HARVARD UNIVERSITY.

LIBRARY

OF THE

MUSEUM OF COMPARATIVE ZOOLOGY.
\Y.20\0

GIFT OF

ALEXANDER: AGASSIZ:
SE

A Ny

JUN 4 1904

\A.25\0
Noes ET:

REPORT: FOR 1908,

ON THE

LANCASHIRE SEA-FISHERIES LABORATORY
THE Bee as OF -LIVERPOOL,

AND THE

SEA-FISH HATCHERY AT PIEL.

DRAWN UP BY
Professor -W.- A. Herpman; D.Sc; F-R:S.,
Hon. Director of the Scientific Work,
Assisted by Mr. Anprew Scort, A.L.S., and

Mr. James JOHNSTONE, B.Sc.
WITH <TELUSTRALTIONS.

LIVERPOOL

PRINTED BY -C.-TImNLING AND Co., 53,° VICTORIA STREET.

L 9-0-4.

vet
det A nat ¢
Mate

nie tA
on)

hick

JUN 4 1904

Report on the Investigations carried on during 1903
in connection with the LAncAasSHIRE SEA-FISHERIES
Laxsoratrory at the University of Liverpool, and
the Sea-Fisnh Hatcnery at Piel, near Barrow.

Drawn up by Professor W. A. Herpman, F.R.S., Honorary
Director of the Scientific Work; assisted by Mr.
AnpREW Scott, A.L.S., Resident Fisheries Assistant
at Piel; and Mr. James Jounstonr, B.Sc., Fisheries
Assistant at the Liverpool Lahorators

With Compliments from

Proressor W. A. HERDMAN, F.B.S.,

UNIVERSITY COLLEGE,
LIVERPOOL.

ceive your publications im
ho will be glad to recewe ¥ }

exchange.

Ww

(1) The hatching operations and other similar work
carried out at Piel by Mr. Andrew Scott;

(2) Laboratory investigations on fish and on their
parasites and diseased conditions, by Mr. James Johnstone:
at the University of Liverpool ;

(3) Practical Laboratory Classes for Fishermen and
for school teachers, conducted by Mr. Johnstone and Mr.
Seott, at Piel;

(4) Observations at sea on board our Fisheries
Steamer “John Fell,”

JUN 4 1904

Rerort on the InveEstications carried on during 1903
in connection with the LANcASHIRE SkA-FISHERIES
Lasoratory at the University of Liverpool, and
the Sra-Fisnh Harcuery at Piel, near Barrow.

Drawn up by Professor W. A. Herpman, F.R.S., Honorary
Director of ‘the Scientific Work; assisted by Mr.
AnpReEw Scott, A.L.S., Resident Fisheries Assistant
at Piel; and Mr. James Jonnstonr, B.Sc., Fisheries
Assistant at the Liverpool Laboratory.

(With plates, charts and figures in the text.)

CONTENTS.

1. Introduction and General Account of the Work. (W.A.H.) 1
2. Sea-Fish Hatching ut Piel. (A.S.) - - - - = al
3. Classes and Visitors at Piel. (A.S.) - . . - - 165
4. Trawling Observations. (J. J.) - - - - 20
5. Parasites found on Fishes in the Irish Sea. (A. 8.) - - 33
6. Myxosporidia in Flat-Fish. (H. M. Woodcock) - - 46
7. A Remarkable Parasite. (H.M. Woodcock) — - - - 68
8. On the fecundity of the Plaice. (R. D. Lawrie) - = fe
9. An outline of the Shrimp question. | (W. A. H.) = - 77
10. Investigations on Pearls in Shell-Fish. (W. A. H.) - 88
11. Sewage and Shell-Fish. (W. A. H.) - - - - - 98
12. Syllabus of Fishermen’s Class at Piel. (J. J.) - - - 109

13, ApPpENDIx :—Memoir on AreEniconA, the Fisherman’s
Lug-worm, by Dr. J. H. Ashworth - - - - 129

INTRODUCTION AND GENERAL ACCOUNT
OF THE WORK.

Tue work of the past year has been chiefly :—

(1) The hatching operations and other similar work
carried out at Piel by Mr. Andrew Scott;

(2) Laboratory investigations on fish and on their
parasites and diseased conditions, by Mr. James Johnstone>
at the University of Liverpool ;

(5) Practical Laboratory Classes for Fishermen and
for school teachers, conducted by Mr. Johnstone and Mr.
Scott, at Piel;

(4) Observations at sea on board our Fisheries
Steamer “ John Fell.”

9)

—

Some matters that can be treated briefly I shall
remark upon in this introductory part of the Report; the
others will be discussed more fully in the special articles
that follow.

Tam glad to say that the very full account of the Fisher-
man’s “ Lugworm,” which Dr. J. H. Ashworth (formerly
of Owens College, Manchester, now at the University of
{dinburgh) has been preparing for some years, is now
finished, and I am able to add it as an Appendix to this
Report. The expense of lithographing the beautiful
plates that illustrate this Memoir has been largely met
from an outside source.

Dive. Piel, Matebe sya

Mr. Scott’s account of the Sea-Fish Hatching at Piel
will be found in the next section of the Report. As on
former occasions, the fish dealt with were the Plaice and
the Flounder, and out of close on seventeen millions of
eggs obtained nearly fifteen millions were hatched and
distributed in the sea as fry. The total loss from all
causes during the operations was just under 11 per cent.
It can scarcely be doubted that the natural mortality in
the sea during the corresponding period in the life of the
young fish embryo must be enormously greater than this.
The benefit of protection would be, however, still further
increased if we had the accommodation necessary for
keeping and rearing the larve to still later stages. This
is impossible without a fish pond; and Mr. Scott points
out that he cannot, with his present small tanks deal with
much larger numbers than those that passed through his
hands this year. An open-air fish pond has proved a
success elsewhere. An American fish-culturist, Professor
Mead, of Brown University, who visited the Port Krin
Biological Station last summer, expressed his satisfaction

3

at seeing the fish pond there, and evidently regarded it as
a necessary addition to any hatchery. I would repeat
again what I stated to the Committee last year, that no
hatchery is complete without a spawning and rearing
pond, and that the want of one at Piel seriously impedes

Mr. Scott’s operations.

ra wince Re sa lt sit
an)

We are now preparing for the hatching work of the
coming season, and once more we are indebted to the
courtesy of the Fishery Board for Scotland for permission
to trawl for large plaice in their closed waters of Luce
Bay. As before the Fishery Board asked us to make
observations and to give them a record of our results.
Two trips were made to Luce Bay in October and Novem-
ber and our Naturalists who accompanied the steamer
were able to make a series of interesting hauls on both
oceasions. The results are fully discussed by Mr. John-
stone in his article on ‘‘ Trawling Observations,” which
will be found below. These results confirm those obtained
in 1902, and reinforce the conclusions which I drew in
last year’s Report as to the remarkable differences in the
catches which may result from very slight differences in
the positions and conditions of the grounds trawled. The
bearing of these observations upon the danger of any
attempts to draw conclusions from samples taken
relatively far apart, even on areas where uniform condi-
tions are supposed to obtain, must be obvious.

Mr. Johnstone also draws attention to the very large
average size of the plaice in the closed Scottish waters,
and shows how the much smaller size on the Lancashire
coast may be regarded as the natural result of constant
and practically unrestricted fishing.

1

The ‘Classes in Biclogy at’ Paes

I have also received from Mr. Scott a report upon
the other work and the leading events of the year at our
Piel establishment. It will be found below, and consists
mainly of a record of the practical classes held in the
laboratory, and of the visits of scientific men, and other
Sea-Fisheries and Educational Authorities.

Our Fisheries Exhibition is still on view at the Piel
Laboratory, and is a useful adjunct to the teaching
resources. It can, however, be sent out on loan, as
formerly, when required; and any public institutions
within the contributing counties desiring to show the
exhibit should apply to the office at Preston for a copy of
the conditions upon which it may be obtained.

Fish Parasites and Diseases.

Some time ago I suggested to Mr. Scott, who has
been working for years, at odd moments as opportunity
offered, upon the parasitic Crustaceans of our seas, that
he should extend his observations to the parasitic worms
and other lower animals that may cause diseased condi-
tions, and give us a list of all the fish-parasites he was able
to detect. A first, and very considerable instalment,
appears below, consisting of four Protozoan, ten Trema-
tode, one leech and forty-six Copepod parasites, taken, as
will be seen, from a varied assortment of fishes, and from
very different positions in the body. The Cestodes (tape-
worms) and Nematodes (thread-worms), not included in
this paper, will follow on some future occasion.

Mr. H. M. Woodcock, of University College, London,
has examined for us two of the Protozoan parasites, and
contributes a useful paper on “ Myxosporidia in Flatfish,”
which enumerates all these parasites which have yet been

~

oO

found, and also contains a description of a new species,
Sphaerospora platesse, from the Plaice. Mr. Woodcock
in a second paper describes a very remarkable parasite,
Lymphocystis johustonei, from the Flounder.

Oiinh ene | Wrormke.

Mr. R. D. Laurie, a former student of our Zoological
Department at the University, has contributed a short
note bearing on the question of the number of eggs that
can be produced by an adult plaice. His results for
plaice, of about 20 inches in length, from the Irish Sea,
agree with those obtained for other seas. Of the three
or four hundred thousand large eggs present on the
average in such a fish only a comparatively small number
are mature at a time, the plaice setting free its ova in
successive small batches over an extended spawning
period. In stripping a spawning plaice only a certain
small proportion of the eggs in the ovary can be extruded.

The subject of pearl formation in Molluscs, such as
mussels and oysters, has been brought into prominence of
late years by several investigations and reports both in
this country and abroad. As the matter is one of con-
siderable public interest and importance, and as there is
at present a good deal of misapprehension in connection
with it, caused by sensational statements derived from
some of the French papers, I have thought it well to give
a brief account of the more important recent discoveries
and views bearing upon the subject of pearl-formation.

The relation of sewage disposal to the pollution of
our coasts, and to the possible infection of edible shell-
fish with pathogenic organisms, has become a matter of
national importance. Some previous work done in our
laboratory 8 years ago,* drew attention to the matter

* See Report of Ipswich meeting of British Association, Sept.,
1895, and Lancashire Sea-Fisheries Memoir, No, L., 1899.

6

locally, and since then investigations have been carried
on at various points round the British coasts, and for the
last few years the Royal Commission on Sewage Disposal
has been taking evidence and deliberating on the subject.
Both Mr. Dawson and I, in our evidence before the Royal
Commission, have drawn attention to the very serious
state of affairs on some parts of the Lancashire and
Cheshire coasts, and we have lately planned a more
thorough examination into the condition of the shell-fish
beds of the district. Mr. Scott has inspected for me
several of the mussel and cockle producing areas in the
northern part of Lancashire, and Mr. Johnstone has made
a bacteriological examination of the samples of shell-fish
that have been sent to the laboratory. As the Royal
Commission has also just issued a Report? dealing with
these same questions, and very much on the lines we have
adopted, I have thought it appropriate to devote a few
pages further on to a discussion of the matter.

A suggestion, made by Mr. Fell, that we should report
upon the intricate question of the inter-relations between
shrimps and young flatfish, has led to the preliminary
statement of the subject which, with Mr. Johnstone's
help, I have drawn up. It is evident that a great deal of
exact information is still required. I have tried to focus
attention upon what is known and what is unknown, upon
what the essential problems are and what investigations
are necessary in order to solve them. But it is clear that
this is one of the matters upon which we cannot get
wholly satisfactory evidence until we have, on the West
Coast of England, a steamer devoted solely to scientific
fisheries work, so that an organised scheme of investiga-
tion, combined with the collection of statistics, can be

‘arried out. It would probably require a couple of years

+ Pollution of Tidal Waters with special reference to contamina-
tion of Shell-fish. London, 1904.

7

of such organised work before reliable conclusions could
be arrived at. Still the outline of the sub-divisions and
relations of the investigation given below may be useful
to the Committee as showing the complexity of such a
question, and the need for a very thorough systematic
investigation of all such fishery matters.

Finally, I may refer to the most important event of
the past year in connection with Sea-Fisheries Organisa-
tion and Administration in this Country, viz., the trans-
ference of the Official Government department dealing
with these matters from the Board of Trade to what is
now the Board of Agriculture and Fisheries. This must
be a matter of congratulation in so far as it gives to our
subject more of the high relative position and the im-
proved status to which its importance entitles it,, and
which it possesses in most civilised countries. Although
not yet an independent department of State, with a
Minister for Fisheries, it is now conjoined on an equality
with the allied subject, Agriculture, under a President,
Lord Onslow, who recognises fully its claims to his
attention, and will assuredly give sympathetic and
adequate treatment to the new division of his department.
The union of Fisheries with Agriculture is a natural one,
which we see working well in Ireland, in several of the
Colonies and elsewhere. Aquicriture and Agriculture have
similar disciplines, and similar methods should give
similar results. The operations that result in the
harvest of the sea being now placed under the same
guiding hand as those that affect the harvest of the land,
we may hope that in the former case as in the latter the
returns from nature will be increased as the result of
scientific cultivation.

From the scientific point of view the present division
of the territorial waters of England and Wales into Sea-

8

Fisheries Districts is not satistactory. The Districts are
too numerous and unequal, the boundary lines are arbi-
trary and unnatural, the methods of the Authorities are
too diverse; and, as a result, the fisheries are very un-
equally treated both as to administration and investiga-
tion. A glance at the details of expenditure of the
difterent Committees is enough to show how perfunctory
and inadequate the examination and protection of the
fisheries must be on some parts of the coast.

For these, and other reasons, the Iechthyological Com-
mittee in their Report last year recommended for purposes
of fisheries investigation a consolidation of the Districts
and Authorities on each of the three great coast lines of
England and Wales—LHast, South and West. It may be
worth while to reproduce once more the accompanying
rough sketch plan in order to bring this idea clearly
before the mind and to show how the three suggested
Districts form natural coast areas. Mr. Fell has since
shown* that there would be advantages in the amalga-
mation of the present Committees on each coast, not only
for purposes of investigation but also for administration.
He has gone into the question of probable income and
expenditure and finds that each such large area would
have a rateable value of about thirty millions sterling,
yielding, on the rate of one-sixteenth of a penny in the
pound, a sum which, according to our Lancashire scale
of expenditure, ought to be ample for the proposed work.
In these calculations London is left out of account. Its
contribution, from a similar rate, if obtainable, might be
applied to general central expenses or to special work
applying to the whole country.

Looking at the West Coast as now administered it is
obviously unnatural and inconvenient that the large

* I quote from a letter and from a speech by Mr. Fell. So far as
I am aware his tigures have not yet been published.

i)

FISHERY COUNGIL
FOR
ENGLAND

Fic. 1.—Sketch map of the British Islands for the purpose of

indicating the positions of the chief marine laboratories and sea-fish
hatcheries, and the proposed division of the coast of England into
three great fisheries districts—the Hast coast, the South and the
West—as recommended by the Ichthyological Committee.

10

Lancashire and Western area should be cut off from the
Solway Firth to the north and from the Bristol Channel
to the south. In studying the distribution and move-
ments of plaice throughout the seasons of the year, and
the life of the fish, it is evident, even from our few obser-
vations during the last couple of years, that the great
shallow water areas of the Solway are of considerable
interest. This is recognised by the Fishery Board for
Scotland as well as by ourselves, and on more than one
occasion now they have asked us to make observations for
them from our steamer, and to aid them in obtaiming
young fishes for their transplantation experiments. We
are also at the present time preparing to co-operate with
the Fishery Board in certain drift-bottle experiments for
the purpose of determining the movements of the surface
waters of the Irish Sea and the Clyde Sea-area, such as
may affect the drift of fish eggs and larve. This is as it
ought to be, and if the whole west coast from the Solway
to the Severn were in the control of one Authority, effi-
ciently equipped with boats and observers, an organised
co-operation with the Fishery Board for Scotland would
be natural, and a joint investigation of the Solway and of
any other problems of common interest would undoubtedly
be effected.

The Isle of Man should also join this proposed
western amalgamation. The seas round that Island are
closely related to the Lancashire waters, and whatever the
fishermen may be required to do, the fish respect no terri-
torial boundaries. The Isle of Man has everything to
gain by coming into line with the English counties. To
administer the insular fisheries alone would be an extrava-
gant process. Joined with Lancashire and the other
counties in a western combination, in return for a very

A,

moderate rate the Manx fisheries would be adequately

dal

exploited and policed—-the regulation and administra-
tion would be the same as over the adjoining English and
Welsh coasts. We should then have in this northern
part of the Irish Sea a natural sea-fisheries district ad-
ministered by one Authority, having one steamer for
police regulation and another for scientific investigation,
having central laboratories in the University of Liver-
pool, with Marine Stations and Hatcheries at several
distant points, probably in the north of Lancashire (Piel),
in the Isle of Man (Port Erin), and somewhere on the
coast of Wales. The co-relation between such labora-
tories and those on the other coasts of England, and again
between Mngland, as a whole, and Scotland, Ireland and,
it may be, other Countries, might well be as was outlined
in the Report of the Ichthyological Committee. If such
a national scheme of fisheries co-ordination were carried
out it would lead, in addition to increased efficiency of
administration, to a marked increase in the scientific
knowledge of our fishing grounds, the absence of which
successive Select Committees and Conferences have had
to deplore.
W. A. HERDMAN.
Tur University, Liverrootn,
January, 1904.

12

SEA FISH HATCHING AT PIEL.
By Anprew Scort, A.L.S.

In the operations carried on during the fish hatching
season of 1903, the eggs of plaice (Pleuronectes platessa)
and flounder (PJ. flesus) were again dealt with. At the
beginning of the year there were 100 mature plaice and
200 flounders in the tanks. The plaice, as in former
years, were brought from the closed waters of Luce Bay
by the fisheries steamer, and the flounders were collected
in Barrow Channel by Mr. Wright. The fish, on the
whole, were not so large as those used in the hatchery work
of 1902, but from the increase of numbers, and by main-
taining a good circulation of water, we were able to
improve upon the results then obtained.

Under the present system we have probably nearly
reached the maximum number of fish that can be accom-
modated with safety. Further development, as we
pointed out in last year’s Report, can only be secured by
an addition to our present resources. The fish hatchery
at Bay of Nigg, and the hatchery at Port Erin have both
open air ponds which are of immense use in all hatching
work, and must be considered as an essential to further
progress.

The first fertilised eggs were collected and placed in
the hatching boxes on March 9th, and the last on May 7th,
so that the spawning season with us extended over a
period of two months, or about two weeks less than in the
previous year. During the spawning season nearly
seventeen millions of eggs were collected and incubated
and those eggs produced close on fifteen millions of fry
which were set free as before near the centre of More-
cambe Bay. ‘The periods of incubation of the plaice and
flounder eggs were practically the same as last year, from

13

ten to seven days for flounder, and from seventeen to
fifteen days for plaice. The total loss during incubation
from all causes was just under 11 per cent.

The following tables show the numbers of eggs
collected and of the fry set free on the dates specified.

PLAICE.
Eges Collected. Fry Set Free.

Mareh 9’ -.» 40,000 35,000 ... March 26
a 50,000 44,000 ... April 8
me we lihe. 4.500.000 44,000 ... i ;
ge 2S 00,000 | 44,000... ni Ny
we 5c 000 43,500... x We
ee 2Oe o45 60,000 08,0005): - 16
ee SU... <p0 KO, O00 | 62,000... 2 3

Aprils.2 .... 60,000 53,000 ... oe 27

ms GO dee ph OOOO 62,000 ... a
3 ent. 4 00/000 53,000 ue *
3 9 ee ul 0000 62,000 . -
ba eS 5.25 60;000 D000, ss. 4, Me
cs La -=..4 200,000 53,000 ... May 5
- Le > 560,000 93,000) 42: ie *
Me Mf, 3b, 000 67,0005 * 22. is 5s
s 20. “2.24 9 O,000 62,000... ay i
re 22... £60;000 5}3}(0, 010) Nae * 13
- 951 2257,60;000 53,000... a a
FF Diy eee, 10000 62,000... a uf
Cs SO 22 (0,000 62,0005 =;.. iS 92.
May De 60,000 | aaa, C005 s. ‘ i
- 4... €0,000 62,000 ... a i
an eure. (60000 BorOleld) Wess 7 ‘es
Total Eggs 1,400,000 1,237,000 Total Fry

14

FLOUNDER.

Higgs Collected.

March 9 ... 200,000
tO ie ST OO0C
oe aes WATOLO00
io dl» ee 54803000
~ , 23 27 000000
oy eee 4a OUU
~ al) oe 600006

April 2 ... 600,000

a 4... 800,000
0 S2 GG; 000
- g 900,000
. 11 igi 000,000
: 3,22. 900000
iy ise ee 700,000
i 1. a S00000
‘ 20... 800,000
Ss 2 228" 3800000
i 95 800,000
a P| al ,000,000
¥ 30. TOO B00

May amma 6.001 0.016)

fe 7 eae 600,000
7 «3 400,000

Total Begs 15,300,000

Total Number of Eggs
Total Number of Fry

Fry Set Free.

178,000 ... March 26

498,000... April
428,000 ... ,,
4970000. sien
445,000 ... ,,
498,000 ... _,,
582,000 ... __,,
532,000... ,,
715/000: 1 eee
623,000 ... _,,
BOd'O00:, ames
BOGKIO.-1 2 wae
800,000... May
623,000... ,,
TO 00. ae Mae
TiO O00; 8
fREUUC Venerol
712500 0 es
890,000: ai
623,000... ,,
582,000 ... ,,
582,000 ... ,,
56/0000 ne

13,630,000 Total Fry.

16,700,000
14,867,000

8

—
Or

CLASSES, VISITORS, &c., AT PIEL LABORATORY.
By ANDREW Scott.

The Fishermen’s Classes, conducted at Piel under the
auspices of the Lancashire County Council and the Sea-
Fisheries Committee, have now become an established in-

stitution. Hach year they are held the competition for
places gets keener. The grant given by the County

Council in 1905 enabled us to take forty-five men, fifteen
more than in the previous year. Applications for places
were to be sent to Mr. Dawson, and by the beginning of
March no less than sixty-two names had been received,
all of fishermen from between Southport and Roosebeck.
Three classes of fifteen men to each were formed, and the
selected men were notified regarding the date and times
of attendance. They all duly presented themselves at
Piel and went through the course of instruction as in
previous years. At the end of each class the usual votes
of thanks to the Sea-Fisheries Committee and the County
Council for the privileges afforded the men for acquiring
a better knowledge of the life histories and habits of the
economic marine animals were duly proposed and carried.
Some of the men expressed the hope that in the near
future a second and more advanced course would be pos-
sible for those who had already gone through the first
one. The suggestion has also been made by some
Members of the Committee that one or two prizes, such as
a small microscope and some pocket lenses, might be
offered for competition in each class. This would have
the additional advantage of encouraging some of the men
to continue the work after returning to their homes.

Mr. Johnstone, from the Liverpool Laboratory, again
had charge of the classes, and the following are the names
of the men who attended :—

16

Class held March 9th to 20th.—J. J. Peet, Lytham;
Thomas Newsham, Lytham; John Leadbetter, Fleetwood ;
Krnest C. Leadbetter, Fleetwood; David Moss, Fleet-
wood; John Colley, Fleetwood; James Carter, More-
cambe, James Johnstone, Morecambe; Wilfred \Wood-
house, Morecambe; J. G. Gardner (Secretary Fishermen’s
Association), Morecambe; Hugh Rimmer, St. Anne’s;
James Robinson, Southport; William Jackson, South-
port; Thomas Wright, Southport; John Wright,
Southport.

Class held March 231d to April 83rd—lLawrence
Abram (Ned’s), Banks; John Wareing (Stephen’s),
Banks; Richard Sharples, Banks; Richard Wright,
Marshside; Nicholas Wright (Selby), Marshside; John
Harrison, St. Anne’s; Harry Melling, St. Anne’s; John
C. Pegler, Fleetwood; T. P. Ball, Jr., Fleetwood; William
Wilson, Fleetwood; Thomas Wilson, Fleetwood; James
Bond, Morecambe; George Bond, Morecambe; William
Brown, Morecambe; John Birkett, Morecambe.

Class held April 20th to May 1st.—Robert Wright,
Marshside; Jeffrey Ball, Marshside; Robert Harrison,
St. Anne’s; Nicholas Parkinson, Lytham; Thomas
Whiteside, Lytham; Robert Clarkson, Lytham; Fred. H.
Pegler, Fleetwood; Richard Bond, Morecambe; Richard
Bond, Morecambe; Walter Bell, Morecambe; James
Cocking, Morecambe; William Johnson, Ulverston; J.
Bouskill, Flookburgh; James Butler, Flookburgh; David
Wilkinson, Baicliff.

In addition to these Classes for Fishermen, two
courses in Nature Study for School Teachers were
arranged, and proved a successful experiment. The first
one was attended by seventeen head masters, head
mistresses, and assistants from the schools under the
Barrow School Board. It was held on two evenings and

17

the Saturday afternoon of each week during the last of
the series of Fishermen’s Classes. The second class was
held by desire of some of the Morecambe teachers, and
was taken advantage of by the head master and_ first
assistant from three of the schools. | The Barrow teachers
travelled to and from Piel by train each day. The six
Morecambe teachers came during the Whitsuntide vaca-
tion and lived in the establishment during that week.
Four hours’ instruction were given on the Tuesday, Wed-
nesday, Thursday and Friday, and the men spent the
remainder of the time investigating the shores and neigh-
bourhood. The first class was conducted by Mr. John-
stone and myself: the second one, in the unavoidable
absence of Mr. Johnstone, I carried on alone. The
course im each case was a practical one, and instruction
was given in the structure, life history and habits of
common marine animals, such as the cod, the shore crab
and its allies, the cockle, the mussel, the oyster, micro-
scopic life in the sea water collected by the tow-net, the
various animals living on the shore between tidemarks,
and material washed up from the sea bottom.

Much interest was shown by the teachers in the work,
and from the remarks made at the conclusion of the
course, it was evident that a continuation of these Nature
Study Classes at Piel would receive much support from
school teachers in Lancashire. For teachers resident in
Barrow, evening and Saturday meetings are most con-
venient; for others, vacation courses alone would be pos-
sible, unless other arrangements, involving leave of
absence, could be secured.

To the school teachers of Lancashire, Piel offers many
advantages for the study of common marine animals and
plants. From a distance the shore at low water may
seem very uninteiesting and barren, but a more careful

B

18

examination shows that it is far from being so. Many
species of Molluses occur, including the ordinary mussel,
some of which here produce pearls in abundance; the
sand is teeming with the ordinary “ lug-worm,” with its
beautiful external branchial plumes; various forms otf
erustacea abound, and there is a varied assortment of
fishes. The rough scars provide many species of sea-
weeds, and in the spring and early summer the water
contains a good general floating fauna and flora which
can be collected by tow-net. Even the debris washed up
by storms and strewn along high water mark, as we have
found from experience, proves a mine of interest. ‘To
the teacher, where time is a consideration, it may be
pointed out that it is possible to leave Manchester or
Liverpool by 5-45 p.m. train and arrive at the Piel
Laboratory at 8-45 p.m. the same evening. Other trains
from Barrow to Piel are also run. ‘There are also con-
-venient trains for returning.

On January 28th a meeting of representatives from the
various Technical Instruction Committees in the county
was held at Piel, for the purpose of hearing an address
from Professor Herdman, on “ Technical Instruction in
Sea-Fisheries Science” (see last year’s Report), and also
to inspect the equipment of the Laboratory with a view to
teaching fishermen and others.

The Special Subjects Committee of the Barrow School
Board visited the establishment during the course of the
second fishermen’s class in order to see the men at work.
They seemed much impressed by the keen interest dis-
played by the fishermen in the instruction given and in
their practical work.

The Chairman and Members of a number of the
Lancashire local Technical Instruction Committees under

19

the leadership of Mr. James Fletcher and Mr. Dawson,
paid an inspection visit during the course of the third
fishermen’s class. Several members of the party delivered
short addresses to the men.

Mr. Thomas Baxter and party from Morecambe
visited the establishment while the Morecambe school
teachers were at work.

Another meeting of Representatives from the Techni-
eal Instruction Committees of the Lancashire County
Boroughs was held in the Laboratory at the end of July.
The meeting was for the purpose of further developing the
facilities for the teaching of Marine Natural History to
fishermen, school teachers and others. Mr. Fell, Mr.
Ragdale, and other members of the Committee addressed
the Representatives. They pointed out the advantages
that the Piel establishment presents, and the ease of access
to it from all parts of the county. Reference was made
to the satisfactory reports on the teaching work already
accomphshed under more or less temporary conditions.

The St. James’ Rambling Club and the Barrow
Naturalists’ Field Club also visited the establishment
during the summer.

Many visitors have been shown through the Labora-
tory and tank-house. We have also had an inspection
visit from Mr. Fryer, of the Board of Agriculture and
Fisheries. Professor Herdman and the late Mr. I. C.
Thompson, F.L.8., from Liverpool, stayed over a week
end in order to make some investigations, in addition to
shorter visits at other times during the year.

20

TRAWLING OBSERVATIONS AND RESULTS.

By Jas. JOHNSTONE.

(1) Sax,i\Hauls an Luce: |) Bayggeae
October 26th, £4905.

By permission of the Fishery Board for Scotland the
Lancashire and Western Sea Fisheries Committee’s
steamer was enabled to make a series of hauls with a
trawl-net in the preserved waters of Luce Bay, on October
26th, 1905. The primary object of these trawling opera-
tions was to obtain a stock of mature living plaice for the
Committee’s Sea-Fish Hatchery at Piel. Advantage was
taken, however, of the opportunity thus afforded to com-
pare the results usually obtained by fishing on the plaice
grounds within*the Lancashire and Western Sea Fisheries
area, Where trawling is permitted under certain restric-
tions, with those obtainable by fishing in waters strictly
preserved against all forms of trawling. In order
to obtain the fish in as healthy a condition as possible a
series of short hauls were made with a rather small trawl-
net of 50 feet beam, and with 7 inch meshes throughout.
By using such a net a very hmited number of inverte-
brates were captured, and few small fish were obtained.

\—

The smallest plaice obtained in any of the hauls was 8:

NS

t

inches in extreme length. The results of these hauls are
given in the table on following page.
Physical observations during the hauls.

Wind, 8.W., light;

Sea, smooth ;

Weather, unsettled ;

Barometer, 29°4 to 29°6 inches;

Air temperature, 0°-5- C2 to Ade: GeO

21

6G
89T

“SUOT SO[LUt Z
“oryeanp
moy T
“INVA, 499

ian)
ae)
laa)

“SUOT SoTIUt $7
‘uolyRanp
sanoy FT

“IAVAL 44g

"COG ‘HI9QZ NYAOLOQ NO AVG OAT NI stavzT 9 ao

0G
CT
0G
VV

“Suuoy soqrut ET
‘uoryeanp
inoy =
“TAVA WF

OFT

‘SUOT Sop $7
‘molyeanp
sanoy FT -

‘INVA, pig

IGG CTT OOOO POLLO OCPD mist slsiere qysneo SOUst iy [PIO 7,
PS | |

5 G i i i ei i i aera) Ssprvuans) Aaaty

Ti Peer mmm mers e reese ses rssseesccesceseers oulry

sie) ele /e\e) ele alele (eels selec eve s/n s\eleieieleiels sbielein.6 SUITpoO

T ee ee ed eee rete ee topunoy] iT

7 | IF ORI CNM CR MCN HMC MOTE HY CHC SCT Ue ESIC Ur Se SOLO

2 | Teer ae: (srupjna.ua vlpyy) Keay

OF | Se BNE coRicnac cat (nppa yo plpa7) Awry

99 OT ie ferereranolotersleysuetousisvereatelcterekatexie efereveveie “sqeq

ze GT ““UYSusy [VIO] UL ‘UL FT TAAO oorelg

90% GE —-"YASusy [e404 UT “UT FT topun aoe] gq

“SUOT SoTTut £7
‘toTyRaNp
samoy ET

"IAVE, pug

“Suo] soprur $7
‘TOryRanp
samoy tT

"TOVET ST.

“LHDOV() HSI

SUTASAY

22

Sea temperature at surface, 104 C. to 11%) C.;
bottom, 10°°6 C. to 1192 C.;
Specific gravity of sea at surface, 1025 to 1027;

a4 bottom, 1:025 to 1°027.
The positions of the hauls are shown on the sketch
chart below.
The results of these hauls demonstrate strikingly the

99 bi]

restricted distribution of fishes on an area of very limited

re . ; aN
{ wat SK
Sandhead x
\ SS
\ —S
< a x
Ny
(Port William

\ \
mS \ LUCE BAY

( baronet

ha, = aa

NS Mull of Galloway
Chart of Luce}Bay.

extent, and over which the physical conditions, which
might be supposed to influence the abundance and nature
of the bottom fauna, are very similar. The chart shows
that fishing was restricted to the west and north-west
margins of the bay. The bottom was uniformly sandy,
and the depth varied from 9 to 5 fathoms. Hauls 1 to
3 are comparable in all respects; the depth varied from

23

7 to 9 fathoms, the duration and length of the drags were
identical, and all three were made dragging with the
stream. Nevertheless, the number of plaice taken varied
from 51 to 438, the dabs from 10 to 68, and the ray from
26 to 40. The fifth haul was made dragging in towards
shallow water. The fourth and sixth hauls were shorter
than the others, being of one and three-quarters and two
miles length respectively. They differed, however, to an
extent which is not accounted for by their difference in
length, as the fourth yielded only 64 plaice, while 197
were obtained in the sixth. The sixth haul, too, was
made in the dark when, according to general experience,
plaice are more difficult to catch in the trawl net.

There is a general similarity between the results of
the first three hauls obtained on this occasion and those
obtained on October 21st, 1902 (see last year’s Report, p.
85). The positions, states of the tide and lengths of drag
are very approximately the same in each series. Both
the first hauls, dragging north from Drummore yielded
poor catches (14 and 68 plaice, respectively), the second
hauls gave much better results (438 and 157 plaice), while
the third were again poor (17 and 51).

