P A T T E R N S I N T H E I N T E G U M E N T OF I N S E C T S
67
was raised in folds which extended proximally and distally around the
graft. We may conclude that there is a gradient in appendages similar in
nature to that in the abdominal segments.
Experiments upon the arrangements of bristles have an advantage over
similar experiments upon the dorsal abdominal cuticle, in that the bristles
indicate the direction of the whole ripple pattern in the abdomen. The
abdominal pattern only shows orientation. There is no way of inferring
the direction of a gradient from the normal transverse ripple pattern or
FIG. 34. Grafts in Rhodnius involving integument without the ripple pattern.
Grafts were made on the fifth instar and the effect observed in the adult. The distortions of the host ripple pattern make it possible to recognize the axial level from
which a graft has come, even though the graft itself may have a different pattern
altogether. This verifies that the repeating gradient is a feature of segmentation and
not a peculiarity of the ripple pattern. (After Locke, 1960b.)
from the pattern of concentric ridges which arises in a displaced graft,
although the direction of the gradient might be revealed by experiments.
The appendages are more useful in this regard, for the bristles give both
orientation and direction. In an abdominal graft isolated from the host
pattern, the ripples may form a concentric "bulPs-eye" pattern. In the
leg grafts in which the position in the axis has been disturbed, the comparable pattern has radially arranged bristles. It is as if tissue isolated
from the host becomes locally autonomous and establishes a new gradient
67
was raised in folds which extended proximally and distally around the
graft. We may conclude that there is a gradient in appendages similar in
nature to that in the abdominal segments.
Experiments upon the arrangements of bristles have an advantage over
similar experiments upon the dorsal abdominal cuticle, in that the bristles
indicate the direction of the whole ripple pattern in the abdomen. The
abdominal pattern only shows orientation. There is no way of inferring
the direction of a gradient from the normal transverse ripple pattern or
FIG. 34. Grafts in Rhodnius involving integument without the ripple pattern.
Grafts were made on the fifth instar and the effect observed in the adult. The distortions of the host ripple pattern make it possible to recognize the axial level from
which a graft has come, even though the graft itself may have a different pattern
altogether. This verifies that the repeating gradient is a feature of segmentation and
not a peculiarity of the ripple pattern. (After Locke, 1960b.)
from the pattern of concentric ridges which arises in a displaced graft,
although the direction of the gradient might be revealed by experiments.
The appendages are more useful in this regard, for the bristles give both
orientation and direction. In an abdominal graft isolated from the host
pattern, the ripples may form a concentric "bulPs-eye" pattern. In the
leg grafts in which the position in the axis has been disturbed, the comparable pattern has radially arranged bristles. It is as if tissue isolated
from the host becomes locally autonomous and establishes a new gradient