i8gg J Birtwell, An Example of Aptosochromatism. 3*5 



Upon certain occasions when it was difficult to obtain Sparrows 

 or mice, I gave beef mixed with cotton wool which appeared to 

 be perfectly acceptable. Food was given upon alternate days, 

 usually about dusk, and an average of two ounces of food was 

 given each time. Sometimes the bird would voluntarily fast for 

 three and four days. For the major part of the time I conducted 

 the feeding personally and when unable to do this had it carried 

 on under strict orders. Each few days, cast off feathers were 

 carefully sought for and a very limited number found, not 

 enough for an average of three a week excepting during the 

 moult of September, 1898, when a complete renewal ensued. By 

 far, down feathers were shed in the greatest abundance, and the 

 few contours found were, in the majority of cases, injured or 

 abraded. 



Thus once and for all we may dismiss any possibility of 

 increased feather loss causing direct interference with my follow- 

 ing remarks. 



At this point it may be well to discuss briefly a few of the 

 terms employed. A great deal of useless controversy has been 

 expended over the comprehension of exact definitions, and it is 

 my purpose to avoid this. Aptosochromatism and Ptosochroma- 

 tism have been defined in my article on the ' Occurrence of 

 Aptosochromatism in Chrysotis levaUlanti' (Osprey, April, 1899), 

 and as such will be employed here. ' Moult ' is an exceedingly 

 convenient term as defined by Dr. Chadbourne (Auk, April, 1897, 

 p. 146) and is thus used. Ptosochromatism may be regarded as a 

 restricted process of moulting, although the two terms are by no 

 means synonymous. ' Color change,' unless modified by qualify- 

 ing terms, refers exclusively to alterations of color or structure 

 within the feather itself, due to vital causes within the feather 

 organism. 



From April 3 until the 12th (the birds fasting until the 3d) 

 various kinds of food were given, the birds meanwhile becoming 

 accustomed to their change of quarters, but after the last named 

 date, a careful feeding of beef, lamb and chicken livers (and 

 sometimes kidneys) was begun and maintained until May 27, 

 ^98 — a period of 53 days. During this time about 46 ounces of 

 liver and kidney were eaten and two or three Sparrows. As- 



