[Reprinted from Science, N. S., Vol. XL, No. 269, 

 Pages 392-299, February 23, 1900.'] 



TRE OCCURRENCE OF APT0S0CHR03IATISM 

 IN PA8SERINA CYANEA.* 



The following remarks upon the Aptoso- 

 chromatism of Passerina cyanea, although 

 of insufficient importance to establish the 

 phenomenon of color change without moult 

 as a constant occurrence in the species, are 

 conclusive enough, I am convinced, to 

 prove the possibility of such a change, and 

 are merely offered as such for what they 

 may be worth. 



Individual error and dogmatism have 

 greatly retarded honest effort in this most 

 important branch of ornithological science- 

 It is a singular fact that certain individuals 

 have conceived the idea that a feather once 

 having passed its premature condition is 

 utterly disconnected with the vital system 

 of the bird, and such individuals cling to 

 this belief with a tenacity wonderful to be- 

 hold. They do not tell us, by the way, 

 how it is that certain species of birds lack- 

 ing external sebaceous glands manage to 

 present as brigTit plumage as their allies so 

 provided. Doubtless they may attribute 

 the presence of oily matters upon the sur- 

 face of the feathers of those species in 

 which these glands are wanting to osmotic 

 action ; but-admitting this, why not admit 

 AptosochromatiSm ? 



In his article on alleged changes of color 

 in feathers (Bull. Am. Museum Nat. Hist. 

 1896), Dr. Allen compares a feather to a 

 green leaf, which when once formed, can- 

 not extend its growth to repair any injuries 

 which may arise from insects, etc. This 



* Read before the Nuttall Ornithological Club of 

 Cambridge, Maas., June 5, 1899, with exhibition of 

 the bird worked upon. 



