112 The Animal Mini 



to pricks, were abolished by cocaine. Risser (638) reports 

 that while sight seems to be more important than smell in 

 determining the mature toad's reactions to food, tadpoles 

 failed to distinguish packets containing food when their 

 nostrils were plugged. Immature Amblystomas, which in 

 the normal condition react positively both to motionless 

 food and to moving inedible objects, lost the first type of 

 response when their nasal pits were removed, and the sec- 

 ond t5rpe when their eyes were operated on (112). — 



In birds sight and hearing are so well developed that 

 the chemical sense assumes less importance. Birds seem 

 to have a sense of taste : the chicks experimented on by 

 Lloyd Morgan, for example, showed disgust on picking 

 up bits of orange peel instead of yolk of egg (506, pp. 40- 

 41). Herring guUs make similar manifestations on being 

 fed salt fish, and take bread soaked in meat juice more 

 readily than water-soaked bread (697). Raspail (626) 

 thinks that birds abandon eggs which have been handled 

 because they detect the fact by smell; that they find 

 buried grubs by smell, and are guided by this sense to con- 

 cealed food and water. The last statement he supports 

 by the observation that their tracks lead straight to hidden 

 food on their first visit to it, showing that it was not found 

 by accident. Strong (696) made a careful study of the 

 olfactory apparatus in twenty-seven of the thirty-five 

 existing orders of birds. He concludes that "the olfactory 

 organs of birds are of too great size to be set aside as non- 

 functional," but that as one passes from the lower to the 

 higher orders of birds there is a tendency towards retrogres- 

 sion in these organs. The crow family, sometimes con- 

 sidered to be the highest birds, show extremely minute 

 smell organs. "The sense of smell has evidently been 

 disappearing in birds with the great development of vision." 



