§4] 



DIRECTION OF LOCOMOTION 



279 



)0:5S 



Fig. 72. — Camera drawing, showing the successive positions assumed by Amceba 

 proteus when acted upon by external agents uniformly in all directions. Mag- 

 nified 16 diams. 



Fig. 73. — Tracks made on paper by larvse of Musca csesar moving in the dark from 

 a central spot of colored fluid. (From Pouchet, '72. Revue et Mag. de Zool. 



(2) xxm.) 



