292
mature oocyte was said to be surrounded by the “yolk membrane” [fertilization envelope] when still in the ovary
(Vigelius 1884a , pl. V, fi gs 69, 71). The partially detached
envelope wall is depicted on the side of the partially ovulated
oocyte exposed to the zooid cavity. Challenging the statement of Joliet ( 1877a ), Vigelius found that testes develop on
the zooid wall but not within a funiculus. Like Ehlers ( 1876 ),
he described the irregular shape, sometimes paired, and wide
distribution of testes [spermatogenic tissue] across the zooid
wall in the proximal part of the cystid and noted that the
ovary does not degenerate after the fi rst ovulation, but continues to produce new eggs: Vigelius thought that the new
ovary originated from the remains of the previous one, or
could be built up again from the parietal epithelium.
Moreover, functioning ovaries were observed in zooids with
a brown body and regenerating polypide, and these observations were used as evidence against Joliet’s ( 1877a ) statements on the “polypide origin” of the ovary. There is also a
detailed description of spermatogenesis in his papers.
Vigelius thought that the release of sperm was achieved
through the zooid aperture only after polypide degeneration
and destruction of the body wall. Fertilisation itself he supposed to occur externally, inside the ovicell.
In his later paper, Vigelius ( 1886 ) studied sexual reproduction in Bugula calathus including the structure and development of its ovicells. Here the ovary is suggested to be a
product of “mesenchymatous parenchyma” (a similar opinion is also in the works of Ostroumoff ( 1886a , b ), who wrote
that both testes and ovary have a mesodermal origin), developing on the basal wall of the cystid. Vigelius noted that
some ovaries lose their contact with the basal wall during
oogenesis, either lying free [because of ovulation?] in the
body cavity or connected to the basal wall by the single
parenchymatous [funicular] strand. In comparing ovary
structure in B . calathus and Chartella membranaceotruncata ,
Vigelius stressed the striking difference between these
species; in contrast with the ovary of Chartella , with its basal
part consisting of tightly packed large, cylindrical cells, the
ovary of Bugula is represented by a few small, fl at cells with
a loose arrangement. It is noteworthy that in two instances
Vigelius depicted some tiny bodies between the oocytes and
the ovary wall ( 1884b , pl. 3, fi g. 39, 1886 , pl. 26, fi g. 4) that
might be so-called “basal ovarian cells”, a term introduced
by Hageman ( 1983 ) based on his ultrastructural studies.
Judging from his illustrations (pl. 26, fi gs 3–4), Vigelius
often saw oocyte doublets, young as well as mature, consisting of the oocyte and its nurse cell with a nucleus occupying
the major part of the cell. Vigelius also described a large
transparent vacuole, seen in the nucleoli of many oocytes,
and a change in the position of the nucleus (from central to
excentric) in the course of ovum growth and vitellogenesis.
Though mentioning brown yolk granules, he termed the eggs
of Bugula as alecithal. The simultaneous development of
male and female gametes in the same zooids persuaded him
to accept intrazooidal self-fertilisation in this species. One of
Vigelius’s most interesting fi ndings was the discovery of a
cylindrical epithelium [embryophore] in the ooecial vesicle,
and unusual “bodies” [possibly groups of the nutrient-storage cells] with granular cytoplasm, associated with its cells.
This hypertrophied cell layer, now known as a placental analogue, was probably found fi rst by Reid ( 1845 ) in B . fl abellata (see above). Vigelius also depicted an increase in the
size of incubated embryos (a consequence of placental
brooding), but, like many of his contemporaries (Hincks
1861 , 1873 ; Nitsche 1869 ; Joliet 1877a ; Calvet 1900 ), did
not recognized the importance of this fi nding.
Finally, Vigelius ( 1887a , b ) published two papers in which
he summarized the contemporary view on bryozoan anatomy, mentioning that sexual products are formed from “parenchymatous tissue”. Judging from his description ( 1887a ,
p. 238) this “tissue” is of mesenchymatous origin and
includes peritoneal and funicular cells.
