of Edinburgh, Session 1885-86. 
663 
that they assume a form resembling a series of cups or crowns 
inserted one within the other. Each scale is continuous round the 
whole circumference of the fibre. 
The internal structure of the wool fibre is usually much less easily 
distinguished than in the case of hair, because the cells forming the 
cortical substance are much smaller and more transparent. They 
seldom exhibit any traces of neuelei, and it is only in special fibres 
that any medullary axis is visible, and in most cases where this is 
revealed there are external indications of reversion to the character 
of hair. Plate XXIV. fig. 6 represents the longitudinal section of a 
coarse fibre of Lincoln wool, which may be compared with the 
similar section of Cheviot hair given in fig. 2, when the distinction 
will be easily seen. In the Lincoln wool the medullary cells are 
larger, but less distinctly marked, and they exhibit hardly any trace 
of neuelei. 
In examining the variations from this typical structure of wool, 
we cannot do better than commence with the surface configuration 
of this fibre of Lincoln wool, the section of which is given in Plate 
XXIV. fig. 6, and the external appearance in fig. 7. The scales are 
large and distinct, with well-defined and denticulated margins, and 
standing out from the general surface of the fibre, so as to present a 
strongly serrated edge when seen against a dark background. 
This fibre was taken from the coarsest part of the fleece, on the 
flanks of the sheep, and treated with caustic alkali after washing 
with a mixture of alcohol and water. Even when a fibre was drawn 
from the shoulder of this sheep, where the best wool is always found, 
the same characteristics were exhibited, although in a less marked 
degree, but there was no trace of any medulla. This fibre from the 
shoulder is figured in Plate XXIV. fig. 8, so that the relative fineness 
in diameter of the two fibres can readily be determined. 
These fibres may be taken as representatives of those which are 
found on all the long-woolled breeds of English sheep, such as 
those of Leicester, Yorkshire, and Nottingham. They are all dis- 
tinguished for the brightness and high lustre of the cuticular scales, 
which are always large and distinct. 
Closely allied to these bright-haired wools are the fibres derived 
from the alpaca goat (Auchenia Paco) and the Angora goat ( Capra 
Angora ), which is known commercially as mohair. The fibre 
