58
SIRKKA KUPILA-AHVENNIEMI AND EEVA THERMAN
The regeneration of the conductive tissue around the wound, before the
wound callus formation or at least independent of it, has attracted considerable interest. The earlier literature has been reviewed by Bloch
(1952). The regeneration of the xylem has been studied by Jacobs in a
series of papers (Jacobs, 1952, 1954; Thompson and Jacobs, 1966) and
also by Roberts (1960), Roberts and Fosket (1962), Hepler and Newcomb (1963), and Thompson (1966). The consensus is that the xylem
regeneration is largely dependent on the amount and transportation pattern of auxins. The connective strands are formed of wound-vessel members (Roberts and Fosket, 1962) that differentiate from the parenchymatous cells without further division or change in form. The depth of the
wound is an important factor in the wound-vessel formation. Cortical
wounds do not induce wound vessels. If, however, the primary phloem
is ruptured, differentiation occurs. Pith parenchyma wounds that result
in damage to the primary xylem are unable to promote wound-vessel
formation (Roberts and Fosket, 1962). The differentiation of sieve elements around a wound has been described, for example, by Kaan Albest
(1934), Eschrich (1953), LaMotte and Jacobs (1962), Thompson (1966),
and Thompson and Jacobs (1966).
The ability of wound callus to produce tissue that differentiates inward
into normal-looking xylem and outward into phloem is also well known.
This differentiation often takes place in the area of the stele. P. M.
Warren Wilson and J. Warren Wilson (1961) have described the production of normal-looking xylem and phloem in the intraxylary sieve areas
of certain solanaceous plants.
2. Development
of Crown Gall
Since the studies of Erwin F. Smith and others in the early decades of
the century, many of the papers published on the crown gall problem
have included descriptions of the anatomy of the gall. The majority of
the papers are concerned with the development of the gall in the stem
internodes. Most of the earlier investigators have examined microscopically only fully developed tumors without paying attention to their
development. Among the exceptions are Riker (1923a,b, 1927), Geneves
(1946), and Noel (1946). The earlier studies on crown gall anatomy
have been reviewed by Braun and Stonier (1958) and by Kupila (1963).
According to Kupila (1958), the crown galls on the stems can be
divided into two types, the development of which depends on the characteristics of the host species. To the first type, called the teratoma type,
SIRKKA KUPILA-AHVENNIEMI AND EEVA THERMAN
The regeneration of the conductive tissue around the wound, before the
wound callus formation or at least independent of it, has attracted considerable interest. The earlier literature has been reviewed by Bloch
(1952). The regeneration of the xylem has been studied by Jacobs in a
series of papers (Jacobs, 1952, 1954; Thompson and Jacobs, 1966) and
also by Roberts (1960), Roberts and Fosket (1962), Hepler and Newcomb (1963), and Thompson (1966). The consensus is that the xylem
regeneration is largely dependent on the amount and transportation pattern of auxins. The connective strands are formed of wound-vessel members (Roberts and Fosket, 1962) that differentiate from the parenchymatous cells without further division or change in form. The depth of the
wound is an important factor in the wound-vessel formation. Cortical
wounds do not induce wound vessels. If, however, the primary phloem
is ruptured, differentiation occurs. Pith parenchyma wounds that result
in damage to the primary xylem are unable to promote wound-vessel
formation (Roberts and Fosket, 1962). The differentiation of sieve elements around a wound has been described, for example, by Kaan Albest
(1934), Eschrich (1953), LaMotte and Jacobs (1962), Thompson (1966),
and Thompson and Jacobs (1966).
The ability of wound callus to produce tissue that differentiates inward
into normal-looking xylem and outward into phloem is also well known.
This differentiation often takes place in the area of the stele. P. M.
Warren Wilson and J. Warren Wilson (1961) have described the production of normal-looking xylem and phloem in the intraxylary sieve areas
of certain solanaceous plants.
2. Development
of Crown Gall
Since the studies of Erwin F. Smith and others in the early decades of
the century, many of the papers published on the crown gall problem
have included descriptions of the anatomy of the gall. The majority of
the papers are concerned with the development of the gall in the stem
internodes. Most of the earlier investigators have examined microscopically only fully developed tumors without paying attention to their
development. Among the exceptions are Riker (1923a,b, 1927), Geneves
(1946), and Noel (1946). The earlier studies on crown gall anatomy
have been reviewed by Braun and Stonier (1958) and by Kupila (1963).
According to Kupila (1958), the crown galls on the stems can be
divided into two types, the development of which depends on the characteristics of the host species. To the first type, called the teratoma type,