74 CHARLES W. BARGITT 



agreement in beha\"ior by experience and heredity may like- 

 wise be accepted as a general conclusion not open to serious 

 debate. But that all must show the same reactions all the while 

 and under all circumstances, whether in their native habitat or 

 under the artificial conditions of a laboratory, only he whose 

 intellectual horizon is bounded by the bias of preconception 

 and theory will be likely to claim. These conflicting (so-called) 

 aspects of behavior are the exceptional methods by which a 

 given individual endeavors to meet an exceptional condition. 

 Colors in a living creature may be fixed, as in the dead pigments 

 of feather or hair, or they may be the expression of the compli- 

 cated play of living cells or tissues. In some cases they have 

 become in the course of phylogeny more or less adaptive ; and 

 in some they seem under individual control. That they should 

 at times exhibit differences and peculiarities need excite no 

 startling exclamations of surprise or incredulity. 



Other experiments. Various other stimuli were made use of 

 in the course of my studies. Among them may be mentioned 

 a few dealing with the matter of physical irritation, such as 

 pricking with a needle, pinching with forceps, etc. These were 

 tried with both species and in each series with essentially similar 

 results. In such an experiment the specimen would be placed 

 in a shallow box or dish, and by using a sharp pencil or some- 

 times a needle it would be made to leap actively about for 

 some time, in some instances almost to the point of exhaustion. 

 In the case of H. arborea the specimens would often emit during 

 such treatment the most plaintive little squeaks at each leap, 

 or when sharply pinched. But while in some cases these stimuli 

 would be associated with a definite darkening of the skin color, 

 at other times it would have just the opposite effect, the color 

 becoming just as evidently lighter. 



It was the same in case one pinched the skin of body or leg 

 with the forceps. Some would rapidly darken, others become 

 lighter, and. still in other cases not the slightest change. So 

 too, in holding with the fingers or forceps while the creature 

 struggled to escape, some would change color, others would 

 show no response. The experiment was also tried of picking 

 up a jar with specimens and moving it quickly, or roughly 

 about, or even shaking it from side to side; and here again with 

 similar results. In these respects the behavior of H . versicolor 



