direct light of the windows — for the spider-crab is 

 extremely averse to strong light — I prepared a 

 small tank for the reception of Jim. This tank, 

 composed entirely of glass, I covered around the 

 sides and bottom with a thin layer of transparent 

 varnish to which some red dye had been added. A 

 pane of glass large enough to cover the top was 

 similarly treated. As a control tank for the experi- 

 ment I proposed, I placed alongside the red aquar- 

 ium, one of the same size but coated with green. 

 Into each was put an equal number of small sea- 

 weeds all of an approximate size. The seaweeds, 

 however, were of two kinds, green sea-lettuce 

 (Ulva lactuca) and red Irish moss (Chondrus 

 crispus), and these were evenly distributed in the 

 two tanks. Thus, the red tank contained an equal 

 amount of red and of green seaweeds; likewise the 

 green container. 



Removing Jim from the big aquarium, I 

 stripped from him the material with which he was 

 masked, and cleaned his carapace well; then put- 

 ting him into the red receptacle, I watched to see 

 how he would react. 



The first few moments were marked by a de- 

 cided uneasiness on his part because of his recent 



[236] 



