Page:GrouseinHealthVol1.djvu/135

Rh counted in series, and the weakest of all is the ninth counting from the distal to the proximal end. The diagrams on page 64 show very roughly the sequence of growth in the primaries of chick and pullet. The growing power, as judged by the size of the root sheaths of these feathers, increases from the ninth distally, so that at one period of growth (F) the feather No. 4 is the longest, then a little later (G) No. 3, then still later (H) No. 2. But No. 1 remains permanently shorter than No. 2. By the time Nos. 1 and 2 are approaching full growth, the weak chicken feathers Nos. 9, 8, 7, and so on have been shed, and in their place have appeared strong feather -roots growing strong, round-ended, uniform black primaries, instead of the weak, mottled, more narrowly pointed chicken primaries. This shedding and replacement continues as far as No. 3 of the chicken primaries, but when No. 3 falls out Nos. 2 and 1 are found to have grown into such long and strong feathers as to fall into the series of new replacement feathers, and so they remain, now fully grown, and they can be recognised (K) by their more pointed ends having rather more of the buff markings on them than have the remainder of the primaries just grown from No. 9 to No. 3. No. 3, moreover, being the latest of the whole series of primaries to emerge, is for a time the shortest one; and, even when as long as No. 2, will be still the last one grown, and will therefore upon withdrawal produce blood at the quill end when squeezed between the finger and thumb. This sign of blood in the quill of the third primary is not an infallible sign of youth, for it is evident that as soon as the feather finishes its growth the quill becomes as hard and dry and bloodless as all the others. The only indication will then be a slight difference in the shape and contour of the two last feathers as indicated above. Moreover, in September it is easy to find birds obviously adult with claws attached but on the point of being shed, and having all the primaries moulted except the two most distal ones. The third then will be found to be a short feather actively growing, and if it is pulled out the growing root will be full of blood. Therefore not every bird that gives this sign is necessarily a bird of the year. The condition of the ends of the primaries, and especially of the two most distal feathers will, however, be a fair indication of age.

Another sign often used to test the age of a bird is the strength of the lower jaw. The weight of the bird is allowed to hang without support by