. Beginners' Zoology . //. The partof the shaft bearing thevane is called the racJiis(ra-kis). The vane consistsof slender l)arbs which arebranches of the shaft (II,Fig. 292). As the nameindicates (see dictionary), abarb resembles a hair. Thebarbs in turn bear second-ary branches called bar-bu/es, and these again haveshorter branches called bar-bicc/s (III, Fig. 292). These are sometimes bent in theform of booklets (Fig. 292, III), and the booklets ofneighbouring barbules interlock, giv-ing firmness to the vane. When twobarbules are split apart, and then re-united by stroking the vane betweent
. Beginners' Zoology . //. The partof the shaft bearing thevane is called the racJiis(ra-kis). The vane consistsof slender l)arbs which arebranches of the shaft (II,Fig. 292). As the nameindicates (see dictionary), abarb resembles a hair. Thebarbs in turn bear second-ary branches called bar-bu/es, and these again haveshorter branches called bar-bicc/s (III, Fig. 292). These are sometimes bent in theform of booklets (Fig. 292, III), and the booklets ofneighbouring barbules interlock, giv-ing firmness to the vane. When twobarbules are split apart, and then re-united by stroking the vane betweenthe thumb and the finger, the unionmay be so strong that a pull uponthe vane will cause it to split in anew place next time. There are four kinds of feathers,(i) the qui// feathers, just studied;(2) the coutoiir feathers (I, Fig. 292),which form the general surface of the body and give it itsoutlines; (3) the downy feathers (Fig. 293), abundant on Fig. 292—I, Contour Feather. II, III. Parts of Quill Feather, Fig. 293. —a DownFeather, enlarged. BIRDS 157 nestlings and found among the contour feathers of theadult but not showing on the surface ; (4) the pin feathers,which are hair-like, and which are removed from a pluckedbird by singeing. The contour feathers are similar instructure to the quill feathers. They protect the bodyfrom blows, overlap so as to shed the rain, and, with theaid of the downy feathers, retain the heat, thus accountingfor the high temperature of the bird. The downy feathersare soft and fluffy, as they possess few or no barbicels;sometimes they lack the rachis (Fig. 293). The pin feath-ers are delicate horny shafts, greatly resembling hairs, butthey may have a tuft of barbs at the ends. A feather grows from a small projection (or papilla) foundat the bottom of a depression of the skin. The quill isformed bv being moulded around the papilla. Do you seeany opening at the tip of the quill for blood-vessels to enterand nourish the feather } What is
Size: 1339px × 1866px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookidbeginnerszoo, bookyear1922
