78 L. W. SACKETT 



seconds with four errors, and 3 minutes with eight errors. 

 The third day of the memory test brought him to his old stan- 

 dard of a single error in 7 with i minute 30 seconds for the trip. 

 Conclusions from these variations are: 



1. The trail of a beaten path, whether it be by smell, or vision, 

 or touch, or all coml)ined is a slight but not an essential factor 

 in the porcupine's al)ility to follow a known way to a given point. 



2. The sense of direction in the porcupine is strong, though 

 probably not playing the role of a dead reckoning. The sur- 

 rounding trees are probably used as visual landmarks if one 

 may judge from the tendency of the animals to work in parts 

 of the maze nearest to the surrounding trees. It has also been 

 observed that when in the natural runways they cross an open 

 space they generally emerged from and re-entered the forest 

 under cover of low-hanging trees and creep beneath all the in- 

 ter^'ening evergreens. 



3. The kinaesthetic sense depending on a complex of muscle, 

 joint, and tendon sensation is the one most effectually modified 

 by rotating the maze on the slope and is, doubtless, one of the 

 most important elements in retention. 



4. The porcupine's eye is either adaptable to exceedingly dim 

 light, or they can follow a known path without the sense of 

 sight. 



5. Memory of the maze through a period of 100 days with no 

 intervening practice and with little diminution of ability, sug- 

 gests either that sufficient experience had been given with the 

 new problem to fix the habit or that the problem of the maze 

 is comparable with those on which the survival of the species 

 depends. 



RESUME 



1. In the foregoing study 16 porcupines have been used. 

 Eight were male, four were female, and in the cases of four the 

 sex was not ascertained. Conditions as near to the natural 

 environment as possible have been maintained at all times by 

 means of outdoor cages, dark dens, natural Ijarks for food, etc. 



2. It has been ascertained that porcupines are nocturnal and 

 perennial, showing little or no hibernal tendencies. Their span 

 of life is not known but is probably a decade or more. They 

 usually give birth to but one young each year. Young are 



