Nov.. 19161 Y. KUW ADA.— SOME PECULIARrFTES OBSERVED. 349 



Loeb'^ studied noL only ])hysicc'd influences as temperature, but 

 also effect of chemicals in the environment such as esters, acids, 

 CO., etc. In order to see whether CO^ is a cause, also in the pres- 

 ent Chlainvdomonas, of the change of behavior to light, the 

 following experiment was undertaken. 



A small rectangular glass vessel, commonly' used as the elec- 

 tric bath, was employed as the culture- vessel. The vessel was 

 put near the window in such a position as the broader sides 

 of it to be perpendicular to the window plane. The corners of 

 the vessel were found somewhat sunk from the general level of 

 the bottom. The swarmspores formed collections at the two of 

 these corners, which lay at the side away from the window, and 

 not at the corners of the window^ side. The vessel v^ras turned to 

 the left through 90° in order to make the broader sides parallel 

 to the window, so that the positions of the corners, in which 

 the organism collected, were changed to the right hand side, 

 one corner being at the window side, and the other at the side 

 away from the window. The vessel was kept undisturbed till 

 the next morning, when the collection at the window side was 

 found almost to have disappeared, leaving only a green spot, 

 while a new collection appeared at one of the left hand corners 

 of the vessel, which was awa}' from the window. This confirms 

 that the sense of reaction is negative under the present condition. 

 The CO2 was then allowed for one minute to bubble in the water. 

 The collections were disturbed and the swarmspores were dis- 

 tributed without anv order in the culture medium, so that the 

 latter became green in colour. At about two hours after the 

 operation a part of swarmspores showed a sign of positive 

 phototaxis in migrating towards the wnndow side, and the 

 next morning it became clear that they responded positively to 

 light forming collections at the window side corners. On the 

 third da}' after the operation the collection at the right hand 

 side corner disappeared, but that at the left remained unchanged. 

 Loeb"^^ mentions that the positive phototaxis produced in this 



1) LoEB, J., The Dynamics of the Living Matter. 1906. 



2) Leob, J., I.e. 1906. 



