284 



KNOWLEDGE. 



August, 1913. 



medulla and scaling to disappear, but will render 

 the disposal of the pigment very distinct. 



In the case of sheep's wool, fibres containing 

 black or brown pigment are relatively uncommon, 

 whereas in the hair of the camel and many other 

 animals, they are of frequent occurrence. 



Arrangement of the pigment in dashes or lines, or 

 in a congeries of dots, is often characteristic of the 

 hairs of particular animals, as may be seen by 

 reference to the illustrations of the hairs of the 

 bears and some of the apes. The Himalayan 

 goat or serow produces hair (see Figure 298), which 

 may be taken as typical of the bristle type of fibres. 

 Among the hairs will be found some so heavily 

 charged with pigment that in places they are quite 

 opaque. Other bristles, however, of equally coarse 

 character contain but little pigment. In both these 

 types of fibres the medulla is very pronounced (A), 

 nearly down to the base, while in the dark-coloured 

 fibres the pigment extends nearly the length of the 

 hair (C). In some of the fibres of a less coarse 

 nature there is no medulla, and the scaling is less 

 pronounced. 



From what has been said the general points to be 

 studied in examining the hairs of animals will be 

 readily understood, but it may be of interest to 

 amplify our remarks by reference to the fibres of 

 particular animals, and especially those of allied 

 species. 



In the hair of the dog, as in the case of sheep's 

 wool, considerable differences will be found in the 

 fibres produced by different breeds, the wire-haired 

 dogs having hair of different type from the silky- 

 haired dogs. In the woolly hair of the Bedlington 

 terrier, to which allusion has already been made, the 

 scaling projects and no medulla is visible, so that 

 the general appearance of the fibre resembles the 

 wool of an Angora kid (see B, C, Figure 299). The 

 stoutest type of hairs (D) are of a bristly character 

 and show a pronounced medulla, while intermediate 

 between these extremes are fibres showing an inter- 

 rupted medulla, fine scaling, and faint longitudinal 

 markings. 



It is interesting to note that the coat of the 

 native Australian dog, the dingo (see Figure 300), 

 has fibres of the three types and shows to an even 

 more pronounced degree an analogous cellular 

 structure of the medulla. 



On the other hand, the few remaining hairs of 

 the Mexican hairless dog (see Figure 301) show a 

 very different structure. In the fibres without 

 medulla the surface is covered with fine scales, 

 resembling that upon the hairs of some of the 

 apes, while the other fibres have a very coarse 

 medulla which does not show the cellular structure 

 usually found in the hairs of ordinary breeds of dogs. 



In the fur of the wolf (see Figure 302) the cellular 

 structure of the medulla is apparent in some of the 



fibres, whereas in others there is a very broad con- 

 tinuous medulla. In the former the scaling causes 

 the edge of the hair to appear sharply serrated, while 

 in the latter the edge is nearly smooth and the 

 scaling very fine. The type of fibres marked A is 

 intermediate between these extremes. 



Wide variations in structure are also shown by 

 the hairs of the African jackal (see Figure 303). 

 These include coarse black and white bristles, having 

 an opaque medulla (A) and ending in a fine point 

 (B), and fine woolly hairs which are well covered 

 with scales. In the latter the medulla, which in 

 places has a chain -like appearance, stops near the 

 apex, where the fine scaling resembles that of merino 

 wool. 



Similarly, in the fur of the fox (see Figure 304) 

 the fibres contain a small proportion of bristles 

 having a w ide medulla which becomes intermittent 

 towards the tip, which ends acutely (C). Most of 

 the hairs, however, are soft and curl}-, with scales 

 projecting from the edges, and this, in conjunction 

 with the structure of the medulla, gives to the fibre 

 the appearance of a jointed chain. 



Coming next to the cats it will be noticed that in 

 the fur of the domestic cat, the fibres end in a very 

 fine point, while the scaling is well marked, and all 

 show a medulla which here and there is interrupted. 

 In the full-grown animal the medulla may be wide 

 and show a reticulated structure (C, Figure 305), 

 but in the case of the kitten the hairs have pro- 

 jecting scales and a medulla made up of a series of 

 single cells. 



It is interesting to note that the leopard shows 

 fibres of an analogous character, the medulla in 

 some being wide and continuous (see Figure 306), 

 while in others, which show fine scaling, it is inter- 

 mittent. Examples of the unicellular structure of 

 the medulla seen in the hair of the common kitten 

 may also be found. 



Mention may also be made here of the so-called 

 sea-cat of Chili, which is valued for its fur. The 

 fibres are of the most variable type. On the fine 

 hairs the scales are very prominent but not plentiful, 

 and in some cases (C) project so much as to give 

 a feathery appearance to the hair. The fibres 

 terminate in a somewhat blunt point, and have 

 a medulla which ends near the base (see Figure 307). 



The reticulated structure of the medulla which is 

 shown by some of the fibres of the cat is much more 

 pronounced in the hair of the brown rat (see 

 Figure 308). These are of the bristly type, with 

 scaling well marked towards the base, and end in an 

 abrupt point. 



Examples of hairs from the fur of different species 

 of bears are shown in Figures 309-311. 



In the fur of the Himalayan bear some of the fibres 

 are dark brown and very opaque, while others are 



