240 The World-Evidence. 



or is there a range of difference, slight yet perceptible, 

 even in the eggs laid by one bird ? Fain would we 

 learn something of these things, as well as satisfaction 

 on the question of weight, and whether in weight the 

 eggs of different tint or colour vary from each other, 

 and within what range, if any, among themselves. 

 For that we must wait yet, we fear, a long while : 

 and mention the point merely in the hope of bringing 

 these elements for comparative purposes a little time 

 sooner. 



II. We have found record so frequently that the 

 eggs of our common cuckoo found in nests are more 

 advanced towards hatching than those amongst which 

 they are placed, as to be almost forced to the con- 

 clusion that they hatch in a shorter space of time 

 than do the eggs of the victimised birds. The eggs 

 of the cow-bird hatch in eleven days, as against four- 

 teen to sixteen days in the case of the birds into 

 whose nests they are intruded. Nehrling tells us that 

 when the cow-bird drops an egg into the nest of a 

 smaller bird it is first hatched ; getting all, or nearly 

 all, the heat of the sitting bird's body. 



III. The molothrus manages, somehow, to dis- 

 pose of the other young birds in the nest ; for soon 

 after exclusion from the shell they disappear. 



Mr. Nehrling writes: 



" In Texas I found two parasitic eggs in the nest 

 of the painted bunting, and of three in the nest of the 

 orchard oriol, only one was hatched, while the other 

 disappeared in a mysterious way with the foster- 

 parent's own eggs. In the nest of a yellow-breasted 

 chat, in South-Western Missouri, three cow-bird's 

 eggs were found, together with one of the rightful 



