454 JOHN B. WATSON AND K. S. LASHLEY 



EXPERIMENTAL AND OBSERVATIONAL STUDY OF INSTINCTS 



Amphibia. Hargitt (10) gives some interesting data upon 

 food taking and hibernation in two species of tree frogs (Hyla 

 versicolor and H. arborea). In regard to food taking he says it 

 is evident that the tree frog responds only to moving objects. 

 A motionless spider may remain for hours in the cage without 

 being disturbed; the moment it becomes active, however, the 

 frog will seize it. The frog usually leaps to take its prey, rarely 

 stalking it. It waits until the prey is within leaping distance, 

 which may mean several feet. It springs upon the victim, 

 taking it with ease and rarely missing. Its prey apparently 

 is not seen at close range. 



In regard to hibernation the author says that the laboratory 

 specimens show no tendency to hibernate so long as normal 

 temperature is maintained. Several specimens were taken into 

 a cool, damp cellar, the last week of December. Very soon after 

 the change they showed signs of dormancy and burrowed (this 

 consists of backing, using the hind feet and sharp posterior end 

 of the body) under the mass of debris. The experiment upon 

 hibernation was not completed because of the death of the 

 animals. 



In regard to color changes, it may be said that there is a 

 wide variation in the native habitat even where the environ- 

 mental conditions, so far as could be observed, are the same. 

 Experiments show that, as a rule, light tends to bleach the skin 

 and rob it of its pattern. Darkness seems to have no positive 

 effect upon the color change or skin pattern. Some exceptions 

 to the lightening effect upon the skin of light are to be found. 

 In some cases a greenish color was induced by sunlight which 

 persisted for days. High temperature seems to act much as 

 does strong light — in general producing lightening of the skin. 

 There are also some exceptions to this rule. A low temperature 

 seems to have no effect upon color change. Contact stimuli 

 seems to be equally void of effect upon color change. 



Reptiles. Ruthven (20) makes some interesting observations on 

 the breeding habits of Butler's garter snake (Thamnopsis butleri 

 Cope). He concludes that the breeding season is about a month 

 long, its initiation depending on the climate, being in Southern 

 Michigan from the latter part of March over most of April. In 

 the case observed by him courtship lasted for five days, copu- 



