THE MOVEMENTS AND REACTIONS OF AMCBBA. 



161 



is supported by the variations to be observed in the relation of the clear 

 substance to the granular substance at the anterior end. These varia- 

 tions arise chiefly from the different rates of movement of the two 

 substances, and may be summarized as follows : 



i. The clear substance moves fastest at first, and therefore becomes 

 separated from the granules as a broad band in front (Fig. 52, a); this 

 is then immediately filled completely by the granules. Even large 

 granules or vacuoles pass to the very anterior edge, so that one sees 

 but a line between these and the outer water. 



"f&fff 



FIG. 52.* 



2. The clear substance advances fastest, and so continues to do, so that 

 it remains a long time as a broad, clear band in front of the granules. 



3. The two substances advance at the same rate, so that there is no 

 separation between them. The granules and vacuoles are then found at 



* FIG. 52. Distribution of hyaloplasm and granules at the anterior end in 

 Amceba Umax and its relatives : a, hyaloplasm without granules at the anterior 

 end; b, granules and vacuole at the anterior edge; c and d, two successive 

 instants in the locomotion ; at c the anterior half of the body is free from gran- 

 ules, the latter being heaped up behind a well-marked barrier; at d the barrier 

 has burst at a certain point (*), allowing a stream of granules to flow forward to 

 the anterior edge; e and/, two successive stages at the advancing anterior end; 

 in e the clear hyaloplasm has stopped at the line x-y; at/ the hyaloplasm has 

 advanced, while the granules are heaped up behind the same line x-y. 



