to the animal's choice. 



Dr. Loeb's experiment? are conducted with the irivatest simplicity 

 of apparatus and the result- are at QHOe evident, yet it is to be home 



stages of their existence and even then the reaction to light may he 

 neutralized or modified by the co-existence of other modes of stimula- 



such manner as to place their bodies with reference to adjoining sur- 

 faces ; some for instance, taking up positions upon projecting corners of 

 a box, others only in the hollow angles. 



The form of reaction to contact stimuli is distinguished as "Stereo- 

 tropism" and together with geotropism will be later seen to play an 

 important role in the resulting movements of animals when exposed to 

 light. 



The fifth section of the brochure deals with the experiments upon 

 the caterpillars of Porthesia chrysorrhasa and serves as an introduction 

 and detailed illustration of the methods and results subsequently 

 described in other cases. 



The experiments are as follows : 



About 100 small caterpillars that have escaped from the nest in which 

 they pass the Winter and which have not as yet taken food, are put 

 into a test tube in a room at 12°-15° C. 



When placed horizontally upon a table covered with black paper 

 and with the axis of the tube at right angle to the window the cater- 

 pillars all crawl toward the window on the upper side of the tube, the 

 head and ventral side directed towards the light; reaching the end of 

 the tube thev remain p >ii :r;_- towards the light. 



As often as the tube is turned through 180° the caterpil 

 the movement. If then the test tube is put parallel to the window 

 the caterpillars scatter all along it but only upon the upper ode. 

 When in the first position the animals ha\ 

 end of the tube thev leave that end as sooi 





