AUTONOMOUS LOCOMOTORY MOVEMENTS 



535 



into the main axes. These movements are much more prominently exhibited 

 by the microscopic branches than by those visible to the naked eye ; such fila- 

 ments are being perpetually pushed out and pulled in, just like fine tentacles, and 

 the shape of theplasmodium is thus constantly altering ; branches shoot out and 

 are withdrawn again, forming and breaking anastomoses, often swelling up to 

 a great size and gradually taking on the characters of the stouter main branches. 

 These alternative movements may be observed in all parts of the plasmodium, 

 but they are readily seen to be more vigorous on the advancing side than behind, 

 and that, anteriorly, the characteristic feature is the protrusion of new branches, 

 while, posteriorly, the 

 reabsorption of older 

 strands is predomi- 

 nant ; hence arises the 

 forward creeping 

 movement of the plas- 

 modium.' The direc- 

 tion of the motion 

 is, however, not infre- 

 quently changed. 



In addition to this 

 change in outward 

 form associated with 

 regional changes of the 

 whole plasmodium, 

 other active move- 

 ments in the interior 

 of the plasmodium 

 may also be observed. 

 The plasmodium con- 

 sists of a colourless, 

 hyaline ground sub- 

 stance, the protoplasm 

 proper, through which 

 are scattered 

 numerous granules, 

 some of them com- 

 posed of carbonate of 

 lime, others of pig- 

 ments. The stream- 

 ing movements of the 

 protoplasm are easily 

 followed by the passive 

 migration of these 

 granules. Thus we may observe, first of all, in the centre of each branch an active 

 streaming taking place, while the peripheral region, on the contrary, is at rest, 

 not only the hyaline edge but layers still further inwards in which granules occur. 

 The movement takes place as though in a tube, for a time in one direction and 

 later in the opposite direction. In the marginal prominences for the most part 

 numerous streaming movements may be noticed, and not infrequently contiguous 

 portions move in opposite directions. Very often movements arise in regions 

 previously at rest, so that one may assume that canals in which the streaming 

 occurs did not exist there. This is shown even more clearly by the streaming 

 motion spreading laterally, the previously firm hyaline wall becoming fluid 

 and mobile. Rapid movements of the granules always take place, especially 

 in the active anterior regions of the branches, as though this streaming were 

 the cause of the forward movement of the tip of the branch. The smaller 



Fig. 

 paper. 



167. Plasmodium of Fuligo varians, creeping over a piece of filter 

 From a photograph. Slightly reduced. 



