274 Celebes. 



We may also, I think, see in the jieculiar organization of 

 the entire family of the Megapodiclse, or brush-turkeys, a rea- 

 son why they depart so widely from the usual habits of the 

 class of birds. Each egg being so large as entirely to fill up 

 the abdominal cavity and with difficulty pass the walls of the 

 pelvis, a considerable interval is required before the successive 

 eggs can be matured (the natives say about thirteen days). 

 Each bird lays six or eight eggs or even more each season, so 

 that between the first and last there may be an interval of two 

 or three months. Now, if these eggs were hatched in the 

 ordinary way, either the parent must keep sitting continually 

 for this long period ; or if they only began to sit after the last 

 egg was deposited, the first would be exposed to injury by 

 the climate, or to destruction by the large lizards, snakes, or 

 other animals which abound in the district, because such large 

 birds must roam about a good deal in search of food. Here 

 then we seem to have a case in which the habits of a bird 

 may be directly traced to its exceptional organization ; for it 

 will hardly be maintained that this abnormal structure and 

 peculiar food were given to the Megapodidae, in order that 

 they might not exhibit that parental affection, or possess those 

 domestic instincts so general in the class of birds, and which 

 so much excite our admiration. 



It has generally been the custom of writers on natural 

 history to take the habits and instincts of animals as fixed 

 points, and to consider their structure and organization as 

 specially adapted to be in accordance with these. This as- 

 sumption is however an arbitrary one, and has the bad effect 

 of stifling inquiry into the nature and causes of " instincts and 

 habits," treating them as directly due to a " first cause," and 

 therefore incomprehensible to us. I believe that a careful 

 consideration of the structure of a species, anrlpf the peculiar 

 physical and organic conditions by which it is surrounded, or 

 has been surrounded in past ages, will often, as in this case, 

 throw much light on the origin of its habits and instincts. 

 These again, combined with changes in external conditions, 

 react upon structure, and by means of " variation " and " nat- 

 ural selection " both are kept in harmony. 



My friends remained three days, and got plenty of wild 

 pigs and two anoas, but the latter were much injured by the 



