FURTHER INVESTIGATIONS ON HELIOTROPISM '.:* 



Within the next few days the six first-incut ioncd animals 

 further elevated their heads, so that the animals on Decem- 

 ber "2'2 eight days after being placed in the aquarium 

 were all similarly oriented toward the light. The IK-IK! inix 

 diri'ctcd fatrnnl the irindoir, and flic a.rix of xi/ni me/ >>/ of 

 the /////s irhicli ircrc c.rjHmcd fo flic Injht lot/ in flic direction 

 of the more iiifciixc /v///.s- of <l<ii/li<i/tf irhich eidered from 



FIG. 8 



trUhonl (tin/ ahore. I waited to discover whether this orien- 

 tation would last. The aquarium remained undisturbed 

 until February 1<>, ISllQ; that is, for more than two months. 

 The animals also did not change their positions, as indicated 



in Fig. 



. 



3. On the afternoon of February 17, 1890, the aquarium 

 was turned 180 about its vertical axis, and the zinc box 

 was again inverted over the aquarium so that the movable 

 end was directed toward the window. BV turninc- the 



J 



aquarium around in this way, the heads of the animals, 

 which had been until then directed toward the source of 

 light, were suddenly turned toward the room side of the 