The results obtained on the present occasion confirm
then those obtained in 1902, that is, that a trifling
difference in position of the ground dragged over may
correspond with very remarkable differences in the volume
of the catches. This, indeed, is well known to fishermen,
but it is a factor which has not been sufficiently recog-
nised in statistical trawling operations, where it has been
generally assumed that the distribution of fish on a large
area is fairly constant.

Sizes of the plaice obtained.
The main object of the trawling operations was to

obtain mature plaice, and in each haul all the fish of over

a4

14 inches in extreme length were at once separated out
and brought back alive. The number of these obtained
in each haul is given in the Table, and is about 11°5 per
cent. of the total number caught. The sizes of the fish
caught were, so far as could be judged by a mere inspec-
tion, very similar in each haul, and it was considered
sufficiently exact to measure the individual fish in one
catch only, and assume that the average so obtained
applied to all the others. This was done for the first haul
and an average length of about 111 inches was obtained.
As the net used had a uniform mesh of 7 inches (12 inches
along each side), and the drags were short ones, no plaice
of less than 8 inches in length were obtained.

The size of the plaice obtained in the preserved waters
of Luce Bay is in striking contrast to that of the plaice
which inhabit the corresponding areas in the Lancashire
and Western Fisheries District. We have no reason to
suppose that Luce Bay is a better feeding ground, or
differs in any essential respect from many plaice grounds
in the former area. The nature of the bottom, the depth
and physical condition of the water, the bottom and
pelagic faunas resemble closely the corresponding condi-
tions on many extensive areas on the North-west Coast of
Iingland. Still, there is no inshore area known to us
where 10 per cent. of the plaice caught are over 14 inches,
and a fair proportion are 18 or 20 inches in length. The
only difference is that Luce Bay has been closed against
trawling of every kind for about 16 years, while every
plaice ground off the Lancashire and Cheshire coast is the
scene of an active trawl fishery, with only very limited
restrictions in force. “There appears to be no doubt that
the comparatively large size of the plaice on this portion
of the Scottish coast is directly due to the prohibition of

trawling, and conversely that the much smaller average

25

size of the plaice further south results from the practically
unrestricted exercise of this method of fishing.

The size of the plaice captured also suggests some
doubts as to the accuracy of the generally accepted theory
of the life history and migrations of that fish. It is
usually stated that the mature plaice inhabits and spawns
in comparatively deep water (10 to 20 fathoms), that, the
fertilised eggs and larve drift inwards towards shallow
water, and that as the fish grows it migrates outwards
towards the 20 fathom line. The observations made in
Luce Bay, where plaice of 20 inches in length were found
close in towards the shore in water of six fathoms and less
in depth, show, however, that the above distribution is not
universal, and that there is no necessary relationship
between the depth of water and the size of the fish on the
bottom.* Large plaice are found in Luce Bay because
trawling is prohibited there and they are not interfered
with. It is, however, reasonable to suppose that the
absence of mature plaice on the inshore grounds of such
an area as the Lancashire and Cheshire District is due to
the great extent to which these grounds have been fished
over. The amount of fshing on the inshore grounds is
much greater than in deeper water, and the fish on the
latter area are much less disturbed. ‘The eftect of this
extensive fishing inshore has been to reduce greatly the
average size of the plaice present, and it is to be noted
that investigations into the hfe history of this fish have
been made in comparatively recent times—since the ex-
ploitation of the inshore grounds by the trawlers on the
modern scale has taken place. This effect of trawling in
reducing the average size of the fishes present on a
ground is well known, and was first demonstrated by

* Our observations, however, have been confined to the months of
October and November. Possibly the large plaice may migrate from
the Bay in winter and during the spawning season.

26

MeIntosh in regard to certain fisheries on the east coast of
England and Scotland.”
Invertebrates taken in the trawl net.

No special attention was paid to the bottom inverte-
brate fauna, but the following forms were identified among
the contents of the net :—

Mytilus modiola, Alcyonidium, various compound and
simple aseidians, lustra, Pecten, Asterias, Solaster, Astro-
pecten, Echinus, Cucumaria frondosa, Ophioglypha, Fusus,
Dentalium, Hyas, Stenorhyncus, Pagurus, Portunus, Porcel-
lana, Aphrodite, Sabella and other Polychaetes, and Actino-
loba. Pontobdella (from a ray) was also taken. Zostera was
present in the North Western portion of the bay. A female
lobster of 83 inches in length was caught in the first haul,
and two females, one recently berried, 10 inches in length,
were obtained in the third haul.

Food of the fishes taken.

The majority of the fishes were examined for food
contents of the stomach. Ray were feeding on fishes (too
much decomposed for identification); plaice and dabs on
Scrobicularia and Nucula (especially the latter), and the
soles on annelids with a few Scrobicularia.

Plankton.

Surface tow-nettings were taken during every haul
except the last. The pelagic organisms present were,
however, remarkably scarce (not more than 10 ce. in all
the five hauls), and the only animals present were Plewro-
brachia (relatively abundant), Caligus rapaa (male), a
young Cyclopterus lumpus, some larve decapods, and the
Copepods Paracalanus parvus, and Oithona similis. This
is in marked contrast with the fishing operations in
October, 1902, when an enormous catch of Copepods (over

*See Report of the Trawling Commission, Appdx. A., p. 378,
and Report, p. xvi.; 1885.

27

250 cc.) was obtained in the second drag. These consisted
chiefly of Acartea discaudata, with a few Acartia clause
yy 4 :
and Temora longicornis.
Average catches.
These were greater in 1903 than im 1902, as the
following table shows : —

Everage:caven, oF fishes, L902) 2 ee 179:
» » We LOU aye we eles
re s plaree 1902 8) 2 oe
” %» pe LOGOS) Meu weet SNOT

(aye iwo hauls am Wieton Bay ‘on
November 9th, 1908.
I. Beam Trawe of 30 ft. beam and with 4-inch meshed
pockets and tails.
Dragging N.N.E. for 1} hours, and for a distance of
25 miles towards Innerwell Point. 8-45 a.m. to 10-0 a.m.,

1} hours’ ebb.

iBlaice elie tx as 4216, Ain, to Lim,
(avge. size about 9in.).

Sole ee ce “Qumy
WenGee see eee OU! veo Aneto Oia
avete te, eee ee eA. OLN ton COIN.
Sikaieweee aan cy i, ime
Whiting euemerer ge gO 9S Gimeeto hun:
Codling eerie tl Oe SS Gimaviior Lorn
Yellow gurnard........ 1 .. 4}in.
Herring ee acs. 1! hoe edt tOeeInE
Poor-cod (Gadus

moms ae ss) 2 et aime fo Sin:

Motal <i. 4 257 Toe

28

II. Suanx Net, 12ft. wide, }-inch mesh; one haul off
Innerwell Point for + hour and for } mile; 10-15 to
TO=3U "a. am:

Shrimps. jvc ee meee Mypummit
Dabses (eC uyyee ea eee: ... Lh. long.
Placecard oe iale ime be
Poor-cod CNG esi eat Ole oe) fo. 9 er -f
Grobies er oan eee ieee et es
Pipe-fish ey Ferre Ec hoses

During these hauls the following observations were
made:—

Wind, fresh W.S.W.
Weather, fine; sea smooth ;
Barometer, 30°5;

Air temperature, 8°°6 C.;

Sea temperature at surface, 9°°8 C.;

i ~ “bottom 10°: 0.Cs
Specifie gravity at surface, 10242;
a - bottom, 1:024;

Depth, 4 fathoms; transparency, 5 feet.

The common invertebrates taken in the nets during
these hauls were:—Oysters (about 12), Turritella (very
numerous), Pagurus, Buecinum, Portunus, Polynoe,
O phiura, Serpula (on the oysters), small actinians (on the
oysters), Sertularia, Asterias, Solaster, and one male lobster
113 inches long. Only one tow-netting was taken, but
very few organisms were obtained, the commonest being
Pleurobrachia.

The object of these hauls was to ascertain whether
small plaice (3 to 6 inches long) were present to any great
extent in Wigton Bay. It was possible to find time for
only two short hauls on the west side of the Bay, and these
yielded very few small fish of the size in question.

&

29

(3) -Bive hawlssan hice “Bay 07
November Oth, L908.

One haul was made with a trawl net with 4-inch
meshes, the object being to ascertain as before whether
small plaice were present in the Bay in any abundance.
The following fishes were taken : —

Place: a5. 7... 14 —18 inches long.
% ame oe wen Or lyr eee ‘:
Dabs et MeO Oy died an * -
Ray sees, OOS ee 4216.55; is
Mellow curnards, G6 \.... 6 —.7 . ,, 26
Whiting Ae 6... 63— 8 ,, -
Herrings a Sal eee 7— iT ,, a8
Soles ie ere Or weet fol Ld 3 “3

otal) yes.) 542)
Very few small plaice (6—S8 inches long) were
captured.
Four hauls were then made with a net of 7-inch

mesh on the north and west sides of the Bay, the results
of which are as follows : —

If JOE TL IV.
24 miles. 2 miles.|2 miles.|1? miles

Pia CGs gsJe2: Rola 2 Opin NOM. eee ee oy a ee 12
Plaveer. 222: 120, less than 14 in. long.) 545 927136
absense. (OVE aha eee Soe ge | 440
Ra: cstes 00 NO ae eee mereR ee Che ee 40 4 30
Javed 252 LOUIS) a ele ie eee eRe Ear | |
otal. 3... 7) 6 RPA SAR ERE A ticks Brea 172 £82) ¢} 28

30

Three of the ray captured in haul III. are the largest
we have taken in the Bay; they measured 54, 56, and 48
inches respectively. Large mature plaice were, however,
not so abundant as they were on October 26th, and as the
trawling was interrupted by bad weather, only about 80
such fish were obtained.

Physical observations.

Wind, strong from W.N.W. and N.W.;

Weather, unsettled, some rain;

Sea, choppy;

Barometer, 30°5 in.

Air temperature, 994 C. to 11°77 C.;

Sea temperature at surface, 9°°4 C. to 1095 C.;

Specific gravity at surface, 1:0258 to 1026;

Transparency of sea, about 5 feet.
Invertebrates taken.

These were similar to those taken on October 26th.
Townettings only were taken on two hauls, but the organ-
isms captured were very few, principally Plewrobrachia.

(4.) Four hauls off the Isle od Marne

Several hauls with a 7-inch meshed trawl net were
made off the North end of the Isle of Man between Jurby
Point and Point of Ayre, the object being to obtain some
large mature plaice for the Port Erin Hatchery.

The hauls were made in water of from 9 to 5 fathoms
in depth and about half-mile from the shore, the direc-
tion of the drags being towards Point of Ayre. The
ground was very rough, and the net caught three times,
and had to be hauled. Five plaice were caught in these
first three hauls. Two were large females, one being
192 inches and the other 253 inches long. The latter
weighed 4 lbs. 11 ozs, The others were smaller fish, and

31

one shewed a remarkable malformation, which was
evidently the result of an accident. The fourth haul was
about two miles long; the net was, however, torn, and
only 2 plaice (15 inches and 8 inches long) and 1 lemon
sole (S inches long) were taken.
Physical observations.

Wind, W. light breeze;

Weather, fine;

Sea, smooth;

Barometer, 30°85 ;

Air temperature, 10°°5 C.;

Sea temperature at surface, 10°85 C. ;

3 a bottom, 11°25 C.;

Specific gravity at.surface, 1:0258 ;

Transparency, 20 feet in hauls 1-3, and 12 feet in

haul 4.

No tow-nettings were taken during these hauls, and,
in consequence of the catching and tearing of the net,
very few invertebrates were taken. A dog-fish purse,
with a well-advanced embryo, was picked up during the
last haul.

The size of the plaice taken in these hauls is very
noticeable, when it is remembered that they were made
in territorial waters and in comparatively shallow
water—-the 251n. plaice was caught in 7 fathoms. It is
apparent that large plaice are relatively abundant at the
North end of the Isle of Man, and, as clean trawling
ground is to be found there, there should be no diffieulty in
supplying the Port Erin Hatchery from its own area in
a very convenient manner.

The malformed plaice (Plate I.) caught in the third
haul presents a very interesting peculiarity, in that a

noteh of about 2 mehes long has been taken out of the

32

anal fin and the adjacent ventral portion of the body. It
is, of course, impossible to say how this injury occurred,
but the shape of the notch suggests a bite by some
carnivorous fish. The injury had probably occurred
when the fish was much younger. Ilealing has been per-
fect, for there is no obvious cicatrix, and the pigmenta-
tion of the ocular side extends round the ventral margin
on to the blind side. That this perfect healing has
occurred is remarkable, for this part of the body is fairly
well supplied with blood-vessels, and bleeding must have
been copious. Dr. Fulton describes a somewhat similar
case.*

The fish is a female, of 15} inches in extreme length.
It ought to be mature, but the ovaries are small and thin,
that of the blind side being only 12 inches long. Pro-
bably the injury had inhibited the maturation of these
organs. It is interesting that the white haloes round the
ocelli are not clearly evident in this fish, and this lends
support to Petersen’s contentiont that these white-edged
ocelli in the plaice are indicative of the condition of sexual

maturity.

* Rept. Fish. Bd., Scotland, No. 21.

+ Publications de circonstance, No. 1. Cons. Perm. Internat. Explor.
de la Mer. Copenhague, 1903.

Puate I,

AOIVIgd CGHNYOd'TV IL

+
itt
t
TTS+
+
7

vale

SOME PARASITES FOUND ON FISHES IN THE
IRISH SEA.

By AnpREw Scorr.

No subject offers a more enticing attraction to the
Zoological student than the one that deals with those
members of the animal kingdom which through some
acquired habit have become partly or altogether dependent
on other animals for their food. This branch of research
has been very prominently brought to the front within
the last two years by the further investigations relating
to the formation of pearls in the common mussel of our
sea shores, by Dr. IH. L. Jamieson, and of the extremely
valuable oriental pearl from the Ceylon pearl oyster, by
Professor Herdman and Mr. James Hornell.

It has long been known that the completion of the
life cycle in some parasites, such as the “ liver fluke ” in
sheep, is wholly dependent on part of the development
being carried on in another animal; and it is becoming
more and more evident that the life-cycle of these parasites
can only be completed when the creature has successfully
passed from one stage to another, and reached its final
host where reproduction takes place.

The difficulties that await the student who contem-
plates investigating the life histories of parasites are great,
but by no means insurmountable. Extreme care and
much patience are necessary, but the work is well worth
the labour expended and there is still much to do.

In the following notes a list of the parasites that have
been recorded from the fishes caught in the Irish Sea is
given, with remarks on some of the more important points
connected with each. It is probably far from exhaustive,
but will form a foundation for future additions. Up to

c

bd

the present we have four species of Protozoa, ten species
of Vermes (Trematodes) and forty-six species of Crustacea
(Copepoda).

The Protozoan parasites are found on and in various
parts of the fish, such as the brain, the intestines, and the
skin. In a few instances the presence of these parasites
is easily recognised, but in the majority, careful dissection
and examination of the tissues is required before they can
be detected. The most noteworthy appearance of the
presence of Protozoan parasites that has come under our
notice is the one on the skin of the ordinary “ white fluke,”
Pleuronectes flesus. It usually takes the form of small
white globular bodies attached to the skin of the body and
fins. Ina specimen recently secured, the upper and lower
lips of the mouth were thickly covered with the cysts,
which doubtless interfered with the fish securing food.
The gills were also much infested. Occasionally larger
masses, sometimes the size of a marble, may be present.
This disease in the white fluke has attracted considerable
attention for many years, and is, no doubt, the origin of
the theory long held by fishermen that white flukes carried
their eggs attached te their body. We have a species of
Glugea recorded from the plaice, a Sporozoan from the
flounder, which is probably a new genus, also Glugea
fophii and another new form, Spherospora platessa, which
infests the auditory capsule of the plaice. The two new
species will be discussed in another section of this Report,
in special papers by Mr. Woodcock. ,

The Trematode parasites may be found attached to
the gills, or skin, and, in the case of one species, even in
the Cloaca. Occasionally more than one species may be
found attached to the gills of a single fish. These para-
sites are of various sizes, and usually colourless, except as

regards their excretory and reproductive systems. The

35

posterior sucker may be entire and circular in outline, or
divided into pairs of separate suckers. One genus has a
small secondary or “ adhesive ” dise attached to the large
one. These parasites live for some time after the death
of the fish and adhere very closely to the gills or skin, in
fact it is sometimes quite impossible to detach them with-
out injury. <A very convenient way to remove them is
to leave the gills, or portions of the skin to which they are
attached, in fresh water for some hours; this treatment
eventually kills the parasite and at the same time causes
it to relax its hold.

I._Species with posterior sucker entire :-

Callicotyle kroyeri, Diesing.

From the cloaca of Rata clavata. It is also found
on other rays, but always in the cloaca. The posterior

sucker has seven strong bands radiating from an inner
circle, the spaces between the rays are conical in outline
with the apices towards the centre.

Phyllonella solew, van Beneden and Hesse.

‘

Attached to the seales on the ‘‘ white side” of the
common sole. This trematode is of moderate size but
easily overlooked owing to the colour resembling that of

the fish.
? Placunella pint, van Beneden and Hesse.

This trematode which we identify as P. pzni has only
been found on the gills of the yellow gurnard, T'rigla
hirundo. Wt has eight distinct and two indistinct rays in
the posterior sucker.

Deplectanum cequans, Diesing.

Found on the gills of the “bass.” A very small

species and sometimes abundant.

II.—Species with no distinct posterior sucker, having

36

instead, a number of cupules which may be either stalked .

or sessile.

Phyllocotyle gurnardi, van Beneden and Hesse.

On the gills of the common gurnard, Trigla gur-
nardus, and yellow gurnard. A small species and easily
overlooked. Three pairs of sessile cupules.

Microcotyle labracis, van Beneden and Hesse.

On the gills of the “bass,” Labrar lupus. A
moderately large species with a number of sessile cupules,
but not common on any of the fishes examined by us.
Octobothrium scombri (Kuhn).

On the gills of the common mackerel. A very slender
species and easily overlooked. Four pairs of sessile
cupules.

Octobothrium merlangt (Kuhn).

On the gills of the whiting. A large species of a dark
colour. Four pairs of cupules on short stalks.
Dactylocotyle pollachi, van Beneden and Hesse.

On the gills of the pollack. A large species of a
dark colour. Four pairs of cupules on moderately long

stalks.

I11.—Species with cupules, and a bifurcated median
appendage :—

Onchocotyle appendiculata (Kuhn).

On the gills of various Elasmobranch fishes (rays and
dogfishes), sometimes very common. ‘Three pairs of large
cupules and a slender appendage, bifurcate at the apex.

In addition to these Trematoda one representative of
the Hirudinea is known from the Ivish Sea fishes. The
large skate leech, Pontobdella muricata, Leach, with its
corrugated, warty skin, is often found on rays captured

by the fisheries steamer,

a4
ol

There are many different kinds of worm parasites
infesting local fishes, and as this group has only recently

been seriously investigated in our district, we expect that

the present list will soon be greatly extended. The
Cestodes and Nematodes have still to be worked out. © In

addition to the fishes, many marine invertebrata are also
more or less infested with parasites, some containing im-
mature stages of the fish parasites.

The Copepod parasites are almost entirely confined to
places in divect communication with the exterior. They
may be found on the skin, the fins, in the mouth and
branchial chamber, in the lateral line canal, attached
to the gills and operculum, in the nostrils, in the
eye and sometimes even burrowing into the abdominal
cavity. In many cases their life history and anato-
mical structure ave only partly known. Some are
almost free, but the majority are true parasites,
depending entirely upon their host for food, and having
no means of locomotion. The males of the attached forms
are extremely small and easily overlooked. © All hatch
from the egg as Naupli and undergo very considerable
metamorphoses before arriving at maturity. In some
genera the development is wholly progressive. In others,
such as Lernwa, when a particular stage is reached 1
becomes retrogressive. At one end of the group the para-
sites are practically free swimmers, and at the other they
are mere inert sacs whose relationship with such forms as
Caligus appears very remote.

Bomolochus solew, Claus.

In the nostrils of cod, greater fork-beard, plaice, &c.,
also on the skin of the common sole. A number of
specimens of this copepod can usually be secured by
forcing out the mucus from the inner part of the nostrils

of medium sized cod. On placing the mucus in a watch

38

glass with water, the copepods, if present, can easily be

seen.

Caliqus curtus, Muller.
A very common species, and may be found on various

kinds of fishes, cod, ling, hake, plaice, &c.

Caligus rapaxr, M. Kdwards.

Also a very common species and as widely distributed
amongst fishes as the former. The males and immature
females are often taken in tow-net collections.

Caliqus diaphanus, Nordmann.
In the gill chamber of the common gurnard and

yellow gurnard, occasionally moderately frequent.

Caligus gurnardi, Kroyer.

The only record of this species from the district is
the one by my late colleague and fellow-worker, I. C.
Thompson, whose reports have been of much service in the
preparation of the present lst. The specimen was
obtained from dredged material and had evidently been
detached from its host.

Caligus brevicaudatus, A. Scott.

This is a moderately large species, 5°3 mm., and has
only so far been found in the mouth of the common gur-
nards caught at Piel.

Caligus labracis, 'T. Scott.

Frequently found attached to the gills of the wrasse.
Caligus scombert, Bassett Smith.

Occasionally found in the gill chamber of the
mackerel.

Caligus minimus, Otto.

This well-marked species is sometimes very common

in the mouth of the bass, Labrae lupus.

39

Pseudocaligus brevipedes (Bassett Smith).

Found attached to the inner side of the operculum of
the three bearded rockling, Onus tricirratus. This genus
is distinguished from Caligus, its nearest ally, by the
structure of the fourth pair of feet, which have no
exopodite.

Lepeophtheirus pectoralis (Muller).

Our experience of this species is that it occurs more
frequently on the flounder than on any other member of
the Pleuronectidie. The pectoral and pelvic fins often
have their under surfaces covered with this parasite; on
one occasion thirty-two adult females were counted
adhering to a pectoral fin. Males and immature females
appear to be more common on the general surface of the
fish.

Lepeophtheirus nordimanne (M. Edwards).

This is one of the larger species of Lepeophtheirus, and
sometimes measures half an inch in length. It is found
on the short sun-fish Orthagoriscus mola.

Lepeophtheirus hippoglossi (Kroyer).

Found generally distributed on the surface of halibut,
occasionally in considerable numbers. On the * white ”
side of one specimen we have counted 100 individuals, but
that was on a fish in the Aberdeen fish market.
Lepeophtheirus stromi (Baird).

Frequently found on the salmon captured in the
estuaries. Its black metallic lustre makes it a con-

spicuous object on the bright scales of the fish.

Lepeophtheirus obscurus, Baird.

From the gills and inner surface of the operculum,
and under the pectoral fins of the brill. It is probable
that this species may only be a form of L. thompsona,
Baird, which is found on the gills of the turbot.

10

Lepeophtheivus pollachii, Bassett Smith.
Attached to the inside of the mouth of the pollack.

Trebius caudatus, Kroyer.
On the skin and inside the mouth of various species of
Raia. The pink colour of the living animal renders its

presence easily visible to the naked eye.

Lehthrogaleus coleoptratus (Guerin).

On the skin of the picked dog-fish, Squalus acanthias,
but not of very frequent occurrence. The ovisacs are very
slender and of great length.

Pandarus bicolor, Leach.

Also occasionally found on the skin of the picked
dog-fish. It has been recorded by other observers from
Galeus canis (tope), Scyllium catulus (greater spotted
dog-fish), and Carcharias glaucus (the blue shark).
Dichelestium sturionis, Kroyer.

A large white cylindrical species only found in the
gill chamber of the sturgeon. The fish is not often
caught in the district, and this makes the parasite rather
rare.

Clavella labracis, van Beneden.

This is a very small parasite, egg-bearing females
beig scarcely one millimetre in length. It usually
occurs in abundance, however, and is found on the gills

of the wrasse, Labrus miatus and L. maculatus.

Cycnus pallidus (van Beneden).

A small slender species, sometimes very common, on
the gills of conger.
Kudactylina acuta, van Beneden.

Attached to the gills of the angel-fish, Rhina
sqguatina. A number of specimens are found on each
moderately-sized fish.

Al

Eudactylina acanthi, A. Seott.

Of frequent occurrence on the gills of the picked
dog-fish. | Van Beneden records Mudactylina acuta from
the angel-fish and the picked dog-fish, but we have never
seen it on the latter. he present species is very distinet
from 1. acuta. Another species, 4. semelis, VT. Scott, from
the gills of Rava radiata, and a fourth from the gills of
Trygon are known, but, so far, have not been met with

in the Ivish Sea.

Lernecnicus spratte (Sowerby).

Anchored in the eyes of the sprat, Clupea sprattus ;
not very common, but one or two specimens are
frequently found in each catch of sprats. Usually only
one specimen is found on a fish; occasionally two, one
on each eye. We once met with a sprat that had two
parasites in one eye and one in the other. The parasite
measures 18 millimetres in length without the long egg
sacs, but when these are added the length may reach to

one and three-fourth inches.

Lernecnicus musteli, van Beneden.

On the gill rakers of the smooth-hound, Squalus
mustelus. It is a large species, but does not appear to be

a COMMON one.

Lernea branchialis, Linn.

This well-known and easily recognised parasite 1s
moderately common on the gills of various members of
the Gadide. The cyclops stage is often abundant on the
extremities of the gills of plaice and flounder, and the
next stage is occasionally taken in tow-net collections. An
account of this curious form, and the changes that take
place before it reaches maturity, have already been given
in the Fisheries’ Laboratory Report for 1900.

42

Lernea minuta, T. Scott.

On the gills of the common goby, Gobius minutus.
When present, this parasite is easily noticed, as it causes
a considerable expansion of the operculum, and projects

from under it.

Haemobaphes cyclopterinus (Fabr.).

This appears to be a rare species and is not often met
with; only one specimen has been observed by us. — It
was found on the gill rakers of Cottus scorpius.

Oralien asellinus (Linn.)

Occurs frequently on the gills of the common gurnard.

Other workers have also recorded it from the gills of plaice

and halibut.

Chondracanthus cornutus (Muller).

Occasionally found on the gills of plaice. Size, 6
min. to 7 mm.
Chondracanthus clavatus, Bassett Smith.

On the gills of the lemon sole, Pleuronectes micro-
cephalus. Size, 6°59 man.
Chondracanthus solee, Kroyer.

A well-marked species occasionally found on the gills
of the common sole. Size, 7°59 mm. to 85 mm.

Chondracanthus lophi (Johnstone).
This appears to be one of the more common members
of the Chrondracanthide, and is frequently found in the

gill chamber of the Angler fish.

Chondracanthus merluecii, Holten.

Very common sometimes in the hake, and may be
found on the roof and sides of the mouth, and also on the
under side of the tongue, and attached to the inner surface
of the operculum. Size 12°5 mm.

In all the Chondracanthus the males are very small,

43

being little over half a millimetre in length, and usually
found on the abdomen of the female.

Thysanote impudica (Nordmann).
A moderately rare species and only appears to be
found on the gill rakers of T'r2gla hirundo.

Lernanthropus kroyeri, van Beneden.

At first examination this species might be mistaken
for Chondracanthus merluccii, but can easily be distin-
guished from that parasite by the structure of the appen-
dages. Only found on the gills of the bass, Labraw lupus.
Its deep brown colour makes it a conspicuous object
amongst the bright red coloured gill filaments.

Charopinus dalmanni (Retz.)

This species appears to be confined to the spiracles of
the grey skate, 2. batis, where it is anchored by the large
second maxillipedes. It is of large size and sometimes
measures nearly 24+ inches from the apices of the second
maxillipedes to the end of the ovisacs; usually only one
specimen is present in a spiracle, but occasionally two

and three specimens are found in one spiracle.

Charopinus ramosus, Kroyer.

A much smaller species than the last, being only
about one-fourth the size. It has quite a different habitat
from that of C. dalmannz, and is found attached to the
gills and gill rakers of Raia clavata and R. maculata.
third species, U. dubius, T. Scott, is found on the gill
rakers of 2. ctreularis and Lt. fullonica. It has not been
recorded from the Ivish Sea but we have taken it from FR.
fullonica captured off Dubh Artach and landed at Fleet-
wood by one of the trawlers.

Lerneopoda galei, Kroyer.
On the claspers and fins of the lesser spotted dog-

14

fish, Sey/lium canicula, aud occasionally on the fins of the
tope.
Lernwopoda bidiscalis, W. V. de V. Kane.

A remarkably distinct species, and always found on
the ends of the claspers of the male tope, Galeus canis.
These claspers, where the parasites are adhering, are
almost Invariably found to be torn and bleeding. A
third species, Lernawopoda clutha, T. Scott, 1s found on
the gills of Rata fullonica; a fourth LL. salmonea
(Gisler), on the gills of the salmon; and a fifth JZ.
elongata (Grant), attached to the eye of the Porbeagle
shark and the Greenland shark, but none of these have,

so far, been recorded from the Ivish Sea.

Brachiella ovalis (Kroyer).
Attached to the gill rakers of the common gurnard,

more common on half-grown fish than adults.

Brachiella insidiosa, Heller.

A moderately-large species, and found only on the
eill of the hake. A considerable number are sometimes
found on one fish. Another species, Brachiella merlucer,
Bassett Smith, attaches itself to the gill rakers of the
hake, but so far has not been seen by us.

Anchorella uncinata (Muller).

Very frequent in the mouth, &c., of species of Gadus,
such as whiting.

Anchorella appendiculata, Kroyer.

From the hake, but the position in which they were
found is not stated.

Nicothoé astaci, Aud. and M. Edw.

This peculiar copepod is sometimes found in con-
siderable numbers on the gills of the common lobster.

The wing-like projections of the fourth thoracic segment

45

give it an unusual appearance. Several times we have
attempted to ascertain the fate of this copepod when the
lobster casts its shell, but so far have been unsuccessful.
None of the lobsters that moulted in our tanks happened
to have parasites on the gills.

The Branchiurid, Argulus foliaceus (Linn), has
been found on trout sent to us for examination from the

Ribble.

46

ON MYXOSPORIDIA IN FLAT-FISH.
By H. M. Wooncock, B.Sc. (Lond.).

Myxosporidia are Sporozoan parasites frequently
found in fishes generally, and often the cause of severe

ee

disease, e.g., the “ Pockenkrankheit ’ of carp, and the
‘ Barbenseuche”’ of the barbel, which have at times
ravaged these fish in continental rivers.

The group is characterized (a) by the fact that repro-
duction by spores goes on throughout the growing or
“trophic ” period, and (6) by the complicated process of
spore-formation and the nature of the spores. ‘These con-
tain, besides the germ or ‘ sporozoite,”’ one or more
‘ polar-capsules ” (very similar to hydrozoan nemato-
cysts), from which filaments—serving as organs of attach-
can be extruded.

ment to the epithelium of the new host

Until recently the Pleuronectidie were thought to be
immune to the attacks of these parasites, and, in fact,
to-day, there is, so far as IT am aware, only one paper which
specifically describes their occurrence, and at most two or
three which record cases of disease in flat-fish either cer-
tainly or probably to be ascribed to infection by
Myxosporidia.

In 1899 tagenmiiller (2) gave a short account (un-
fortunately without any figures) of a Myxosporidian
infecting Flesus passer, Moreau (= Pleuronectes flesus, the
flounder), a common member of the fauna of brackish,
littoral pools in the neighbourhood of Endotime. At least
fifty per cent. of the specimens captured harboured the
parasites, which turned out, on investigation, to be a new
species of Nosema (Glugea), to which Hagenmiiller gave
the name V. stephani. This genus belongs to the sub-order

Cryptoeystes (Microsporidia), comprising forms which

47

are always (at first) cell-parasites, with very minute
spores possessing only one polar-capsule, invisible in
the fresh condition. In all cases the parasites were
found in the gut-wall, ranging, indeed, from the
esophagus to the rectum. The cysts were lodged
according to the author, either in the muscular or
connective tissue (sub-mucosa), or else projecting
into the celomic cavity, and only covered by the
peritoneal epithelium. They were also found under the
peritoneum investing the liver, and in the mesenterial
folds in which the blood-vessels run, but were completely
absent from the other organs, spleen, kidney, &e. With the
exception of certain species of J/yvobolus, this invasion of
gut is quite unique among Myxosporidia of fishes, the
Myxobolide causing the above-mentioned devastating epi-
demics, usually occurring in the tissue of the liver, spleen,
kidneys, bladder, &e. Hagenmiiller goes on to describe
briefly the minute anatomy of the parasites and their
relation to the host’s tissues as seen under a high power,
and reference to one or two points in his account will be
found below.

The next record of intestinal cysts in a flat-fish is
that by Johnstone (3), who describes and figures Sporo-
zoan cysts from two specimens of the plaice (P/ewronectes
platessa). On examination of sections like that from
which the author’s fig. 2 was drawn, prepared from
material which he was kind enough to forward me, I had
no hesitation in deciding that these were also cases of a
Glugea”* infection. Hagenmiiller did not give the size
and shape of the spores of G. stephani—the principal,
though rather arbitrary, criterion of specificity among the

* There is some doubt as to which of the two generic names,

Glugea or Nosema, should be employed, so I have retained the former,
which is well known and established,

48

Glugee——but contented himself with remarking that the
cysts scarcely ever exceeded 1 mm. in diameter. Taking
into consideration, however, the agreement in size and the
very similar habitat and appearance of the parasites in the
two cases, there is every probability that those in the
plaice also belonged to this species.

About the same time Linton (4) published his syste-
matic researches on fish parasites. Under Pseudopleuro-
nectes americanus, the winter flounder, is a note (p. 485)
concerning two small specimens infected with cysts. The
gut-walls of one throughout almost the entire length, and
of the other for a short distance, were entirely covered
with ‘“ sporocysts ”’ (7.e. seen from the outer or eclomic
side). The cysts were irregular in shape where crowded
together, and where not—which was in but few places—
they were elliptical or spherical. Their size varied, but
none much exceeded 1 mm. in diameter. Fig. 1 is re-
produced from Linton’s fig. 4, Pl. 1, and shews the
general appearance of a portion of the intestine wall.
Compared with Johnstone’s fig. 1, Pl. D., the similarity of
the two is readily apparent, allowance being made for the
difference in magnification. Linton’s figure, however,
does not shew the areas or regions which are observable
in Johnstone’s specimen. ‘lhe spores were oblong-ovate,
about °0038 mm, (8) im length by ‘0015 mm. (1gu) in
width, and these agree very well with the dimensions I
have found, both for those from Johnstone’s plaice and
from my own. In short, I am quite confident that this
specimen of Pseudopleuronectes was also infected with
Glugea stephani.

