FOOD-REACTIONS OF AMEBA PROTEUS 409 
But in the case of the variability of the ameba's conduct toward 
Euglena there is less weight to these criticisms. Frequently 
Euglenas are taken into wide vacuoles while their flagella are 
lashing vigorously. When a Euglena is caught by the advancing 
ends of an ameba's pseudopods, as shown in figure 12, there is 
no reduction in the intensity of the stimulation, for the flagellum 
is quite as active as it was before the body of the Euglena was 
laid hold of. In this case the water in the forming vacuole is, 
if anything, more greatly disturbed than when a vacuole is form- 
ing about a Euglena that has not thus been grasped. Despite 
this lashing of the flagellum within the vacuole that had been 
formed, in the beginning, with reference to a Euglena free to 
move out of its embrace, the type of reaction was changed as 
soon as the body of the flagellate was held in the ameba's grip. 
This sort of modification of the ameba's conduct gives it a quali- 
tative character rather than a quantitative one. 
Finally the conduct of ameba toward Chilomonas Paramecium 
indicates the qualitative character of its food reactions. 
Chilomonas is captured only as it Hes apparently quiet. This 
httle saprophytic flagellate is a very active creature. Kent ('80) 
says this "animalcule rushes to and fro, though with the anterior 
end foremost, at a speed too rapid almost for the eye to follow, 
while at the next moment it comes as it were abruptly to anchor, 
with its body perfectly quiescent and one flagellum adherent to 
the glass slide or covering glass, while the other maintains a 
vibratory motion" (p. 425). By placing these animals in a 
mixture of India ink and water or by studying them in water 
containing many non-motile bacteria, we were able to determine 
the extent to which these apparently quiet Chilomonases dis- 
turbed the surrounding water. By this method, together with 
checks or controls of specimens in aquarium water, we were able 
to determine that but a very few anchor themselves as Kent 
describes. The smaller or ventral flagellum in this case lashes 
the water slowly in such manner that a vortex of water arises 
beyond the anterior tip of the Chilomonas, for about the length 
of its body, and this is drawn down over the gullet; from here it 
passes, at right angles to the axis of the body, to the dorsal side. 
