Although the role of
microorganisms in the transformations of organic matter was not recognized
until the middle of the nineteenth century, microbial processes have been used
by humans since prehistoric times in the preparation of food drink and
textiles. Such traditional microbial processes became perfected to an
astonishing degree as used in bread making and production of beer and wine,
pickling, making of vinegar, cheese and butter and retting of flax.
The rise of microbiology led to
great improvements in many of these but also to the development of new
industries based on the use of microorganisms. However, the present discussion
shows the use of microorganisms in a way that had arguably never been attempted
before–in delineating a complex biological structure.The feather
is an extraordinary device and among the most prominent of a series of
adaptations that facilitates flight in birds. The main structural support is
the rachis from which arise hundreds of side branches, the barbs. The rachis is
symmetrically located in contour feathers but nearer the leading edge in flight
feathers.
The outer shell or cortex
comprises the bulk of the material of the rachis and has been shown to account for
most of its tensile strengt. It is constructed of compact β-keratin, the
keratin of reptiles and birds (sauropsids), a light, rigid material comprising
a fibre-matrix texture. Filshie and Rogers’ study on the microstructure of the
rachis using histological techniques and early use of electron microscopy
showed that it comprised fine fibres, nanometers in diameter. This view has
dominated our ideas on feather microstructure through the decades.
No comments:
Post a Comment