From another Pleuronectid, Rhombus (Stromateus)
triacanthus, the butter-fish, Linton further describes (p.
455) a.“ sporocyst”’ occurring in the liver, white and

globular, and about 15 mm, in diameter. When com-

49

pressed, it liberated immense numbers of spores, which
were in great part aggregated into globular or oblong
clusters, the larger being as much as ‘02 mm. (20”) in
diameter. The spores themselves were short and thick,
with bluntly-rounded ends, their length beimg about
0025 mm. (24), and a little less in breadth. Here also
there is little doubt that we have to deal with a Crypto-
eyst (Microsporidian), but in the absence of figures it is
rather uncertain in what genus this parasite should be
placed. From the mention of distinct clusters or clumps
of spores, and the shape of these latter, I am somewhat
inclined to regard this case as one of infection by
Pleistophora, rather than by Glugea—the reason will be
referred to below.

My own acquaintance with these parasites began in
the summer of 1901, when Mr. Todd, then Assistant to the
Director of the Plymouth Marine Biological Laboratory,
brought to my notice the intestine of a plaice which,
although, unlike Johnstone’s specimen, it was quite
healthy in appearance, presented certain abnormal
features.

The gut had been fixed in Corrosive and Acetic, and
preserved in spirit, and shewed at intervals little oval
patches, usually projecting shghtiy, on the outer coelomic
side. Besides these, there were little out-growths of the
tissue of the wall, often in the form of pear-shaped appen-
dages, attached by the narrow end to the gut. These
patches and projections indicated the site of the infection,
and were readily to be distinguished by their rather
different colour, having a faint reddish tinge added to
the pale nondescript shade of the preserved gut. I
gathered from Mr. Todd that, when fresh, the spots were
of the usual Sporozoan opaque-white. A point worth
noting in the position of the parasites is that they were

D

50

all on that side of the gut to which the mesentery was
attached, and in which the blood-vessels ran; indeed,
often they were quite close to these latter, although never
actually in their walls. The infection was, in this instance,
a comparatively limited one, and the functional activity
of the intestine would be in no way interfered with—a
very different state of affairs from that described above.
There was no enlargement of the folds or pleats (con-
sequently no occlusion of the lumen), and on opening, the
internal surface (the mucosa) appeared quite normal.

In size, the patches averaged about 1 mm., while the
out-growths were sometimes 1}—2 mm. in length. Figs.
2 and 3 shew some examples drawn natural size. In fig.
2 there are three appendages (par) visible on one of the
pyloric ceca, and close to the pyloric branch of the mesen-
teric artery (art). In fig. 3 some more are seen, also
mostly near the attachment of the mesenteric blood-
vessels.

Johnstone’s specimen and my own aptly illustrated,
respectively, the two chief modi vivendi of the Glugee, viz.,
(a) cyst-formation, and (6) in the condition of “ diffuse
infiltration,” ‘Thelohan’s (7) term for signifying an
infected area in which the parasites and the tissue of
the host completely intermingle. Fig. 4 represents a
section of a portion of the wall of the intestine and an
appendage under a very slight magnification, where the
darker shaded part (par) shews the diffuse infiltration,
and the hghter region is normal uninfected tissue. The
out-growth, it will be seen, is practically entirely a para-
sitic development, with the exception of a delicate
covering of connective tissue and peritoneal epithelium,
which is, in places, broken down (ep.). But, here also, at
(cy.) an attempt at cyst-formation has taken place, really
a pseudo-cyst, since in origin and nature these are very

; 51

different from the true cysts in Johnstone’s plaice, which
I will call in future specimen A. Before describing the
two varieties minutely, it will, perhaps, help to understand
their structure, to give briefly the course that the develop-
ment of the parasites has followed in the two cases.

In both, the infection is a ripe, well-matured one, but
whereas in A it is very strong, and must have proceeded
from a great number of centres (in other words, the host
swallowed very many spores), in my plaice (B) it is only
a slight one. Perhaps this supplies, at any rate partly,
the reason for the fact that here the individual parasites
have tended to spread the infection further, invading the
neighbouring tissue of the host largely by the process of
endogenous multiplication (‘ multiplicative reproduction ”
of Doflein (1)) in the young forms. Indeed in the case of
Glugea, where cell-infection prevails, this condition of
diffuse infiltration is, to a very considerable extent, the
result of endogenous reproduction, and, therefore, ap-
parently differs rather in origin from the condition
as it is generally understood to occur in the larger Myxo-
sporidia; although I think it is by no means unlikely that, in
these also, it will be found that endogenous reproduction
has a larger share in the result that is at present ascribed
to it, for Doflein (l.c.) describes in one instance (J yrobolus
cyprini, the cause of “ Pockenkrankheit ”’) a similar multi-
plicative reproduction of young forms while still intra-
cellular. There is, therefore, no need to restrict, as he
would, the term diffuse infiltration to such larger forms,
which, when adult, are intercellular. Thélohan, in first
describing the condition, was not aware of this endogenous
reproductive capacity, and looked upon it as a more or less
continuous ramifying infiltration of the parasitic body,
with displacement and disturbance of the surrounding

tissue. Whereas, as we have just seen, it is far more

52

likely that it is caused by a multiplication and separation
of young individuals, which break down and leave the
host’s cells, the intercellular nature of the adults being
the only point in which the diffuse infiltration here differs
from its occurrence in the Glugee.

Anyhow, in these, to return to (B), the final result
is that the infected area consists of a confused mass of
tissue-cells (many broken down), spore-containing cells,
and clusters of free spores. In A on the other hand, this
process is not evident, and I greatly doubt whether it has
been at work. Probably owing to the strong infection,
with its attendant effects on the host’s metabolism, the
parasites do not seem to have attempted to spread further
(except, as it were, automatically by growth), but to have
concentrated their energies on becoming large spore-
forming individuals. The cysts are well-defined, and
sharply limited, and there is no sign of “ diffuse
Ausliiufer.” Each is, I consider, the result of growth of
a single individual.

Doflein (l.c.) is of the opinion that the cysts of G.
lophii, which he describes (p. 334 et seqg.), result from the
fusion of 3-4, and this may well be, for he is evidently
dealing with “ pseudocysts” and an infiltration con-
dition, more or less similar to my specimen B. In A,
however, the minute structure shews clearly that each
cyst is a single unit. [ere the parasites are never, as
sometimes in Hagenmiiller’s case, in the muscles, but
entirely in the areolar tissue of the sub-mucosa. The
intestinal epithelium is also free from infection, and
though often broken round the much-enlarged internal
end of the folds or ruge, it is still quite evident and
normal up the furrows. For a general idea of the size
and arrangement of the cysts, the reader is referred to
Johnstone's fig. 2, Pl. D.

53

Figure 5 is a section through a portion of a cyst.
“The outer, celomic, side of the gut-wall lies to the right,
and the muscle-layers, though a little thin, perhaps, are
free from infection, and present no feature worth drawing.
At the left is a fold (endoth.) of the mucosa, also quite
normal, at the head of a furrow. At ect., ect. 1s seen the
thick, practically structureless external layer (ectoplasm )
of two adjacent cysts, which are separated by a
few delicate layers of connective-tissue (areol. tiss.).
Hagenmiiller, who maintained that the cyst membrane
is formed of elements belonging to the host, was cer-
tainly referring to pseudocysts, which, however, he did
not recognise were intimately connected with diffuse
infiltration. He does not seem to have seen true cysts at
all. In these, there is no transition whatever visible
between the surrounding tissue and the firm ‘“‘ectorind” (as
one may term the modified ectoplasm) of the parasite, nor
any signs in this latter of flattened-out nuclei or cells.
I entirely agree with Thelohan in thinking that the cyst
membrane is a modified ectoplasm, and for this reason
propose the term ectorind, to distinguish it from an ecto-
eyst. Against its being an ectoplasmic secretion——com-
parable to the cyst-envelopes of Gregarines—I would say
there is no other layer which can be regarded as the ecto-
plasm. Immediately internal to the ectorind is a delicate
layer without any sign of spore-formation, but which is
structurally identical with the endoplasm into which,
indeed, it passes, and, therefore, I regard it also as such.
(In some sections through a Glugea anomala, from a
stickleback, which I possess, there is an equally distinct,
here finely-striated, ectorind, thus confirming Thelohan’s
fies. 158 and 159, pl. 9). Internal to the ectorind, and ex-
tending all round, we see the typical Myxosporidian endo-
plasm (end.). It is a comparatively narrow layer, as by

54

far the greater part of the cyst consists of an immense
number of spores. The endoplasm is the seat of spore-
formation. In the Microsporidia, this starts and pro-
ceeds either from one centre or from several. In the
latter case, each centre comprises (at first) a single
nucleus and a small portion of the cytoplasm in the
immediate neighbourhood, the whole becoming segre-
gated to form an “organella” of reproduction. Hach
such centre is termed a pansporoblast. When, as in the
one family, including Thelohania, Pleistophora, &c., there
is only one, it signifies that the whole dividual becomes
a reproductive organella and commences to sub-divide up
into sporoblasts and spores (just as, for instance, a
Gregarine does). So that, in Plezstophora, a ripe infec-
tion consists of a number of relatively small indi-
viduals, each being a single cluster of spores. This
fact, together with the blunter and thicker shape of the
spores in this genus, leads me to surmise that Linton’s
sporocyst from the liver of Rhombus triacanthus (see above)
was probably a Plezstophora.

To return to our Glugea specimen. The endoplasm
contains a great number of spore-forming organelle in
various stages of development, from little uninuclear ones
to large ones which are practically clumps of sporoblasts
(spbl.). The actual transition from sporoblast to spore
is extremely difficult to follow in the case of these minute
spores; for a full account of the development in the large
forms, Thélohan’s paper should be consulted. I may
add, in passing, that anyone who desires complete informa-
tion on the group, cannot do better than read Minchin’s
up-to-date and concise résumé (5). Scattered about in
the endoplasm, and also oc easionally met with in the
central mass, are large, sometimes drawn-out nuclei (n.)
with fragmented chromatin and a distinct nucleolus (?).

55

They stain more deeply and brightly than the sporo-
blasts, and cannot be mistaken for these. Thélohan
does not describe them, and since mine are all ripe
eysts I have no means of ascertaining their origin
and significance. Passing inwards we come to clusters
of ripe spores, and these soon almost entirely
replace the endoplasm, snd run together to form
the central mass of spores, the organelle themselves
having broken down and disappeared. Often, however, I
noticed, as it were, tongues of endoplasm projecting inter-
nally towards the centre, and in some sections appearing
as isolated patches, some of which were fertile, but others
apparently sterile. These are not to be confounded with
the islands of residual-tissue described below. Although
I have examined sections through many cysts, I have
not seen any instances of the degeneration of the spores
such as is described in the central part of “ over-ripe ”
cysts. In all mine, the central spores are as healthy in
appearance and as deeply-staining as those of the peri-
phery. A noteworthy difference in the central mass of an
A cyst from that of a B one, is the absence in the former
of the areas or patches which are the more or less colloidal
residua of the degeneration of tissue-cells, &c., of the host.
Moreover, the spores themselves in the former case are
quite free, and not embedded in any matrix. These facts,
together with those already set forth, emphasize the dis-
tinction which I wish to bring out between the two kinds
of cyst. While the one (A) is practically all parasitic
tissue, and represents one individual, the other (B)—the
pseudocyst—is the consequence of the massing together
and circumscribing of (a portion of) an infiltrated area,
originally comprising many tiny, daughter, individuals
(of which, im an old pseudocyst, nothing is left save
spores) diffused in and among the host’s tissue (also

56

broken down). ‘There is not the slightest possibility that
an A cyst could ever become a B cyst, or vice versd. And
now to describe the latter.

Fig. 6 is part of a section through the periphery of
the lower cyst in the appendage of fig. 4. All around
(though the upper cyst happens to be close to it on one
side) is the infiltration, a condition easier to describe ver-
bally than to draw, as it would be most difficult to
reproduce except very diagrammatically.

These pseudocysts arise as the result of an endeavour
on the part of the host to limit the infiltrated area by the
arrangement of the hypertrophied connective-tissue in a
series of concentric layers round the centre of infection.
(The marked hypertrophy here is in strong contrast to
its complete absence in the A cysts). This re-action of
the host, not always so well-defined, seems to be without
much success, for the parasitic invasion usually spreads
further, often leading to another attempt at restriction ;
in fig. 4 for example, the upper pseudocyst is of later
formation than the lower. Young ones, therefore, are
simply areas of diffuse infiltration with the layers con-
centrically arranged; but, with age, and probably, to a
certain extent, the pressure of the surrounding parts on
the enclosed tissue, the cells of this latter disintegrate
and degenerate, leaving a mass of spores embedded in their
remains as a ground-substance, with frequently patches or
islands free from spores and staining only with the plasma
stain (deg.). The spores are in a much more closely
packed condition than in the comparatively loose, infil-
trated tissue of the appendage (not shewn in the fig.). It
need hardly be added that there is no trace of endoplasm,
nor of sporoblast-formation round the margin, nor, of
course any ectorind, and, in fact, no sharply-marked ex-
ternal limit

a great contrast to fig. 5. The periphery

57

is formed by loose clusters of spores in artificial chambers
bounded by delicate strands of connective-tissue (cham.).
Outside, again, there are several concentric and partially
imbricate layers of connective-tissue (con. tis.). The
comparative looseness of the peripheral layers is partly
due to the shrinking together of the central residual mass
on fixation, and also to the fact that, once the “ cyst” is
in the appendage, any further layer-formation, and, of
course, the proliferating infiltration, is free to expand.
From Hagenmiiller’s account it is quite evident that his
cysts were nothing more or less than a similar modification
of the infiltrated condition.

Before passing on to consider the spores, there is an
interesting point which a comparison of the two types of
infection, as set forth above, leads me to regard as being
very probable, namely, the potential independence of the
pansporoblasts in Glugea (7.e. their capability of existence
as separate individuals in certain circumstances).
Stempell (6), p. 263, has already suggested that
Thelohania, Pleistophora, &e. (those forms where the
whole individual becomes one reproductive organella),
are examples of a phylogenetic individualization of the
pansporoblasts. Now, I am inclined to think this may
take place normally—for instance, in the condition of
diffuse infiltration

as a stage in the life cycle. Quite

probably * multiplicative reproduction ” is, here, simply
a separation of the pansporoblast rudiments, as daughter-
individuals. Indeed, the whole nature of the diffuse in-
filtration in Glugea seems to me to support this idea.
There is no question of the individual parasites attaining
size, still less of any continuity of a protoplasmic mass
ramifying in and between the host’s tissue-cells. It is
far rather a cell-infection, visible, when ripe, as sepa-
rate clumps of spores, each formed from, and

58

representing, one pansporoblast, and either still sur-
rounded by a hypertrophied host-cell, or else free, but only
owing to the latter’s break-down. ‘Such an origin and
nature of the daughter-individuals would obviate any
necessity for Doflein’s hypothetical “ swarm-spores,” the
occurrence of which would be without analogy in the
Sporozoa.

The spores themselves are seen in fig. 7 (a) and (6).
They are oblong-ovate in shape, and average 3u by 15—
13u in size. They are the same in the two cases, those
drawn in (a) coming from specimen A, and those in (6)
from B. Glugea spores are usually pear-shaped, but, after
very careful examination, I cannot, with certainty, dis-
tinguish any difference in this respect between the two
ends of those of G. stephani. Linton (Le.) also says
nothing about the spores from his specimen being pear-
shaped. Not having had any fresh material to work
with, I have been unable to observe the expulsion of the
polar filament in this species, but in fig. 7 (¢) are seen a
few fresh spores of G. anomala from a stickleback, one
of which shews the filament extruded. The clearer space
at the opposite end (which is nearly always evident in
fresh Glugea spores) represents a vacuole—also generally
apparent in the stamed spores of G. stephani. In-one or
two instances [ saw a faint longitudinal suture (s) marking
the junction of the two valves of the spore. The contents
are most difficult to interpret correctly, sice, owing to the
absence of a pear-shaped end, one cannot say positively
where the polar-capsule is situated. There are usually
two unstained clear areas, with the sporoplasm (2.e.,
the germ) lying between. One of these is well
marked, and invariably contains a small, rounded,
deeply-staining granule; whilst the other seems to vary
in size, and is not always very obvious. The former is,

0

Or

probably, the polar-capsule, in which case the dot would
be the capsulogenous-cell nucleus. The granule
itself is certainly not the capsule, for, in other spores, I
have never found the capsule to stain up at all, and
besides, it is very rarely terminal in position. Moreover,
in one instance (at x) it is distinctly double, as if the
nucleus had divided—as, in fact, Stempell (l.c¢.) main-
tains it does in the spores of T’helohania. On this view.
the other clear area (v.) would represent the vacuole seen
in the fresh condition. JI am semewhat inclined to think
this tends to increase in size with the ripening of the
spore (as indicated by the number of nuclei), and I
suggest, tentatively, that it may have some such func-
tion as the oval body in the spores of Coccidiwm, to assist
in separating the valves and liberating the germ. In the
sporoplasm itself, there is not much to be made out save
the nucleus (N). In the earlier stages this is single and
round, but in its most general condition in my sections
it has the form of a horseshoe, being drawn out prior to
division. Sometimes, however, as im the two upper
examples, it has distinctly divided into two. Stempell
is of the opinion that these two nuclei (representing two
germs, although the sporoplasm has not divided) again

‘

fuse, this action constituting a “ conjugation,’ which is,
as yet, unknown for the order. This requires confirma-
tion before it can be accepted, as it 1s, a@ prior, most
unlikely that two germs, so closely related and, indeed,
barely separated, would conjugate; such a proceeding
would be entirely without precedent. Once or twice the
sporoplasm possessed three nuclei, the reason for which I
have not made out.

While revising these notes, I have received from Mr.
Johnstone a slide, a smear preparation, made, he writes,
from cysts in the otic capsule of a plaice. The car-

60

tilage was much hypertrophied, and the cysts were little
cpaque masses about 1 mm. in diameter. The smear con-
sists of a mass of spores, two of which are seen in
fig. 7 (¢d); each is spherical in shape, and _ possesses
two polar-capsules (p.c.). The spores are 8-94 in
diameter, and the polar-filaments, many of which are
expelled, have a length of about 70u. There are several
refractile oil granules (g) visible, but the stain has not
penetrated sufficiently to shew up the nuclei. I could not
make out any vacuole in the sporoplasm which would cor-

‘

respond to the ‘‘ iodinophilous vacuole” of a Mywobolus
spore. Moreover, the length of the filament is much longer
than is usual for this genus. Hence, although there are
one or two JIZyeoboli with spherical spores, I am more
inclined to place this new species in the genus Sphero-
spora, as S. platesse, presumably polysporous, and with
unornamented, spherical spores.

We may, therefore, summarize the Myxosporidian
parasites of flat-fish as follows :—

Host. Organ or Tissue. Parasite.
Plewronectes flesus| Gut-walland | Glugea stephani,
(flounder). mesentery. | Hagenm.
P. platessa (plaice). Gut-wall. 1 Doe do.
Do. do. | Otic-capsule. Sphaerospora
| platess@, Nn. sp.
| -y .
?seudopleuronectes Gut-wall. | G. stephana,
americanus | Hagenm.

(winter flounder). |

Rhombus | Liver. Pleistophora sp.
(= Stromateus) | (probably n. sp.).
triacanthus (the | |

butter-fish). |

61

BIBLIOGRAPHY.

1. Dorin, F. Studien zur Naturgeschichte der Protozoen. III.
Ueber Myxosporidien.
Zool Jahrb. Abth. Anat. 11, pp. 281-350, pls. 18-24, 1898.

2. HaGmnmutter, P. Sur une_ nouvelle Myxosporidie (Nosema
stephant), parasite du Hlesus passer, Moreau. C.R. Ac. Sci.,
129, pp. 836-839, 1899.

3. JoHNSTONE, J. Note on a Sporozoan parasite of the Plaice
(Pleuronectes platessa). P. Liverpool Biol. Soc., xv.,
pp. 184-187, pl. D., 1901.

4. Linton, E. Parasites of Fishes of the Woods Holl region.
Bull. U. S. Fish. Comm. 19, pp. 405-492, 34 pls., 1899
(publ. 1901).

5. Mincuin, EK. A. Chapter on Sporozoa in Lankester’s Treatise on
Zoology, pt. I., fascicle i., pp. 150-360, 127 text-figs., 1903.

6. SreMpPELL, W. Ueber Thelohania miilleri (i. Pfr.) Zool. Jahrb.
Abth. Anat., 16, pp. 235-272, pl. 25, 1902.

7. THELOHAN, P. Recherches sur les Myxosporidies. Bull. Sci. France
Belg., 26, pp. 100-394, 3 pls., 1895.

EXPLANATION OF PLATE.

All figures except 7 (c and d@) refer to Glugea stephani.
Figures 4-7 drawn with the aid of the camera lucida.

Iron Haematoxylin followed by Orange, Thionin
followed by Eosin, and Klemenberg’s Haema-
toxylin, were the most successful stains.

Fig. 1. Linton’s “sporocysts” from Pseudopleuronectes
americanus reproduced. A portion of the gut
shewing the infection. x 2. sp. = the cysts.

Fig. 2. Part of the stomach and the pyloric caeca of my
plaice (specimen 5), shewing the little parasitic
appendages (par.). art. is the pyloric branch
of the mesenteric artery. x 1.

Fig.

Fig

Fig.

Fig.

62

e. 3. A portion of the intestine shewing the same. The

centrally placed parasite is still a swelling, not
having yet become an appendage. x 1.

4. A section through a piece of the gut wall and an

ect.

Wes

Td.

appendage. The dotted line divides the two.
The darker shaded part (par.) is the “ diffuse
infiltration,” the lighter part representing un-
infected tissue. ep. is a thin layer of connective-
tissue and peritoneal epithelium covering the

“cc

appendage. cy. isa “ pseudocyst.“ x 20.

. 51s part of one of Johustone’s cysts (specimen A), and

.6 is part of one of mine (B). For description, see the

text.

= ectorind (ectoplasm), end. = endoplasm.
endothel. = a fold of the mucosa, shewing its
normal appearance, n, = large nuclei in
endoplasm. Pspbl. = various stages in

the development of spores (sp.) from the re-
productive organelle. x 500, Zs. 3mm. Apochr.
1:40 O.1., C.E. 4.

Spores from (A). 7 (b). Spores from (B). N.
= nucleus of sporoplasm, p.c. = polar capsule,
x = nucleus of latter. s = suture, v = vacuole.
x 1,600. Zs. 2mm. Apochr. 1°40 O.I. C.E. 8.

Fresh spores of Glugea anomala, treated with

iodine sol. in 50°/, ale., one of which shews the
polar filament extruded. x 1,200.

Spores of Sphaerospora platesse, one shewing

the 2 polar-filaments expelled. g = refractile
granules. x 900. Z. 3mm. Apo. 1:40 O.L,
C.E. 8.

Puate Tl.

=
3s

eo
3

SCO
aN
2

vv,

SYS “Pspbl.

ea eg . SS GF) |
ee oe > aa) |
900 Hig Ua. Ey
pee x/200 \)

ee MY XOSPORIDIA. SE:

63

NOTE ON A REMARKABLE PARASITE OF
PLAICE AND FLOUNDERS.

By H. M. Wooncocx, B.Se. (Lond.).

In corresponding with Mr. Johnstone about the
Glugea-infection of the plaice, above described, he in-
formed me of what seemed to be another Myxosporidian
infection of a flounder (Pleuronectes flesus), instances of
which, he says, are not unfrequently met with. In
looking up the literature on parasites of flat-fish, I came
across the papers by Lowe (2), McIntosh (3), and Sande-
man (4), which would appear to refer to the same thing.
As Sandeman practically gives the substance of
MeIntosh’s two papers, accompanied by figures, a brief
abstract of his note “ On the Multiple Tumours in Plaice
and Flounders ” will suffice.

The tumours were prevalent more or less all the year
round, occurring principally from May to November, and
giving the fish an emaciated appearance. The situation
of these cyst-like swellings was in the skin and dermal
tissue of the fins, the operculum, and the tail, usually pro-
jecting externally. Sandeman does not say whether the
gut or other internal organs were aftected. The little
swellings are described as pearly-white spheres, not firmly
attached, but loose in the connective-tissue, covered over
by the pigmented epithelium, and exuding on pressure a
creamy-white, structureless substance. The larger masses
form tumours up to nearly an inch in size, composed of
many spheres from 1 to 15 mm. in diameter, often, how-
ever cuboidal or polygonal owing to mutual pressure, and
eacn limited by a distinct membrane. The author remarks

on their great resemblance to a mass of eggs, but admits

64

that it would be impossible for any animal to force such a
quantity under the skin, as to give rise to a pedunculated
tumour. (Since, as I shall presently shew, they also
occur in the mesentery, this possibility is entirely nega-
tived). In none, though he noticed them all the year
round, could he discern any development.

Sandeman apparently only examined the cysts under
a low power, and judging from his description and figures,
I thought it very probable that this was another case of
a Glugea-infection. There is considerable resemblance
between his fig. 3 (a section through a tumour of many
cysts), and Johnstone’s fig. 2 (l.¢c., above), for example.
In order to identify it, Johnstone kindly forwarded me a
well-infected flounder from the Fisheries Museum collec-
tion in the University of Liverpool, together with a
drawing of the head-region, shewn in fig. 1. On see-
tioning the parasites, I soon realised they were very
different from what I expected to find them.

The specimen was taken in the Barrow Channel in
January, 1901, Both sides of the head are plentifully
averaging 14-1) mm.

covered with opaque white cysts
in diameter—some spherical, others more ovoid. On the
dorsal side, just in front of the fin, are two or three con-
tiguous tumour-like masses—not, strictly speaking,
tumours, however, for there is, practically speaking, no
proliferated tissue, the whole thing being a mass of cysts
with, of course, a little vascular connective-tissue between
and around them. Solitary ones are also scattered about
on the operculum, ventral fin, and tail, and they shew a
tendency to aggregate along the lateral line, especially
posteriorly. Under the pectoral fins an Entomostracean
eetoparasite (Lepeophtheirus) is fairly abundant, but there
is no connection between the two kinds of parasite.

The cysts lie beneath the skin (on the upper side

65

the pigmented epithelium over them is distinctly dis-
cernible) in the dermal lymph-spaces, held in place by
the surrounding tissue, but not embedded in it, and they
can easily be removed with only a few lymphocytes, &c.,
attached. They are quite absent from the somatic mus-
eulature. On opening the body-cavity, numerous parasites
are seen in the gut-mesentery, usually close to, but not
actually in the wall of, the blood-vessels. Fig. 2 elves
an idea of their appearance in the mesentery of one loop
of the intestine, from which it will be seen that, when
internal, the cysts are uniformly shghtly smaller than
when beneath the skin. ‘They are generally oval or
elliptical, and never exceed 1 mm. in diameter.
Unfortunately, I have, so far, not found any younger, or
different, stages, but it is most likely that the parasites,
when smaller, pass into a blood-capillary or lymph-
channel from the gut, and there grow and encyst (?),
since in section (fig. 5) they are surrounded by a space
(spa.). All the internal organs are quite free and normal,
and for this reason I should not say the hosts are harmed
to any dangerous extent. The two or three afflicted speci-
mens which I have so far seen certainly cannot be

.

described as ** emaciated.”

Minute structure. Notwithstanding the size the
things grow to (up to 1} mm. in diameter) each is,
undoubtedly, a single cell; as to that I have not the
least doubt. There is no trace of cell-division, nor of
cell-nuclei in the ordinary sense, in it; whatever a cyst
represents, it is, as a whole, unicellular. Fig. 3 is a sec-
tion, sightly magnified, through one in the mesentery, the
space around representing an enlarged capillary or a lymph-
channel, as already mentioned. This happened to be
more spherical than the internal ones usually are; it is
surrounded by a layer of amoebocytes, Kc. (lym), rather

E

66

closely aggregated. (A portion of the same cyst more
strongly magnified is seen in fig. 6.) The most external
layer belonging to the parasite is a thick, faintly-
staiming, structureless membrane, which I have denoted
by (ect.). Next comes a thick zone (end.), more deeply-
staming, of a finely granular nature, the greater part of
which presents a most unusual appearance, and gives the
organism its remarkable character. Centrally is what
ean only be a nucleus (N), although of relatively huge
size as in fig. 4, which is a section through another,
larger, cyst, from underneath the skin. In each nucleus
are several nucleoli (n), or rather karyosomes, since they
retain the chromatic stain. Fig. 5 is part of the nucleus
drawn under a high-power, and shews a faintly-staining,
regular reticulum, which traverses a_finely-granular
ground-substance, with karyosomes of all sizes, the larger
being vacuolated and the smallest little more than
granules. The nuclear-membrane is very thin and
extremely irregular, and sometimes appears only as a
boundary between the nucleus and the inner limit of the
cortical region (shewn on the left im the fig. ).

In fig. 6 [ have attempted to indicate the appearance
of a portion of the cortex, as seen under a high power. It
consists of a finely-granular matrix, staining with the
plasma stain, in which are innumerable, usually separate,
veticula or net work (vet.), in every variety of shape and
size. These stain up deeply with chromatic stains, and,
so far as I can make out, ave made up of threads of rodlets
or granules, not easy to resolve. fach network is
developed round a centre (which stains sometimes less,
sometimes more, than the general ground-substance) ap-
parently at its periphery. These structures do not com-
mence quite at the external limit of the cortex and they

cease some distance before its inner limit. On the whole,

67

the smaller ones are more peripherally situated, though
there is no regular increase in size as one passes inwards.
The only other point to note is a series of tiny spherules
(sph.), each with one, or sometimes two granules, at the
outer margin of the cortex, almost abutting on the mem-
brane (ect.), but I have seen no transition between these
and the deeply-staining reticula, nor are they obvious in
all my sections. I should add that in fig. 3 these latter
are more closely packed and rather more strongly-stained
than in fig. 4.

In endeavouring to arrive at some idea of the nature
and affinities of these remarkable cysts it will be most con-
venient to commence by the process of elimination.
In the first place we have, certainly, not to deal with
a Trematode or other Metazoan parasite. Further, Dr.
Nabarro and Professor Oliver, who have kindly examined
it, are of the opinion that the cysts are the result of neither
a bacterial nor a fungal infection, and, indeed, it is almost
inconceivable that an ordinary cell could be so enormously
hypertrophied by bacterial or hyphal invasion, and retain
as much of its structure as these bodies do (compare the
amoebocytes and connective-tissue cells around). More-
over, Mr. Pollard, of the Bacteriological Laboratory at
University College, has stained sections for me by the
usual methods adopted for Bacilh, &c., without result.
The localized and restricted nature of the infection is also
against this view, the cells around being quite normal.
So that we may dismiss the idea of the cysts being caused
by a bacterial or hyphomycetic parasite. Kach cyst-
like body is one organic unit.

I can only think of two remaining hypotheses,
namely, that the bodies must represent either eggs or
parasites. Now, although, as stated above, it was

absolutely impossible that they were the eggs of some

6S

other animal, for the simple reason that they are also in-
ternal, yet it was conceivable that they represented
enormously modified and hypertrophied ova, which had
become detached from the genital stroma (germinal epi-
thelium) when very young, had been carried about—
absorbing a great quantity of nutriment which had formed
the remarkable chromatic development-—and thus finally
grown into these huge cysts.* Unlikely as this hypothesis
might at first sight appear there were two or three points
in favour of it, and I have, therefore, carefully considered
it. For one thing, the resemblance between the nucleus
of one of these bodies and that of a flounder’s egg is quite
striking. Though differing greatly in size (and I may
here say that the diameter of a cyst averages about four
times that of a normal egg, and the nucleus is relatively
larger), their structure is practically identical. Indeed,
the nucleus reminds me more of a germinal vesicle than
anything else. It is not like a Protozoan nucleus, that of
a Gregarine being the only one which can be compared
with it, from which this differs chiefly in relative (to say
nothing of absolute) size, and in the ill-defined mem-
brane, lacking any marked affinity for the chromatin
stam. ‘The outermost layer (ect.) would also serve for a
thick egg-membrane, but in noue of my sections is any
radial striation visible, correspondimg to the “zona
radiata’ of the eggs, although I. should add_ that
Sandeman meutions and figures something of the kind
in his deseription. The chief difference is in the cortical
zone. Whereas, in an egg, the cytoplasm is filled with
large, spherical, refringent, oil or fat globules, there is not
the least sign of such in the cortex of these bodies

*T should prefer to think of their origin thus (z.e., from differentiated
ova, however small), than to suppose they had originated from wander-
ing (‘‘ vagrant ’’) indifferent germ cells,—because of their single and
markedly ovarian nature. In the latter case, there would more
probably have resulted (by proliferation) ‘‘ cell-nests”’ of ordinary
indifferent cells.

69

Whether, owing to differences in nutrition and chemical
metabolism, the remarkable chromatic reticular-centres
could have arisen instead, it is now scarcely necessary to
discuss, for while this note was being prepared tor the
printers I received from Mr. A. Scott, at Piel, another
equally infected specimen, which turned out to be a
male. This, of course, left me with only the parasitic
alternative, as one cannot imagine such an abnormal
ovarian development occurring im a male.

