RESPOXSIVE LIFE OF ORGAxXISMS 479 



which binds the other materials together; this is the har- 

 dened secretion from glands that open through the labium 

 of the larva, which exudes as a fluid, and hardens after con- 

 tact with the water. This secretion is all the equipment the 

 larva needs for building or repairing its cases. 



I. To test the adaptability of case building to present 

 physical needs: 



I.) Cut a hole in the side of the case, exposing a vulner- 

 able part of the body, and see if it will be repaired. 



2.) Slit a case lengthwise, in a narrow opening from end 

 to end and leave it to be repaired. 



3 .) Cut a case in two crosswise, and leave one part of it 

 only on the larva for repair. 



II. To test the adaptability of case building to con- 

 ditions of environment. 



4) . Provide a background of a different color from the 

 natural one, (background may be placed under the bottom 

 of a glass dish) , and materials for case building of suitable 

 size and of a color to match the background (strips and 

 bits of mica, glass, colored celluloid, whitewood, etc.). 

 Provide also the materials ordinarily used, but which are 

 unsuited to the new background, being there conspicuous 

 when viewed against it. See what materials a larva, re- 

 moved from its case, uses for making a new one. 



5). Leave a larva, removed from its case, upon the old 

 background, but provide it only with case-building materials 

 that will be conspicuous against that background, and note 

 the result. 



The record of this study will consist of an illustrated 

 account of the experiment, setting forth their results. 



Learning by experience. — Many of the lower animals are 

 born educated almost to the full extent of their capacity, 

 the possible lines of action of their whole lives being pro- 



