283
A. Ostrovsky, Evolution of Sexual Reproduction in Marine Invertebrates: Example of gymnolaemate bryozoans,
DOI 10.1007/978-94-007-7146-8, © Springer Science+Business Media Dordrecht 2013
Appendices
Appendix I: History of Research on Sexual
Reproduction in Gymnolaemate Bryozoa
Introduction
Studies on sexual reproduction in marine bryozoans have
attracted zoologists since the beginning of the nineteenth
century. Many early naturalists analyzed and reassessed
existing publications, but most of these works, especially
short papers, have often been neglected if not forgotten. One
can also fi nd reviews on this topic in some old (Bronn 1862 ;
Hincks 1880 ; Calvet 1900 ; Korschelt and Heider 1893 , 1910 ;
Delage and Hérouard 1897 ) and more recent monographs
and textbooks (Marcus 1926a , b , 1938a , 1940 ; Cori 1941 ;
Brien 1960 ; Kaestner 1963 ), but little attention has been paid
to these, too, as most of them were written in German, French
and Portuguese.
Reviews on bryozoan sexual reproduction published in
English (Franzén 1956 , 1977 , 1981 , 1983 ; Hyman 1959 ;
Ryland 1974 , 1976 ; Ström 1977 ; Hayward 1983 ; Nielsen
1990 ; Reed 1991 ; Woollacott 1999 ; Mukai et al. 1997 ) show
that considerable information has been accumulated.
However, they all aimed to characterize structures, patterns
and processes rather than stages in the development of our
understanding of this diversity, and many key names and
works were not mentioned. Only Hageman ( 1983 ) undertook
a review of this kind, but it was never published.
Three extensive reviews of both early and recent literature
concerning the history of research on sexual reproduction in
Bryozoa (predominantly Gymnolaemata) have recently been
published (Ostrovsky 2008a , b ; Ostrovsky et al. 2008 ), and
this Section adds to them. I have chronicled the main steps
in the history of research on the topic in question (dealing
with the origin of the germ cells, gonado- and gametogenesis, fertilization, oviposition and embryo incubation) in
marine gymnolaemate bryozoans, with particular emphasis
on observation and recording of different structures and phenomena and development of the modern understanding of
the specifi c processes involved. It should be stressed that,
apart from many data and ideas that have been completely
forgotten, later authors sometimes incorrectly interpreted the
hypotheses or conclusions of the previous researchers.
Sometimes, mistaken traditional opinions survived for many
years despite the emergence of new facts and contradicting
data as happened, for instance, in the case of bryozoan fertilization (see Sect. 1.3.6 and Ostrovsky 2008a ). I will highlight these contradictions where appropriate. In an effort
towards making the review as comprehensive as possible, I
have analyzed many obscure papers and listed small descriptive details in all species studied. This gave me the opportunity to resurrect many forgotten names and facts. Thus, this
review represents an integrated picture of the available literature on bryozoan sexual reproduction and associated taxonomic diversity. It should be noted, however, that some
diffi culties were encountered in trying to trace a small number of short papers and some incidental reports of the reproductive organs in several works. Also, papers devoted
exclusively to bryozoan embryogenesis and larval morphology are not discussed and referred to here.
Eighteenth Century: First Microscopic
Observations and Suggestions
During the eighteenth and the beginning of the nineteenth
century freshwater bryozoans were more popular objects for
observations on their internal structure than were marine
ones, mainly because of the transparency of their body walls
(reviewed in Allman 1856 ).
As for marine Bryozoa, Ellis ( 1753 , pp. 116–117) was the
fi rst to describe and illustrate ovicells (“spherical testaceous
bodies”) in the cheilostomes Bugula plumosa and B. neritina
(as “upright feathered Coralline” and “snail bearing
Coralline”). In observing brown bodies, Ellis supposed they
were embryos that “swell … into spherical testaceous bodies…, burst through … [the frontal] membrane, and sit in the
front of the cell [zooid] … till they come to maturity”. His
further suggestion was that these “rows of very small sea
snails, or rather testaceous bodies, of the shape of the nautilus, [after maturation are] ready to drop off, and provide for
themselves” (p. 116).