Perhaps the chief reason why I gave so much con-
sideration to the above hypothesis was because the bodies
are so utterly unlike any known Protozoan. The para-
site, for which I propose the name Lymphocystis
johnstonez, 1s, in truth, the strangest Sporozoan (this being
the only class in which it can possibly be placed) that I
am aware of, and until I obtaim further stages in its life-
history, I can only interpret the above-described features
in very general terms. Kiet. may well represent the
ectoplasm, now modified into an ectorind, while end.
corresponds to endoplasm. Presumably the large
nucleus is the vegetative or “ trophic ” nucleus, although
in this respect Lymphocystis differs from any known
Sporozoan, im that while sporulation is proceeding (for
what else can the chromatic centres represent 7), the vege-
tative nucleus persists undivided. In a Myxosporidian,
spore-formation certainly goes on during the trophic
phase of the life-cycle, but here there are many nuclei,
some only of which originate reproductive-organelle, the
others continuing vegetative in function. This single
nucleus in our parasite recalls more the condition in
Gregarines, but there the original nucleus breaks up
altogether at the close of the trophic period to form repro-
ductive nuclei. Nor in the Sporozoan “ lumber-1oom ”
(already well filled) is there anything similar. The sole
form with which Lymphocystis seems to have any point of

70

agreement 1s Lymphosporidium trutte, the cause of a
brook-trout epidemic in America. In most respects this
parasite, described by Calkins (1), is very different from
Lymphocystis, the adults bemg amoeboid, relatively
minute, and with no well-defined nueleus--the chromatin

oe

being in the “ distributed ” form, The two parasites are,
however, not without certain points of resemblance.
Lymphosporidium is, especially in the adult sporulating
stage, chiefly met with in the lymph-spaces surrounding
the various organs and of the dermis. Moreover, its
manner of reproduction rather recalls that of Lympho-
cystis. .Aecording to Calkins, deeply-staining granules
collect 1m masses to form many spores. The chro-
matin next forms a layer around the periphery of each
such centre, and breaks up into rounded granules, eight
in number, which separate (¥) to form the sporozoites.
From Calkin’s figures, it does not seem to me unlikely
that the complicated reticular areas in Lymphocystis (2.e.
the threads of rodlets or granules above described) may
represent a modification of this process, although at
present one cannot say so with certainty. In that case
the ultimate germs must be extremely minute (only
about | or 13 uw) and numerous. Whether the little
spherules at the margin of the endoplasm have any con-
nection with spore-formation and are in any way com-
parable to the reproductive organelle or ** pansporo-
blasts ” of Myxosporidia has also yet to be ascertained.

In conclusion, Lymphocystis would appear to com-
bine, to a certain extent, Gregarine and Microsporidiam
characters—with remarkable results. I do not feel
inclined to place it in the Serosporidia (the order to which
Lymphosporidium belongs), as these forms, though of
similar habitat, are all very small. I have, unfortu-
nately no alternative but to leave it for the present, to
swell the ranks of the * unattached ” Sporozoa.

BrpuioGRAPHY.

1. Caukrns,G.N. Lymphosporidium truttae n.g.n. sp. The Cause
of a recent epidemic among Brook-Trout, Salvelinus
fontinalis. Zool., Anz. 23, 1900, pp. 513-520, 6 text figs.

2. Lown. Fishes of Norfolk, in Trans. Norfolk and Norwich
Naturalists’ Society, 1874, p. 39.

3. McInrosw. Diseases of Fishes, in 3rd Ann. Rep. Scott. Fish.
Board for 1884, pp. 66-67, and 4th do., for 1885, pp. 214-215.

4. SanpEMAN, G. On the multiple Tumours in Plaice and Flounders.
11th Ann. Rep. Scott. Fish. Board for 1892, pp. 391-392,
pl. 17.

EXPLANATION OF PLATE.
All figures refer to Lymphocystis johnstonet.
Figs. 5-6 were drawn with the aid of the camera.

The stains mostly used were Iron Haematoxylin
followed by Orange or Hosin, Kleinenberg’s Haema-
toxylin and Fuchsin, and various — bacteriological

methods.

Fig 1. Head of the flounder, shewing the parasites
(par.) beneath the skin, but projecting ex-
ternally. At tum. are three huge aggregations
of cysts (not proliferations, see text). x
Drawn by J. Johnstone.

Fig. 2. View of one of the coils of the intestine, with
?

attaching mesentery (mes.) and blood-vessels

(blv.). Par. ave the numerous parasites. x 1.

7%)

im
Fig. 5. Section through one of the parasites in the

mesentery. It is lying in an enlarged lymph-
space (spa.) in the latter. Lym., a layer of

lymphocytes around it, ect., ectoplasm,
end. = endoplasm, ret. = chromatic reticula,
NV = nucleus, n = Karyosomes. x 45.

Fig. 4. A section through another, of different shape
and larger, beneath the skin (only partly drawn
in). Vonn.-tiss. = a layer of connective-

tissue. x 45.

Hig. 5. Part of a section through the nucleus, shewing
the fait, irregular reticulum, and kary-
osomes (7.). m = the nuclear membrane (see

text). x 110-(drawn in under a high power).

3 Part of a section through the periphery of the
parasite. sph = the clear spherules at the
margin of the endoplasm. Other letters as in
fig. 3. x 500. Zs. 3 m. Apochr. 145038
C.E. 4.

‘
con.tiss.

HMWeel Fgh AS. cel,

LYMPHOCYSTIS JOHNSTONEL

: 73

THE FECUNDITY OF THE PLAICE.
By R. D. Laurie.

It may be useful to put on record two estimations
of the number of ova produced by a plaice, which I made
at Prof. Herdman’s suggestion while working, during
last aster vacation, at the Port Erin Biological
Station. The determinations were made by Dr. Fulton’s
method,” in which a fractional portion of the roe (or
ovary) of the fish is weighed and the ova are counted, and
from the numbers so obtained, and the total weight of the
two ovaries, the total number of ova present is calculated.
No determinations of this kind have hitherto been made
from the fish in the Irish Sea.

The fishes dealt with were two ripe mature females,
which died in the tanks at Port Krin during April, 1905.

The data are as follows :—

Total length | Total weight Total weight of

(in centimetres). | (in grammes). | both ovaries.
1 | 49 (193 inches) 1,346 | 3155
y 52 (204 inches) 1,318 bet i Ges

Small portions of the ovarian substance, weighing LO
grains each, were taken from various parts of the
organ, and the ova were counted. The results of these
counts are given in the following table :—

* Oth An. Report Fish. Bd. for Scotland. Pt. III., pp. 243-268.

74

(1.) Anterior region, 10 grains contained —..._ 744 ova.
* ss - . a aa) eee
Middle region, zs * - oe | ee
73 53 3 . ee / 2) ee
Posterior region, ,, *5 is > SO
5 a Fr af x 2 ee
Average for 10 grains = 1732 ova.

(2.) Anterior ventral region, 10 grains contained 804 ova.

is * = ay i = 189
Anterior ventral lobe, e I Fe Soaueee
2 ss 55 a - ws STO ees
Middle region, a A As ra Sig
5 Esc = a Soi ss
Posterior region, —... a be rs SSOnae-
Average for 10 grains = 838 ova.

The differences in number of the ova in the various
samples were due chiefly to the mixture in various pro-
portions of eggs of slightly different size, and also to the
varying admixture of water and connective tissue —both
sources of error which are unavoidable in this method of
investigation. ‘Two kinds of ova are present im the roe of
the plaice, (1) large ova lightly attached or lying freely
in the lumen of the ovary, and smaller immature oya still
adherent to the epithelium. In fish (2) which had not
begun to spawn, I counted 492 large mature ova in one
ovary; their diameter was 1:32 mm. Nearly all the
remaining ova were about 1 mm. in diameter, and there
were few intermediate in size. ‘This is in accord with the
general belhef that the process of ripening, or the absorp-
tion of fluid by the ova, is very rapid. Fish (1) had just
begun to spawn, but a similar contrast between mature
and immature ova was evident.

75

The following values were calculated from the
figures so obtained :——

Total length. | Total weight. Total number of ova
Cms. | Grms. in the fish.
1 49 1,346 | 306,278
2 o2 1,318 | 234,640

It may be useful to compare these results with those
obtained by other investigators. Fulton, in the paper
quoted, gives the following estimations :-

Total length. Total weight. Total number of ova
Cms. Grms. in the fish.
i 44-5 | 1,368 223,497
2 44:5 1,191 148,470
3 52:0 ito 323,166
4 560 1,914 487,087
5 56°5 2,140 324,749

These figures present much the same appearance as
those I have obtained.

Reibisch,* in 1899, made a lengthy investigation of
this nature. His method differed in principle from that
devised by Fulton. The ovaries were put into cold
‘water on being removed from the fish and the water was
gradually heated to the boiling point and kept at this for
+ hour. This facilitates the removal of the ova from the
ovarian epithelium. ~The ova, after being separated in
this way, are counted by the method employed by Hensen
in the quantitative determination of plankton. ‘This is

a more accurate method than that of weighing, for in the

** Wiss. Meeresunt. Kiel u. Helgoland. N.F. Bd. 4, Abth. Kiel,
pp. 233-248, Taf. 1. 1899.

76

latter method a certain amount of ovarian tissue is
estimated as ova, and a number of very small ova which
will not be spawned at the next spawning period are also
included. — In two of Reibisch’s estimations the weight
of the ovaries after complete spawning was 7°8 grms. and
185 grms. By employing this method Reibisch made a
large number of estimations, some of which are quoted
in the following table :—-

Total length in | Total weight in ‘Total number of ova
Cms. | Gims. in the fish.
; | |
1 54 lo “e770 223,250
2 45 969 109,500
3 42 1,100 | 558,500
4 | 40°5 | 698 | 736,250
a | 38°5 585 250,750
|

Reibisch did not count the very small eggs which are
always present in the ovary. If these had been included
values of 24 millions of ova would have been obtained in
some cases, and this represents a degree of fecundity
certainly not attained by the plaice. Such very small
egos he contends cannot ripen for the next spawning period.

All these results, and my own have the same tendency,
show, as Keibisch has observed, that there is no recog-
nisable relationship between the size or weight of the fish
and the number of eggs produced by it at the spawning
period. The age of the fish has in all cases to be consi-
dered. We know that the rate of growth is very variable.
Probably most plaice attain sexual maturity at the same
age, but the size and weight at this age may be very
different in a number of specimens. Thus a mature
female 13 inches long, and an immature female of 19
inches, have been taken from the Irish Sea.

=~]
a |

AN OUTLINE OF THE SHRIMP QUESTION.
By W. A. Herpman.

In the course of last summer Mr, Fell, the Chairman
of the Lancashire and Western Committee, sent me a letter
in which he suggested that it might be useful to give in
this Report a detailed statement in regard to the natural
conditions under which shrimping is carried on in
Laneashire waters, and as to the relations between the
shrimps and the young flat-fish. It is very desirable that
such a statement should be drawn up, but the time has
not yet come when we are in a position to do so in any
detail or with any finality. Periodic investigations
carried on over a couple of years, such as cannot be under-
taken until we have a scientific steamer at our disposal,
are necessary to clear up certain points in life-history and
bionomics. Still it may be useful to give now an outline
of what is known and what has still to be determined in
connection with the subject, and to take what steps are
possible to us during the coming year to obtain statistics
which may aid us im tackling some of the unsolved
problems.

The subject is a very diverse and complicated one,
which leads us into economie as well as scientific questions,
and although one might desire that any proposed regula-
tions of the shrimping upon grounds frequented by young
fish should be considered and settled on the scientific evi-
dence, still it can seareely be doubted that administrators
will take cognisance of the economic questions even if they
do not adjudicate wholly upon them. Consequently in
any discussion of the subject we must be prepared to take
fully into account the important mterests involved in the

shrimping industry, and not to sacrifice unduly any pre-

78

sent material advantages to what may be considered some-
what problematical benefits in the future. We must be
prepared to give full and accurate information as to the
economic effects of any suggested restrictions the effects,
that is, upon the fishermen and others engaged in the
industry, and upon the markets and supply to the public,
as well as upon the shrimp and fish populations in the sea.

We desire to know, amongst other things :

(1) The number of boats and men employed in
shrimping on each of the grounds.

(2) The produce of the fishery throughout the year,
and especially during certain periods—March to June,
July to September and October to February.

(5) The approximate amount of destruction of young
fishes under various circumstances.

(4) The subsidiary interests involved, e.g., potting and
selling the shrimps.

(5) The probable effect upon employment which
would be produced by the imposition of a close season.

(6) The extent to which foreign preserved shrimps
are imported, and the probable effect of any change in
restrictions upon such mmportation.

In regard to some of these matters we already have
a good deal of information, and can readily obtain more.
For example :—

Under (1)—There are now 70 boats fishing on our
coasts hailing from Southport and Marshside alone, all
engaged in shrimping at some time of the year. These
are all half-decked boats, and most of them have been
built during the last six years. The catching power of
this fleet is said to be now ten times as great as was the
case 25 years ago. Hach boat is worked by two men, and
the takings are divided into 5 shares, of which each

man takes two and the boat the fifth share. Each

79

fisherman finds one net and the boat has to find two nets
when engaged in shrimping. We can readily give similar
“information in regard to other parts of our coast.

Under (2).-The average take at Southport during
the twelve months ending December 51st, 1902, was 30
quarts per boat for each fishing day. The statisties for
other boats and periods can readily be ascertained.

Under (4.)--In addition to about 200 fishermen in
Southport and Marshside all more or less engaged in
shrimping, the potting of the shrimps is an important
local industry, and provides a fair amount of work im
boiling, picking and potting the catch. There are in all
about 50 shrimp-potters in Southport, and.they utilise
nearly all of the shrimps that are caught on our coast,
and distribute them to nearly every town in Great
Britain. The fishermen’s wives and children boil and
pick the shrimps, and make them ready for the potters to
prepare for market. During the last 15 years the South-
port shrimp-potting industry has increased tenfold.» It
must also be remembered that the boat-builders, net-
makers, butter merchants, printers, pot manutacturers,
and railway companies all share, more or less, in the pro-
fits derived from the local shrimping industry.

So far we have been dealing with fairly easily ascer-
tainable facts, but 1m (5) and (6) we come upon contentious
matters which are not strictly scientific, and in regard to
which it might be difficult to get agreement. In (3) we
also meet with difheulties, but of a ditterent nature.
This is a scientific question, and the answer is to be
obtained as the result of a large number of reliable
statistics. Preeautions must be taken to see that the con-
ditions under which statisties may be taken are normal
and such as hold good in the course of the fishery. More-

over, the practice may vary from time to time, or with

80

different boats, and so affect the result. At the best, it
‘an only be an approximation that will be obtained; but,
still, it can searcely be doubted that the annual destruc-
tion 1s enormous, and that the young flat-fish so lost are
potentially very valuable. It seems probable that the
total annual destruction of young fish by shrimping in
our district 1s to be measured by the hundred million.
We know, moreover, that the Lancashire shrimping
grounds constitute our most valuable fish nurseries, which
bear a definite and important relation to the fishing
ground off-shore, and we may assume that if young fishes
are allowed to grow undisturbed on the in-shore nurseries,
they will later on become marketable fishes on the off-
shore fishing grounds. We may state also that as all the
common. flat-fish pass through a stage in which they
inhabit a shallow-water area, the number of marketable
fishes on the off-shore grounds will vary as does that of
the small fishes in the nurseries. If, then, we are able to
protect our young fishes in the coastal waters, under
ordinary circumstances they should turn up a year or two
later on the grounds outside. The preservation of
immature fishes ought to be very beneficial to the off-
shore fisheries more beneficial even than the preserva-
tion of spawn, because the mortality during the period
between hatching and the stage when the young fishes
make their appearance im the nursery is so very great that
a given number of young fishes represents many hundred
or thousand times that number of eggs or embryos.
Now, this a prior? argument is probably quite a
good one, and if we had no other means of investigating
the matter, we should probably be justified in relying upon
it. But the points enumerated in the last paragraph in
relation to the life-history of the fish, are eminently suit-
able for biological and statistical investigation. And it

81

would be manifestly unfair to the shrimping industry to
impose restrictions, and possibly interfere with the liveli-
hood of so many fishermen, before making those further
investigations that are practicable, and are most likely
to throw much light upon the matter.

We may take the probable effect of such restrictions
upon shrimping as have been suggested as an instance that
will show the problems that confront us, and the kind of
information we want. It is interesting to speculate upon
what would be the resulting effect upon the fish and
shrimp populations if shrimping were either stopped
or restricted to certain months on particular grounds.
The number of immature fishes would probably increase,
at least for a time—possibly permanently—and _ this
might be expected to lead to an increase in the market-
able fishes on the off-shore grounds a year or two later.
The great numbers of young fish at present destroyed
would be preserved, and, no doubt, the number of shrimps
would also increase considerably. Interesting questions
would then arise as to whether the fish and shrimps would
be competitors for the same food, and whether there
would be enough for both in their increased numbers.
Taking the plaice as an example of the young fish, we
know that when very young it feeds mainly on Copepoda
—we have found their stomachs crowded with Jonesiella
hyene and other allied forms. But, after the meta-
morphosis, the young fishes from, say, 11 to 4 inches in
length, feed largely upon worms such as Wereis and
Pectinaria, upon small Crustaceans such as Mysis and the
Amphipoda, and even upon small shrimps. Later on, the
fish adopts its proper adult food, which is Mollusca
(mainly small cockles, mussels and allied bivalves).

Shrimps, we know, are general feeders (using small
Molluses and other animals, and also Algw) and

F

82

scavengers, and will subsist largely on dead material.
Consequently, if there should be any scarcity of food, I
do not doubt that they might, to some extent, compete
with the little fish by eating the worms and smaller
erustacea, but it is improbable that there would be
any such secareity. We may put great trust in the
recuperative powers of the invertebrate fauna of the sea-
bottom. Even in the spots where fishes are most crowded,
we bring up plenty of invertebrate food material in the
dredge and trawl; and, moreover, if there were any
scarcity of food the star-fishes and crabs, which are so
abundant on these grounds, would move away.

A greater danger might be brought about by the
increased numbers of shrimps and young fishes attracting
many skates, rays and other larger predaceous fishes
to the ground. In fact, the disturbance of the fauna
might be very wide spread. Some forms of invertebrata
might be either favoured or the reverse by the changed
conditions, and then that change in the food might re-act
upon the fish population. For example, if the smaller
crabs which are usually present in enormous profusion on
the shrimping grounds, found conditions uncongenial and
migrated to other banks and channels, the Gadoid fishes,
which feed largely upon such crabs, might in their turn
be affected.

The chief enemies of shrimps in our district (see our
Report for 1894) are skates and rays, whiting, gurnard,
and the larger Gadoid fishes. The latter are not abundant
on the shrimping grounds, but skates and rays seem to
have increased on the Blackpool closed ground, possibly
as a result of the more abundant feeding upon that
sanctuary. <A careful detailed comparison of this closed
area with the open grounds on both sides of it might give
information as to effects to be expected by closing other

83

parts of our fish nurseries to shrimping. We desire to
know not merely the statistics of the ‘‘ catch,” 7.e., the
fish and shrimps in each haul, but also the relative
abundance of invertebrate (food) animals on closed and
open grounds, and full details as to their kinds and
abundance, their life-histories and changes throughout the
year, and their food, for comparison with that of the
shrimps and fishes.

Furthermore, we obviously require to have full infor-
mation in regard to the structure and habits of both the
shrimp and the fishes throughout their life-histories before
we can be sure that any alteration in relative numbers will
be permanent. We know a good deal about such matters
already, either in our own seas or in other parts of the
world. Professor J. S. Kingsley,* in America, has made
us acquainted with the development of the early stages of
the shrimp (Crangon vulgaris), and Dr. Ehrenbaum has
given us much information as to the structure and life-
history of the shrimp at Heligoland.+ All that is a help,
but still there are many local details that must be worked
up on our own ground. We must know exactly where
and when the various stages occur, and in what abundance,
and in what association.

Then turning to the little fishes, if we take the plaice
again as an example, Mr. Johnstone has given, in the
appendix to our own Report for 1901 (No. X., p. 211), a
summary of what is known as to the development on our
coasts, and the habits and food at the various stages. If,
however, we take the young sole—a very valuable, and
frequently abundant, constituent of the fauna on the

shrimping grounds—much less is known, and the exact

* Bulletin of the Hssex Institute, 1887 and 1889.

+ Naturgeschichte von Crangon vulgaris, 1890.

84

history of the young stages in our district has still to be
written.

In our Report for 1900 (No. [X., p. 39), we had an
article by Mr. Johnstone and Dr. Jenkins on the shrimp
trawling statistics of the Mersey grounds, in which they
give a description of this remarkable region, samples of
various kinds of hauls and such conclusions as they were
able to draw from an examination of our statistics (over
1,000 forms) for the period 1895-99.

The accompanying figure shows the great banks sur-
rounding the mouth of the Mersey, and the channels
between them. Shrimping is carried on over almost the
whole of this ground, the extent of which is roughly 16 to
18 square miles. This is only a sample of the remarkable
Lancashire and Cheshire shrimping and nursery grounds.
Similar areas exist in Morecambe Bay, off the Ribble, and
in the estuary of the Dee, and on these grounds we find
associated with the shrimp an abundant fauna of both
fishes and invertebrates.” The chief fish are the plaice,
dab, flounder, sole and solenette, with occasional whiting,
haddock, cod, young brill and turbot, sprats, sand-eels and
sting-fish. The commonest invertebrates are crabs, star-
fish and shrimps. Examples of hauls on different nursery
grounds, and at different times of year, are given in
our ninth and tenth Reports, and in the Memoir, “ Fishes
and Fisheries,’ by Mr. Dawson and myself, and need not
be repeated here. Mr. Johnstone has summarised his
previous work, from our statistics, as follows :—

(1.) The great abundance of young flat-fishes on the
shrimping grounds. They are, in order of frequency,
dabs, plaice, and soles; solenettes are also very abundant,
in some areas nearly as abundant as the soles.

* See Herdman and Dawson, Lancashire Sea Fisheries Memoirs,
No. Il. Fishes and Fisheries of the Irish Sea, 1902,

85

(2.) These fishes are generally most abundant during
June, July, August and September. But on certain of
the grounds in winter (December and January) plaice

may be more abundant than im summer.

ON on
Ro WHARF

Mersey Shrimping Grounds.

(3.) The number of fish caught by}the shrimp trawl
varies greatly from time to time. On the Mersey grounds
the average for September, 1893, was nearly 3,000 per
haul, and the average for September, 1899, was nearly

86

95 per haul; the average tor the seven years (1895-99)
was nearly 967 per haul.

(4.) The number of fish caught on closely-adjacent
grounds is sometimes very different, even when the
depth and bottom are very similar. Caution is, therefore,
necessary in comparing neighbouring grounds, even when
these are similar physically, unless we have previously
ascertained that they are almost similar biologically.

(5.) Our statistics for the 10 years 1893-1902 show
that : —

1. Young plaice on the shrimping grounds have
diminished.

r
~

2. Young soles on the shrimping grounds have
increased.

The distribution and relative abundance of these
young food fishes throughout the year on the various
banks and other shrimping grounds will have to be still
further studied from more abundant statisties before
these variations can be considered as established and
understood.

In regard to the shrimp, also, we want more informa-
tion as tothe relative abundance of the sexes, the
spawning periods, the time of hatching, the rate of
growth, the proportional numbers throughout the year,
and the distribution on and about the shrimping grounds.
It must be remembered that work done in other seas
cannot be utilised in our own district except as a general
guide to investigation. An intensive study of the fish
and shrimp populations on the areas we propose to deal
with will have to be undertaken.

Such investigations as we contemplate would require
one whole day’s trawling per week on each of the prin-

cipal grounds to be compared, say in Morecambe Bay, on

87

the Blackpool ground, and on the Mersey banks. — It
seems unlikely that we shall gain much further, or more
exact, information than we now possess with regard to
the distribution and inter-relations of the shrimps and
fishes with any less expenditure of time. Three hauls on
different parts of the grounds should be taken during
pach day’s work. It need scarcely be pointed out, how-
ever, that these hauls would also give us statistics im
regard to other fishes, and generally add to our know-
ledge in various other useful directions. It would, pro-
bably, be impossible to report satisfactorily upon all the
matters referred to in the above outline in less than two
years, and a consideration of the work and_ statistics
required to solve the problems shows how necessary it is
that we should have a second steamer in this district,
devoted solely to scientific and statistical investigation.

RECENT INVESTIGATIONS ON PEARLS IN
SHELLFISH.

By W. A. Herpman.

In last year’s report I referred to the work done by
Dr. H. L. Jameson upon pearl-formation in the Common
Mussel at Piel. Since then Mr. Hornell and I have
published a preliminary notice* of our results obtained
with the Ceylon Pearl Oyster: and more recently several
French investigators, Seurat, Giard, Dubois and Boutan
have written short notes dealing with the same unportant
matter.

As is so often the case, the first statement of the
correct view was made long ago and afterwards forgotten
or contradicted, and the more modern work is largely a
resuscitation, extension and demonstration of an older
view. Filippi, in 1852, showed that the parasitic Trematode
worm Distomum was the cause of pearl-formation in the
freshwater mussel of rivers and lakes, and other naturalists
soon after extended the discovery to other pearl-producing
molluses and to other worm parasites. To Dr. Kelaart
belongs the honour of having first connected the formation
of pearls in the Ceylon oyster with the presence of vermean
parasites. He and the Swiss Zoologist Humbert, who was
with him at a pearl fishery off Aripu, found various parasitic
worms infesting the viscera and other parts of the pearl
oyster, and they agreed that these worms played an
important part in the formation of pearls. Melaart more-
over, in 1859, made the remarkable suggestion, in the case
of the Ceylon pearl oyster, that it might be possible to
inerease the quantity of pearls by infecting the oysters in

* Southport British Association Report, Sept., 1903; and Report
on Ceylon Pearl Fisheries, Part I., Royal Society, Noy., 1903.

89

other beds with the larvee of the pearl-producing parasites.
This is exactly the idea that has lately been revived by a
French professor.

Turning now to Kuropean shell-fish we find that our
countryman Robert Garner in 1871 associated the produc-
tion of pearls in our common English mussel (Mytilus
edulis) with the presence of Distomid parasites.

Professor Giard, in 1897, and other French biologists
since have made similar observations in the case of Donax
and other Lamellibranchs—Giard describing* the Distomid
worm which he found as a species of Brachycoeliwm.
We now come to quite recent years, during which
there has been great activity. Prof. Raphael Dubois in
1901 ascribed the production of pearls in mussels on the
French coast to the presence of the larva of Distomum
margaritarum. The next year (1902) Dr. H. L. Jamesont+
followed with a more detailed account of the relations
between the pearls in Mytilus edulis and the Distomid
larvee, which he identified as belonging to Leucithodendrium
(Brachycoelium) somaterie—the same sub-genus as Giard
had found some years previously. Jameson’s observations
were made partly at Billiers (Morbihan), the same locality
at which Dubois had also worked, and partly at our
Lancashire Laboratory at Piel. Dubois published a
further note} in January, 1903, in which he stated that
Jameson had come to Billiers after his departure and had
confirmed the discovery made previously, first by Garner
and then by himself. But Jameson had really done more
than that. He had shown that it is probable that the
parasite causing the pearl formation in our common mussel
(not however in the Ceylon Pearl Oyster) is the larva of

* Comptes rendus, Soc. de Biol., 13th Nov., 1897, p. 956.
+ Proc. Zool. Soc., Lond., 1902, p. 140.
+ Comptes rendus, Acad. Sei., 19 Jan., 1903.

90

Distomum somaterie, a Trematode worm, the adult of
which lives in the intestines of the Eider duck and the
Seoter duck. He also stated that the larva inhabits Tapes
or the cockle as a first host before getting into the mussel,
and gave figures of the parasite in various conditions.

Two very important matters are, however, left ina
somewhat unsatisfactory condition by Jameson's paper.
The first of these is the mode of origin of the epithelial
sac which encloses the larval parasite, and which secretes
from its cellular walls layer after layer of nacreous material
so as to form a pearl. The presence of this sac was known
before (Von Hessling, 1858, and Diguet, 1899), but no one
has yet satisfactorily traced its origin. Jameson several
times compares it with the epithelium on the outer surface
of the mantle, using such terms as “similar to ” and
“indistinguishable from’ but he evidently considers that
it has nothing to do with that epithelium, although it
produces an identical pearly secretion. He describes the
sac round the parasite as formed by the proliferation of a
few cells which “are basally continuous with fibres of
connective tissue.’ He also says of it, “ This epithelium
appears to arise quite independently of the outer
epidermis.” Now such a mode of origin as this is very
unlikely, and although I have not had the opportunity of
re-examining pearl-bearing mussels on this pomt since
Jameson's paper appeared, | think there can be little or no
doubt that the cells of the pearl sac are directly and
genetically connected with the exactly similar cells on the
outside of the mantle. It is almost certain that the
parasite in burrowing into the mantle carries in with it one
or more epidermal cells which proliferate to form the sac.
As the Distomid larve are found moving on the inner
surface of the shell before coming to rest in the mantle
they must traverse the ’ epidermis, and it is natural to

1

suppose that in their migration they may push some
epidermal cells in before them. At least this is not such
a violent assumption as that the connective tissue in the
centre of the mantle can produce an epithelial sac the cells
of which are indistinguishable both in structure and in
functions from the epidermis outside.

In giving a preliminary account of pearl formation in
the Ceylon Pearl-Oyster to section D of the British
Association last September I took up the position that the
sacs enclosing the pearls were in all cases of ectodermal
(epidermal) origin: and I am glad to find that Prof. A.
Giard, in a recent note* on the subject, takes the same
view, and considers that in the case of Jameson’s mussel
there is a “passive immigration” of the epithelial cells
caused by the migrating parasite.

The second point which I feel is not yet satisfactorily
settled, is the supposed infection of the mussel with
parasites by the ‘apes in France and the cockle in the
Barrow Channel. So far as regards the latter case,
Jameson’s conclusion is based upon the experiment of
placing some mussels, which he supposed to be free from
parasites, in a tank with French Tapes which were infected,
and examining the mussels from time to time until he
found they contained the parasites (Cerearia). Now in
such an experiment it is necessary to be quite sure of the
material used, to deal with sufticiently large numbers
and to have control experiments. Jameson does not seem to
have taken these precautions. He says of the material :—
“These mussels, of which I examined a number, were
practically without parasites. About one in every tive of
the largest examples contained a Cercaria, one had two
Cercarie, and one contained a small pearl.’ This can

*Comptes rendus, Soc. de Biol., Paris, 19 Dec: 703; 1v.,1p: 1618.

92

scarcely be described as free from parasites! He used 70
mussels; if we take his own figures, one in five, as correct,
then about 14 of the mussels were infected at the
beginning of the experiment. We find from his records
that he only examined 13 of these mussels (2 after 11
days, 6 after 2 months and 5 after 63 months), and found
12 of them infected. But it is obvious that that number
might possibly have been infected from the beginning or
may have become infected at any time from neighbouring
mussels. ‘The theory of transference of the parasite from
one molluse (such as cockle) to another (the mussel) may
be true, but it is not proved by these experiments. It was
not shown that the mussels were free from parasites at the
start, the numbers in the recorded experiments are too
small to yield definite conclusions, and the observations
should clearly be repeated using hundreds of cockles and
of mussels with well-devised control experiments. In
order to show the necessity for large numbers in this kind
of work I may add that Mr. Andrew Scott having informed
me of Dr. Jameson’s observations at Piel, | had some
samples of these same mussels and cockles sent to the
Liverpool laboratory where, along with Mr. Walter
Tattersall, B.Sc., and Mr. J. Pearson, B.Sc., I made (in
October, 1902), an independent examination of them with
results that do not altogether agree with Dr. Jameson's.

We may distinguish between 4 kinds of mussels,
examined by Jameson and myself, as follows :-—

(A.) From the beds opposite the Piel Hatchery—* where
every specimen is abundantly infected . . . -
and almost every specimen contains pearls
(Jameson).

(B.) From the piles of the old pier at Piel—* practically
without parasites ’’ (Jameson).

93

(C.) From Roosebeck Sear, outside Barrow Channel—
“not infected ”’ (Jameson).

(D.) Roosebeck Scar mussels transplanted to foreshore
at Piel two years ago—“ all were infested ’’—‘“‘ each
contained several small pearls ” (Jameson).

Of (A.) I examined a sample of 25 mussels, which
contained in all 151 pearls and 11 parasites, but 4 of
the specimens had neither pearls nor parasites, and
no less than 18 out of 25 had no parasites. I
cannot therefore agree that “ every specimen is
abundantly infected.”

Of (B.) I examined also 25 mussels, which showed in all
21 pearls and 22 parasites, 7 had neither pearls nor
parasites, and 13 had no parasites. These then
showed far fewer pearls than (A), but twice as many
parasites, and fewer of them were free from infection.
They can searcely be called “ practically without
parasites.”

Of (C.) I examined 28 mussels, which contained 73
pearls and 37 parasites, 4 had neither pearls nor
parasites, and only 9 (out of 28) had no parasites.
These then are evidently just as much infected as
the mussels on the Piel foreshore. (A.)

Of (D.) I examined 24 mussels and they contained 65
pearls and 26 parasites, 3 had neither pearls nor
parasites, and 12 out of 24 had no parasites. So in
place of these transplanted ‘‘ Roosebecks ”’ having
become more infected on the Piel shore, they on the
whole showed rather less infection than the mussels
taken direct from the parent bed.

Finally, | examined a sample of 25 cockles from Piel,
and found in them eight pearls, but no parasites at all of
the right kind. This does not support the view that the

94

cockle contains the earlier stage of the parasite, and passes
it on to the mussel.
A couple of weeks later, at the end of October, 1902,
Mr. Scott and Mr. Johnstone being together at Piel,
examined some further samples with the following results :—
(A.) Examined 61, got 390 pearls and 191 parasites.
(B.) Examined 103, got 100 pearls and 61 parasites.*
(D.) Examined 53, got 161 pearls and 66 parasites.
(Roosebeck Scar mussels could not be got at the time).
The most noteworthy difference between these results
and mine are in the case of the parasites in (A.), where Mr.
Scott found about seven times as many as we did. The
sample of (B.), in this case also, it will be noticed, is by no
means free from infection. Since then Mr. Scott has ex-
amined a few more samples with slightly different results :
but I do not wish to attach too much weight to any of
these figures. The point I desire to make is that in
working with these comparatively small samples each
examination gives a different result, and that consequently
it is necessary that some one lke Mr. Scott, living on the
spot, with abundance of material at hand, and with tanks for
experiments under constant observation, should make a
comprehensive investigation of some hundreds of each kind
of mussel and cockle, in order to clear up the distribution
of pearls and parasites, and settle the question of infection.
Prof. McIntosh + describes the examination of 700
mussels from near St. Andrews, and finds that 300 in
all, or nearly 48 per cent., were pearl-bearers—a small
proportion compared with ours at Piel.

