FEATHERS AND PATTERNS
23
expiants (all from the Brown Leghorn capon breast tract) behave fairly
similarly, but several points emerge of considerable theoretical interest.
First, the relationship between temperature and periodicity is far from
linear; if anything, it calls to mind a harmonic system with strong overtones of a saw-tooth waveform. (This may derive in part from uncertainty at high and low wavelengths: 1 and 0 barb ridge per millimeter
are indistinguishable, and more than 40 per millimeter are probably
impossible for the cellular system. The shapes of peaks and troughs are,
therefore, highly dubious.)
Second, there seem to be regions of high stability and of high instability. Not altogether surprising is the fact that the range of 38°41 °C is apparently the most stable, and is also the flattest part of the
"curve." (Note that Figs. 9 and 10 are not intended as graphs; they
merely serve as pictorial portrayal of the results.)
Third, the mode of barb-ridge formation is itself variable. A single
furrow may appear, and then ridges appear at either side progressively
distant from it, or an edge of the culture may become "toothed" or
"scalloped," these irregularities then proceeding into the mass as barb
ridges. In a few cases the edge of the expiant may grow out as a series
of fairly discrete "bars" with only the faintest web between them (see
Figs. 7 and 11).
Fourth, the initial periodicity may be "rubbed out" if the temperature
is changed suddenly, and the new set of ridges may appear, not only
with a different periodicity, but also with a different orientation (see
and a tentative value of 38 barb ridges per millimeter has been assigned to it.
(4 days)
C. 33.0°C. Island formation in the outgrowth from this culture was initially
scored, but infection supervened and the culture was not scored in Fig. 10. However, this phase photograph of the early culture shows "island formation" well.
(48 hr)
D. 21.5°C. The edge of the culture (outgrowth?) shows regular scallops at 18
per millimeter. A similar periodicity is seen deep in the culture mass, but does not
show well in the photograph. (4 days) See also G.
E. 36.1 °C. From 9 to 10 barb ridges per millimeter. Note the melanocytes several
abreast along the ridges and the ridge that turns back on itself as a loop. (4 days)
F. 36.1 °C. Twenty-three barb ridges per millimeter, very darkly pigmented
despite the short sojourn in culture. (48 hr)
G. 21.5°C. Eighteen barb ridges per millimeter at opposite edge of same culture
as D. These are "falling over" the edge of the culture as in Fig. 7D. The author is
a little dubious of the reality of these as entirely produced in culture, despite their
unnatural periodicity. (4 days)
H. 21.5
Ô
C. Four barb ridges per millimeter in two directions at right angles.
Other cultures with long "wavelength" showed the same phenomenon, for example,
one of the two at 31 °C, with 2 barb ridges per millimeter.
23
expiants (all from the Brown Leghorn capon breast tract) behave fairly
similarly, but several points emerge of considerable theoretical interest.
First, the relationship between temperature and periodicity is far from
linear; if anything, it calls to mind a harmonic system with strong overtones of a saw-tooth waveform. (This may derive in part from uncertainty at high and low wavelengths: 1 and 0 barb ridge per millimeter
are indistinguishable, and more than 40 per millimeter are probably
impossible for the cellular system. The shapes of peaks and troughs are,
therefore, highly dubious.)
Second, there seem to be regions of high stability and of high instability. Not altogether surprising is the fact that the range of 38°41 °C is apparently the most stable, and is also the flattest part of the
"curve." (Note that Figs. 9 and 10 are not intended as graphs; they
merely serve as pictorial portrayal of the results.)
Third, the mode of barb-ridge formation is itself variable. A single
furrow may appear, and then ridges appear at either side progressively
distant from it, or an edge of the culture may become "toothed" or
"scalloped," these irregularities then proceeding into the mass as barb
ridges. In a few cases the edge of the expiant may grow out as a series
of fairly discrete "bars" with only the faintest web between them (see
Figs. 7 and 11).
Fourth, the initial periodicity may be "rubbed out" if the temperature
is changed suddenly, and the new set of ridges may appear, not only
with a different periodicity, but also with a different orientation (see
and a tentative value of 38 barb ridges per millimeter has been assigned to it.
(4 days)
C. 33.0°C. Island formation in the outgrowth from this culture was initially
scored, but infection supervened and the culture was not scored in Fig. 10. However, this phase photograph of the early culture shows "island formation" well.
(48 hr)
D. 21.5°C. The edge of the culture (outgrowth?) shows regular scallops at 18
per millimeter. A similar periodicity is seen deep in the culture mass, but does not
show well in the photograph. (4 days) See also G.
E. 36.1 °C. From 9 to 10 barb ridges per millimeter. Note the melanocytes several
abreast along the ridges and the ridge that turns back on itself as a loop. (4 days)
F. 36.1 °C. Twenty-three barb ridges per millimeter, very darkly pigmented
despite the short sojourn in culture. (48 hr)
G. 21.5°C. Eighteen barb ridges per millimeter at opposite edge of same culture
as D. These are "falling over" the edge of the culture as in Fig. 7D. The author is
a little dubious of the reality of these as entirely produced in culture, despite their
unnatural periodicity. (4 days)
H. 21.5
Ô
C. Four barb ridges per millimeter in two directions at right angles.
Other cultures with long "wavelength" showed the same phenomenon, for example,
one of the two at 31 °C, with 2 barb ridges per millimeter.