•I 



y' 



50 



i\^ 



c 







.nH ♦{ ^< '"f ^ ^"))i.orts the solectinK, sijacin"; and reveiN,,, 



and oieninK the one or the other of tlie food boxes F or F,. 



II the talile B is shown the are, 5, the condenJer 19 and the slit 20. Inside the compartment C is placed the collimator 21, the prism 25 and the objective 

 •sing devices. The stand E supports the rotating sectors P and K and the motor 77 which rotates them. At W are shown the speculum mirrors M and L 

 Jchroiruitic beams. Ihe animal is placed at W and must make a choice of the two colors as evidenced by his passing to the right or the left of the parti- 

 i! or Fi. ./ 1 o ^ 