}Ann. and Mag. Nat. Hist., June, 1903.

*As this was going to press Mr. Johnstone informed me that
before he made the examination referred to a gale had washed away
some of the piles of the old pier, and that his sample of (B) was
obtained from a lower level than Jameson’s, and so may have

“ contained more parasites.

Prof. R. Dubois has recently turned his attention to the
Mediterranean Coast. He found that the Southern French
mussel (Mytilus yallo-provincialis) forms pearls caused by
another Distomid, distinet from that of Brittany. He then
worked at the acclmatisation of a true Oriental Pearl-
Oyster (‘‘ Pintadine’’) in French waters, and the artificial
production of pearls.* He brought the pearl-oysters from
the Gulf of Gabes, in South Tunis, to the marine laboratory
at Sfax, and caused them to multiply and increase in size.
The pearls produced in Tunis are small and very rare—
it is necessary to open 1,200 to 1,500 oysters to find one
pearl: but Dubois tells ust that by placing them on ground
where Mytilus gallo-provincialis becomes infested with
pearls and parasites, he very easily provoked the pro-
duction of fine pearls in the “ pintadine ” to such an extent
that three successive individuals opened contained each
two little pearls.

This, if corroborated, is a remarkable circumstance
from several points of view. First it will, if it proves a
success, be a striking verification of what Kelaart in
Ceylon, fifty years ago, declared might be done. Secondly,
if the ‘‘pintadine”’ in question is really the same species
as the Ceylon Pearl-Oyster (Giard considers that it is not),
it is curious that a Distomid parasite should prove to be
so efficacious in setting up pearl-formation, since Mr.
Hornell and I found in the Gulf of Manaar that the
pearl-parasite is a Cestode of the genus T'etrarhynchus.
Thirdly it is remarkable that the parasite of the Mytilus
should transfer itself so readily to a new host belonging to
a distinet family.

* Comba had, however, in 1898, introduced the same molluse on
the south coast of Italy, and experimented in artificial pearl
formation.

+ Comptes rendus, Acad. Sci,, 19th October, 1903, p, 611,

96

It is this last paper by Dubois that has given rise
to various more or less exaggerated or even erroneous
statements in the public press, such as that the Pearl-Oyster
must be infected with a microscopic germ in order to
render it pearl-producing: or even that imoculation with
a serum causes the oyster to produce artificial pearls. The
parasite that causes the irritation is, as has been known
for many years, not a “germ,” and still less a “serum,”
but a worm which is visible to the eye

a worm which in
Mytilus seems to be usually a Trematode, and in the
Ceylon Pearl-Oyster (Margaritifera vulgaris), according to
Mr. Hornell’s and my observations, is certainly a Cestode.
According to an interesting note by Prof. Giard* the
discovery of Cestode larvee as nuclei of pearls, which we
made upon the Ceylon Pearl-Oyster in 1902, has been
corroborated by M. G. Seurat, working imdependently in
his laboratory at Rikitea in the island of Mangareva
(Gambier Archipelago). The oyster on which Seurat
worked was a Meleagrina, and the Cestode parasite found
is, according to Giard, an Acrobothrium, or some allied
form. It is possible that some of our Ceylon Pearl-Oyster
parasites may also belong to the genus <Acrobothrium,
although others of them are certamly Tetrarhynchids.
Giard, in a further note in the same Journal (p. 1225),
discusses the statements that have been made in regard to
“margarose artificielle,’ and evidently considers that
Dubois’ claim to have established the artificial production
of pearls is not yet justified by the facts. Last of all M-
L. Boutan+ shows that fine pearls do not really differ from
nacre-pearls, smce both are secreted from open or closed
epithelial sacs, derived from the epidermis; and Giard

* Comptes rendus, Soc. Biol., Paris, 6th Nov., 1903, lv., p. 1222.
+ Comptes rendus, Acad. Sci., 14th Dec., 1903, p. 1073.

97

very properly replies a few days later* that this fact is quite
in accord with general principles, and was previously
known. M. Boutan in a letter (20th Jan., 1904) informs
me that he is on the point of departure for the East in
order to investigate the matter further.

Notwithstanding this recent activity, especially amongst
our French neighbours, there is still a good deal of work to
be done before the whole process of pearl formation can be
considered as cleared up. We want to know especially :—
Ist, The exact details of formation of the pearl-producing
epithelial sac when deeply placed in the tissues, and 2nd,
the complete life-history of the parasite inside the sac.

* Comptes rendus, Soc. Biol., Paris, 19th Dec., 1903, p. 1618.

a
C2

98

SEWAGE AND SHELL-FISH.

By W. A. Herpman.

The first ‘ Laneashire Sea-Fisheries Memoir”
(Oysters and Disease), by Prof. Boyce and myself in 1899,
drew attention to the serious amount of sewage contamina-
tion in certain samples of shell-fish. Since then much
additional evidence has been obtained, both in our own
district and also from other parts of the coast, that, as the
result of the discharge of unpurified sewage into tidal
waters, extensive pollution of the shell-fish beds and of the
waters generally of our coastal fisheries takes place—
causing serious injury to health, and affecting the
prosperity of the fishing industries. It has now been
established, and is generally admitted, that shell-fish
contaminated by sewage may produce enteric fever and
other illness in human beings.

Mr. Dawson and I, in the evidence we gave before the
Royal Commission on Sewage Disposal, both discussed
cases of serious contamination of shell-fish beds in our
district. Since then, however, Mr. Dawson has made a
special survey of the mussel beds, and has drawn up a
report which, with his permission, I insert here in order
that it may be placed on permanent record. This report
was submitted to the Lancashire and Western Sea-
Fisheries Committee last November, and has since been
made public,

9Y

Report by Mr. R. A. Dawson, Superintendent Lancashire
and Western Sea Fisheries, on the Mussel Beds
of the District with reeard to danger of pollution
by sewage.

“At the last meeting of the General Purposes
Committee, held on the 14th August, | was instructed to
lay before the Committee, at the next meeting, a list of
‘Mussel beds, in my opinion, contaminated by sewage.
Together with Dr. Sergeant (the Medical Officer of Health
for the County of Lancaster), Mr. Halliwell (Chief
Inspector of the Ribble Watershed), Mr. Scott (the
Resident Scientist at Piel), and others, I visited and
inspected the sewage outfalls in Barrow Channel, Ulverston,
Morecambe, and Heysham, and the Mussel Beds in the
Lune. I have also inspected the different sewer outlets im
other parts of the District likely to cause contamination
to Mussels.

The sewage from Barrow and Dalton is discharged into
Barrow Channel in great volume, and has the appearance
of being untreated. This sewage joins the stream in the
Barrow Channel, and together they flow over the different
erounds where Mussels ave found. On the day we were
there, the sewage was being discharged as late as low water.
I may remark that, although some Mussels are taken
from here for human food, the bulk are only used for bait:
Periwinkles, however, are taken in large numbers, and
London seems to be the chief Market for them. The sewage
from Piel also flows into the Barrow Channel.

At Ulverston, although some treatment is attempted,
the effluent appeared to me to be very dirty. This
discharge joins the main stream at the west end of the
Slag Bank, about a mile above a Mussel sear; they flow on
together round the edge of the Mussel scar at low water

100

and down Channel over other scars; earlier on the ebb
tide the stream will flow over the first sear.

At Morecambe and Heysham there are in all eight
sewer outlets, all of which discharge some considerable
distance away from the principal Heysham Mussel Beds.
At the same time, three of them empty close to where
sizeable Mussels can be taken in payable quantities. I
understand, however, it 1s the intention of the Authorities
to turn all the Morecambe sewage out through a new pipe,
which is now laid down and in use, and to do away with the
old sewers referred to. With regard to the new sewer
outlet, it does not, to my mind, project far enough into the
channel, and should be carried about 75 yards farther out.
It discharges on a sear which, although not a main bed, is
one where sizeable Mussels can be obtained in fair
quantities, and this scar might easily become well stocked
with fish. The fishermen agree that the sewer outlet
should be carried farther out. I may also draw attention
to the fact that, at the time I refer to, the sewage was being
discharged at low water, and, although some of it is -
supposed to be treated, what we saw appeared to me to be
untreated.

In the Lune the, sewers discharge a considerable
distance up the river, above the Mussel Beds; and
although they join the main stream which flows alongside
and, in some states of the tide, over Mussel Beds, there
was nothing we saw that, in my opinion, exposed the fish
to serious danger of contamination. In the Wyre, with
the exception of a sewer outlet at [Knott End, the sewage
is discharged on the Fleetwood side of the river, and some
distance from the Mussel Beds. In the Ribble the Preston
sewage is dealt with at the sewage farm: but at Lytham
the sewage joins the main stream and together they flow
on over the Mussels attached to the traming walls, and

101

over the Chureh Sear Mussel Bed about a mile below

Lytham. At St. Annes the sewage is discharged not far

from the Mussel Bed. and flows with the ebb tide over it.
In the Mersey five sewers discharge about the

Kevemont Mussel Bed, one on to the bed, and the other
four

although the pipes have been carried down to low
water—discharge close to the bed, and in fact over that
portion which does not come adry. A few Mussels are at
times also taken near the sewer mouth at Rock Ferry.
The Wallasey Bed les some distance below the sewer
outlet at New Brighton.

At Ithyl very few Mussels are taken. In the Conway
river there are valuable Mussel Beds. The principal beds
lie a considerable distance below the sewer outlets; but
Mussels are found and taken near the Deganwy sewer
outlet, and also not far from the Conway sewer outlet.
Opposite Deganwy, and in the Channel, a large strike of
Mussels has taken place which extends along the opposite
side of the river for a considerable distance, both up and
down stream.

At Portmadoc the main sewer empties into an open
ditch or stream about 1,000 yards above the harbour, and
then flows on through the harbour down channel seawards.
There are also two smaller sewers, one which empties into
the harbour and the other just above it. Mussels are
taken in the harbour and in different parts of the channel
over which the sewage and stream together flow. Mussels
are also taken from the scars which he to the south of the
harbour. At Barmouth the sewage is discharged a con-
siderable distance below two of the beds. The third bed is
situated opposite the sewer outlet, but on the south side of
the river—the sewage being discharged on the north side.
In the Dovey, the Aberdovey. sewage outfall enters the
main stream about 220 yards below a Mussel Bed, and 650

102

yards further down stream there is a second bed. The
sewage is mixed with a large quantity of water on joining
the main stream, and is carried seawards over the bar—a
short distance away—on the ebb tide.

| have thought it better to describe the different
sewage outfalls at length, in order that tle Committee may
know their position in relation to the Mussel Beds.

As regards the list of Mussel Beds which, in my
opinion, are contaminated with sewage, | think there can be
little doubt that grave danger to health exists i eating
Mussels gathered from the Egremont Bed. Here we have
direct evidence that death has resulted from eating
Mussels gathered near the Egremont Ferry slip. At the
moment there are not many sizeable Mussels left, but on
tides which cause big ebbs a number of persons may
be seen gathering them. A strike of young Mussels has,
however, recently taken place, and the fish are now growing
fast. Considermg the very large quantity of sewage
discharged into the Mersey in this neighbourhood, I am of
opinion that Mussels should not be removed for human
food between Rock Ferry and New Brighton. To this
there can be no reasonable objection. The fishermen
are not dependent on Mussels from this place ; the beds
are of little value; and the danger to health from
eating them is, I think, a serious matter. With regard to
other Mussel Beds, I hesitate to report on them, pending
Dr. Sergeant's report to the Public Health Committee for
Laneashire, and the report of the result of the analysis of
the samples of the water taken by Mr. Halliwell from the
vicinity of the beds.

The whole question of pollution of Shell-fish by
sewage is both a difficult and complecated one. In the
case of the Egremont Bed, which is practically situated in
the centre of sewage deposit, there can be little doubt as to

105

the advisability of prohibiting Mussels being removed for

human food: but there are other places where—although
sewage outfalls are nearer the Mussel Beds than one could
wish—the deposit is mixed with a large quantity of water,
and there is no direct evidence that the fish are in anyway
polluted. To my mind it would be of assistance in safe-
guarding the public if samples of Mussels were regularly
sent to the Laboratories, examined by experts, and when
found polluted the Sea Fishery Committees should have
power to temporarily close the bed pending further action
by the different County Authorities, Local Government
Board, or Board of Trade.”

It will be seen that in this report, made in October,
1908, Mr. Dawson recommends that when samples of
mussels were found to be polluted the Sea Fisheries
Committees should have power to temporarily close beds
pending further action by County and Central authorities.

As a result of Mr. Dawson's report, samples of mussels
from the Mersey were sent to the Liverpool Sea Fisheries
Laboratory for inspection, and I give below the report
which I sent in as the result of Mr. Johnstone’s bacterio-
logical examination. This report has also been laid before
the Committee and made public, and has been submitted
to Lord Onslow at the Board of Agriculture and Fisheries.

Bacteriological Report on Mussels collected at Rock Ferry,
on 4th November, 1903.

“The mussels brought to the laboratory were rather
small, and the fish were very thin and soft. The mantles,
or parts of the body where the spawn should be developing
rapidly at this time of the year, were very thin. ‘The
byssus or ‘ weed’ was very easily torn away. ()uite apart
from the question of sewage contamination, the fish were in
very poor condition as articles of-food.

104

Sufficient time has not yet elapsed to make a complete
bacteriological analysis of the mussels. We have only
attempted to demonstrate whether or not the mussel bed
was grossly contaminated with sewage matter, and whether
the fish had been feeding on the sewage. The stomachs of
a dozen fish were examined, as well as the water in the
shells. All the stomachs, with the exception of two (which
were sterile), contained sewage bacteria in quantity.

In the examination of the stomach contents, cultures
were made on phenolised agar, on Dr. Grunbaum’s neutral-
red, bile-salt, agar medium. and in milk tubes. The object
of the first two ecultivations was to isolate bacteria of
intestinal origin, and of the latter, to isolate Bacillus
enteritidis sporogenes. Hardly any bacteria except those
belonging to the ‘ colon-group’ and the ‘typhoid-Gaertner ’
eroups grow on these media. The presence of colon
bacteria in any quantity in water or in an article of food
is regarded by most bacteriologists as undoubted evidence
of fecal contamination. Bacillus enteritidis sporogenes
is a virulent bacterium which is regarded by Dr. Klein as
the cause of certain outbreaks of epidemic diarrhea. The
presence of these bacilli together is regarded as certain
evidence of sewage pollution.

Both of these groups of bacteria were found in nearly
all of the mussels examined. Colon bacteria were abundant
in all the cultures made. Bacillus enteritidis sporogenes
was not so abundant, but was present in all the special
cultures made to determine its presence, and gave all the
characteristic reactions. There is no doubt then, that this
mussel bed is grossly contaminated with sewage matter,
on which the shell-fish have been feeding, and_ that,
consequently, if used as food these mussels may be, in
certain circumstances, the source of grave danger.”

105

Since that date other samples of mussels from various
beds have been examined bacteriologically in our laboratory,
and in these also extensive pollution by sewage organisms
has been demonstrated. I wish to state that in all cases in
which sewage contamination has been reported we have
not relied upon the bacteriological evidence alone. We
have used it as the corroboration, not as the sole proof.

It is evident to anyone who has watched recent
investigations that we must have still further knowledge in
regard to the distribution of the organisms of the “coli”
group in nature, and of the bacteriology of the absolutely
clean shellfish before we can place implicit trust in bacterio-
logical results taken alone. Professor C. A. Fuller, of
Brown University in the United States, read a paper on
“The bacterial flora of the Oyster’s intestine,” before the
Society of American Bacteriologists, in March, 1903, in
which he gave the results of extensive studies of the oysters
of Narragansett Bay. He found that the ‘ coli”’ organisms
do not occur in oysters from clean sea water far from shore,
but are present in those nearer land and in less pure water.
He concludes “ From the results of these experiments it
appears that the colon bacillus is not normally present in
the intestine of oysters, and when present always indicates
contamination.”

Also Miss Chick shows (Thompson-Yates Reports,
vol. 3, pt. 1, pp. 1-29, and pt. 2, pp. 117-129) B.coli is not
found at all in any unpolluted soils and fresh waters.
When it was found there was always other evidence of
sewage pollution. It was not found in dry road dust. It
does not withstand even a short exposure to drying. (If
it is found in the sea it apparently always comes from
polluted land drainage).

On the other hand, in the recently issued Fourth

Report of the Royal Commission on Sewage (1904) we
H

106

find that Dr. Houston examined for the Commission over

oe.

one thousand oysters, from “ some of the purest waters,”’
and from others “ obviously lable to pollution,” with the
result that nearly all the oysters, ‘from whatever laying
they were taken, contained Bacillus coli communis, or other
B. coli closely allied to it.” Dr. Houston found, however,
a very much smaller number of these organisms in the
oysters stored in pure waters than in those from polluted
waters. Consequently the Commissioners state that they
should not be justified in recommending that the closing
of a bed or laying should depend as a matter of routine on
the results of a bacteriological examination—which is very
much the conclusion at which we had arrived, and the view
that I gave in my evidence.

In taking samples of suspected shell-fish I would
attach great importance to personal supervision by a
scientific or fisheries expert. The samples should obviously
not be taken by the parties interested, and they should not
be taken by disinterested, but untrained collectors who
may miss seeing some qualifying factor or some important
piece of evidence. A knowledge of the local conditions, of
the influence of tidal and other currents, and of prevalent
winds, may be of great value in judging of the presence and
extent of pollution, and of the parts hable to be affected at
a particular time of day or month. Consequently a
personal examination of the locality by a scientific man
is always important. Samples from various parts of the
same bed may have to be taken at different states of the
tide, and these should be chosen with knowledge and
discrimination.

Any additional evidence that can be obtained from an
inspection of the physical and biological conditions on
the bed is all the more important because of our want of
exact knowledge as to the meaning and yalue of some

107

bacteriological results. The topographical observations
and the laboratory work ought always to be considered
together, and must be regarded as parts of the same
investigation conducted by the one authority. The
bacteriological examination may at once confirm the field
work in such a manner as to leave no doubt as to the
purity or pollution of the locality, or it may give useful
indications which suggest the necessity for further observa-
tion of the local conditions. It may also give a measure
of the amount of pollution. “The question has been
raised as to whether it is possible to fix a standard of
pollution which should be regarded as dangerous to health.
Can we say that all samples yielding say 10, or say 20
B. coli per ec. c. must be condemned, but that those
showing less than say, 5 per c. c. may be tolerated /
Before answering such a question we must have further
investigations. There are still teo many of the points
involved which are left in doubt. For example, we cannot
be certain that all samples yielding 10 BL. coli per c. c. are
equally dangerous. Even if we assume (as we probably
may safely do) that pure oceanic sea-water is free from
B. coli and allied organisms, and that these are to be
taken as an indication of some sewage contamination,
we do not know how remote im time the pollution may
have been and how comparatively harmless from a
pathogenic point of view it may have become. It is
possible, or even probable, that B. coli may be distributed
to considerable distances in the excreta of fish and sea-
birds, possibly with some modification. Then again the
bacteriology of the shrimp’s alimentary canal requires
examination, and we may add the fishes that feed upon the
shrimp. There are also other sewage feeding invertebrates
that may conceivably pass on some organisms and not
others, and may favour the distribution of B. coli under

105

circumstances that deprive its presence of any special
significance.

I am not arguing against the value of bacteriology, but
against a possible abuse of the method, and in favour of a
much wider investigation in which the laboratory work will
in all cases be supplemented, guided and inspired by the
marine biologists’ work in the field. The case of each
estuary, bed, or laying must be regarded as a separate
problem to be solved with a full knowledge of all the local
conditions.

109

SYLLABUS OF THE LESSONS GIVEN IN THE
CLASSES FOR FISHERMEN.

Two lessons are given each day, each lesson lasting for
about two hours.

First Day.

The work of the first lesson is introductory, and will
deal with the use of the microscope and dissecting tools.

Before going on to the study of fishes and other
marine animals, it is necessary to learn something about
water and ai, so as to understand the way in which
animals breathe.

The Atmosphere.— Air consists chiefly of three gases,
nitrogen, oxygen and carbone acid gas. In every 10,000
parts, by bulk, of air there are a little less than 2,100
parts of oxygen, about 7,900 parts of nitrogen, and about
four parts of carbonic acid gas.

The oxygen of the air is necessary for the breathing
of animals and plants, and for combustion. Without it
animals or plants would not live, and fuel would not burn.
When an animal breathes, oxygen is taken into the body,
and combines with certain substances in the muscles and
elsewhere, producing mechanical energy and heat. When
a piece of charcoal or coke burns in the air, it combines
with oxygen.

Nitrogen is not really necessary for breathing or for
combustion. It merely serves to dilute or weaken the
oxygen.

Carbonic acid gas in the air comes principally from
the breathing of animals and from combustion of fuels.

110

Water is made up of oxygen and another gas
called hydrogen. But water also contains air dissolved
in it. When water is boiled, it loses its air, and until it
dissolves more air marine animals, like fishes, can not
live in it.

Experiments will be made in order to prove these
statements.

The Breathing of Animals.

Most large animals that live on the land breathe by
means of lungs. Oxygen is taken into the substance of
the body, and carbonic acid gas is given out. Plants also
breathe in oxygen and give out carbonic acid gas.
Marine animals obtain their oxygen from the sea water by

means of gills mstead of lings.

Second Day.
The Structure of a Fish.

The stomach, the liver and the digestion of the food.

The blood, heart and gills; the circulation of the
blood through the body.

The red blood of a fish consists of a clear colourless
liquid, in which there are a great number of small reddish,
oval particles, about 5,4, part of an ineh in diameter.
These are the corpuscles, and their use is to carry the
oxygen to the tissues of the animal.

The heart is a force-pump, which propels the blood
all through the body. From the heart the blood goes to
the gills, where it takes in oxygen from the water, and
gets rid of its carbonic acid gas. It then flows in the
blood vessels all through the body.

The brain, the nerves and the senses.

The Breeding of a Fish.— Fishes are either male
or female, but with the exception of the skates, rays,

111

sharks and dogfishes, there is no direct connection between
the male and female at the breeding season.

The generative organs are the parts of the body in
which the spawn is formed.

Toe Mate Fisu.—The generative organ is the testis
or soft roe; the milt is formed in this. The milt consists
of sperms.

THe Femate Fisn.—The generative organ is the
ovary or hard roe: the spawn proper is formed in this.
The spawn consists of eges.

Shel

-Head-biece.

rave. Tail—=piece
or

Flagellum

se EEE
Ss
Microbyle

The sperm of a fluke The egg of a fluke magnified
magnified 1,500 dia. 30 dia.

Fertilisation.—tThe way in which the eggs of
a fish, such as the flounder or cod, are fertilised will be
shewn in the hatchery. If the eggs are simply taken
from the female fish, and allowed to remain in clear sea-
water, no development takes place. But if the milt from
the male is mixed with the watey in which the eggs are
floating fertilisation takes place. One sperm enters each
ege through the micropyle, which then closes. The

development of the egg then begins.

112

At the spawning season the eggs and milt are shed,
and drift about in the sea. Fertilisation then takes place
as deseribed above.

The eggs of all the flat fishes, and of most round
fishes (the cod, haddock, whiting, gurnard, sprat, &c.)
float near the surface of the sea. The eggs of the skate,
rays and dogfishes, herring, and some other fishes (which
are not used as food) sink to the bottom, and pass through
their development there.

The average number of eggs spawned by a single
female fish in the course of one season are :—

In the Turbot ... eh a 8,600,000
5 od oe BS. ee 4,500,000
os ie Oleg a2 2 oe 570,000
» Haddock ae rae 450,000
js,” pe eGes he ey. ae 300,000
, Whiting ey ee: 120,000
<a) blerrimnat. oe ie 31,000

» Skates, rays and dogfishes, about a
dozen or less in the season.

THirp Day.
The Mussel.
The structure of the mussel.—tThe
mouth and stomach; the gills; the mantle; the foot or

ce

“tongue ’’; the byssus or “ weed.”

The feeding of the mussel.—tThe mussel
feeds “by suction.” Its food consists of exceedingly
small animals and plants that float about in the water.
The water containing this food is sucked into the cavity
of the shell and the food is then taken into the mouth.

The mussel breathes by means of its gills. When the

vill is examined under the microscope it is seen to consist

118

of very fine threads or filaments. These are hollow tubes
and blood from the heart flows down inside them. Hach
filament is covered by an immense number of very small
hairs or celia, and as long as the mussel is alive these are
waving backwards and forwards and causing a current
of water to be sucked into the shell. This current passes
over the gills towards the mouth. The food is strained
by the gills, caught up by the lps, and taken into the
mouth. At the same time the oxygen in the water passes
through the filaments of the gills into the blood and the
carbonic acid of the blood passes out into the water.

Diagram of the structure of a mussel. Natural size.

Breeding of the mussel.—Mussels are
male and female. It is impossible to tell the sex except
by examining the animal microscopically. The eggs and
milt are contained in the mantle. Spawning takes place
in the spring, and immediately on spawning the fish
become thin and in poor condition because the eggs and
milt have been expelled from the body.

The little animal which hatches out from the egg is
not at first like a mussel, and it swims about in the water.

I

114

After a time it grows a shell and settles down as a fully
formed little mussel.

Sperm.

Various stages in the growth of the mussel. (All magnified).

The Development of the Flounder .—
Eggs of the flounder will be examined with the micro-
scope every afternoon. On the second day of the class a
number of eggs will be taken from several female fish, and
these will be fertilised by milt from male fish. A sample
of this batch of eggs will be examined every afternoon,
and the little fishes studied as they form inside the egg-
shell. These fish will hatch out in from seven to ten days,
according to the temperature of the sea-water.

FourtH Day.

The Tow-net and Plankton.

Although the sea-water may look perfectly clear, yet
it nearly always contains great quantities of very small
animals and plants. These can be caught by means of a
tow-net, which is a small net made of fine silk, or muslin,

115

with 100 or more meshes to the inch. It is towed slowly
behind a boat, and when it is fished the catch is shaken
out into a bottle of clean water.

Examination of a tow-netting taken im Barrow
Channel. (Such a catch will be examined in the class.)

The commoner things present in the tow-netting.

Diatoms.—these are very small plants, some of
which live in the sand and mud at the sea bottom, but
most of which float about in the sea. hey are yellow-
green in colour. Their bodies are enclosed in hard, glass-

hike, flinty shells.

=,

SS
Dee ee SU
ease?

ar
aero
SED
be

i)
;
>
a>
SS
a)
Ie,
pace ieeres ty

3
%
&
si
o

Diatoms.—1 and 2 are floating diatoms, but 3 to 6 live
at the bottom. All highly magnified.

Diatom Ooze.—In some parts of the sea far
away from land and in very deep water (about 2,000
fathoms) the mud at the bottom is soft and white, and
when ‘it is examined with the microscope it is seen to
consist of nothing but diatom shells. These little plants

116

are so extremely abundant in the sea, that when they die
their dead shells fall to the bottom, and form a layer of
mud or ooze.

The difference between an animal and a plant.

Most animals have a very different appearance from
plants, but in the case of diatoms, and other small
creatures, it is quite impossible to tell by their appearance
whether they are animals or plants. The real difference
hes in the methods of feeding.

An animal must live on food which is either alive, or
has been alive. So animals feed on the living or dead
bodies of other animals or plants.

A plant lives on material which has nevet been alive
—~on the carbonic acid and the substances containing
nitrogen, which are in the air or are dissolved in the sea-

water.

Maenified about 70 dia.

Noctiluca.

N oetiluca.—tThis is a small animal which is
always present in some parts of the Irish Sea during the
summer. It is sometimes so abundant as to colour the
water brown. It is simply a httle round blob of jelly-like

material. It feeds on diatoms, and these will usually be

117

seen inside its body. It is one of the things which cause
the phosphorescence, or “ fox-fire,” of the sea.

Ceratium is another small animal which is some-
times extremely abundant in the sea. It forms a large
portion of the food of some small fishes.

Firtu Day.

Copepods.—These are the most abundant animals
in the sea. ‘They are very small animals belonging to
the same class as the shrimp. Many young fishes live on
them, and they are the principal food of many full-grown
fishes like the herring and mackerel.

A Copepod.—Magnified about 45 dia.

The arrow worm isa little worm about an inch
long. It is nearly always found in the sea. It forms
part of the food of some fishes and it is said to eat fish
eggs.

Other common animals found in the tow-nettings.

Food of marine animals.—tEverything in
the sea lives on something smaller than itself. But this
cannot go on without coming to a stop, and in the long

118

run we find that the smallest animals in the sea live on
the Diatoms.

Thus—

The Cod feeds largely on Crabs,
The Crab _,, Rp} ,, Worms,
The Worm ,, . ,, Diatoms.

The Plaice feeds largely on Shellfish (mussels and
cockles),
Shellfish _,, ‘A , Diatoms.

The Herring and Mackerel feed largely on Copepods,
Copepods feed on Diatoms.

So everything im the sea depends for its food on the
Diatoms or on other plants living in the sea. The
Diatoms and other plants feed on the carbonic acid in the
sea water and on substances containing nitrogen which
are washed down from the land into the sea.

A number of pictures will be shown by the lantern on the
last afternoon of the first week of the class. These pictures
will be explained, and they will illustrate the work of the first
week.

SrxtH Day.
The structure of Fishes.

Skates and Rays and Dogfishes.—
These fishes difter in many ways from the round fishes
like the cod and haddock. Their bones are gristly, they
breed in a different manner, and their gills are different.

The structure of a skate—Its bramang
nerves; the ear; the heart, stomach and intestine; the
gills.

119

The electric apparatus of a skate; other fishes with
electric apparatus.

Breeding.—NSkates, rays, dogfishes and sharks
breed quite differently from all other fishes. In the case of
most round fishes, flukes and soles, the eggs and milt are
shed into the sea and fertilization takes place there so that
there is no actual connection between the male and female.
But in the case of the skates, rays, dogfishes and sharks
the male makes connection with the female at the breeding

Flounder

@
Plaice

@
Halibut.

Eggs of various Fishes.—All natural size.

season and the milt is passed into the body of the female
and fertilizes the eggs before they are shed.

The eggs of these fishes are quite different from those
of the other fishes. They are very much larger and they
are enclosed in a hard horny case called the purse.

Then most other fishes lay a great number of eggs at

one time (30,000 to 9,000,000), while a skate or dogfish

only lays two. But the other fishes only spawn during
one or two months during the year, while the skate
probably spawns during most of the year.

The plaice and ‘*dab.—tThese fishes (and also
the other flukes and the sole) are very like the round fishes
as far as their structure and method of breeding is con-
cerned. But they are flat instead of round. The
coloured side of a plaice is not its back, but is really its
right side. Its head has been twisted so that both its
eyes appear to be on the right side of the body.

The sole and solenette.—tThe solenette is
often mistaken for a young sole. It never grows to more
than about five inches in length. It differs in appearance
from a young sole in being redder in colour and in having
bigger scales. If a solenette of 4-5 inches long is opened
about March, spawn will be found in it—-either eggs or
milt. This shews that it is a full-grown fish. Spawn
will never be found in a sole of the same size.

Male and female soles.

Sizes at which fishes spawn.—A fish
is called mature when it spawns for the first time. The
sizes at which various fishes come to maturity differ.

The Plaice becomes mature at about 15 inches long.

Dab a 56 6% 9)

Flounder .., 6 ' 11

Sole i . hs TOUNAS .

Cod 24 é ‘, 5 Opes

Haddock .,, a is 1a "

Whiting .., » ‘. DW ile -
These are the average sizes for the females. The

males are usually smaller than the females, and also
produce mult for the first time at a smaller size.
The sprat and herring.—tThis is another

121

case like the solenette and sole. ‘I'he sprat differs from
the herring of its own size in having a row of prickles
along the edge of the belly. It is a full-grown fish, and
produces ripe spawn when it is about three inches long,

whereas the herring does not become mature till it is over

eight inches long. The eggs of the herring sink to the
bottom when they are spawned. ‘The eggs of the sprat

float on the surface.

SEVENTH Day.

The Shrimp and Crab.

The Shrimp.—trhe stomach, liver, ovaries and
testes.

Breeding of the Shrimp.—Difference
between the male and female shrimp.

All shrimps carrying “berries,” or eggs, are females.
The males never carry berries. All shrimps without ege's
are not males however, for some may be females which
have hatched out their eggs. The males are always
smaller than the females, and not so numerous; but the
only certain way to tell the sex is to examine their legs.
The fifth pair of legs, counting from the tail, are different
in male and female.

Also, if the shrimp is opened up, and the generative
organs examined, it will be seen that the male produces
sperms, while the female produces eggs.

Spawning.—The shrimp spawns twice in the
year—in the late spring and in the autumn. When it
spawns the eggs pass out of the ovaries and become
fastened on to the legs. The mother then carries them
till they hatch out, which takes place some months after
spawning. When newly spawned the eggs are white, but
the nearer they are to hatching the darker they become.

122

A large berried shrimp carries about 5,000 eggs.

Examination of the eggs under the microscope. Also the
berries will be hatched in the tanks and the newly-hatched
little shrimps exanuned,

The Lobster breeds in just the same way as the
shrimp, except that it spawns only once in the year.

Male and female lobster.

The Crab—tThe stomach, liver, ovaries and
testes.

Three stages in the growth of the Crab. (All magnified).
Ps
The “Casting” of the Crab-—the shell
the crab is * cast,” or thrown off, many times during the
first year of its life. Afterwards it casts its shell about
once in each year. Growth only takes place while the
crab is “ soft,’ and before it grows a fresh shell.

1B}

A female edible crab becomes mature for the first
time, and produces spawn, when it is about five inches
broad.

