290
Joliet came to the conclusion that different gonads and,
subsequently, gametes should have the same origin.
Considering examples when the ovary was observed on the
cystid wall, he showed that the gonad could be moved
from the funiculus to the body wall in some species (for
instance, in Farrella repens ) (as Laguncula ). This observation,
although criticized by Hincks ( 1880 ), is actually correct; in
several instances the ovary is removed from the developing
polypide bud (where it originates) to the basal cystid wall
obviously due to growth of funicular tissue (see Ostrovsky
1998 ; Moosbrugger et al. 2012 ).
Interestingly, Joliet ( 1877a ) described two different kinds
of eggs in different zooids of certain species, one developing
on the funiculus and another (“parietal”) on the body wall.
For instance, in Bicellariella ciliata (as Bicellaria ) he found
ovaries on both the funiculus and the cystid wall [in different
zooids], as recently observed by Moosbrugger et al. ( 2012 ).
Puzzlingly, he stated that he never saw the ovicells, formed
by the fertile zooid in the second case (was it an egg then?).
Joliet supposed that the parietal eggs should originate in connection with funicular strands passing through the communication pores. Since the work of Müller ( 1860 ) the funicular
system was considered as “colonial nervous system” by
some authors (Smitt 1865 ; Claparéde 1871 , discussed in
Hincks 1878 ). Joliet also used this term although thought
that the origin of germ cells in the funiculus was a strong
argument against its “nervous nature”. These doubts fi nally
resulted in the introduction of the term “endosarc” for funicular tissue (see also Joliet 1877b ). An ovary was recorded on
the funiculus of a zooid with a developing polypide in Bugula
avicularia , and early male germ cells near a young polypide
bud in F . repens . In the ctenostome Walkeria uva (as Valkeria
cuscuta ) he also recorded formation of spermatogenic tissue
and an ovary on the funiculus of the early polypide bud and
described spermatogenesis in detail.
Joliet described the release of sperm in W. uva , but could
not recognize the pore through which mature sperm leave the
zooid cavity. In this species Joliet found that eggs do not
degenerate in the ovary during polypide recycling, but that
one of them begins to grow faster instead. Much later,
Dyrynda and Ryland ( 1982 ) found that vitellogenesis commences during polypide recycling in the cheilostome
Chartella papyracea (see below). In Joliet’s case a modifi ed
polypide without tentacles develops prior to oviposition in the
fertile zooid. It can be seen in his illustrations ( 1877a , pl. 13,
fi gs 5–9) that the brooded embryo increases in size in the
introvert, which is evidence of extraembryonic nutrition in
that species. Joliet’s description and illustrations show that he
often saw developing oocyte doublets (in cheilostomes), of
which one cell [the leading oocyte] grows and the other [nurse
cell] remains small. In agreement with Claparède ( 1871 ),
Joliet believed that the second cell waits its turn to develop or
divide. Describing oogenesis in Lepralia martyi (a presently
unknown cheilostome taxon) Joliet wrote that he observed a
cavity [intraovarian space?] developing in the ovary in which
two eggs originate. He thought that upon ovulation, the new
(second) ovary is established in place of the former one. In
this species Joliet recorded up to six eggs formed during the
lifetime of the fertile zooid. In stating that the majority of the
species studied possessed hermaphrodite autozooids, he demonstrated the presence of gonochoristic zooids in L . martyi .
Going against general opinion, Joliet ( 1877a ) remarked
that cross-fertilization should occur in some species, ctenostomes as well as cheilostomes, in which protandrous zooidal hermaphroditism or zooidal gonochorism occurs.
Differences in the timing of gamete maturation, massive production of spermatozoids and their possibility to swim
actively in the surrounding water led him to believe that
cross-fertilization is the rule. He suggested that fertilization
by alien sperm, “distinguished” by the absence of the nucleus
in the egg, occurs in different species (1) inside the maternal
zooid (within the tentacle sheath in the brooding ctenostomes
studied or within the zooid cavity), (2) during oviposition, or
even (3) in the ovicell. Joliet wrote that he also observed
embryo development inside the introvert in Bowerbankia
imbricata and Farrella repens (as Laguncula ). The second
case is wrong, as Marcus ( 1926a ) noted. Joliet thought that
sperm was released through the thin wall of the tentacle
sheath during a sharp withdrawal of the polypide. In cheilostomes he observed the egg positioned below the zooidal
operculum prior to oviposition and suggested the presence of
a “communication canal” for egg removal. Finally, from
observations on colonies of Bugula spp., with serially positioned eggs and embryos in the ovicells along the branches,
Joliet wrote that each ovicell could be used repeatedly.
There is some information on the structure and appearance of ripe oocytes in the embryological monograph of
Barrois ( 1877 ).
An extensive review on bryozoan sexual reproduction
was included in the monograph by Hincks ( 1880 ), who, apart
from analyzing the results of previous authors, also mentioned his own observations ( 1861 , 1873 ). Summarizing the
earlier data and opinions, he wrote that “the testicle is all but
universally derived from the funiculus, invariably from some
portion of the endosarc [mesenchymatous tissue] – that the
ova in the considerable number of species also developed in
the funiculus – that in one case at least they originate from
the endosarc apart from this organ [funiculus], but in connexion with a communication-plate – and that in several
cases they are placed on the cell[zooid]-wall, but whether a
product of the endocyst [epidermal layer of the cystid wall]
or endosarc [associated funicular tissue] is still undetermined” ( 1880 , pp. xlix–1). In the ctenostome Alcyonidium
mytili he recognized female and male zooids and mentioned
the intertentacular organ [also in Alcyonidium sp. (as A . gelatinosum ) and Membranipora membranacea ]. In another
Appendices
Joliet came to the conclusion that different gonads and,
subsequently, gametes should have the same origin.
