AMOEB.E OF THE INTESTINAL TRACT. 131 



served in organisms which have been exposed to room 

 temperature for some time, and consists in the active 

 extrusion of pseudopodia unaccompanied by pro- 

 gressive motion, the processes of ectoplasm being con- 

 tinually projected from the periphery of the parasite 

 and as quickly withdrawn. In such instances the 

 endoplasm does not flow into the pseudopodia, as a 

 rule, but occasionally this occurs, though progressive 

 movement is prevented by the projection of new 

 pseudopodia. This form of motility is only observed 

 in organisms which have been exposed to unfavorable 

 conditions, as lower temperature and solutions of 

 chemical substances, so that it is fair to assume that it 

 is an evidence of abnormal environment. 



The third variety of motion is rarely observed. 

 It may be called an intra-protoplasmic form of 

 motility, consisting of currents evidently produced 

 within the endoplasm. The contents of the endoplasm 

 are observed to be in motion in a circular manner, 

 the nucleus, vacuoles, red blood cells, and other sub- 

 stances being whirled about within a boundary formed 

 by the ectoplasm, while an undulatory motion of 

 the latter is sometimes observed. The movement of 

 the current is generally slow, but it may be very 

 rapid, and may continue for several minutes. 



Of the significance of this form of motion we are 

 ignorant. It is somewhat similar to that occurring 