Rate at which the Shrimp Breeds —
The shrimp produces on the average about 5,000 eggs. If
there were no destruction in the sea, and all these eggs
developed into young shrimps, then starting with a single
pair of shrimps—

one male shrimp |

. - 1st generation.
one female shrimp |)

The female spawns 5,000 eggs, which develop into

4000 females |

- Ynd generation.
and 1000 males ) 8

At the next spawning each of these 4,000 females will
spawn 5,000 eggs, that is 4000 x 5000=20,000,000, and
they will develop into

16,000,000 females | ard kj
, - 3rd generation.
and 4,000,000 males — } 3 4

At the next spawning again each of these 16,000,000
females will spawn 5,000 eggs, that is 16,000,000 x 5000
=80,000,000,000, and these will develop into

64,000,000,000 females ie Paes ea atc
and 16,000,000,000 males ) °°

Thus if we start with two shrimps, and imagine that they
only breed once in their lifetime, and that all the eggs
come to maturity, then in the fourth generation we shall
have 80,000 millions of shrimps, and at the fifth genera-
tion there would be spawned 820 billions of eggs.

Hienrnm Day.
The Cockle.

Structure.Mouth and stomach, foot, siphons,
gills, manner of feeding and breathing; male and female
cockles.

Food of cockle—tThe cockle like the mussel
and oyster feeds by “suction.” It gets its food from the
diatoms and other microscopic life which are present in
the water sucked into the shell by the action of the gills.
These diatoms, &c., are to be seen in the intestine of the

cockle, mixed with a great quantity of sand and mud.

Exhalent

2 = a
ZY S

*=74 Inhale
ee Siphon

Diagram of the structure of a Cockle.

The Oyster.

Structure of oyster
heart.

Manner of feeding and breathing.

mouth, palps, gills, stomach,

Male, female and hermaphrodite oysters.

Different kinds of oysters—Deep-sea oysters,
American oysters, Portuguese oysters.

Tropical oysters, pearl oysters, pearls and pear! shells.

Pearls in the common mussel. The parasite which
is the cause of the pearls.

Artificial cultivation of oysters in France.

125

Ninto Day.
Fish Parasites.

Nearly all animals harbour parasites. | When one
animal lives attached to another, either clinging to the
skin, or living inside the body, and feeding on the blood or
juices of the animal to which it is attached, it is called a
parasite,

Thus the fish-louse found on the skin of the flounder
is a parasite of this fish, and the flounder is said to be the
host of the fish-louse.

But the pea-crab which lives inside the shell of the
mussel is not a parasite, for it does not live on the blood
or juices of the mussel. It gets its food from the small
animals and plants in the water which enters the shell of
the mussel.

The little white warts which are occasionally found
on the skin of the flounder are also parasites, and not the
egos of the fish as many fishermen imagine.

Barnacles. Three different kinds of barnacles
are frequently found by fishermen.

1. The common barnacle, or “ scab,” which grows on
the bottoms of boats during the spring.

2. The ship barnacle. This does not grow in British
Seas, but occasionally comes here attached to floating
wreckage.

3. The crab barnacle. This is a round soft animal
which is often found attached to the under side of the tail
of different kinds of crabs. It is not the spawn of the
crab as many fishermen imagine; if it is opened its own
spawn will be found inside the body.

The common barnacle and the ship barnacle are not
parasites, but the crab barnacle is. It is always a female
which is parasitic on the crab, and the male barnacle 1s
parasitic on the female, and lives attached to it.

These three barnacles are very like each other when
they are just hatched.

126

In these two stages the young barnacle drifts about in
the sea. After passing through stage 2 they fix them-
selves—the common barnacle to stones, piles, the bottoms
of boats, &c.; the ship barnacle to the bottoms of
ships, &c.; and the crab barnacle to various kinds of

crabs.

1—Barnacle just hatched. 2—Later stage of the same.
Magnified about 60 dia.

These young barnacles are always found in the tow-
nettings during the early spring, and will be studied.
Development of the Flounder.—the

ege of the flounder just before hatching. The newly-
hatched fish. When it issues from the egg, the little

flounder is a round fish, hke the newly-hatched cod or
haddock. When it is about six weeks old the body
flattens out and the eyes twist round until they both
appear to be on the same side of the fish. Up to this time
the little fish swims about in the sea, but when it has
become a “ flatfish ” it sinks to the bottom.

127

The Eggs of the Plaice and Newly-
Hatched Plaice.

“ready ce hatch.

Various stages in the development of the Plaice,—Magnified 25 dia,

128

When the plaice hatches from the egg it is unable to
feed, and for about a fortnight it obtains its nutriment from
the food-yolk contained in the yolk-sac which is attached
to its belly.

Magnified 14 dia.

After about a fortnight the young plaice begins to
feed. The yolk has then been used up. The food of the
little fish is at first diatoms and then copepods. Afterwards
it begins to feed on small shellfish

little cockles, &e., and
then as it becomes older it feeds on larger animals such as

bd

“hen-pens.’

TentH Day.

The work of this day will be a general review of what
has been done during the fortnight.

APPENDIX.

MEM OLR ON ARENDOCOLA.

The Fisherman’s Lugworm.

By J. H. Asuwortn, D.Sc.

(Lecturer in Invertebrate Zoology in the University of Edinburgh.)

ConTENTs.
PAGER
INTRODUCTION: HABITS; VARIETIES; DISTRIBUTION ..............: 130

EXTERNAL CHARACTERS : Segmentation ; Parapodia; External

Apertures ; Gills ; Sete; Epidermis; Pigment ................ 133
(EON IEVAUIET PATNUAIPOMIN a lars aiciciesys's/e'usisiala'soravare said aajeiarsioain's daislejaisieieai.ocicisoe siete « 147
IVI S CHCA AMUU TUM artes rcisiscicmeesivsteise cron sc nlgasiea ate aircon ameat nem cece sens 149
COMMOMMAND NC GWONC) HMGUTD! fe ceccceemceteemecsecisccacasaeresecanccosenee 151
ENTSIOVUBIN STAVE an © AINA nS UENO WII O° rates.) -icteistre mera chicos suicieieeisisise searisee eee 154
VASCULAR System: Heart and Heart-body .................0.0.0c0+0s 159
INGHISISA SIDI ON ogpaaaaed beneaccbaderesconas Soistseadacecnememmeeecaan oomee 5 See aareete 164
EVEN OL) Us Cimtavaiie OR GHAI Sip ete siess(s.ocee scree sleeiohow sibiele bls sine smaeind ainaiiencteen 170

Neryous System: Brain; Csophageal Connectives; Ventral
Nerve-cord ; Giant Cells and Giant Fibres ..................... aly}

SENSE ORGANS: Otocyst ; Nuchal Organ; Eyes; Prostomium... 179

HD) HAVA OB MIBINGT erent eerie iicc(eisisns/sainoie aac <eisiw eleseiewe etaisee cistioscissones aneee cane 183
OSH AAT: AS TUAICEH Groeelnaincion aciantcne gate atetetsailemie Gineite chun aweioaee octceeacee 188
SYSTEMATIC POSITION and CLASSIFICATION -........s2.cscssescessceeee 196
PATRAS, Siaeevre) tomes Serene ciel scec atciscnseiists steels ates ian en owe daaen ti einaetoncedte see 207
DIRHSTIONS HOR VE RACTIOAI: ViOREK ccs aceskceracseensceccanscasececsteede 208
CON OMIC RSE OION Iter ites cent saccomraeces aeesece sree sa eeen coeemadeer eens 219
DASCRIPTION: ONE TATE ss sae cocsise se teseioeyierscchninanerse crs gneeee galdrentows 229

K

130

INTRODUCTION.

Arenicola* is a genus of abundant and _ widely-
ranging Polychet worms, represented in the British
fauna by three species,t all of which may be found
between tide marks in the neighbourhood of Port Erin
(Isle of Man) and Plymouth.

The common lugworm, Arenicola marina, forms a
convenient type of the genus. It is abundant on most of
the sandy shores around the British Isles. Its presence
is indicated by the small heaps or coiled castings of sand,
which are familiar objects between tide marks. The
animal may be found on digging to a depth of one to
three feet near such castings, and it is commonly so
obtained by fishermen, by whom it is extensively used as
bait.- Its general appearance may be seen in Fig. 1. It
is almost invariably slightly inflated in the anterior
region, being widest at a point about one-sixth of its

length from the anterior end.

Hapirs, VARIETIES.
There are on the Lancashire coast and in the Firth of
Forth, two varieties of A. marina which differ in habits
and in two structural points.

* While the following account owes much to the memoir published
in 1898 by Dr. F. W. Gamble and myself (Quarterly Journal of
Microscopical Science, Vol. 41) it should be said that a large portion
of it is new, consisting of observations on the development and post-
larval stages and of new points relating to some of the systems of
organs. All the statements from the earlier memoir used in the
present one have been carefully revised and some of them corrected in
the light of further investigations I have made on the genus during
the last six years.

+ A. marina, Linneus; A. grubw, Claparéde; <A. ecaudata,
Johnston.

+ T have added a section (see p. 219) dealing with some points of
economic importance, such as its abundance in various sands, its
efficacy as compared with that of other bait, etc.

131

Typical specimens of A. marina are found in the
littoral zone. Their burrows are usually U-shaped (see
below). One end of the burrow is marked by a casting
and the other by a funnel-shaped hole through which the
head was probably withdrawn, and through which it may
be again protruded when the burrow is covered by the rise
of the tide. The worm is almost invariably found head
downwards in such a position that the tail and posterior
part of the body lie in the limb of the burrow connected
with the casting, while the head and anterior part of the
body le either in this or in the horizontal limb of the U.
The worms average about seven to nine inches in length,*
and their gills, which are best developed in old, deeply-
pigmented specimens, are composed of nine to eleven
stems each provided with three to five pairs of short
lateral branches (fig. 22). These littoral forms breed in
the spring, usually from the end of February onwards for
about a month but specimens containing ripe ova may be
occasionally met with up to the end of April,t and on the
Lancashire coast even later. The smallest specimens
found in the sand are 17 mm. in leneth (see below),
possibly smaller ones are present but have escaped obser-
vation. Young specimens are pinkish in colour, due to
the fact that numerous blood-vessels are seen through the
translucent body-wall, and their gills are usually bright

* The largest specimens of the littoral variety I have seen, are

several found near Musselburgh, on the Firth of Forth, measuring
340 mm. (about 133 inches) in length.

+ I am inclined to believe that, in some localities at any rate,
Aremicola marina also breeds about August or September. Large
specimens were taken near Musselburgh in July, 1903, which contained
great numbers of ova and sperms in an almost ripe condition. In
other full-grown specimens from the same area, taken near the end of
October, not a single large egg or mass of spermatids was to be found.
Among the specimens examined on both occasions were both littoral
and Laminarian forms. In others, taken early in January, 1904,
genital products are small and scarce in the colomic fluid.
A month later, in males, spermatogonia and spermatids, and in
females young ova (06 mm. in diam.) are present in quantity.

132

red. Older specimens, especially if taken from sand in
which the amount of organic matter is considerable, are
nearly black in colour and their gills, which are also
pigmented, are better developed than in young specimens.

The second variety of A. marina is found in the upper
part of the Laminarian zone, and can only be readily
obtained at very low tides. It breeds in the spring, from
the beginning of March onwards.t = When fully grown
it is one of the largest Polychets of our shores, measuring
as much as 400 mm. (16 inches) in length and nearly three
inches in girth at its widest point. It is dark brown or
almost black in colour. Its burrow, in which the worm
is found head downwards, appears to be simply vertical
and not U-shaped. The most distinctive character of this
variety is, however, the gill, which is a highly developed
pinnate structure (fig. 19) consisting of about twelve stems
united by a connecting membrane at their bases and
bearing ten or more branches on each side of the axis.
The Laminarian differs from the littoral form also in the
sub-division of the interval between the second and third
chetigerous annuli; in the former this region is divided
into two rings and in the latter into three (see figs. 1 and
2)

~/.

There do not appear to be any other structural points
of difference. The Laminarian variety is abundant on
certain parts of the Lancashire coast, ¢.g., near Blackpool,
where specimens are obtainable at low tides on digging to
a depth of about three feet in the sand near extreme low-
water mark. I have recently found four specimens* of
this variety in a collection of Arenzcola from the sand
between Portobello and Musselburgh on the Firth of

Forth. The Laminarian variety has also been found in

+ See footnote (+) on p. 131.

* The gills of two of these were not as obviously pinnate as those
of the Laminarian forms of the Lancashire coast,

133

Jersey and has been figured, probably from the coast of
Normandy, by Milne Edwards in the plates of Cuvier’s
* Regene Animal” (dition de Disciples, Plate VIII., Fig.
1), where it may be recognised by its characteristic gills.
From the records of A. marina, made by Scandinavian and
other naturalists who have examined specimens from
northern seas, it would appear that the littoral variety is
the only one with which they are acquainted.

DISTRIBUTION.

Arenicola marina has been recorded from both sides
of the Atlantic, e.g., from the shores of Western Hurope,
Norway, Spitzbergen, North Siberia, Iceland, Greenland,
and along the northern coast of America from the Bay of
Fundy to Long Island.” — Latitude 40° N. marks approxi-
mately the southern limit of A. marina on the Atlantic
shores. South of this it is replaced on the American
coast by «A. cristata, and in the Mediterranean by A.

claparedii and A. cristata.

EXTERNAL CHARACTERS.

The description of the external characters of
Arenicola will be better understood after a brief reference
to those of some other Polychet, such as Verezs, in which
the segmentation is more clearly shown.

At the anterior end of Verezs is the distinct ‘ head,”
at the posterior end the “tail,” while the intervening
portion is sub-divided by a series of shallow grooves into
a number of segments which are practically identical in
their external characters except in size. Each segment
bears laterally a pair of muscular out-growths provided
with bundles of bristles, or setee, and with certain sensory

* It is also reputed to occur on the shores of Vancouver Island
and in Angra Pequena Bay (West Africa).

134

organs termed cirri (fig. 9). These out-growths, or para-
podia, are locomotor organs, and, by their active move-
ment in the living animal, enable it to creep or swim as
occasion demands. fach parapodium consists of a basal
piece from which extend outwards two almost equal,
usually bilobed, processes, a dorsal one (the notopodium ),
and a ventral one (the neuropodium). In each of these
two vami of the parapodium there is a large setal sac,
formed by invagination of the epidermis, the lips of which
are well seen in Vere?s. From the inner end or bottom
of this sac the sete arise, each being formed by products
from a single cell. The bundle of setee contained in each
sac may be protruded o1 retracted or moved in various
directions by means of a number of slender muscle bands
inserted into the bottom of the sac. In addition to these
sete, which may project a considerable distance beyond
the lips of the setal sac, there is in each notopodium and
neuropodium a stouter, dark-coloured, needle-shaped aci-
culum of a similar constitution to the sete. Its base
extends further inwards than the bases of the ordinary
sete, but its pointed tip projects only a short distance
beyond the surface of the parapodium. The two acicula
serve as an internal skeleton to the parapodium, and to
them the museles which move the bundles of setze are
attached. On the dorsal side of the notopodium, and on
the ventral side of the neuropodium, is a finger-shaped,
or filamentous sensory process, or cirrus.

The head or prostomium of WVere?s (figs. 7 and 8) is
pre-oral. It is tollowed by the peristomium on the
antero-ventral surface of which the mouth is situated.
The prostomium bears on its dorsal surface two pairs of
eyes, in front a pair of short sensory tentacles and ventro-
laterally a pair of much stouter sensory and muscular

palps. The peristomium, which bears some resemblance

135

in shape to a body segment, though frequently larger and
always without parapodia, bears on each side at its
anterior edge four long slender filiform sensory ciz71.

On the last or anal segment of the body, the “ tail,”
the anus opens posteriorly, and though without parapodia
or sete this segment bears a pair of long anal cirri, which
probably correspond to the ventral cirri of the trunk
segments.

The prostomium and parapodia of <Arenrcola are
reduced compared with those of Mere’s, and the peris-
tomium and the segmentation of the body are much less
distinct in the former than in the latter.

The prostomium of Arenicola may be seen on exam-
ining the anterior end of the animal in the mid-dorsal
line. It is a trilobate structure which, in fully-grown
Specimens, is about 1 mm. in length by nearly 2 mm. in
breadth. It is hable to be retracted within the crescentic
nuchal groove which lies immediately behind it, and in
that case is difficult to see, but if well-expanded the pros-
tomium assumes the form shown in fig. 5. — It does not
bear any sensory processes, and eyes, though present, are
minute and sub-epidermal, and are not visible in the
adult except in sections.

There is good reason for believing that the peri-
stomium is represented by the first two annuli, and that
the third and fourth annuli represent a segment which has
lost its sete, but the limits of the peristomium and the
composition of the region between the prostomium and the

first cheetigerous annulus will be discussed below.

meenientatran, Annulation, Parapodia.

Leaving out of account the prostomium, the peris-
tomium, and the following achztous segment, Arenicola

may be, for descriptive purposes, divided into three por-

136

tions :—(1) an anterior bearing parapodia, but no gills,
2) a middle region bearing both parapodia and gills, and
(3) a posterior portion or tail, which has neither sete nor
gills. Wach of these parts is composed of a number of
segments, but the segmentation is somewhat obscured by
the sub-division of each segment into a number (generally
five) of rings or annuli,

One of the annuli of each segment is larger than the
rest and bears the parapodia. ‘The latter may be best
seen in the middle branchiferous segments. ‘They are
obviously much reduced compared with those of eres,
and their two rami are different in shape and more dis-
sociated than they are in .Vere’s. The notopodium is a
small conical elevation situated dorso-laterally, on the
rounded apex of which is the mouth of the setal sac from
which the tips of a small pencil of hair-like sete project
toa greater or lesser extent (fig. 19). The neuropodium
is a muscular ridge traversed dorso-ventrally by a narrow
slit, the mouth of the setal sac, in which are situated in
a linear series the numerous chet or crotchets. The
first few neuropodia are small, but in the posterior part of
the branchial region they are well developed and extend
ventrally until those of the right and left sides almost
meet in the mid-yentral line. Each has the appearance
of a pair of closely applied tumid lips between which only
the tips of the curved cheetee project. There are no cirri
or acicula in the parapodia of Arenicolu. Fora detailed
description of the sete, see below.

There ave thirteen branchiferous segments, and in
the region in front of the first gill six chetigerous
segments may be recognised. The interval between two
cheetigerous annuli is sub-divided into four rings, except
between the first and second chetigerous annuli, where

there are only two rings, and between the second and

137

third, where there are either two rings (as in the
Laminarian variety), or three (as in the littoral variety).

The exact limits of the segments are not obvious,
but from a consideration of the internal anatomy, it can
be shown that the second groove behind each chetigerous
annulus marks the posterior lmit of that segment.
Internal septa, where present, are inserted at this level,
not only in A. marina, but in all other species examined
(see below). Kach of the segments posterior to the third
consists of the annulus which bears the parapodia,
together with the three annuli in front of and the one
behind it. The parapodia are therefore situated slightly
behind the middle of the segment to which they belong.
The third chetigerous segment consists, in the littoral
variety, of four annuli, viz., the chetigerous one, two in
front of it, and one behind it; while in the Laminarian
variety this segment contains only three annuli, the
middle one of which bears the sete. The extent of this
third segment is easily determined, as it is delimited both
anteriorly and posteriorly by internal septa. The second
segment consists of three annuli, the middle one bearing
the parapodia. ‘The first segment is composed of two
rings, the anterior of which is chetigerous. This
segment is bounded in front by the first diaphragm
(fig. 2.)

Between the first chetigerous annulus and_ the
prostomium there is a region sub-divided into four rings,
each of the first three of which may be again sub-divided
into two; but usually there is little difficulty in recog-
nising the four primary annuli (figs..5, 6). This
region is composed of the peristomium and a_ body
segment, the sete of which are minute, and disappear
early. The evidence in support of this statement is

derived from (1) an examination of post-larval stages,

138

(2) a comparison of this region in the adult and in post-
larval stages, and (3) a consideration of the position of
certain giant nerve cells present in the adult.

In all post-larval stages the region between the first
chetigerous segment and the prostomium is clearly
divided into two parts by a groove (figs. 57, 58). The
posterior of these is a body segment, which in all the
seventeen post-larval stages I have examined is achetous,
but in which a small seta was observed by Benham. This
seta, though it disappears early, indicates that there is a
distinct trunk segment in front of the first adult
chetigerous segment. The anterior part of the region
under discussion is undoubtedly the peristomium, and
never bears sete. The otocysts, which in most other
Polycheta in which they are present are peristomial, may
be seen near its anterior margin (figs. 56, 57).

In post-larval stages in which the annulation 1s
making its appearance, the peristomium and_ the
achetous body segment are each divided by a shallow
groove into two annul, together therefore consisting of
four annul. In two or three of these specimens the
metastomial grooves, which mark the track of the
cesophageal connectives, may be clearly seen uniting
ventrally near the middle of the third annulus (fig. 58).
The annulation of these post-larvee corresponds, there-
fore, to that of the adult (cf. figs. 6, 58). It is evident
from the above facts that of the four annuli in the adult
between the prostomium and the first chetigerous
annulus, the first two belong to the peristomium and the
third and fourth to a segment from which the sete have
disappeared in early hfe. Confirmatory evidence is
afforded by the giant nerve cells present im the nerve
cord. These cells occur singly or in couples near the
hinder limit of each segment, 7.e., just behind the level

139

of the parapodia (see below). Just behind the meeting
pot of the csophageal connectives there is a single
giant cell, which is therefore situated either in the
posterior part of the third or, more usually, in the fourth
annulus (fig. 52). This cell, whose position near the
hinder border of the somite corresponds with that of the
giant cells of other somites, must therefore belong to the
segment from which the sete have disappeared. The
first chetigerous segment of an adult Arenicola is, there-
fore, really the third segment, as it is preceded by a
segment bearing a giant cell and vestigial seta, and this
again by the peristomium.

The tail, which is without parapodia and gills, varies
considerably in different specimens. It is usually marked
by a number of shght constrictions, best seen when the
tail is stretched, which indicate the boundaries of the
somites and correspond in position to the internal septa
(fig. 1). There may be as many as seventy segments, but
in most specimens there are fewer as the worm has a ten-
dency to throw off the last few segments when irritated.
New segments are apparently formed at the anterior end
of the tail region. Here the segments are short from
before backwards, but further back they are longer and
sub-divided into a number of annuli, as many as ten in
some of the last segments. Near the posterior limit of
each segment in the mid-tail region there is an annulus
slightly larger and often more deeply pigmented than the
rest, and upon which the epidermal papille are distinctly
larger than on the other annul. Each of these larger
annuli occupies a position in the segment roughly corres-
ponding to that of the chietigerous annulus in the pre-
caudal segments of the worm. ‘These larger annuli and
their papille are best seen near the middle of the tail,
behind that point the distinguishing characters above

140

described become gradually less obvious, and near the
anus practically disappear.

Traversing the whole length of the mid-ventral lne
of the animal is a shallow groove which marks the position
of the ventral nerve cord (fig. 6). Just behind the middle
of the third annulus (?.¢., a short distance in front of the
first cheetigerous annulus) this groove unites with two
others which pass round the sides of the peristomium in
an antero-dorsal direction to the nuchal organ. These
ave termed the metastomial grooves; they indicate the

course of the esophageal connectives.

External Apertures.

The mouth, when the proboscis is withdrawn, is a
crescentic transverse slit on the antero-ventral aspect of
the peristomium. It is overhung by a small upper lip,
and bordered all round by a series of papill (fig. 2).

The anus is terminal, opening on the end of the last
tail segment. Through it the terminal part of the intes-
tine occasionally protrudes for a short distance.

The nuchal organ is a transverse crescentic, or V-
shaped, ciliated sensory groove formed by invagination of
the epidermis of the sides and hinder end of the pros-
tomium (fig. 5). The prostomium may be withdrawn
into this groove so as to be almost hidden from view.

The openings of the otocysts are minute and difficult
to see. They may, however, be found in large specimens.
They are situated dorso-laterally in the peristomium close
to the point where the metastomial groove crosses the first
inter-annular groove (fig. 5).

The openings of the six pairs of nephridia are small
oval slits situated immediately dorsal and_ slightly
posterior to the upper ends of the fourth to the ninth
neuropodia (figs. 1 and 19),

141

Gers

There are thirteen pairs of gills borne on the
seventh to the nineteenth chetigerous segments inclusive
(fig. 1). They are well supplied with blood, and, there-
fore, generally red in colour, but in old specimens they
usually become pigmented, and then have a dark brown
colour. The first pair is nearly always considerably
smaller than any of the others, and may be much
reduced or even suppressed (fig. 10). The largest gills
are usually found about the middle of the branchial
region.

The form of the gills varies considerably in the two
varieties. In the Laminarian variety the gill consists of
about eleven to fourteen main stems, 5 to 6 mm. long in
full-grown worms, which radiate from a point situated
slightly dorsal and _ posterior to the notopodium
(fig. 19). These stems are connected at their bases by a
web-like membrane. ‘The ventral stems are the smallest
and apparently the last formed. Each of the main stems
bears from ten to twelve pairs of branches, which are,
however, not strictly opposite, but in some cases almost
alternating. Each branch divides dichotomously a
number of times, and may give rise to as many as twenty
or twenty-five gill filaments (fig. 21). This type of
gill, with its well-developed and numerous _ lateral
branches, is known as the pinnate type. In some speci-
mens the gills have lost some of their branches, either
owing to friction against the sand, or to the attacks of
enemies.* The gill of the littoral variety is not so well
developed (fig. 22). It forms a more bushy structure,
consisting of eight to twelve stems, about two to three

** See, for example, the description of the attacks of the Amphipod

Corophium longicorne upon Arenicola, M, C, d’Orbigny. Journal de
Physique, tome 93, p. 198, 1821.

142

millimetres long, each of which bears only about three to
six pairs of lateral twigs, which are not so richly branched
as in the pinnate gill described above. This may be
called the dendritic type.

Kach gill is a hollow out-growth of the body wall
enclosing an extension of the celom (fig. 56). The
wall of the gill is thin; it is formed of an external cubical
or flattened epithelium, below which is a thin layer of
muscle fibres. The cavity of the gill is lined by the
celomic epithelium, between which and the muscle layer
the branchial vessels are situated. The coelomic cavity
of the gill is crossed at intervals by muscle strands. The
gill is a contractile structure, and, as Milne Edwards
pointed out, the successive contraction of the branchiz,
which often proceeds regularly from behind forwards,
must exert a considerable influence in forcing the blood
into the efferent branchial vessels and into the vessels
of the body wall.

The gills arise in the post-larval stage. One speci-
men, 39 mm. long, has already the full complement of
gills, but in other specimens examined the gills are not
formed until the animal is considerably longer. In the
fifteenth to the eighteenth chetigerous segments of a post-
larval specimen, 46 mm. long, the blood-vessels
immediately behind the notopodium form a loop pre-
paratory to the production of a gill, and there is a very
slight elevation of the body wall in this region. These
elevations soon become conical outgrowths, then digiti-
form and commence to branch. As Benham has pointed
out, the gills of Arentcola are from the first special
respiratory structures, and not as in /unice, and some
other Polycheta, modifications of dorsal cirri. There is
no trace of sense-hairs upon the epidermis ot the develop-

ing gill, while such hairs are present in cirri.

148

The afferent branchial vessels arise from the ventral
vessel. They enter the gills, and at once divide to supply
a trunk to each of the main stems. ‘These trunks in turn
give off branches into each pinna, and these again to each
gill filament. There is a corresponding series of efferent
vessels. The afferent and efferent vessels merge imto one
another in each gill filament, where one limb of the
vascular loop is derived from the afferent, while the other
is in connection with the efferent vessel. The first six
gills return blood to the sub-intestinal vessels, while the
efferent vessels of the remaining gills open into the dorsal
vessel (fig. 25).

Setzx.

Kach notopodial seta is a slender capillary chitinous
structure inserted at its proximal end, along with many
other similar sete, in a setal sac, which is moved by
special retractor and protractor muscles (figs. 24 and 36).
The seta has an almost uniform diameter for a consider-
able portion of its length, but it tapers at its distal end to
a fine point (fig. 12). On the distal fourth or fifth of its
length the _seta bears numerous minute, regularly
arranged, pomted processes, which are usually present on
both sides of the seta. They are moderately obvious on
one side, but on the other they are very minute and borne
on the edge of a thin border or lamina (fig. 14). This is
well marked im the large sete of the Laminarian variety,
in which the lamina may be traced for about a millimetre
along the seta, and attains a width of 20u (fig. 15). In
some of the sete the lamina is not denticulate at its
margin, and in others is only very faintly so; but it is
crossed by fine oblique lines the intervals between which
correspond roughly to the size of the teeth on dentigerous

laminze. It seems probable that the lamina at first

144

possesses an entire margin, but later this tends to break
up from the edge inwards, thus giving rise to the minute
teeth or processes which are usually seen on full-grown
setee. The notopodial setee may attain a length of 75 mm.
(in a specimen 250 mm. Jong).

Each neuropodial cheta or crotchet consists of a
shaft, generally somewhat curved, bearing at its distal end
a beak-like rostrum placed at an angle to the shaft vary-
ing from about 90° to about 150° (figs. 15-18). There is
eenerally a slight dilatation of the shaft near the middle
of its length. Near the end of most chet from young
specimens, immediately behind the rostrum there are
visible two or more minute pointed teeth, the tips of which
are directed towards the tip of the rostrum, while below
the rostrum at its junction with the shaft there is often a
minute process—the subrostral process. On careful
focussing shghtly above the level of the teeth and
subrostral process there comes into view a number of
other fine teeth situated on the sides of the rostrum, so
that the latter projects from the centre of a series of teeth
arranged round its base. The small subrostral process
marks the position of the base of the lowest (and often
the smallest) tooth of the series. Only unworn cheete
show these lateral teeth. By isolating the entire band
of neuropodial chetze the number in each neuropodium
and the different stages in their growth may be seen.
New chietee are formed at the ventral end of the series,
the rostrum being first formed, then the teeth, and finally
the shaft which is at first comparatively short (fig. 18).

The néuropodia of the anterior segments are short
and contain few setze, but those further back extend by the
addition of crotechets ventrally so as to almost reach the
mid-ventral line. The neuropodia of young specimens
contain very few crotchets, but in old specimens there is

145

a large number in the neuropodia of the branchial region.
One of the neuropodia of a specimen only about six inches
long contained 110 fully formed cheetee and eight or nine
others in course of formation at the ventral end of the series.

The crotchets show considerable differences according
to the age of the specimen from which they have been
taken. Those of post-larval specimens (5'1 mm. long) are
‘03 to ‘04 mm. long, and bear two, or occasionally three,
sharply marked teeth behind the rostrum and also a well-
marked process, ending in a fine point, under the rostrum
(fig. 15). In older specimens 17 mm. long, which have
assumed the adult characters and mode of life the
crotchets are ‘1 to ‘12 mm. long, and bear two well-marked
teeth. Specimens about 100 mm. long have cheete which
are ‘4 to ‘5 mm. long, each of which bears two or three
very small teeth and also a very small subrostral process.
The crotchets of large specimens, especially those of the
Laminarian variety, may attain a length of ‘85 mm.
From the time of their formation they are devoid of teeth,
but bear a rather blunt subrostral process. It is inter-
esting to note that as the animal grows in size the rostrum
of the crotchet, which in the post-larval stages is at right-
angles to the shaft, in later formed chietze makes a con-
siderably greater angle with the shaft, the angle
increasing with the age of the worm from which the
cheete are obtained, so that in a cheta from a large worm,
e.g., a Laminarian specimen about 250 mm. long, the angle
between the rostrum and shaft is almost 130°. Concur-
rently there is a reduction in the size of the teeth of suc-
cessive generations of chet, so that although in post-
larval stages the teeth are large and comparable to the
rostrum in size, they are entirely absent from the chete
of very old specimens. (For method of isolation and
preparation of sete, see under practical work).

L

146

Epidermis: Pigment.

There is a well-developed cuticle formed by the
mucus cells of the epidermis.

In adult specimens the skin of the anterior and
middle portions of the animal is sub-divided by grooves
into a series of squarish, oval or polygonal areas
(fig. 5). These are ‘composed chiefly of large club-
shaped mucus cells and of elongate columnar cells, many
of which are almost filled with pigment granules,
especially in old specimens. These granules, which are
dark yellow or brown when viewed singly, but nearly
black in the aggregate, are more abundant in the distal
part of the cells, and give to many of them a clavate
appearance. Pigment cells are present all over the
epidermis, extending on to the prostomium, but are less
numerous in the nuchal organ than elsewhere. The
epidermis in the grooves between the raised areas is com-
posed of shorter cells, in which the pigment is present
in less quantity and mucus cells are wanting.

In the tail the epidermis is raised into rounded
papille (see above) the structure of which corresponds to
that of the raised areas described above.

Sensory cells are also present in the epidermis, being
specially abundant in many of the grooves.

When specimens of Arenicola are handled a yellowish
or greenish pigment exudes from the skin and stains the
hands. This, which is readily soluble in alcohol, and to
some extent in sea-water, is probably a lpochrome.
There is also a brown or black pigment, the fine granules
of which are insoluble in alcohol, and are readily seen in
sections, especially of old specimens. According to
MeMunn (Q.J.M.S., Vol. 30, p. 74), this pigment
resembles melanin in its resistance to solution, and he

147

suggests that it is possibly derived from the yellow
lipochrome. Fauvel (C.R. Acad. Sciences, Paris, Tome
129, p. 1273) has recently adduced evidence in support of
this suggestion, showing that the formation of melanin
granules may be due to a chemical modification of the
lipochrome taking place in the interior of the cells under
the influence of some acid.

GENERAL ANATOMY OF THE INTERNAL ORGANS.
(See Plate IIT.)

The body cavity is best opened by an incision through
the body wall along the mid-dorsal line. It often
happens that in freshly killed specimens the middle part
of the alimentary canal is forced out through the incision
owing to the fact that the animal has died somewhat
contracted, and the contents of the ccelom are under con-
siderable pressure. At the same time a quantity of the
ceelomic fluid will escape through the aperture.

