342 yournal of Comparative Neurology and Psychology. 



and his failure to mark intermissions in practice precluded the presentation of records 

 of "play trials." 



Although Mr. Davis finds marked dilFerences in learning due to practice effects, 

 we are nowhere told in what order he used the several fastenings. This is a most 

 serious omission and greatly impairs the value ot his paper for comparative pur- 

 poses. For example, in one case he tested a raccoon on fastening No. 3, then passed 

 to No. 9, and in the latter case finds remarkable stupidity. Now if fastenings No. 9 

 were really the ninth fastening this animal had tried, the result is new and unusual, 

 but if it is the fourth, third, or second fastening, the animal's behavior agrees closely 

 with that of other raccoons, and entirely loses its marvelous character. 



Further, we read that while all the raccoons were "fully grown" when received, 

 yet distinct difi^erences in learning were found between the younger and the older 

 animals. We should expect, therefore, a statement of the approximate age of each 

 animal when received. Instead we are ofl^ered what seems to be the most useless 

 possible statement, namely, "the approximate age of each animal " at death or escape 

 or , for the summer of IQoy, some months after his work was completed (cf. pp. 462, 

 448). This defect greatly lessens the value of the experimental records. Fortu- 

 nately reparation can be made by the publication of the date at which each ani- 

 mal was received, the length of time during which it was tested, and the order in 

 which the tests were given. This addendum ought certainly to appear. 



Finally, so far as we can learn from the paper, only one box was used and the 

 latches were all so fastened to it as to be most inconspicuous. This, of course, 

 tends to stamp in the box feature of the situation, and, therefore to make the animal 

 more dependent on kina?sthetic sensations. Varying the position and size of boxes 

 and doors gives control experiments which rarely fail to modify an investigator's 

 first conclusions. 



The conflict between the author's several conclusions leaves one in doubt 

 whether the raccoons are, in intelligence, nearer the cats, which possibly have 

 "no images or memories at all," or nearer the monkeys which exhibit even "a low 

 form of general notion." 



Color Perception. The color perception of the raccoons was tested, and it is con- 

 cluded that they do not discriminate colors as such, but depend on differences in 

 brightness alone for their successful reactions. While the tables seem to show this 

 they may prove merely that discrimination of brightness is easier for the animals 

 to make than discrimination of color, for the method employed is very defective. 



With the first piece of apparatus used the raccoons could both look into and reach 

 into the vessel which contained the food, and into the five similar vessels which 

 were empty. The experimenter must have felt this disadvantage, for the second 

 piece of apparatus "did not allow the animal to look into the container inwhich the 

 food was placed" (p. 479), but the food could be obtained by reaching through an 

 opening 2 by I^ inches, in the vertical slides. The food was placed back of one 

 color and when this was moved every other color was given a new position also. 

 Thus with the second device each container could be explored by touch. If the 

 animal reached into a no-food vessel an error of color discrimination was recorded 

 against him. There seems thus no means of distinguishing true errors of color dis- 

 crimination from the cases in which the animal paid no attention to the colors, 

 except that brightness tests gave better results than color tests. "The two pieces of 

 apparatus were used indifferently. " Under these conditions there were 52 per cent 



