the Coloration of Eyys. 551 



enemies from far and near that will flock to it daily when 

 hungry enough) or to a need for recognition by parents, or 

 to both, is a problem to be solved by special observation. 

 To a case of variability that I have myself begun to 

 investigate (namely. Weavers* eggs) I will refer later. 



Another factor contributing to diversity (within or as 

 between species) would doubtless be Wallace's — of pro- 

 cryptic adaptation in varying directions, often from bases 

 already different. It would apply not only to those eggs 

 the coloration of which does definitely contain a procryptic 

 element at present, but, indirectly, to eggs formerly in dif- 

 ferent ways procryptic but now brightened through having 

 become possessed of a counteragent to conspicuousness 

 (c/. Darwin on caterpillars. Descent of Man, 2nd ed. p. 501*). 



3. Consjncuousness. — Given the existence of nauseousness, 

 conspicuousness would be useful in relation to the mistaken 

 attacks of enemies through the assistance it would give to 

 recollection and recognition, and its selection might be 

 brought about even in a but slightly deterrent species either 

 in this connection or through any other factor making for 

 conspicuousness whenever a suitable counteragent already 

 existed or was developed pari passu with it. Where the egg 

 is concealed up to the moment at which the enemy looks 

 into the nest, its appearance might be usefully regarded as 

 a vivid last appeal to the enemy's memory, the distinctive 

 nest-appearatice being the first — a suggestion as to why the 

 habit of building true to type might have been selected. 

 And the very fragility of eggs must render their need the 

 greater for mnemonic coloration of a particularly memorable 

 kind, and must aid in its eftective selection {cf. Darwin, 

 lac. cit. p. 499). 



* This point, with the additional counteragents suggested in a previous 

 footnote, the view that any variation in the direction either of variability 

 or conspicuousness will survive provided a probable counteragent is 

 forthcoming, and the influence of cuckoos towards both distinctiveness 

 and (especially) polymorphism in the eggs of their hosts may seem to 

 some to constitute, without nauseousness, a sufficient explanation of the 

 coloration of eggs. Actually, all this fails to account completely for 

 the facts. 