The ceelom is spacious and continuous from one end
of the animal to the other. In front it is sub-divided
transversely by three fenestrated septa, or diaphragms.
The first of these is placed at the anterior boundary of the
first chetigerous segment, and is inserted into the body
wall at the level of the anterior edge of the first chetigerous
annulus. It is perforated by some of the retractor
muscles of the pharynx by which, in some specimens, the
septum is pulled back ventrally, so that at first sight its
ventral edge appears to be inserted near the posterior
margin of the first chetigerous annulus. Further
examination shows that the diaphragm is not obliquely
placed, but is situated dorso-ventrally at the anterior edge
of the annulus. The second and third diaphragms mark
the posterior limit of the second and third chetigerous

148

segments. They are placed at the posterior margin of the
ring which succeeds the second and third chetigerous
annuli. Between the first and second diaphragms
there are dorsal and ventral mesenteries* supporting the
corresponding blood-vessels; the dorsal mesentery
terminates in front about the level of the posterior margin
of the first cheetigerous annulus. The funnels of the
first pair of nephridia perforate the third diaphragm, and
le on its anterior face. Behind this diaphragm the body
is uninterrupted by septa almost to the base of the tail,
but rudimentary septa may be recognised as strands of
connective tissue accompanying some of the afferent and
efferent vessels connected with the nephridia and gills.
Towards the posterior end of the gill region this tissue
increases in amount so as to form in the last, or last two,
gill segments an almost complete septum.

It will be seen that all vessels connected with the
stomach are attached to its ventral face. This arrange-
ment, together with the absence of mesenteries from this
region, allows considerable freedom of motion to this part
of the gut without endangering the blood-vessels which,
by their length and flexibility, appear to readily permit
this motion. During digestion the stomach is swung
backwards and forwards by movements of the body, and
the arrangement of the blood-vessels indicates a con-
siderable amplitude of swing. There is, however, a
structure which probably acts as a sort of safety cord to
prevent the backward motion becoming so great as to
rupture the vessels. This is a solid pinkish cord of con-
nective tissue, which may easily be mistaken for a vessel ;
it is attached ventrally to the anterior wall of the stomach,
lies alongside the afferent vessel of the fourth nephridium,

* The ventral mesentery also runs backwards through a con-
siderable part of the third chetigerous segment.

149

and is inserted into the body wall just behind the level
of the sixth chetigerous annulus. This cord and the
other rudimentary septa are all placed at the boundary
of the segment to which they belong.

Between the intestine and the body wall in the tail
there is a comparatively small coelomic cavity crossed by
septa, which are much closer in the anterior than in the
posterior caudal region, especially in young specimens,
in which the anterior tail segments are very short.

(For a description of the alimentary canal, the
vascular system and the nephridia, see below.)

MUSCULATURE.

There is a small amount of connective tissue between
the epidermis and the well-developed underlying muscula-
ture of the body wall, which consists of a layer of circular
muscles below which are seen the bands of longitudinal
muscle fibres. The latter, which are covered by the thin
celomic epithelium, abut upon the cceelomic cavity (see
figs. 24, 35, 36 and 54). In the anterior region of the
body there are usually a few circular muscle bands which
are stronger and more obvious than the rest (fig. 23).

The thin bands of muscle seen in dissections arising
at the sides of the nerve cord and inserted right and left
into the body wall at the level of the notopodial sacs are
the oblique muscles which are very characteristic of
Polycheta. They commence behind the third diaphragm
and extend to the base of the tail. They divide this region
of the celom into three longitudinal compartments, a
dorsal median portion containing the alimentary canal,
and two ventro-lateral portions containing the nephridia
(fig. 36). The oblique muscles partially cover the
nephridia and one of the bands is usually attached to the

150

nephrostome and binds the latter to the body wall (figs.
23, 24 and 20).

Kach bundle of notopodial sete is enclosed in a sac
to the inner end of which are attached (1) a single re-
tractor muscle strand, which is inserted into the body wall
at the side of the nerve cord, and (2) six to ten protractor
muscles, which are inserted into the body wall at the level
of the setal sac. Contraction of the latter causes pro-
trusion of the setze beyond the lips of the setal sac, while
by shortening of the retractor muscle they may be almost
entirely withdrawn into the setal sac (fig. 24).

There is a strong sheath of muscle fibres attached to
the pharynx and to the neighbouring body wall (fig. 23).
Contraction of these muscles produces withdrawal of the
pharynx. : It is probably by the help of the ceelomic fluid,
which can be collected here and subjected to pressure, that
the pharynx is protruded. |

The prostomium is provided with a small sheet of
retractor muscle arising from the musculature around the
cesophageal connectives and inserted into the ventral sur-
face of the brain and hinder edge of the nuchal organ
(fig. 34).

The position of the three anterior diaphragms and the
dorsal and ventral mesenteries in the second segment has
already been noticed (see above). Each of these dia-
phragms is perforated by numerous rounded, usually oval,
apertures which are best seen in the third diaphragm
where they are moderately close together and about ‘02
to ‘(03 mm. in diameter (fig. 45). These openings permit
the passage of the coelomic fluid and its cells but prevent
all but the smallest ova and spermatogonia from passing
into the anterior segments. Hach diaphragm is covered
on both its faces by an endothelium composed of flattened
cells between which is a thin layer of connective tissue

151

and intercrossing muscle fibres. The first diaphragm is
perforated by some of the retractors of the proboscis, and
it bears two backwardly projecting pear-shaped or finger-
shaped out-growths which lie to the sides of, and ventral
to, the esophagus (fig. 23). These are not cesophageal
glands. They open anteriorly into the ceelomic space in
front of the first septum. Their walls are muscular and
very vascular and they contract at frequent intervals
during life. Their function is unknown, they may pos-
sibly be of use in aiding the eversion of the proboscis.

The occurrence of rudimentary septa accompanying
some of the afferent and efferent vessels of the nephridia
and gills, and the probable function of the two strands
(septa) attached to the efferent vessel of the fourth
nephridium have been described above.

The caudal septa are incomplete ventrally and ventro-
laterally, z.e., above and at the sides of the nerve cord.
Hach is composed of two thin layers of coelomic epithe-
hum, forming the anterior and posterior faces between
which is a small quantity of connective tissue and muscle
fibres. These septa are not fenestrated like the three
anterior diaphragms. ‘There are in the tail, in addition
to these septa, dorsal and ventral mesenteries, by means
of which the intestine is attached above and below to the
body wall and in which lie the dorsal and ventral blood-
vessels. Owing to their small size these mesenteries are
with difficulty seen in dissections, but they are readily

distinguished in transverse sections of the tail.

Ca@tom anp Ca@tomic FLuIp.

The ceelom, which is lined by a layer of flattened
cells, is spacious and continuous from end to end of the
animal. It is partly sub-divided by septa in the anterior

152

region and in the tail, but in the middle portion of the
animal it is uninterrupted by septa, although, as mentioned
above, these are represented by certain thin bands which
accompany the segmental blood-vessels across the coelom
(fig. 23).

There are numerous canaliform prolongations of the
celom, best seen in sections of the anterior end of the
animal, which penetrate into the musculature, or insinuate
themselves between the brain and the _ prostomial
epithelium, and often accompany the blood-vessels which
supply the body wall. In most of the canals the thin
lining of celomic epithelium may be recognised, and
celomic corpuscles may be found in many of them. They
probably act as nutritive, and possibly also as excretory
and respiratory, channels.

The ccelomic fluid is a mixture of sea-water and
globulins (Krukenberg). Its specific gravity is on the
average 1°0288, but it varies somewhat according to
circumstances. It was found to be greater (1°0511) in
worms which had been kept for thirty-six hours in moist
sand and seaweed than in others which had been trans-
ferred from the moist sand and seaweed to sea-water for
three hours (1-0285), or over-night (1°0270). The specific
gravity of the sea-water used was 10264.

The fluid contains cclomic cells and, during a con-
siderable portion of the year, reproductive products. The
coelomic corpuscles (fig. 44) are abundant, and of two chief
types—(1) fusiform cells about ‘04—05 mm. long, which
are very numerous, and (2) smaller amceboid, or sub-
spherical cells, many of which contain yellow or brown
refringent granules. On exposure to the air a delicate
fibrous network is formed, with which the fusiform cells
(and to a less extent the ameboid cells) become united to

form a clot.

153

The cells of the celomic epithelium and the ecelomic
corpuscles perform excretory functions; carmine granules
injected into the ccelom are taken up by these cells and by
the nephridia (see G. Schneider, Zeitschrift fiir Wiss.
Zoologie, Band 66, pp. 505-507, 1899). Chlorogogen
granules are present in many of the cells of the coelomic
epithelium.

A great proportion of the reproductive cells present
in the coelomic fluid, instead of floating freely, accumulates
in the space between the oblique muscles and the ventral
body wall. In females oocytes in various stages of growth
and varying in diameter from ‘02—16 mm. may be seen.
In males various stages in the development of spermatozoa
from groups of young spermatogonia, consisting of about
eight cells to the masses of spermatids seen in Fig. 65,
may be found.

The celomic fluid is kept in motion by contractions
of the body wall. In a specimen freshly taken from the
sand one usually observes a series of peristaltic waves
arising in the posterior part of the gill region, and
running forwards to the anterior end, producing a pro-
gressive swelling of the body, due to the carrying forward
of the cceelomic fiuid, which, as soon as the wave is past,
flows backwards again. This motion is of considerable
importance in promoting the efficient circulation of the
celomic fluid, in inflating the anterior portion of the
animal, thus aiding in burrowing, in assisting the com-
paratively weak gut muscles to cause the backward motion
of the sand in the alimentary canal, and, when the animal
is in its burrow, in providing frequent changes, practically
a current, of sea-water to bathe the external surface and
the gills.

154

ALIMENTARY CANAL: BURROWING.

The alimentary canal consists of (1) an eversible

c

buccal mass and pharynx or “ proboscis” generally of a
pimish colour in young or middle aged specimens, due
to the contained blood-vessels, but in old specimens liable
to become darkly pigmented; (2) a cylindrical, pinkish or
greenish brown cesophagus, often transversely wrinkled,
which pierces the three diaphragms, and, just behind the
level of the last of these, bears a pair of glands; (3) the
stomach, which has yellow walls on which are numerous
blood streams, extends from the level of the heart to that
of the eleventh or twelfth sete, and gradually merges into
(4) the intestine, which is yellowish brown or dark olive
green in colour, and extends to the posterior end opening
at the anus (fig. 23).

During life the “proboscis” is being constantly
everted and withdrawn, carrying sand into the cesophagus.
During eversion the buccal mass is first extruded, this is
armed with several rows of curved, bluntly pointed, vas-
cular papille, which in old specimens are capped with
chitin (figs. 1,3 and4). Then the more globular pharynx
covered with minute rounded processes is protruded.
These papille, which are covered by a thin cuticle, have
an axis containing muscle fibres and connective and
nervous tissue covered by a columnar epithelium, in which
numerous mucus-forming cells are present. Among the
columnar cells there are here and there fine fusiform
sense-cells, the drawn-out tips of which project into or
through the cuticle covering the papille.

The csophagus is a thin-walled, distensible tube,
which is lined by elongate, columnar cells, among which
are swollen mucus-forming cells and occasional gland cells
of other kinds, the latter being more numerous in the

155

posterior part of the tube. The anterior part of the
cesophagus is non-ciliated, but the portion extending from
about the level of the third diaphragm to the stomach is
lined by cells which bear short cilia.

The csophageal glands or pouches are somewhat
flask-shaped and open into the posterior part of the
esophagus by a hollow stalk (fig. 23 and 35). They are
usually greenish in colour, due to the contained secretion,
but they may also have a pinkish tinge owing to the large
amount of blood present in the sinuses in their walls.
These blood sinuses are connected with the lateral
cesophageal and dorsal vessels. The cavity of each gland
is sub-divided by twenty to thirty incomplete partitions,
which, in young specimens or in strongly dilated glands,
are mere ridges upon the inner wall of the gland, but in
old ones they are, as a rule, lamelle projecting well
towards the centre of the pouch (fig. 35). Hach partition
is produced by infolding of the wall, and is, therefore,
covered on each face by the epithelial lining of the gland.
These infoldings of the wall enormously increase the
secreting surface of the organ. Between these two
epithelial layers is a blood sinus which is slightly enlarged
near the free edge of each partition. The pouch is lined
by cubical cells among which are numerous gland cells.
The secretion of these glands forms a mucous fluid with a
neutral re-action.

The stomach is covered with patches of yellow cells—
the chlorogogenous tissue—which in front are arranged in
symmetrical oval areas right and left of the dorsal blood-
vessel, while more ventrally they are placed in two or
three less regular series (fig. 23). They are separated
from one another by blood sinuses. About the level of
the tenth sete these areas become sub-equal and are
arranged in a spiral manner, and behind the level of the

156

fourteenth sete they are either indistinct or absent. The
epithelial lining of the stomach is strongly folded. It
consists of columnar cells among which are numerous
goblet-like cells, some of which produce a secretion which
is probably digestive, while others form mucus (fig. 51).
Commencing near the middle of the stomach, 2.e., about
the level of the ninth sete, there is a well-marked ventral
groove, the cells lining which are provided with long cilia
which produce a current from before backwards (fig. 36).
There are numerous smaller ciliated grooves on the lateral
walls of the stomach and intestine in which the flow is
downwards and backwards into the ventral groove. The
ventral groove extends to the anus. ‘The intestine is
lined by columnar cells, ciliated in the above mentioned
grooves, among which only a few gland cells are present.

Circular and longitudinal muscle fibres are present
in the walls of the alimentary canal, but they are well
marked only in the esophagus; in the stomach and intes-
tine they are so feebly developed that these parts of the
alimentary canal can have only shght powers of
peristalsis.

The process of digestion has not been fully investi-
gated, but the series of events appears to be somewhat
as follows: —During life the buccal mass and pharynx
are constantly being everted and withdrawn, carrying
sand into the esophagus. As the sand passes along the
esophagus it is mixed with the mucus from the cells
lining this part of the gut, and further back the secretion
of the esophageal glands is poured upon it. The mixture
then passes into the stomach, where the secretion from
the mucus-forming and digestive cells is added to the
mass. The swinging backwards and forwards of this part
of the alimentary canal, brought about by the muscles of
the body wall and by the protrusion and retraction of the

157

pharynx, tends to produce a thorough mixing of the sand
and the digestive substances, and in this way the food,
which consists of organic substances of various kinds in
the sand, is brought into contact with the digestive secre-
tions. The ciliary action of the lateral and ventral
grooves probably separates the digested substances from
the sand, and carries them slowly backwards. The ciliated
grooves are in close association with the blood sinuses in
which the flow of blood is probably slowly forwards. The
ventral groove is in especially close relation to the sub-
intestinal vessels (fig. 56). It seems probable, there-
fore, that the blood in the gastric plexus absorbs the
nutrient materials, conveys them to the hearts which
pump the blood along the ventral vessel to various parts
of the body.

A thin cord of mucus from the ventral groove may
often be seen in freshly-formed castings.

The great abundance of Arenzcola wherever the sand
or mud contains a large proportion of decomposing matter
or sewage, and its absence from or scarcity in long
stretches of coast where the beach is formed of clean
sand, indicate that these animals feed on decaying animal
or vegetable matter. They remove some of the decom-
posing organic matter in the sand, and as they burrow to
a depth of two feet or more, they cleanse the sand to
about this depth, and discharge it on the surface in a
purer condition. (See also under Hconomice section.)

BURROWING.

The burrowing of Avenicola is performed by the
combined action of the proboscis, the swollen anterior
region of the body, and the waves of muscular contraction
which pass along the body from behind forwards. The

158

proboscis is protruded, pressed into the sand and with-
drawn full of sand and again everted. The body is thrust
forward partly by the action of the longitudinal muscles
of the body wall, and partly by the peristaltic waves pro-
duced by the circular muscles, by means of which the
anterior end is also rendered swollen and tense, and is
thus enabled to enlarge the burrow. By these means a
passage is eaten and forced through the sand, smoothed
by contact with the skin, and may be lined with mucus
secreted by the epidermis. The gill region, being
narrower than that which precedes it, is to some extent
protected from friction, and the notopodial sete are also
directed so as to protect the gills. After burrowing
vertically downwards to a depth of from one to two feet,
the littoral forms may make a horizontal or oblique
gallery, and then a second vertical one, which opens on
the surface of the sand in a small funnel-shaped aperture.* .
The burrows of Laminarian worms, and those of some
littoral specimens, are simple vertical excavations (not
U-shaped), in which the animal is almost invariably
found head downwards.t

The amount of work done by Arenicola has been
estimated by Davisont on the Holy Island Sands. As
the result of observations upon the number and weight of

** G@. Bohn (‘‘ Observations Biologiques sur les Arénicoles,’’ Bulletin
du Muséum d’histoire naturelle, 1903, No. 2, p. 62) states that the
burrow of the littoral form is not U-shaped, and that it does not open
at the funnel-shaped aperture. He believes that the latter is due to
subsidence of the surface sand brought about by the subjacent sand
being removed during feeding by the proboscis of the worm. All other
observers agree that the burrows are, in the majority of cases,
U-shaped.

+ For an account of curious seasonal changes in Arenicola and
other burrowing marine animals see G. Bohn, ‘‘ Les intoxications
marines et la vie fouisseuse,’’ Comptes Rendus de ]’Academie des
Sciences, Paris, tome 133, pp. 593-596; and ‘‘ L’histolyse saisonnieére,”’
ibid. pp. 646-648.

} Geological Magazine, vol. viii., 1891, p. 489.

159

the castings in measured areas, he estimates that the
amount of sand brought up by the worms in a year is
1,911 tons per acre, which, if evenly spread, would form
a layer thirteen inches in thickness. Taking two feet as
the average depth to which the worms descend, the layer
of sand in which they burrow passes through their bodies
once in every twenty-two months.

Vascutar SystEM (See Plate III.).

The dorsal blood-vessel arises near the anus, and runs
on the alimentary canal to the anterior end, when it
breaks up into small vessels and capillaries. It contracts
moderately regularly from behind forwards. Connected
with it, in the tail, are intestinal vessels (a pair in each
segment), each of which runs round the intestine and
opens into the ventral vessel. The last seven pairs of gills
send efferent vessels to the dorsal vessel, and between con-
secutive efferent branchial vessels there are two or three
pairs of intestinal vessels. After receiving the most
anterior of these efferent branchial vessels at the level
of the thirteenth seta the dorsal vessel receives no
segmental vessels until it reaches the cesophageal pouches,
but it has numerous connections with the gastric plexus
or sinus.

The dorsal vessel has no direct connection with the
heart. In front of the heart the dorsal vessel receives on
each side (1) vessels from the first three nephridia and
neighbouring body wall, (2) from the esophageal pouches,
(3) from the second diaphragm and the body wall near the
second setal sacs, and (4) from the body wall near the first
setal sacs. It then runs forward, pierces the first
diaphragm, and breaks up into capillaries supplying the
buceal muscles, prostomium, otocysts, &c.

160

Small vessels collect the blood from these parts and
unite to form the ventral vessel which, soon after its origin,
gives off a median vessel to the first diaphragm and
its pouches, then a pair of vessels to the nerve cord and
the body wall in the neighbourhood of the second setal
sacs. <A little further back it gives off « median vessel
running on the second diaphragm to the nerve cord, and
a similar vessel on the third diaphragm to the nerve cord
and first nephridium. From this point the ventral vessel,
as it proceeds backwards, supplies the chetigerous sacs,
body wall, nephridia and gills (in those segments in which
the two latter are present) by segmentally arranged
branches. As it runs along the intestine the ventral
vessel is connected with the dorsal vessel by the intestinal
vessels (see above), and it finally breaks up into capillaries
near the anus.

On the walls of the stomach and intestine are
numerous intersecting blood-streams. In young specimens
the blood is contained in a plexus of small vessels, but as
the animal grows these vessels become converted into a
system of sinuses, and in old specimens the stomach
practically les in a gastric blood sinus, which is situated
between the gut epithelium and the ceelomic epithelium
which covers it. The dorsal vessel is, however, more or
less distinct.

It is convenient to refer here to two portions of the
plexus or sinus which are somewhat differentiated. (1)
There are two vessels (or sinuses) ventrally situated, and
known as the sub-intestinal vessels (figs. 25, 36). They
commence just behind the heart, and may be traced back-
wards to the level of the twelfth setz, behind which point
they gradually disappear. They receive efferent vessels
from the first six pairs of gills. (2) On each side of the

anterior part of the stomach there is a lateral gastric

ss

161

vessel (figs. 25, 56). This is usually first distinguish-
able posteriorly about the middle region of the stomach,
and becomes more clearly differentiated as it proceeds
forwards. Each receives blood from the dorsal and sub-
intestinal vessels through the gastric plexus, and opens
into the auricle, which is a thin walled expansion,
probably of the gastric vessel.

After giving off the lateral csophageal vessel, the
auricle opens into the ventricle, the walls of which are
muscular, and drive the blood into the ventral vessel.
The lateral cesophageal vessel on each side gives off a
branch to the esophageal pouch, and then runs forward,
supplying the lateral walls of the esophagus, and breaks
-up into capillaries between the first and _ second
diaphragms.

On each side of the nerve cord there is a small vessel
which accompanies the cord along the whole length of the
body. These neural vessels arise in front in the triangular
area between the cesophageal connectives by union of
capillaries from that region. Branches of the ventral
vessel enter into connection with them in the five segments
(second to sixth inclusive).

The vessels of the body wall are well developed
(figs. 24, 36). There are on each side two longitudinal
vessels distinguishable from the other vessels of the body
(1) the nephridial

longitudinal vessel which runs on the inner face of the

wall by their somewhat greater size

body wall just ventral to the level of the nephridiopores,
and (2) the more obvious and more important dorsal longi-
tudinal vessel which runs parallel to but above the former,
being slightly dorsal to the level of the notopodial setal
sacs. The former (the nephridial longitudinal vessel) is
only well marked in and for a short distance anterior and
posterior to the nephridial region. The dorsal longitu-
M

162

dinal vessel is distinguishable anteriorly just behind the
first seta, and may be traced to the posterior end of the
animal. It receives blood chiefly from branches of the
afferent vessels which supply the nephridia and_ gills.
There is in each chetigerous annulus a series of connec-
tions between these vessels of the body wall, viz., (1) a
short transverse vessel on each side connecting the nephri-
dial and dorsal longitudinal vessels, (2) a circular vessel
passing across the dorsal middle line, and connecting the
right and left dorsal longitudinal vessels. (3) a vessel on
each side connecting the nephridial and neural vessels,
and (4+) a short vessel passing over the nerve cord connect-
ing the right and left neural vessels (fig. 24.) The
dorsal and nephridial longitudinal vessels supply the body
wall in the dorsal and lateral regions, while the neural
vessels supply the nerve cord and ventral region of the
body wall. All these vessels, which are best seen in
transparent young specimens, are indirectly connected
by a network of capillaries—the parietal vessels (fie.
36).

The ventral vessel is large and turgid in the greater
part of the branchial region, and bears along its course
tufts of dark brown filaments (fig. 25). The extent to
which these are developed depends upon the size and age
of the specimen; they are much more numerous in old than
in young specimens. In old examples the brown filaments
are found in other situations also, e.g., along the gonidial
vessel of the first nephridium (fig. 27), and upon many of
the small vessels situated upon the inner face of the body
wall, especially in the branchial region. dach filament
(fig. 42) consists of a blindly-ending branch of the blood-
vessel on which it is supported, covered with cells which
contain large numbers of yellowish or brownish granules

which are similar to those found in the chlorogogenous

163

cells upon the stomach. Willem* finds on examining
the cells in the fresh state that they contain oleim and
acid urate of sodium (brown), the former substance being
probably of a nature of a nutritive reserve and the latter
an excretory product.

The blood plasma is red, due to the presence of
hemoglobin. The corpuscles are minute colourless
rounded or ellipsoidal, nucleated cells ‘005 to ‘01 mm.
(5 to 10u) in diameter. They are comparatively few in

numbers and their origin is unknown.

Heart anp Heart Bopy.

The hearts are a pair of contractile bulbs connecting
the gastric and ventral vessels. They are capable of
great dilation. The thin walled auricle is merely a
swelling on the gastric vessel. ‘The ventricle has thicker
muscular walls and its cavity is, in adult specimens, in-
vaded by a “ heart-body.” In post-larval and young
specimens the heart contains no trace of this body, but
it has appeared in examples 65 mm. long (fig. 37). At
this stage of growth the ventricular wall consists of an
outer cubical peritoneal epithelium and an inner but in-
distinct endothelium between which muscular tissue is
barely recognisable. The cavity of the ventricle is,
however, invaded by processes which repeat the structure
of the ventricular wall and are probably invaginations of
it. Later on, as the muscular tissue develops in the wall,
fresh invaginations occur (fig. 39). In full grown speci-
mens each process of the heart body is seen to be composed
of a very delicate endothelium, a muscular layer and a
mass of cells, some granular and some glandular, either
forming a fairly definite lining to the invagination or

** Miscellanées Biologiques dédiées au Professor Alfred Giard,
Station Zoologique de Wimereux, p. 556, Paris, 1899,

164

forming a mass loosely filling the process (figs. 33 and 40).
The granules in the cells are in some cases united into a
spherical mass lying in a vacuole; in others they are
minute and scattered. They agree in appearance with
the chlorogogen granules of the peritoneum. These in-
growths begin and are throughout best seen upon the
posterior (and to some extent on the outer) wall of the
heart. In large specimens they encroach on the cavity of
the ventricle to such an extent as to sub-divide it into a
large number of spaces so that the ventricle in section has
a somewhat spongy appearance (fig. 59). The heart body
appears to be a means of preventing regurgitation of the
blood into the gastric plexus after systole, and of ensuring
its passage into the ventral vessel. The presence of the
chlorogogen granules suggests that it may also have an

excretory function.

NEPHRIDIA.

There are six pairs of nephridia which open to the
exterior on the fourth to the ninth cheetigerous annuli, just
dorsal and posterior to the neuropodia,

fach nephridium may be divided into three regions,
an anterior funnel or nephrostome,* a middle secreting
portion and a posterior vesicle or bladder.

The funnel is always bright red in colour owing to its
rich vascular supply. It opens into the celom by an
elongated slit-like aperture which is generally directed

forwards and inwards and is bordered by two lips which

may be described as ventral and dorsal. The ventral lip
is entire and almost semi-circular. The dorsal lp is

slightly larger and fringed by ciliated, vascular processes

placed close together on the edge of the lip (figs. 24 and

** See also under Post-Larval Stages,

165

28). These processes are flattened spatulate or triangular
structures fixed by their narrower end to the lp of the
nephrostome. In young specimens (up to about 50 mim.
long) these processes are represented by small ciliated
tubercles on the edge of the lip (fig. 25), but later these
not only increase in number but become larger and sub-
divided distally. Hach of the processes eventually forms
a flattened structure the edge of which is sub-divided by
deep notches into from two to fourteen rounded lobes (fig.
29). Mach of these lobes contains a blind diverticulum
of the blood-vessel which traverses the edge of the dorsal
lip, hence the processes are bright red in colour. — ‘The
edges of both the dorsal and ventral lips are richly ciliated,
and there are also numerous long cilia within the mouth
of the funnel the motion of which is very obvious in fresh
nephridia examined on a slide in sea water. ‘The action
of these cilia creates a current passing down the funnel
to the oval aperture which leads into the middle or ex-
cretory part of the organ. ‘This current carries into the
nephridium small particles of foreign matter introduced
into the coelom and coelomic cells burdened with excretory
or with foreign particles.

The excretory part of the nephridium is a moderately
thin-walled sac, usually dark brown, sometimes almost
black in colour, owing to the presence of large numbers of
brown excretory granules in the cells lining the sac.
These excretory products are doubtless derived from two
sources from the blood flowing through the network of
vessels upon the sac and from effete materials carried into
the nephridium from the ceelom. This portion of the
nephridium tapers posteriorly and opens into the bladder,
which is usually greyish or brownish in colour. When
expanded the bladder is more or less spherical, but when
contracted it is rosette-like. Mach bladder opens to the

166

exterior by a small oval aperture situated just above and
behind the dorsal end of the neuropodium (fourth to
ninth).

Immediately behind the posterior part of the funnel
there is a small pinkish ovoid, club-shaped or cylindrical
mass of cells. This is one of the reproductive organs of
the worm, an ovary or testis as the case may be. There
is no gonad on the first nephridium.

The funnel and anterior part of the excretory portion
of the organ are attached to the body wall by a thin
mesentery, and the funnel is further held in its place by
one of the oblique muscles which crosses it and is fused
to it.

The nephrostomes of the first pair of nephridia are
situated on the anterior face of the third diaphragm.
They are somewhat smaller than those of succeeding
nephridia (fig. 27). The first and last pairs of nephridia
are subject to considerable variation, and the former
especially are often appreciably smaller than any of the
succeeding nephridia. Out of about 160 specimens ex-
amined eight were found in which there is some departure
from the normal condition. Six of these specimens
show reduction or Joss of the first nephridium. In one
example the first nephridium of each side is very small,
its secreting portion being only as thick as an ordinary
pin; in the second example the first left nephridium is
normal but the right one has no funnel; in the third case
the first nephridium on each side has no funnel; in the
fourth and fifth examples the first nephridium of one side
has a very small funnel while the corresponding one of the
other side is represented by a funnel only; and in the
sixth specimen the first left nephridium is totally sup-
pressed, the corresponding right one being present, but
without funnel. In the other two cases of variation the

167

last pair of nephridia is affected. In a large specimen
(250 mim. long) the sixth nephridium of the right side is
normal, but the corresponding one of the left side consists
of a tunnel only. Another specimen, 100 mm. long, has
only five pairs of nephridia opening on the fourth to the
eighth chetigerous annul, the sixth pair beimg totally
absent. These cases seem to show that the funnel and
the rest of the nephridium are, to some extent, inde-
pendently formed, as in the examples mentioned above
there are four cases in which the funnel is absent, and
three in which a funnel only is present.

In worms about 17 mm. long the nephridia, which are
about “5 mim. long, have already assumed the adult form.
The funnel is of considerable size and has well-marked
lips, the dorsal one bearing from three to five short, blunt,
conical elevations which later become the large spatulate
processes of the older nephridium. The secreting portion
of the first nephridium is a rather wide, almost S-shaped

tube; that of the following nephridia is much wider and
g ney

sac-like. There is a rich vascular supply to all parts of
the nephridium. In a specimen 44 mm. long the

nephridia are about a millimetre in length (fig. 295).
There is little change from the condition described above
except that all the parts are larger; the dorsal lp of the
nephrostome bears from four to seven small, blunt, conical
processes. Nephridia of large specimens may attain a
length of ‘8 mm. The funnel of such nephridia is large
and its dorsal lip bears as many as thirty-two spatulate
processes sub-divided distally into twelve to fifteen lobes.

The lips of the nephrostome are lined by a single
layer of ciliated columnar or cubical cells, supported by
a thin film of connective tissue. here is a fairly sharp
line of demarcation between the cells of the funnel which

have no concretions, and the cubical, columnar, or pear-

168

shaped cells of the excretory portion of the nephridium,
which, even in young specimens, contain some excretory
granules. Sections of the nephridia of young specimens
show that the cells hning this part of the organ bear one
or two long cilia on their inner ends, and that thei some-
what vacuolated protoplasm contains comparatively few
concretions (fig. 30). In older specimens the concre-
tions in the cells are very numerous, filling up the middle
and part of the distal region of the cell. The granules
are either black or yellowish, and some at least consist
of acid-urate of sodium (Willem). The distal fourth of
the cell is almost free from granules; they appear to have
been extruded into the cavity of the nephridium. Con-
siderable collections of such yellow granules are
occasionally found in the lumen of the organ. Finely
powdered carmine, when injected into the coelom, is taken
up by the cells lining the excretory portion of the nephri-
dium, and afterwards extruded in small masses. Below
the excretory epithelium there is a thin, almost structure-
less, layer of connective tissue, while in the walls of the
vesicle there is a thin layer of muscle fibres. in a corre-
sponding position. In young specimens the cells lining
the vesicle contain fewer granules than those of the
middle part of the nephridium; but in old specimens
there is little difference in this respect between the cells
of the two regions.

The network of blood-vessels with which the nephri-
dium is provided les between the excreting epithelium
and the thin celomic epithelium which covers the organ.

From the dorsal vessel a branch is given off which
runs on the anterior face of the first diaphragm. This

divides—one part supplies the body wall in the region of
the third setal sac, and is there connected with the longi-

tudinal dorsal vessel; the other part enters the funnel of

Lov

the first nephridium, and after traversing the nephrostome
and the excretory part of the organ ramifies finally on
the body wall near the nephridial longitudinal vessel, or
opeus into the latter. The funnel of the first nephridium
is also connected with the ventral vessel. Similar
branches of the dorsal vessel pass to the second and third
nephridia, and have a course corresponding to that con-
nected with the first nephridimn. A branch of the
ventral vessel enters the funnel of each of these two
nephridia a little im front of the middle of its length.
Just behind the heart the ventral vessel gives off a branch
which forks near the fourth nephrostome, one part passing
to the dorsal longitudinal vessel, and the other taking
the usual course through the funnel and the excretory
part of the organ to the nephridial longitudinal vessel.
Similar branches of the ventral vessel are given off to the
fitth and sixth nephridia, but these send afferent branchial
vessels to the first and second gills before entering the
nephridia. Their course in the nephridia is as described
for the corresponding vessel in the fourth nephridium.

Connected with all the nephridia there is also a small
branch from the dorsal lougitudimal vessel, which enters
the anterior part of the excretory portion of the organ and
ramifies there. This vessel is apparently sometimes
missing trom one or more of the nephridia.