Later, in his famous “An essay towards a natural history of
the corallines …” he modifi ed this view. He realized that
A. Ostrovsky, Evolution of Sexual Reproduction in Marine Invertebrates: Example of gymnolaemate bryozoans,
DOI 10.1007/978-94-007-7146-8, © Springer Science+Business Media Dordrecht 2013
Appendices
Appendix I: History of Research on Sexual
Reproduction in Gymnolaemate Bryozoa
Introduction
Studies on sexual reproduction in marine bryozoans have
attracted zoologists since the beginning of the nineteenth
century. Many early naturalists analyzed and reassessed
existing publications, but most of these works, especially
short papers, have often been neglected if not forgotten. One
can also fi nd reviews on this topic in some old (Bronn 1862 ;
Hincks 1880 ; Calvet 1900 ; Korschelt and Heider 1893 , 1910 ;
Delage and Hérouard 1897 ) and more recent monographs
and textbooks (Marcus 1926a , b , 1938a , 1940 ; Cori 1941 ;
Brien 1960 ; Kaestner 1963 ), but little attention has been paid
to these, too, as most of them were written in German, French
and Portuguese.
Reviews on bryozoan sexual reproduction published in
English (Franzén 1956 , 1977 , 1981 , 1983 ; Hyman 1959 ;
Ryland 1974 , 1976 ; Ström 1977 ; Hayward 1983 ; Nielsen
1990 ; Reed 1991 ; Woollacott 1999 ; Mukai et al. 1997 ) show
that considerable information has been accumulated.
However, they all aimed to characterize structures, patterns
and processes rather than stages in the development of our
understanding of this diversity, and many key names and
works were not mentioned. Only Hageman ( 1983 ) undertook
a review of this kind, but it was never published.
Three extensive reviews of both early and recent literature
concerning the history of research on sexual reproduction in
Bryozoa (predominantly Gymnolaemata) have recently been
published (Ostrovsky 2008a , b ; Ostrovsky et al. 2008 ), and
this Section adds to them. I have chronicled the main steps
in the history of research on the topic in question (dealing
with the origin of the germ cells, gonado- and gametogenesis, fertilization, oviposition and embryo incubation) in
marine gymnolaemate bryozoans, with particular emphasis
on observation and recording of different structures and phenomena and development of the modern understanding of
the specifi c processes involved. It should be stressed that,
apart from many data and ideas that have been completely
forgotten, later authors sometimes incorrectly interpreted the
hypotheses or conclusions of the previous researchers.
Sometimes, mistaken traditional opinions survived for many
years despite the emergence of new facts and contradicting
data as happened, for instance, in the case of bryozoan fertilization (see Sect. 1.3.6 and Ostrovsky 2008a ). I will highlight these contradictions where appropriate. In an effort
towards making the review as comprehensive as possible, I
have analyzed many obscure papers and listed small descriptive details in all species studied. This gave me the opportunity to resurrect many forgotten names and facts. Thus, this
review represents an integrated picture of the available literature on bryozoan sexual reproduction and associated taxonomic diversity. It should be noted, however, that some
diffi culties were encountered in trying to trace a small number of short papers and some incidental reports of the reproductive organs in several works. Also, papers devoted
exclusively to bryozoan embryogenesis and larval morphology are not discussed and referred to here.
Eighteenth Century: First Microscopic
Observations and Suggestions
During the eighteenth and the beginning of the nineteenth
century freshwater bryozoans were more popular objects for
observations on their internal structure than were marine
ones, mainly because of the transparency of their body walls
(reviewed in Allman 1856 ).
As for marine Bryozoa, Ellis ( 1753 , pp. 116–117) was the
fi rst to describe and illustrate ovicells (“spherical testaceous
bodies”) in the cheilostomes Bugula plumosa and B. neritina
(as “upright feathered Coralline” and “snail bearing
Coralline”). In observing brown bodies, Ellis supposed they
were embryos that “swell … into spherical testaceous bodies…, burst through … [the frontal] membrane, and sit in the
front of the cell [zooid] … till they come to maturity”. His
further suggestion was that these “rows of very small sea
snails, or rather testaceous bodies, of the shape of the nautilus, [after maturation are] ready to drop off, and provide for
themselves” (p. 116).
Later, in his famous “An essay towards a natural history of
the corallines …” he modifi ed this view. He realized that