74 BIRDS-NESTING. 



sion in the bottom stick, as shown in the cut, to 

 prevent the egg rolling about. 



Though worse than worthless unless great care 

 is exercised, the precise measuring of all your eggs 

 is of the highest importance. It will help to deter- 

 mine the amount of variation to be met with in each 

 species, and tend to show whether there is any law 

 governing this, as there seems to be in the case of 

 the plumage and proportions of birds inhabiting 

 widely separated districts. 



The late Dr. Brewer was fond of calling attention 

 to the lesser size of eggs from southern localities 

 as compared with specimens of the same name taken 

 in the northern states or in Canada. He believed 

 this difference to be uniformly the fact, but could not 

 persuade all his correspondents to agree with him. 

 It is a point for your studious investigation. 



Even eggs from the same nest may continually be 

 met with, presenting great disparity in bulk ; one in 

 the number being frequently so small in comparison 

 with the others as invariably to set a collector think- 

 ing it must have been the last laid, and that a partial 

 failure of egg-producing power in the mother-bird 

 must be the explanation of the phenomenon. 



