on each side of the body and bending the 

 ends of them together, so as to prevent slipping on the part of the 

 food.* That this difficulty is no imaginary one will be shown later, 

 in the description of cases where the Amoaba was unable, after many 

 efforts, to enclose the food. 



It is commonly said that the posterior rough, tail-like portion of the 

 body is especially important in the taking of food, though it is sometimes 

 added that one rather more often sees the partly ingested food given out 

 again in this region (see Leidy, 1879, p. 45 ; Penard, 1890, p. 81 ; 1902, 

 p. i6).| I have never seen food taken in at this part of the body, though, 

 as noted above, I have many times seen it taken at the anterior end. 

 While it may be true that food is at times taken at the posterior end, I 



"This lack of adherence between the protoplasm and the food substance is 

 emphasized by Le Dantec (1894, p. 68) as a result of his careful studies on food- 

 taking in Amoeba. 



t The references to food-taking at the posterior end seem all to go back to a 

 paper by P. M. Duncan, " Studies amongst Amoebae," in the Popular Science 

 Review for 1877. I regret that I have been unable to see this paper. 



