214 DARWINISM 



huge goatsuckers — build very similar nests, and their white 

 eggs are protected in the same manner. Some large and 

 powerful birds, as the swans, herons, pelicans, cormorants, and 

 storks, lay white eggs in o])en nests ; but they keep careful 

 watch over them, and are able to drive away intruders. On 

 the whole, then, we see that, while white eggs are consj^icuous, 

 and therefore esj^ecially liable to attack by egg-eating animals, 

 they are concealed from observation in many and various ways. 

 We may, therefore, assume that, in cases where there seems 

 to be no such concealment, we are too ignorant of the whole 

 of the conditions to form a correct judgment. 



We now come to the large class of coloured or richly 

 spotted eggs, and here we have a more difficult task, though 

 many of them decidedly exhibit protective tints or markings. 

 There are two birds which nest on sandy shores — the lesser 

 tern and the ringed plover, — and both lay sand-coloured eggs, 

 the former spotted so as to harmonise with coarse shingle, the 

 latter minutely speckled like fine sand, which are the kinds 

 of ground the two birds choose respectively for their nests. 

 "The common sandpipers' eggs assimilate so closely viith. 

 the tints around them as to make their discovery a matter 

 of no small difficulty, as every oologist can testify who has 

 searched for them. The pewits' eggs, dark in ground 

 colour and boldly marked, are in strict harmony with the 

 sober tints of moor and fallow, and on this circumstance 

 alone their concealment and safety depend. The divers' 

 eggs furnish another example of protective colour ; they 

 are generally laid close to the water's edge, amongst drift 

 and shingle, where their dark tints and black spots conceal 

 them by harmonising closely with surrounding objects. The 

 snipes and the great army of sandpipers furnish innumer- 

 able instances of protectively coloured eggs. In all the 

 instances given the sitting -bird invariably leaves the eggs 

 uncovered when it cpiits them, and consequently their safety 

 de})cnds solely on the colours Avhich adorn them."^ The 

 wonderful range of colour and marking in the eggs of the 

 guillemot may be imputed to the inaccessible rocks on which 



^ C. Dixon, in Seebohm's History of British Birds, vol. ii. Introduction, p. 

 xxvi. Many of the other examples here cited are taken from tlie same valu- 

 able work. 



