296 



SCIENCE. 



[N. S. Vol. XI. No. 269. 



surd to suppose that a single generation in 

 confinement would so alter the natural laws 

 of the organism as to obscure Aptosochrom- 

 atism or Ptosochromatism, if one process 

 or the other be a natural tendency. It is 

 objectively certain that the phenomenon 

 of Aptosochromatism occurs widely, but 

 whether of individual or specific occurrence 

 is not yet clearly shown. While my bird 

 threw out no hint whatever as to the con- 

 stant occurrence of the color change, it did 

 prove that the ' impossibility ' is possible.* 

 It is certain that the heavj' feather loss of 

 my bird but indirectly helped the change ; 

 1st, we have seen that many feathers 

 changed which were not renewed by moult ; 

 2d, we saw that those feathers which were 

 renewed by direct gain and loss were col- 

 ored similarly to those which preceded 

 them, but that later on they changed Apto- 

 sochromatically, and 3d, no purely blue, i. e., 

 changed feathers, were found in an embry- 

 onic condition at any time, although fre- 

 quent careful examinations of the bird were 

 made. 



Although it is of no positive certainty 

 whether, in the new feathers, the vascular 

 connection with the body was severed, it 

 was found that their complete form was at- 

 tained in most cases a week or more before 

 a change set in; and in those unshed 



*Dr. Chadbonrne has informed me, since the above 

 was written, that of three confined male indigo birds 

 • observed by him, two changed color ptosoehromatic- 

 ally and the third ' without any feather loss to speak 

 of,' i. e., aptosochromatically ; and still later on, I 

 was delighted to learn during a conversation with 

 Mr. C. J. Maynard that he too had followed a male 

 Passerina through its entire spring change of color. 

 The bird involved, belonged to a friend of Mr. May- 

 nard, who informed him that the bird had changed 

 its colors during the season just passed without moult- 

 ing its feathers. Determined to follow out the change 

 exactly, Mr. Maynard examined the bird frequently 

 the next season, throughout the entire time occupied 

 by the change, and perfectly satisfied himself that it 

 was totally unassisted by a moult or any considerable 

 loss of feathers. 



feathers carried over from the fall, it is 

 quite reasonable to suppose that all con- 

 nections with the body of the bird were as 

 normal as in other feathers of a similar age. 

 Before the change of color had begun, in 

 December or January, in specimens ex- 

 amined carefully under the microscope, I 

 could detect no presence of carrier pigment 

 cells and found the calamus of each feather 

 to be in the expected dried up condition. 

 The change would thus seem to be confined 

 to activity in the feathers alone. 



In a brief summary of the principal points 

 already discussed in connection with my 

 bird we may conclude (1) that Aptosochrom- 

 atism in my Passerina cyanea occurred 

 beyond doubt, (2) that although present 

 with severe feather loss it does not follow 

 that the gain of color was directly responsi- 

 ble to it, as proved by careful examination 

 of the newly acquired feathers, and (3) that 

 although the feather loss was objectively 

 independent of the Aptosochromatic change, 

 it might subjectively be so, inasmuch as old 

 and imperfect feathers were renewed for 

 active and healthy ones, in which such a 

 color change subsequently occurred. 



The results quoted of Dr. Chadbourne 

 and Mr. Maynard appear to me to be con- 

 clusive in themselves and require no further 

 comment. Microscopically, the color change 

 was not of as much prominence as might 

 have been expected at first thought, but it 

 will be recollected that blue and violet 

 colored feathers depend, in a large measure, 

 for their effects, upon involved objective 

 superstructures, which act in combination 

 with some underlying pigment or pigments. 

 These pigments produce chemical objective 

 effects, due to the absorption of all light 

 rays not depending upon the characteristic 

 color of the pigments. 



Chemically and microscopically, the 

 feathers of my Passerina cyanea appeared 

 to contain two pigments, one, a diffused 

 non-granular tawny colored stain, the other, 



