FEATHERS AND PATTERNS
3
a useful bridge. Its original induction, its changes, and its maintenance
and function are all relatively well known. Perhaps a consideration of
the various levels of pattern exhibited by feathers may be considered as
the first pole thrown across the divide.
B. Patterns and the Feather
Problems of the origins, formation, and maintenance of patterns are
some of the most interesting in modern biology. Biological patterns occur
at all levels of organization of living things, but it must be borne in
mind that examples from behavior studies and from electron micrographs
probably cannot be compared in any useful way; similarities which have
been suggested (von Bertalanffy, 1962; Schubert-Soldern, 1962) are
surely indicative more of properties of the observer's mind than of
the experimental data. Nevertheless, in recent years theories of the development of morphological patterns have proven useful both for the
design of further experiments and in providing clues to the explanation
of some morphogenetic processes. A word, therefore, relating to kinds of
morphological patterns is in place here.
Repetitive morphological patterns occur ubiquitously in biology.
Some—for example, the banding of striated muscle and of collagen
fibers—seem to depend fairly directly on a precise chemical structure
which determines their periodicity ; others—for example, the metamerism
of the annelids and arthropods—are less amenable to an ultrastructural
explanation. Attempts (e.g., Allen, 1959; Rendel, 1965) have been made
to explain these in terms of a "counting" process, but these have not
been very successful (Berrill, 1961, discusses the problem at length; see
also Maynard Smith, 1960). Mathematical analogs have had a great
vogue, but their applicability as agents of explanation, (to most biologists
at least) is dubious. Notable exceptions are Turing (1952) and Goodwin
(1963).
II. Levels of Pattern
Feathers provide a wide variety of examples of morphological pattern.
Furthermore, much of the experimental work on feather material has
stemmed from questions relating to pattern. Before discussing this, a
formal assignment of levels may be attempted, with no initial pretence
either that pattern formation is similar, or that it is different, at the
various levels.
A. The Feather Tracts
The feathers of adult birds may easily be seen to differ from each
other over the surface of the animal. Although in a few cases (for ex-
3
a useful bridge. Its original induction, its changes, and its maintenance
and function are all relatively well known. Perhaps a consideration of
the various levels of pattern exhibited by feathers may be considered as
the first pole thrown across the divide.
B. Patterns and the Feather
Problems of the origins, formation, and maintenance of patterns are
some of the most interesting in modern biology. Biological patterns occur
at all levels of organization of living things, but it must be borne in
mind that examples from behavior studies and from electron micrographs
probably cannot be compared in any useful way; similarities which have
been suggested (von Bertalanffy, 1962; Schubert-Soldern, 1962) are
surely indicative more of properties of the observer's mind than of
the experimental data. Nevertheless, in recent years theories of the development of morphological patterns have proven useful both for the
design of further experiments and in providing clues to the explanation
of some morphogenetic processes. A word, therefore, relating to kinds of
morphological patterns is in place here.
Repetitive morphological patterns occur ubiquitously in biology.
Some—for example, the banding of striated muscle and of collagen
fibers—seem to depend fairly directly on a precise chemical structure
which determines their periodicity ; others—for example, the metamerism
of the annelids and arthropods—are less amenable to an ultrastructural
explanation. Attempts (e.g., Allen, 1959; Rendel, 1965) have been made
to explain these in terms of a "counting" process, but these have not
been very successful (Berrill, 1961, discusses the problem at length; see
also Maynard Smith, 1960). Mathematical analogs have had a great
vogue, but their applicability as agents of explanation, (to most biologists
at least) is dubious. Notable exceptions are Turing (1952) and Goodwin
(1963).
II. Levels of Pattern
Feathers provide a wide variety of examples of morphological pattern.
Furthermore, much of the experimental work on feather material has
stemmed from questions relating to pattern. Before discussing this, a
formal assignment of levels may be attempted, with no initial pretence
either that pattern formation is similar, or that it is different, at the
various levels.
A. The Feather Tracts
The feathers of adult birds may easily be seen to differ from each
other over the surface of the animal. Although in a few cases (for ex-