TOSA FOWL AND WHITE COCHIN. 45 



underlying assumption in both cases is that the selection has been of minute 

 favorable fluctuations rather than the conservation of sports. This is a 

 conceivable hypothesis. 



(3) As a result of functional hypertrophy of the feather follicle. By 

 artificial treatment the blood supply to the follicles might be stimulated so 

 as to make the feather grow longer. Such an effect might be inherited or 

 not, as could be determined by breeding. If the offspring of the long-tailed 

 fowl have a long tail, though untreated, then we would have, on the third 

 hypothesis, an inheritance of an acquired character. Cunningham (1903) 

 believes that the Tosa fowl is a demonstration of such inheritance. 



Growth of tail feathers. The study of the long tail of the Tosa fowl leads 

 us to consider the whole matter of feather growth and of the anatomy of the 

 tail. In early months of their life chicks are constantly losing old feathers 

 and gaining new ones built on a larger scale to meet the needs of the enlarg- 

 ing body. Later, these feathers 

 are all molted during one period ./ 



in the autumn. During develop- A'^ 



ment, the tip of the feather is O c?, ( 



formed first and growth continues **O O Z Q , 



at the base, within a sheath, for a 

 shorter or longer period, depending "^ ^M O 

 on the eventual size of the feather. O Q 



The reason why some feathers, like ^'?Q 

 the contour feathers, are short is 



O 



O 



-9 



o 

 *> 



because growth quickly ceases. 

 The feathers of the hackle, saddle, T 



' FIG. C. Diagram of arrangement of the tail feathers, 

 and tail of the male are long be- A^-A & , feathers of right anterior row; A'l-A's, feathers 



cause the growth period is in them of if an f e ? r T : M ^^ M 'r%"**?*Z f 



right and left middle rows; P\-P* and P'\-F*z, feathers 

 prolonged. The Sickle feathers Of of right and left posterior rows; o. g., oil gland; 



the Leghorn are still growing for D ~ v ' dors - ventral Une = * ri * M ' L < left - 

 three months after the molting period ; consequently they attain a length of 

 300 to 400 mm. If the period of drying up of the growth sheath at the 

 base of the sickle feathers could be delayed in the Leghorn for an entire 

 year they would become each a meter long. The reason for the great length 

 of the tail feathers of the Tosa fowl is that they do not cease growing. In 

 this respect they resemble the long hair of Angora guinea pigs, rabbits and 

 cats, and the head hair of man. 



Morphology of the tail. As just intimated, only certain feathers of the tail 

 of the Tosa fowl grow indefinitely. It is now necessary to describe the 

 structure of the tail. The feathers have the following arrangement : 



The posterior row (P) consists of broad feathers with rounded ends and 

 constitutes the characteristic ' ' fan ' ' of the tail. The middle row ( M) con- 

 tributes the characteristic long growing feathers, those nearest the median 



