Pigmented Keratinous Materials 



305 



Fig. 1. Residue from black feather of Red Grouse, after treatment in 0.5 M sodium thioglycollate, at pH 12. ? hours 



reflux. Note keratin contamination in the background. Magnification 10,000. 



Fig. 2. Pigment-containing granules from black tail hair of cow. Magnification 10,000. 



Fig. 3. Pigment-containing granules from light-brown feather of Mallard. Magnification 10.000. 



Fig. 4. Pigment-containing granules from black feather of pigeon.Twopopulationsof granules. Magnification 10,000. 



observed of the pigment-containing granules isolated 

 from black chicken feathers by boiling in 2.5 A' 

 sodium hydroxide; the removal of some material 

 was evident along the major axes of the granules. 

 The pigment-containing granules, free from keratin 

 impurities, could be isolated if, in addition to the 

 milder reagents listed in Table 1, use was made of 

 enzymic digestion (2) to remove such histological 

 components, of hairs or feathers, which may resist 

 the action of keratinolytic media (5, 7, 10). However, 

 this is an additional complication which is not neces- 

 sary in the case of PHT method; consequently, this 

 latter method was adopted in all experiments de- 

 scribed below. 



Electron microscopy of tlie pigment-containing 

 granules isolated by the PHT method. The pigment- 

 containing granules were isolated from five mamma- 

 lian materials and twenty samples of feathers, and 

 relevant data are collected in Table 2. 



The shapes of granules from mammalian hair arc 

 similar to those described before (6) and their dimen- 

 sions generally fall within the same range. However, 



20 - 568204 Electron Microscopy 



the pigment-containing granules isolated from the 

 skin of grey Fin Whale and the black tail hair of 

 Cow (see fig. 2) show higher width length ratios, 

 0.7 and 0.67, respectively. Two populations of gran- 

 ules were isolated from black hairs of Cat. The 

 data on the granules isolated from Hedgehog quill 

 are of some significance in the x-ray diffraction studies 

 of keratin (6). The granules separated from feather 

 show generally lower width/length ratios (0.27 to 

 0.10, for Hclmeted Guinea Fowl and Mallard (see 

 fig. 3), respectively) except hM- the black feather of 

 Pigeon (see fig. 4) which yielded two populations of 

 granules. Generally, the lengths of the major axes 

 of pigment-containing granules vary from 1.76 // 

 to 0.76 // (for Dipper and Crowned Crane, respec- 

 tively), and those of the minor axes from 0.36 // to 

 0.12 // (for Dipper and Mallard, respectively). 



No simple relation was found between the shape 

 and the dimensions of pigment-containing granules 

 and the apparent colour of hairs or feathers, from 

 which they were isolated; this is in agreement with 

 the previous work of Laxer et al. (6). 