Considering examples when the ovary was observed on the
cystid wall, he showed that the gonad could be moved
from the funiculus to the body wall in some species (for
instance, in Farrella repens ) (as Laguncula ). This observation,
although criticized by Hincks ( 1880 ), is actually correct; in
several instances the ovary is removed from the developing
polypide bud (where it originates) to the basal cystid wall
obviously due to growth of funicular tissue (see Ostrovsky
1998 ; Moosbrugger et al. 2012 ).
Interestingly, Joliet ( 1877a ) described two different kinds
of eggs in different zooids of certain species, one developing
on the funiculus and another (“parietal”) on the body wall.
For instance, in Bicellariella ciliata (as Bicellaria ) he found
ovaries on both the funiculus and the cystid wall [in different
zooids], as recently observed by Moosbrugger et al. ( 2012 ).
Puzzlingly, he stated that he never saw the ovicells, formed
by the fertile zooid in the second case (was it an egg then?).
Joliet supposed that the parietal eggs should originate in connection with funicular strands passing through the communication pores. Since the work of Müller ( 1860 ) the funicular
system was considered as “colonial nervous system” by
some authors (Smitt 1865 ; Claparéde 1871 , discussed in
Hincks 1878 ). Joliet also used this term although thought
that the origin of germ cells in the funiculus was a strong
argument against its “nervous nature”. These doubts fi nally
resulted in the introduction of the term “endosarc” for funicular tissue (see also Joliet 1877b ). An ovary was recorded on
the funiculus of a zooid with a developing polypide in Bugula
avicularia , and early male germ cells near a young polypide
bud in F . repens . In the ctenostome Walkeria uva (as Valkeria
cuscuta ) he also recorded formation of spermatogenic tissue
and an ovary on the funiculus of the early polypide bud and
described spermatogenesis in detail.
Joliet described the release of sperm in W. uva , but could
not recognize the pore through which mature sperm leave the
zooid cavity. In this species Joliet found that eggs do not
degenerate in the ovary during polypide recycling, but that
one of them begins to grow faster instead. Much later,
Dyrynda and Ryland ( 1982 ) found that vitellogenesis commences during polypide recycling in the cheilostome
Chartella papyracea (see below). In Joliet’s case a modifi ed
polypide without tentacles develops prior to oviposition in the
fertile zooid. It can be seen in his illustrations ( 1877a , pl. 13,
fi gs 5–9) that the brooded embryo increases in size in the
introvert, which is evidence of extraembryonic nutrition in
that species. Joliet’s description and illustrations show that he
often saw developing oocyte doublets (in cheilostomes), of
which one cell [the leading oocyte] grows and the other [nurse
cell] remains small. In agreement with Claparède ( 1871 ),
Joliet believed that the second cell waits its turn to develop or
divide. Describing oogenesis in Lepralia martyi (a presently
unknown cheilostome taxon) Joliet wrote that he observed a
cavity [intraovarian space?] developing in the ovary in which
two eggs originate. He thought that upon ovulation, the new
(second) ovary is established in place of the former one. In
this species Joliet recorded up to six eggs formed during the
lifetime of the fertile zooid. In stating that the majority of the
species studied possessed hermaphrodite autozooids, he demonstrated the presence of gonochoristic zooids in L . martyi .
Going against general opinion, Joliet ( 1877a ) remarked
that cross-fertilization should occur in some species, ctenostomes as well as cheilostomes, in which protandrous zooidal hermaphroditism or zooidal gonochorism occurs.
Differences in the timing of gamete maturation, massive production of spermatozoids and their possibility to swim
actively in the surrounding water led him to believe that
cross-fertilization is the rule. He suggested that fertilization
by alien sperm, “distinguished” by the absence of the nucleus
in the egg, occurs in different species (1) inside the maternal
zooid (within the tentacle sheath in the brooding ctenostomes
studied or within the zooid cavity), (2) during oviposition, or
even (3) in the ovicell. Joliet wrote that he also observed
embryo development inside the introvert in Bowerbankia
imbricata and Farrella repens (as Laguncula ). The second
case is wrong, as Marcus ( 1926a ) noted. Joliet thought that
sperm was released through the thin wall of the tentacle
sheath during a sharp withdrawal of the polypide. In cheilostomes he observed the egg positioned below the zooidal
operculum prior to oviposition and suggested the presence of
a “communication canal” for egg removal. Finally, from
observations on colonies of Bugula spp., with serially positioned eggs and embryos in the ovicells along the branches,
Joliet wrote that each ovicell could be used repeatedly.
There is some information on the structure and appearance of ripe oocytes in the embryological monograph of
Barrois ( 1877 ).
An extensive review on bryozoan sexual reproduction
was included in the monograph by Hincks ( 1880 ), who, apart
from analyzing the results of previous authors, also mentioned his own observations ( 1861 , 1873 ). Summarizing the
earlier data and opinions, he wrote that “the testicle is all but
universally derived from the funiculus, invariably from some
portion of the endosarc [mesenchymatous tissue] – that the
ova in the considerable number of species also developed in
the funiculus – that in one case at least they originate from
the endosarc apart from this organ [funiculus], but in connexion with a communication-plate – and that in several
cases they are placed on the cell[zooid]-wall, but whether a
product of the endocyst [epidermal layer of the cystid wall]
or endosarc [associated funicular tissue] is still undetermined” ( 1880 , pp. xlix–1). In the ctenostome Alcyonidium
mytili he recognized female and male zooids and mentioned
the intertentacular organ [also in Alcyonidium sp. (as A . gelatinosum ) and Membranipora membranacea ]. In another
Appendices