70 



THE CELL 



shaped swellings or lateral accumulations in a thread, may be 

 seen to move in a similar manner. Even foreign bodies which 



adhere to the thread 

 substance, and have 

 been taken in by it, 

 are seen to join in 

 this movement, the 

 rate of which may 

 attain to "02 mm. per 

 s econd. Where 

 several threads over- 

 lap each other gran- 

 ules may be seen pass- 

 ing from one into the 

 other. At such places 

 broad flat surfaces 

 may be produced by 

 the heaping up of the 

 thread substance. 



A special kind of 

 protoplasmic move- 

 ment is described by 

 Engelmann (III. 5, 7) 

 under the name of 

 gliding movement 

 (Grlitschbewegung). 

 It has been observed 

 chiefly in Diatoms and 

 Oscillaria. In the 

 former the proto- 

 plasm is surrounded 

 by a siliceous shell, in 

 the latter by a cellu- 

 lose membrane. How- 

 ever, outside this 

 covering there is an 

 exceedingly delicate 

 layer of hyaloplasm, 

 quite free from gran- 

 / | \ ules, which cannot be 



FIG. 40. Gromia owjormis. (A.fterM. Schu^tze.) Seen in the living ob- 



