BY D. embleto:n-, m.d. 83 



shell, and in which the calcareous salts are deposited, may have 

 the function of secreting pigmentary matter. But if this were 

 so, ought we not to find something like coloured patterns on the 

 eggs, showing some degree of definition and regularity, and per- 

 haps also pigment granules in the cells of the coloured spots ? 

 such appearances, however, do not seem to have been observed, 

 or at least recorded. 



YIII. The colours of the plumage of birds, though often so 

 much more brilliant, are even more variable than those of eggs, 

 but there does not appear to be any relationship or correspon- 

 dence between the colours of the plumage and those of the eggs ; 

 nor is there any evidence to prove that Dr. Erasmus Darwin was 

 correct in ascribing the origin of the colours of eggs to the colour 

 of the objects among which the mother bird lives.* 



The colours of feathers are not due to mere escapes of blood. 

 They appear rather to be the result of the operation of gland 

 cells at the roots of the feathers, and pei'haps in the feathers 

 themselves, upon the matters they receive from the blood circu- 

 lating in the capillary vessels around them. 



The colours of some eggs, as those of the plumage of some 

 female birds, appear to be, in a measure at least, in some cases, 

 the means of their protection; but there are too many examples 

 to the contrary, in both respects, to admit of any rule being 

 thereby established. 



There cannot be a doubt that some, as for instance the Bower 

 Birds, admire the nests they build up and ornament with so much 

 skill, assiduity, and even taste ; and that others evince great at- 

 tachment to their eggs, their constant care of which is so conspi- 

 cuous. On the other hand there are some, as the domestic fowls, 

 that are careless, and will lay almost anywhere, even without 

 any nest. With regard to the number of their eggs, birds ge- 

 nerally seem to have only an imperfect notion. 



PosTscRirx. — On the 6th of August, 1876, and sometime after 



* The first record of the impression on the mind or brain, tiirouy:li tlio eyes of a motiier, 

 influencing the colour of her offspring, is to be found, as is generally known, in the last 

 verses of the thirtieth chapter of the book of Ooncsis. 



