Waltzhui Instinct in Ostriches. 171 



only after they had been under observation tor three or four 

 weeks that on first taking them out of their small enclosure 

 they began to dart along the pathway and then, with the 

 fore-part of body elevated and head thrown back, attempt to 

 whirl about. Their movements at first were imperfect, and 

 reversal would take place before a complete turn was effected. 

 Indeed, they never accomplished more than one or two turns 

 in either direction, and at no time became as expert in the 

 performance as chicks which are reared together in large 

 numbers. They afforded an excellent illustration of beha- 

 viour which, though instinctive, never reaches full perfection 

 except under favourable conditions, iu this instance the stimu- 

 lating conditions being a large number of individuals on the 

 open veld. 



Such complex and highly characteristic behaviour on the 

 part of Ostrich chicks must have some biological significance, 

 though apparently no one has attempted the solution of the 

 phenomenon. The theory of natural selection applied to 

 animals assumes that in general all the structures of an 

 animal are of some value to the creature; in whatever 

 manner the structures may have arisen their continuance 

 implies that they are in some way beneficial. Likewise all 

 the activities of an animal must be assumed to be of some 

 advantage at one time or another in the life of the individual. 

 It must be admitted that on the surface the waltzing of the 

 Ostrich appears to be of no direct utility to the bird, but 

 to be merely so much intense playfulness, manifesting an 

 exuberance of spirits, stimulated and encouraged to an ex- 

 cessive degree by the example of others. Even regarded as 

 playfulness, however, one must seek to understand its mean- 

 ing in the economy of the animal. 



Two theories of the biological significance of the playful 

 activities of young animals have been offered. One, that 

 developed by the late Mr. Herbert Spencer, regards play as 

 evidence of an exuberance of spirits, a kind of safety-valve, 

 as it were, for the letting-out of surplus energy ; an explana- 

 tion well suggested by the way a healthy, vigorous bov 

 behaves when first let loose from school. Another explana" 



12* 



