THE ACRASINA
111
interrelations of importance in metazoan development. Further arguments as to why they may be confidently expected to provide the solutions to the major problems of morphogenesis will be found in a large
proportion of the introductions to the publications dealing with them.
Perhaps their greatest drawback is that they cannot as yet be grown on
a synthetic medium; the defined medium of Bradley and Sussman
(1952; Sussman and Bradley, 1954), containing a bacterial fraction, has
not supported growth when prepared by others (Sie and Bonner, in
Bonner, 1961), nor apparently has it been used routinely in Sussman's
laboratory even for biochemical investigations.
Because of the quality and quantity of recent reviews, it is neither
necessary nor desirable to describe once again the mass of solidly established results; lest the reader unfamiliar with this field gains a very
incomplete picture of the vast contributions made by other workers,
especially by Bonner and Raper, whose investigations have done so
much to stimulate the modern phase of research on the Acrasina, he is
urgently referred to the publications of Bonner (1959a, 1961); to the
admirable accounts of the varying degrees of social organization found
in 'solitary' amoebae and the Acrasina (Raper, 1940a, 1960), culture
methods (Raper, 1951), and developmental problems (Raper, 1956a);
and to the reviews of Sussman (1955b, 1956b, 1958; Sussman and Sussman, 1956), particularly for the details of the extensive work carried
out in his own laboratory. The small amount of space available here will
be devoted in the main to deviations, both positive and negative, from
these earlier descriptions, though it is hoped that the reader will not
become too conscious of the value of the expression Σ (x - x). The biochemistry of development will be very largely ignored, despite its
cardinal importance, because what rather slender knowledge we have
has recently been competently reviewed (Wright, 1961). Since the
experiments we perform and the observations we make are so profoundly influenced by what we are looking for, it has been thought
justifiable not only to put forward a number of new speculations, but
to devote some attention to older ones, which otherwise tend to become
accepted 'facts' rather than be quietly forgotten. If the work with which
I am most familiar seems to be scrutinized less critically, it is only
because familiarity makes it harder to detect the residual flaws, and not
because I believe it to be any more firmly established.
B. The Pseudoplasmodium
'Denomination fallacieuse, fondee sur des analogies illusoires'
(Pavillard, 1953). Brefeld (1884) introduced the terms pseudoplasmodium
and scheinplasmodium after his error in believing that Dictyostelium
111
interrelations of importance in metazoan development. Further arguments as to why they may be confidently expected to provide the solutions to the major problems of morphogenesis will be found in a large
proportion of the introductions to the publications dealing with them.
Perhaps their greatest drawback is that they cannot as yet be grown on
a synthetic medium; the defined medium of Bradley and Sussman
(1952; Sussman and Bradley, 1954), containing a bacterial fraction, has
not supported growth when prepared by others (Sie and Bonner, in
Bonner, 1961), nor apparently has it been used routinely in Sussman's
laboratory even for biochemical investigations.
Because of the quality and quantity of recent reviews, it is neither
necessary nor desirable to describe once again the mass of solidly established results; lest the reader unfamiliar with this field gains a very
incomplete picture of the vast contributions made by other workers,
especially by Bonner and Raper, whose investigations have done so
much to stimulate the modern phase of research on the Acrasina, he is
urgently referred to the publications of Bonner (1959a, 1961); to the
admirable accounts of the varying degrees of social organization found
in 'solitary' amoebae and the Acrasina (Raper, 1940a, 1960), culture
methods (Raper, 1951), and developmental problems (Raper, 1956a);
and to the reviews of Sussman (1955b, 1956b, 1958; Sussman and Sussman, 1956), particularly for the details of the extensive work carried
out in his own laboratory. The small amount of space available here will
be devoted in the main to deviations, both positive and negative, from
these earlier descriptions, though it is hoped that the reader will not
become too conscious of the value of the expression Σ (x - x). The biochemistry of development will be very largely ignored, despite its
cardinal importance, because what rather slender knowledge we have
has recently been competently reviewed (Wright, 1961). Since the
experiments we perform and the observations we make are so profoundly influenced by what we are looking for, it has been thought
justifiable not only to put forward a number of new speculations, but
to devote some attention to older ones, which otherwise tend to become
accepted 'facts' rather than be quietly forgotten. If the work with which
I am most familiar seems to be scrutinized less critically, it is only
because familiarity makes it harder to detect the residual flaws, and not
because I believe it to be any more firmly established.
B. The Pseudoplasmodium
'Denomination fallacieuse, fondee sur des analogies illusoires'
(Pavillard, 1953). Brefeld (1884) introduced the terms pseudoplasmodium
and scheinplasmodium after his error in believing that Dictyostelium