Kraepelin ( 1887 ) described and depicted the position of
gonads in the hermaphrodite zooids of two ctenostomes. In
Victorella pavida both gonads are placed on the cystid wall
– the ovary in the distal part of the zooid and the testis occurs
in the middle part. In Paludicella articulata (as P . ehrenbergi ), spermatogenic tissue develops on the funiculus and
partly also on the cystid wall in the proximal part of the
zooid, and the ovary on the cystid wall in its middle part.
Kraepelin also described the shape and movement of the
sperm in the latter species. He believed that both types of
sexual cells developed from the “Peritonealepithel”.
In contrast with all previous published observations,
Jullien ( 1888a ) described and depicted a “testicule glandulaire” with ducts in Figularia fi gularis (as Lepralia ), and
depicted ovaries with a single oocyte doublet in this species
and in Beania sp. (as Diachoris costata ) (Jullien 1888b ). In
all probability, he confused opercular glands with testes
(which do not have ducts). In Celleporella hyalina (as
Hippothoa ) he distinguished ordinary, male and female
zooids and proposed that oviposition might occur with the
help of the tentacle sheath, since he did not fi nd a polypide in
the females (Jullien 1888b ).
Pergens ( 1889 ) briefl y described oogenesis and ovulation
in Fenestrulina malusii (as Microporella ). He stated that the
ovary develops from parietal tissue on the zooid wall in this
species. Division of the cells of the parietal layer results in
the development of the ovary in which a group of 3–5 larger
cells becomes visible. Some of them are resorbed, but two
[oocyte doublet] increase in size and one is transformed into
an egg. Other ovary cells surround this pair, “serving them
for feeding (p. 510).” The ovulated egg released from the follicle is surrounded by the “Chorion” [fertilization envelope]
that is preserved until the end of larval development [in the
ovicell]. Pergens was the fi rst to record oviposition in cheiloAppendices
mature oocyte was said to be surrounded by the “yolk membrane” [fertilization envelope] when still in the ovary
(Vigelius 1884a , pl. V, fi gs 69, 71). The partially detached
envelope wall is depicted on the side of the partially ovulated
oocyte exposed to the zooid cavity. Challenging the statement of Joliet ( 1877a ), Vigelius found that testes develop on
the zooid wall but not within a funiculus. Like Ehlers ( 1876 ),
he described the irregular shape, sometimes paired, and wide
distribution of testes [spermatogenic tissue] across the zooid
wall in the proximal part of the cystid and noted that the
ovary does not degenerate after the fi rst ovulation, but continues to produce new eggs: Vigelius thought that the new
ovary originated from the remains of the previous one, or
could be built up again from the parietal epithelium.
Moreover, functioning ovaries were observed in zooids with
a brown body and regenerating polypide, and these observations were used as evidence against Joliet’s ( 1877a ) statements on the “polypide origin” of the ovary. There is also a
detailed description of spermatogenesis in his papers.
Vigelius thought that the release of sperm was achieved
through the zooid aperture only after polypide degeneration
and destruction of the body wall. Fertilisation itself he supposed to occur externally, inside the ovicell.
In his later paper, Vigelius ( 1886 ) studied sexual reproduction in Bugula calathus including the structure and development of its ovicells. Here the ovary is suggested to be a
product of “mesenchymatous parenchyma” (a similar opinion is also in the works of Ostroumoff ( 1886a , b ), who wrote
that both testes and ovary have a mesodermal origin), developing on the basal wall of the cystid. Vigelius noted that
some ovaries lose their contact with the basal wall during
oogenesis, either lying free [because of ovulation?] in the
body cavity or connected to the basal wall by the single
parenchymatous [funicular] strand. In comparing ovary
structure in B . calathus and Chartella membranaceotruncata ,
Vigelius stressed the striking difference between these
species; in contrast with the ovary of Chartella , with its basal
part consisting of tightly packed large, cylindrical cells, the
ovary of Bugula is represented by a few small, fl at cells with
a loose arrangement. It is noteworthy that in two instances
Vigelius depicted some tiny bodies between the oocytes and
the ovary wall ( 1884b , pl. 3, fi g. 39, 1886 , pl. 26, fi g. 4) that
might be so-called “basal ovarian cells”, a term introduced
by Hageman ( 1983 ) based on his ultrastructural studies.
