cttAP. xvn.] nJliirs J.VD INSTLYCTS. 2(^7 



We mny also, I think, seo in the peculiar organiKation of 

 the entire family of the Mogapoiliilic or Bmsh Tiirkevs. a 

 reason why they depart so widely from the u.sutil Imbi ts nf 

 the Class of birds. Each egg being so lari^e as entirely to 

 fill np the abdominal cavity and with diiUcuUv pioss the 

 walls of the pelvis, a cousidoiuble interval is vequirefl 

 before the successive egf^s can he matured (the natives say 

 about thirteen days). Each bird lay* six or eight eggs or 

 even more eacli season, so that between the first and last 

 there may be an inten^al of two or three months. Novf, if 

 these eggs were hntclied in the oixlinary way, either the 

 parents must keep sirting continually for this; long period, 

 or if they only began to sit after the hi.'^t egg was deposited, 

 the first would be exposed to injury by the climate, or to 

 destruction l>y tlie large lizards, snakes, or other animals 

 which abountl 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 whicli ilie lialiits of a bird may 

 b^ directly traced to its exceptional orguni nation ; for it 

 will hardly be maintained that this abnormal structure 

 and peculiar food were given to the Megapodid.e, in order 

 that they might not ' exhibit thjit parental affection, or 

 possess those domestic instincis so general in the Class 

 of birds, and which so mu(di excite our admiration. 



It has geuei-ally been the custom of writei-s on Natural 

 Ilistory, to take the habits and instincts of animals as fixed 

 points, and to consider their structure an<l organization as 

 specially adapted to be in accordance with these. This 

 aasumptiou is howevei' an arbitrary one, and has the ba*! 

 effect of stitling inquiry into the natiu'o 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, and of the jx-culiar physical and organic conditions 

 by which it is surrounded, or has been surrounded in past 

 ages, will often, as in this ease, throw much light on the 

 origin of its habits and instincts. These again, combined 

 Avith changes in external conditions, react upon structure, 

 and by means of " variation" and " natural selection" both 

 are kept in harmony. 



My Mends remained three days, and got plenty of wild 