Judging from his illustrations (pl. 26, fi gs 3–4), Vigelius
often saw oocyte doublets, young as well as mature, consisting of the oocyte and its nurse cell with a nucleus occupying
the major part of the cell. Vigelius also described a large
transparent vacuole, seen in the nucleoli of many oocytes,
and a change in the position of the nucleus (from central to
excentric) in the course of ovum growth and vitellogenesis.
Though mentioning brown yolk granules, he termed the eggs
of Bugula as alecithal. The simultaneous development of
male and female gametes in the same zooids persuaded him
to accept intrazooidal self-fertilisation in this species. One of
Vigelius’s most interesting fi ndings was the discovery of a
cylindrical epithelium [embryophore] in the ooecial vesicle,
and unusual “bodies” [possibly groups of the nutrient-storage cells] with granular cytoplasm, associated with its cells.
This hypertrophied cell layer, now known as a placental analogue, was probably found fi rst by Reid ( 1845 ) in B . fl abellata (see above). Vigelius also depicted an increase in the
size of incubated embryos (a consequence of placental
brooding), but, like many of his contemporaries (Hincks
1861 , 1873 ; Nitsche 1869 ; Joliet 1877a ; Calvet 1900 ), did
not recognized the importance of this fi nding.
Finally, Vigelius ( 1887a , b ) published two papers in which
he summarized the contemporary view on bryozoan anatomy, mentioning that sexual products are formed from “parenchymatous tissue”. Judging from his description ( 1887a ,
p. 238) this “tissue” is of mesenchymatous origin and
includes peritoneal and funicular cells.
Kraepelin ( 1887 ) described and depicted the position of
gonads in the hermaphrodite zooids of two ctenostomes. In
Victorella pavida both gonads are placed on the cystid wall
– the ovary in the distal part of the zooid and the testis occurs
in the middle part. In Paludicella articulata (as P . ehrenbergi ), spermatogenic tissue develops on the funiculus and
partly also on the cystid wall in the proximal part of the
zooid, and the ovary on the cystid wall in its middle part.
Kraepelin also described the shape and movement of the
sperm in the latter species. He believed that both types of
sexual cells developed from the “Peritonealepithel”.
In contrast with all previous published observations,
Jullien ( 1888a ) described and depicted a “testicule glandulaire” with ducts in Figularia fi gularis (as Lepralia ), and
depicted ovaries with a single oocyte doublet in this species
and in Beania sp. (as Diachoris costata ) (Jullien 1888b ). In
all probability, he confused opercular glands with testes
(which do not have ducts). In Celleporella hyalina (as
Hippothoa ) he distinguished ordinary, male and female
zooids and proposed that oviposition might occur with the
help of the tentacle sheath, since he did not fi nd a polypide in
the females (Jullien 1888b ).
Pergens ( 1889 ) briefl y described oogenesis and ovulation
in Fenestrulina malusii (as Microporella ). He stated that the
ovary develops from parietal tissue on the zooid wall in this
species. Division of the cells of the parietal layer results in
the development of the ovary in which a group of 3–5 larger
cells becomes visible. Some of them are resorbed, but two
[oocyte doublet] increase in size and one is transformed into
an egg. Other ovary cells surround this pair, “serving them
for feeding (p. 510).” The ovulated egg released from the follicle is surrounded by the “Chorion” [fertilization envelope]
that is preserved until the end of larval development [in the
ovicell]. Pergens was the fi rst to record oviposition in cheiloAppendices