The vessel which enters the funnel of the nephridium
gives off a branch to the ventral lip, but the main trunk
traverses the dorsal lip close to its edge, sending a blind
vessel into each of its ciliated processes. | Numerous
branches are given off from the main vessel in both the
dorsal and ventral lips, forming a close network ; some otf
the vessels on the nephrostome have blind dilated termina-
tions (fig. 28). After traversing the dorsal lip of the

nephrostome, the large vessel leaves it at its posterior

170

angle, where it is usually joined by the vessel which has
traversed the ventral lip. The gonidial vessel formed by
their union runs over the excretory part of the organ, and
sends branches to the vesicle, finally opening into the
nephridial longitudinal vessel. In the upper part of its
course the gonidial vessel is surrounded by the gonad,
except in the first nephridium, where it usually bears fila-
mentous blind outgrowths, covered with chlorogogenous
tissue (figs. 26, 27). The excretory part of the nephri-
dium is covered with a network of vessels, which le
between the excretory cells and the ceelomic epithelium.
This network is well seen in the nephridia of young

specimens (fig. 29).

REPRODUCTIVE ORGANS.

The reproductive organs are closely associated with
the nephridia. They are found immediately behind each
nephrostome, except the first, as a small, pinkish, ovoid,
club-shaped or cylindrical mass of cells, ‘4 to 1:0 mm. long,
surrounding the gonidial vessel and apparently produced
by proliferation of its cell covering (fig. 24). The gonidial
vessel is developed on the nephridia in very early life, it
may be recognised even in post-larval stages. In a
specimen 44 mm. long the gonads, though minute, are
recognisable (fig. 25). The gonad is well seen in an
adult stained nephridium, being distinguished by its
affinity for stains (e.g., carmine or hematoxylin). It is a
closely packed mass of cells in which at the anterior end,
2.e., the end in contact with the nephrostome, the cells are
small, almost uniform in size, and have well-marked,
deeply-staining nuclei. In the middle and_ posterior
portions of its length the cells on the surface of the gonad

become difterentiated, and in females young oocytes, and

—
+!
—

in males young spermatogonia may be recognised. — The
anterior portion of the gonad is covered by a thin layer of
celomic epithelium, but the posterior portion, from whieh
oocytes or spermatogonia are being shed is not covered by
an epithelium. The genital products are shed at an early
stage from the gonad into the coelomic fluid where they
complete their growth. The oocytes leave the ovary when
they have reached a diameter of ‘016 to ‘02 mm. While
floating in the coelomic fluid they increase in size and the
nucleus becomes vesicular, its diameter being about halt
that of the oocyte. Very small yolk granules are
deposited in the protoplasm, they are rather more
abundant round the nucleus, the peripheral portion of the
protoplasm contains less yolk. The protoplasm is sur-
rounded by a thin vitelline membrane about Lu im thick-
ness. Oocytes must be produced in the gonads at a great
rate, for the body cavity of large worms is filled with them
almost to bursting by about the end of February. Ripe
ova are not spherical but discoidal. The face of the egg
is either circular (usually) and about “15 mm. in diameter,
or it is oval with diameters of ‘16 mm. and about ‘14 mim.,
while the third axis of the eg
(figs. 67 and 68).

On the surface of the posterior part of the testes

g measures ‘08 to ‘09 mm.

groups of two, four or eight cells, young spermatogonia,
may be seen. They are shed into the celom: the youngest
stage usually found in the ccelomic fluid is formed of eight
spermatogonia arranged around a vesicular mass of proto-
plasm—the blastophore (figs. 60 and 61). The cells
undergo numerous divisions, the products of which remain
attached to the central blastophore. There is then a
period during which the cells do not divide but increase in
size becoming spermatocytes. Kach of these divides

probably twice successively (as in the better known

172

spermatogenesis of other invertebrates) to form four
spermatids. Disc-shaped masses of spermatids are thus
produced, the thickness of which is equal to about one-
fourth the diameter of the face (fig. 65). In each mass
there is a central cavity containing the remains of the
blastophore, a small quantity of a shghtly fibrous
coaguluin being present. Hach spermatid undergoes no
further division, but is gradually transtormed into a
spermatozoon. An early stage of this transformation is
seen in fig. 64. The nucleus is an oval compact body at
one end of which is a small conical mass of protoplasm, by
which the spermatid is attached to the blastophore. This
becomes the apical body or acrosome of the spermatozoon.
At the opposite end of the nucleus there is a clear sub-

‘

stance from which the “middle piece” of the sperma-
tozoon is apparently largely derived, and following this
is the rest of the protoplasm, which is being drawn out to
form the tail of the sperm. When shed into the sea the
ripe spermatozoa soon become free from the blastophore
and move by means of the tail, which appears to be a
somewhat stiff filament capable of comparatively limited
movements (fig. 66). A ripe spermatozoon is about “058
mum. long, it has a curiously shaped head -04 mm. long,
and a long slender tail (‘054 mm. long). The nucleus forms
the greater part of the head of the sperm. At one end is
the apical body forming a cap shghtly sub-divided by a
median groove. It is by means of this apical cap that the

sperm is later attached to the egg with which it is about to

unite. At the other end of the nucleus is the middle
piece which is apparently notched behind to receive the
basal part of the tail. tipe sperms may usually be

obtained about the end of February or the beginning of March.
The genital products, instead of floating freely im the
ceelomic fluid, often accumulate in the space between the

178

oblique muscles and the ventral body wall. In ripe
specimens there is often also a considerable mass of
genital products behind the third diaphragm, and pushing
it forwards into a pouch-like outgrowth (or two such out-
growths, one at each side of the alimentary canal). This
is due to the fact that while the perforations in the
diaphragm allow the passage forwards of the waves of
eelomic fluid (see above), they do not permit the passage
of the ova, or spermatid masses, to any extent. These
are, therefore, as it were filtered out of the ecelomie fluid,
and collect in a more or less compact mass behind the
ventral portion of the diaphragm.

The genital products escape from the animal by
means of the last five pairs of nephridia, the terminal
vesicles of some of which are often found to be distended
with ova or spermatozoa during the breeding season
(fig. 26). In a specimen 200 mm. long the vesicles of
some of the nephridia were 14 mm. long and 6 mm. in
width owing to distension by ova, while in another speci-
men the vesicles were filled with sperms, and were 5 mm.
in length and 4 mm. broad. The funnel of the nephri-
dium is usually widely open during the breeding season.
During the discharge of ova from the female the eggs are

caught m considerable numbers by the slimy mucus which

covers the body. Nothing further is known, however,
about the oviposition. tipe females, with the caelom

filled with ova, are found during the later portion of
February and during March, but by the end of the first

or second week in April the ova are usually all discharged.

Nervous System.
The central nervous system is composed of the brain,
the cesophageal connectives, the stomato-gastriec system

and the ventral nerve cord.

174

The Brain is situated in the prostomium, and even
in large specimens (250 mm. long) is only about a milli-
metre in length. It consists of a pair of anterior lobes
placed well forward in the prostomium, a pair of posterior
lobes which he below the nuchal organ, and an inter-
mediate region which connects the anterior and posterior
lobes (figs. 46, 47).

The anterior lobes are short but broad—in fact this is
the broadest part of the brain; behind these lobes the
brain gradually tapers. Their shape may be seen from
fig. 46. They are separated in front by a coelomic space.
Kach gives off anteriorly and dorsally a series of nerves
to the epithelium of the prostomium, and ventrally nerves
to the upper lip and neighbouring part of the eversible
buccal mass. The anterior part of these lobes consists of
small clusters of cells, separated from one another by
fibrous tracts and by neuroghal tissue. Further back the
delicate neuropile which forms the core of the anterior
lobes is well seen covered by clusters of cells and fibrous
tissue. Bundles of nerve fibrils may be traced from the
bases of the prostomial epithelial cells into the neuropile.
Larger unipolar ganglion cells are found just outside the
neuropile, and particularly on the side nearest the middle
line. These cells are more numerous immediately in
front of the point of union of the anterior lobes, and for
a short distance behind that point. The cesophageal con-
nectives arise from the anterior lobes at the point where
the neuropile reaches its greatest development. ‘The eyes
are found on the dorsal side of this part of the brain.
Passing backwards along the middle region of the brain,
it is seen that the ganglion cells become more restricted
to the dorsal and lateral faces, the middle and ventral
parts being composed largely of neuropile, in which also
neuroglial cells and fibrille may be recognised. The cells

175

situated on the dorsal aspect of this part of the brain are
in close association with the epithelium of the middle part
of the prostomium.

The posterior lobes are small and tapering. On
tracing them backwards, the cells are seen to decrease in
-quantity, and each lobe is continued as a fibrous tract,
accompanied by a thin covering of cells, which hes on the
inner side of the nuchal organ just below its sensory
epithelium (figs. 84, 47). The posterior lobes are separated
by a ccelomic space, containing muscles and blood-vessels.,

The brain has a strong ventral neurilemma sheath,
especially on the anterior lobes, into which some of the
prostomial muscles are inserted. Other muscles pass
between the anterior lobes, and are inserted into the con-
nective tissue underlying the epidermis. The brain
derives its blood supply from the dorsal vessel, small
branches of which break up into capillaries on its ventral
surface.

On examining a number of specimens of gradually
increasing sizes, two series of changes are seen to take
place in the brain. Firstly there is an increase in the
number of elements involving a growth of the brain, and
secondly a differentiation of form and a tendency to the
formation of groups of cells or “centres.” In a_post-
larval specimen, 4°5 mm. long, the brain is ‘11 min. long,
07 mm. wide and (05 mm. deep. Im a worm 75 mm.
long the brain has about twice these dimensions (length
‘2 mm.), and in another 17°5 mm. long the length of the
brain has again doubled (‘4 mm.). Beyond this point the
rate of growth is much slower, and in a specimen 10 inches
(250 mm.) long, the brain is only ‘9 mm. in length. The
description of the minute structure of the braim given
just above is drawn from specimens about 60 mm. in

length, in which the brain is a little more than half a

176

millimetre long. In older specimens the fibrous portion
of the brain becomes proportionately larger and more
complex, and the neuroglia is better developed. The
nerve cells also become aggregated into groups, separated
by bands of fibrous tissue.

The (sophageal Connectives arise from the anterior
lobes of the brain. They run beneath the epidermis and
circular muscles passing round the sides of the pharynx,

and uniting about the middle of the third chetigerous

annulus. The course of the connectives is marked
externally by the metastomial grooves (figs. 2, 6). The

connective of each side gives off (1) a nerve to each of the
first two inter-annular grooves, (2) a nerve to the otocyst,
(5) a nerve to the buccal mass which is probably connected
with the stomato-gastric system, (4) numerous nerves to
the epidermis of the peristomium and following segment.
Each connective is a stout fibrous cord, with numerous
cells upon its outer face. At the point of origin of the
nerve to the otocyst, and along the course of this nerve,
there is a considerable number of ganglion cells
(fig. 49). The connective is enclosed in a sheath of neuri-
lemma, which is better developed in old specimens, and
by ingrowths partially sub-divides the fibrous part of the
connective into two or three.

The Ventral Nerve Cord is usually separated from
the epidermis by the layer of circular muscles, but in some
specimens the cord in the tail and in the last chetigerous
segment, lies only just below the epidermis. — Its blood
supply is derived from the two lateral neural vessels,
which are connected with a series of capillaries lying
chiefly on the dorsal face of the cord (fig. 24).

The cord is non-ganglionated, ganglion cells occur
moderately evenly distributed along the whole length of
the ventral and lateral surfaces of the cord except at the

177

points where the spinal nerves are given off. The cord
gives off a pair of nerves situated in each inter-annular
groove, and lying below the circular muscles, and in each
chetigerous annulus either a pair of stout nerves or two
bundles (right and left) of two to four nerves, which run
outwards towards the parapodia, supplying the circular
and longitudinal muscles between which they lie (fig, 55).

In transverse section the cord is usually oval in shape,
being flattened from above downwards. The cells are
arranged on the ventral and ventro-lateral faces of the
fibrous part of the cord. The entire cord is invested by a
thin sheath of neurilemma, and the fibrous part of the
cord is partially sub-divided into two by a median vertical
sheet of neuroglia (fig. 54),

The ganglion cells are chiefly unipolar, and are small
and sub-equal, though here and there are larger cells,
generally in the neighbourhood of the giant cells.

The Giant Cells and Giant Fibres.—These cells are
much larger nerve cells, placed at segmental intervals along
the cord (fig. 52). There are no giant cells in the brain or
cesophageal connectives; the first one occurs just behind
the point of union of the connectives near the level of the
groove between the third and fourth chetigerous annul.
This cell belongs to the achztous segment (composed of
the third and fourth annuli) immediately following the
peristomium. The next cell is found in the annulus
behind the first chetigerous annulus, and the cells in
most of the other segments are found in a corresponding
position, but they may be a little anterior or posterior to
this level. The cells are, therefore, situated close to the
posterior limit of each segment. In many of the segments
only a single giant cell is present, but in about one-third
or one-half of the segments two cells are found near
together, one in front of the other. They are present in

N

178

the tail, but are not usually recognisable in the first few
segments, which are very small, and probably only
recently formed. Typical giant cells may be seen in some
of the middle and posterior caudal segments, but careful
search has failed to reveal them in a_ considerable
number of the tail segments of the two worms examined.
In the mid-dorsal region of the cord there are one, two
or three giant fibres seen in section (figs. 55, 36).
Anteriorly there is only one, in the middle region of the
body either two or three, and in the tail usually one. At
first sight they appear to be tubes with distinct walls and
homogeneous contents, but by suitably staining, longi-
tudinal sections the contents are found to be distinetly
fibrillar, but the fibrils are so fine that they are scarcely
recognisable in transverse sections. The wall of the tube
is composed of nucleated cells. These giant fibres arise
from the giant cells in the cord. This is not so easily
demonstrated in Arenzcola marina as in A. grubii, in which
the cells and fibres are larger (fig. 53). In the latter
species each giant cell gives off a stout process, which runs
in a somewhat sinuous course through the fibrous part of
one side of the cord towards the dorsal surface. Shortly
after leaving the cell the process gives off one or two
branches, which pass into and ramify in the fibrous
part of the cord. The process then passes dorsally
and enters either the median or, more usually, one of the
lateral giant fibres. The single median fibre present in
the anterior region of the cord arises from the first giant
cell situated just behind the union of the cesophageal con-
nectives. In those portions of the cord where two or three
giant fibres are present there are connections between
them, generally in each cheetigerous annulus. Branches
from one or other of the giant fibres may occasionally be
traced into the spinal nerves.

179

The giant cells and giant fibres of A. marina (fig. 54)
have similar relations to those of A. grubs. As a rule
the giant cells are almost mid-ventral in position, and their
diameter in A. marina is from about ‘04 to ‘08 mm. The
cell is pyriform in shape, and the narrow extremity is
prolonged upwards, and follows the course described
above. Each cell has a fibrillar sheath. The protoplasm
is clear, but in favourable preparations is seen to be
traversed by delicate, darkly-staining fibrille, which
branch; but the branches do not appear to reach the
nucleus. These neuro-fibrille may be traced into the
process of the cell, and for some distance towards the
giant fibre, with which the process is connected. The
nucleus is a large vesicular structure, with a diameter
about one-third that of the cell to which it belongs;
within the well-marked nuclear membrane is a small
amount of chromatin reticulum, and usually one deeply
staming nucleolus. The nucleus is nearly always
excentric, being placed near the broader end of the cell.

The giant cells are not differentiated in a post-larval
specimen 4°5 mm. long. In specimens 17°65 mm. long and
upwards they are well marked, but they are apparently
no larger in specimens 250 mm. long than in others one-
fourth this length.

SENSE ORGANS.

The sense organs are the otocysts, the nuchal organ,
the eyes and the prostomium. To this list of sensory
structures should be added (1) the papille of the proboscis,
in the epithelium of most of which sense cells may be dis-
tinguished ; (2) scattered sense cells in the epidermis, and
(3) the notopodial sete, as Retzius has found nerve endings
around their bases. Even when the animal is at rest the

180

constant movements of protraction and retraction of these
sete suggests that they may have a sensory function.
The Otocysts (figs. 46,49 and 50) are the best developed
sense organs of Arenicola. They may be seen in dissec-
tions close to the outer edge of the dorso-lateral portions
of the csophageal connectives. Hach is a vesicle com-
municating with the exterior by a narrow tube, the
external opening of which is situated in the peristomium
close to the point where the metastomial groove crosses
the first inter-annular groove (fig. 5). The otocyst is
placed at an angle to its tube and both are lined by a
very thin cuticle, best seen in old specimens. The
epithelial wall of the otocyst is thicker in old specimens
than in young ones, due to the elongation of the cells. In
specimens 65 mm. long the epithelium is about 25 thick,
but it is twice as thick in specimens 250 mm. long. The
cavity of the otocyst does not, however, increase in the
same way, it is practically the same size in these two
specimens, its mean internal diameter being -12 to “13 mm.
(cf. figs. 49 and 50). The epithelium is composed of non-
ciliated sense cells and supporting cells. The sense cells
are not always easily recognisable, but in some prepara-
tions they may be distinguished by their fusiform shape,
their more deeply staining nuclei and by the possession
of delicate neurofibrille. In favourable sections, stained
with iron hematoxylin, each sense cell is seen to be
traversed by a delicate, deeply-staiming fibril which
terminates either just below or at the surface of the
cuticle. Similar cells and their fibrilla may also be seen
in the wall of the adjacent part of the tube of the otocyst.
The tube is lined by columnar cells among which are
gland cells; the cells lining its proximal part (imme-
diately after it leaves the otocyst) are ciliated. The
epithelium of the distal part of the tube gradually merges
e

a

181

into the epidermis. The nerve supply to the otocyst is
derived from the cesophageal connectives. Around the
point of origin of this nerve and along its course are
numerous large ganglion cells with vesicular nuclei. The
nerve comes into contact with the otocyst at the point
where the tube leads off to the exterior and is intimately
related to both structures as it provides them with a
sheath of nervous elements. The nervous sheath lies
below the epithelium of the otocyst and tube, among the
nerve fibres occur scattered fusiform or stellate cells.

The otocyst, in life, contains a fluid of a somewhat
viscous nature which consists of a secretion of the walls
of the otocyst and its tube mixed with sea water. It also
contains numerous otoliths in the form of foreign bodies
such as quartz grains, portions of spicules, frustules of
diatoms, &c. In some specimens the original otoliths,
which were irregular in shape, have been covered by layer
upon layer of secreted substance of chitinoid nature, the
resultant otoliths having rounded outlines. This condi-
tion is met with in moderately old specimens (130 to 250
mm. long) in which also the tube of the otocyst has
become closed either by apposition of its walls or by the
blocking of the lumen by a granular substance secreted by
the gland cells in the wall of the tube (fig. 50). That
this rounded character of the otoliths depends upon the
closure of the tube is shown by the fact that in other
specimens (about 170 mm. long), in which the lumen of
the tube is a fair-sized slit, the otoliths are irregular and
uncoated foreign bodies. In most young specimens the
otoliths consist of irregular bodies which are almost naked,
i.e., they have either no secreted covering or else it is ¢
mere film the presence of which is indicated by its staining
with hematoxylin.

Whenever the otocyst is examined fresh under the

182

microscope, either 7m situ in young transparent specimens
or after being rapidly dissected out, the otoliths exhibit a
peculiar quivering and rotatory movement. This motion
is probably due to the action of the cilia in the entrance
to the tube which leads to the exterior.

The otocyst does not appear to be an organ of hearing
as the animal takes no notice of even loud sounds made in
its immediate vicinity. It is more probably an organ
for enabling the animal to appreciate its position in the
sand or in the water and thereby to direct its movements.

The Nuchal Organ (figs. 5, 34 and 47) is a U-shaped
ciliated groove formed by an invagination of the epidermis
of the posterior part of the prostomium. ‘The epithelium
of the organ is composed of columnar cells, some of which
are distinguished as sense cells by the presence of neuro-
fibrille. The intervening supporting cells are rather
stouter, and many of them are ciliated. In old specimens
pigment granules are deposited in many of the cells.
Beneath the epithelium there is a layer of nervous
elements in connection with the posterior brain lobes.
The organ probably has an olfactory function.

The Eyes (figs. 47 and 48).—-Two to five eyes, one of
which (the oldest) is larger than the others, are present on
each side of the prostomium in post-larval stages (figs.
596 and 59). Only in very young specimens from the sand
are they visible externally. They may be found in sections
of specimens up to 70 mm. long by which time they have
sunk below the epidermis and have become imbedded in
the mass of ganglion cells on the dorsal surface of the
anterior cerebral lobes just in front of their point of union.
They are difficult to find in older specimens owing to the
increase of pigment in the prostomium, and they are
apparently wanting in some old specimens.

The eyes are very simple in structure. Each is com-

183

posed of a cup-shaped mass, about ‘01 mm. in diameter,
of reddish brown pigment spherules, grasping the base
of a spherical or ovoid lens.

The animal is sensitive to light. If its anterior end
be protruding from the burrow and light be thrown upon
it, the worm at once disappears from view. In its re-
action to light Arenicola resembles the earthworm, and,
as in the latter, the re-action may be due to the general
sensitiveness of the anterior end.

The Prostomium (figs. 5, 47 and 48).—The epithelium
of the anterior and dorsal face of the prostomium consists
of columnar cells among which slender fusiform sense
cells may be distinguished. These are generally in small
groups and their slender tips are level with or project
slightly beyond the outer surface of the cuticle. The
bases of the cells are in intimate relation to either the
cells of the brain itself or to the fibres of the nerves which
connect the epithelium to the brain. In some prepara-
tions the neurofibrille traversing the sense cells may be
seen. Among the ordinary columnar cells of the pros-
tomial epithelium there are, especially in the mid-dorsal
region, numerous swollen gland cells.

DEVELOPMENT.

The early stages of development of Arenicola marina
are unknown. <A brief resumé may be given of the
development of A. claparedi. We may presume with
moderate certainty that the development will follow
similar lines in the two species.*

* The following account is from observations made during my
occupancy of a Table in the Zoological Station in Naples, in April,
May and June, 1900:—From April 7th onwards specimens of
A. claparedit were examined at frequent intervals, and on April 21st
the first ripe males and females were obtained, the eggs fertilised, and
the early stages of segmentation observed. The observations on the

184

Ripe ova of Arenicola claparedii were artificially
fertilised by adding to the sea-water in which they were
contained a small quantity of sea-water containing
spermatozoa taken from the caelomic fluid of a mature
male. In one to two hours after this the two polar
bodies were extruded, and in about four hours after the
addition of the spermatozoa nearly all the eggs had
divided into two cells (fig. 69), a larger (C D)T and a
smaller (4 B), each of which in less than an hour divided
again.t. Three of the cells (4 B C) so produced were
nearly equal in size; the fourth (D) was considerably
larger than these (fig. 70). By the next division each
cell was cut into an upper or anterior and a lower or
posterior portion. The four upper cells (la, 1b, le, 1d) so
produced become displaced, or rotated, with respect to the
axis of the:egg, so that each no longer lies directly above
the cell from which it arose (fig. 71). This rotation,
which affects nearly all the cleavages of the first day, is
characteristic of the “ spiral ’ type of cleavage found in
Nereis, and other Polycheta. These four upper cells form
the first quartette of ectomeres. From the four lower
cells (14, 1B, 1C, 1D) a second (fig. 72) and a third set
of four (2a, 2b, 2¢, 2d, and 3a, 3b, 3c, dd) are successively

development given in the following account were made on various
batches of eggs and larvee and extended from this date until May 19th,
when the last of the larvie died. I beg to express my sincere thanks
to Professor Dohrn for his generosity in placing a Table and the
resources of his Station at my disposal, and to the Government Grant

Committee of the Royal Society for a grant towards the expenses
of this and other work done in Naples.

+ I have used Dr. Child’s nomenclature of the cells, which is based
on that proposed by Wilson in his classical memoir on ‘‘ The Cell
Lineage of Nereis,’’ Journal of Morphology, Vol. VI.

t The early development of A. claparedii appears to be very
similar to that of A. cristata, which has been studied in great detail
by Dr. C. M. Child (see Archiv fiir Entwickelungs-mechanik der
Organismen, Band IX., Heft 4, May 22nd, 1900). See also
E. B. Wilson, Studies from the Biological Laboratory, Johns Hopkins
University, Baltimore, Vol. II., 1883, pp. 271-299.

s of the egg. The first division of the
but the other quartettes are not followed.

Fertilised Ovum

rst quartette is shown,

.

Diagram showing the early cleavage
The mesoblast and endoderm cells are labelled; all the cells which are derived from

the first, second and third quartettes (labelled 1, 2 or 8 followed by a small letter) are

members of the
ectomeres.

185

2 4 8 16
Cells. Cells. Cells. Cells.
( lia
ia
| la?
A a
| | 2a
1A
| 9A
AB
1s
i=
| ( 152
| i.
| ( 20
NB;
( OB -
We
le
| | ke
(Gis
| 2c
lic!
| 26
CD +

INE Tes dai, ldives5 7

32 About

Cells. 60 Cells.

3a
34 (4a Endoderm.
“ (4A Hndoderm.

3b
ap (4b Endoderm.
ob (4B Hndoderm.
36
30) (4c Hndoderm.

(4C Endoderm.

( 3d

2D | 3p

(4d Mesoblast.
(4D Hndoderm.

In Fia. 73 all the endo-

69. 70, 71. 2B,2C,and derm cells except 4c
2D, are not have again divided,
seen in the and the mesoblast

figure.

cell has sunk into
the segmentation
cavity.

186

cut off, all of which are ectomeres. Then a fourth set of
four (4a, 4b, 4c, 4d) is cut off from the lower cells.
One of these four cells (4d) is very large; it is
the mesoderm cell, or somatoblast, and it soon sinks below
the surface into the cleavage or segmentation cavity. The
other three cells of the fourth quartette (4a, 46, 4c), and
the four lower cells (44, 4B, 4C, 47)) are the endoderm
cells, and they occupy a position at the lower or posterior
end of the larva. At this time the larva consists of (®
about 50 ectomeres, products of division of the cells of the
first, second and third quartettes; (2) the seven endoderm
cells mentioned above, and (3) a mesoderm cell. At the
end of twenty-four hours* after fertilisation, the larva,
when seen from the lower pole, has the appearance shown
in fig. 73. The ectoderm cells are by this time more
numerous (about 70 to 80), and the endoderm cells, dis-
tinguished by the numerous yolk granules in their proto-
plasm, are in this case thirteen in number, each of the
seven primary endoderm cells, except 4c, having divided
into two. Lying in the segmentation cavity, and not
shown in the figure, are two mesoblast cells produced by
division of the primary mesoblast cell (4d). The larva,
now a blastula, is converted into a gastrula by growth of
the ectoderm cells over the yolk-laden endoderm cells.
About twenty-eight hours after fertilisation the anterior
ciliated band is just recognisable and the larvee were found
to be rotating slowly within the vitelline membrane. The
stomodzal invagination had also made its appearance
(fig. 74). Twenty-four hours later both the ciliated bands
of the larva were well marked, a broad one just anterior to
the mouth, and a narrow one near the posterior end of the
animal, and by this time the rotatory motion was much

*“ It is very probable that in shallow water, in sunlight, the
development would be more rapid than it was in the cool laboratory.

187

more rapid. One or two eyes of orange-red colour were
also present on the anterior portion of the larva. During
the third day the animal elongated and contracted at in-
tervals, and evidently both longitudinal and circular
muscle fibres were present. At the end of the third day
the telotroch* larva worked its way out of the vitelline
membrane through a thin area which had previously made
its appearance (fig. 75).

When hatched the larva was about ‘25 mm. long. It
either crawled on the bottom of the dish or swam actively
by means of its cilia. Between the two bands of cilia
there appeared on the ventral surface a broad longitudinal
band of short cilia. Soon after hatching a small spade-
shaped seta (7u long) was observed in one specimen. It
could be protruded and retracted (fig. 76). The larvee
grew very slowly in the laboratory and it was not until
more than four days after hatching that the setz of the
following segment appeared. In the meantime the
spatulate sete of the first segment had been reinforced by
the addition of a seta with a long, drawn-out tip, and a
little ventral to this the first crotchet appeared. Two days
later the alimentary canal seemed to be complete from
mouth to anus, its central part was rather distended with
yolk. The celom was quite obvious post-orally, and the
ventral body wall was thickened, due to the formation
there of the ventral nerve tract. The two belts of cilia
and the longitudinal ventral band gradually decreased in
size from this point onwards. Two days later another
segment acquired its sete. Both the chetigerous seg-
ments in front of this had on each side two sete and a
crotchet, the third segment bore only the newly formed
spatulate seta. The larve crawled about the bottom of

** The term applied to Polychete larve in which the cilia are
arranged in two bands forming a preoral and a peri-anal ring.

188

the dish surrounded by a film of mucus. Although the
mouth was open it was found impossible to induce the
larvee to feed and they died as soon as the yolk in the
stomach was absorbed, 7.e., about a fortnight after
hatching, without having advanced beyond a_ stage
showing three or four chetigerous segments (fig. 77).

Post-LARVAL STAGES.

Post-larval stages of A. marina are found in the
surface waters of the sea, and are almost invariably
enclosed in a mucous or gelatinous tube, which overhangs
the worm at each end: The external diameter of the tube
is from two to three times that of the animal. The young
worm is capable of wriggling movements, which are not
seriously impeded by the enveloping tube.

The term * post-larval stage” was given by Benham
to a stage in the development im which the animal
possesses the full adult number of segments, and is
divisible into an anterior chetigerous region and a
posterior achetous region, or tail, but in which the gills
are not yet completely formed, or have not even made their
appearance. By this definition all the pelagic specimens
of A. marina which I have examined, with one possible
exception, are post-larval stages. This one, a Lytham
specimen, 3°9 mm. long, bears the full complement
(thirteen pairs) of gills, and all of them except the first
two have become branched, being formed of two or three
finger-shaped filaments (fig. 56). In this specimen
also the annulation is well marked, and the prostomium
proportionately smaller than in any of the other specimens
examined. This animal has reached the end of the post-
larval stage, and would doubtless soon have settled down
to its littoral habitat. It is the only recorded specimen

189

in which all the gills are present, and it would therefore
appear that most specimens take to a littoral habit rather
earlier than this one. In point of length it is not, how-
ever, a large specimen, being only 3°9 mm. long. In life
it would certainly be longer; this measurement is taken
from the mounted specimen, which was unfortunately
preserved in a somewhat contracted condition. The
longest post-larval stage I have seen measures 6°5 mm.
from anterior to posterior ends, and this one has no gills.
Evidently, therefore, the time of appearance of these
organs varies in different specimens. Perhaps the two
specimens under consideration belong to the two different
varieties of A. marina, but there are no means of establish-
ing this point in the larger specimens; the smaller almost
certainly belongs to the littoral variety.

Nothing is known concerning the duration ot
the pelagic lite of these post-larval stages, but it is
apparently at any rate some days, judging from the
varying sizes of the specimens captured within a few days
of each other. For example, in a series of eight speci-
mens taken near Plymouth during the last days of March
and early days of April, 1901, there are specimens varying
from 3°5 to 65 mm. in length. Again, the varying sizes
of these specimens, and the length of the period during
which they may be taken in the tow-nets, show that the
spawning period of A. marina may occasionally extend
over two or three months, e.g., post-larval stages have
been taken as early as March 8th, and as late as May 29th.
The latter date is, however, exceptionally late; most
specimens are taken either in March or in the early days
of April. The smallest worms I have found in the sand
were taken near the end of June, and are 17 mm. long.
They possess thirteen pairs of well-branched gills, the

prostomium has assumed the adult form and relations,

190

the nephridia are sac-like, and their dorsal lip bears from
two to five papille—in fact these worms are miniature
copies of adults. Other specimens up to 44 mm. in length
were found at the same time and place which show a
similar condition of the prostomium and_ nephridia
(fig. 25), and are probably but little older than those
17 mm. long. It is probable that these specimens were
produced from eggs laid in the early spring of the same
year, so that the young worms are three or four
months old.

I have examined seventeen post-larval stages of A.
marina varying in length from 3:5 to 65 mm. ‘Three of
the specimens (4°6, 5-6 and 5°6 mm. in length) were ex-
amined living. The following description is drawn from
specimens 4°6 to 5°] mm. in length. Such examples are
‘2 to'3 mm. in diameter and the chetigerous portion of the
worm is nearly three times as long as the tail.

The prostomium is a moderately large and somewhat
lozenge-shaped or spatulate structure at the anterior end
overhanging the mouth (figs. 57, 58). | Upon it are seen
the eyes to the number of two to five on each side of the
middle line (figs. 56, 59). One of these, the oldest, is
larger than the rest. Their structure is described above.
The epithelium of the prostomium bears small scattered
groups of sense hairs (fig. 09). Immediately behind the
prostomium is the nuchal groove, the degree of develop-
ment of which seems to vary in different specimens. In
some it is scarcely recognisable, but in others it is a well-
marked groove extending across the posterior border of
the prostomium. When the lps of the groove are
everted the rapid movement of the cilia may be observed.

Behind this is the peristomium in which the otocysts
are well seen (fig. 57). The internal diameter of these
organs is about ‘04 to ‘(06 mm., and the external aperture

191

of the tube was at times comparatively large. The
otoliths, consisting of quartz grains, were quivering and
revolying rapidly all the time the living animals were
under observation. This motion is probably due to the
action of the cilia of the proximal part of the tube.
The motion of the otoliths almost ceased when sea water
which had been standing over chloroform was added. On
the ventral side of the peristomium at its anterior edge is
a crescentic or nearly semi-circular aperture—the mouth
(fig. 58).

Between the peristomium and the first chietigerous
segment there is a segment which, im all the post-larval
stages I have seen is achetous. Benham* and apparently
also Ehlerst have found a small seta in this segment, but
evidently this is a transitory seta which soon disappears
leaving the segment achtous as it is in the adult. Both
the peristomium and this achetous segment are rather
smaller than the succeeding chetigerous segments and
both are usually divided into two by a faint groove so
that, as in the adult, the region between the prostomium
and the first chetigerous segment is divided into four
rings. In the third of these the cesophageal connectives
unite. By comparing these post-larval stages with adults
it is clearly seen that the first two rings of the latter belong
to the peristomium and the next two to the first true body
segment which has lost its setee and has become fused with
the peristomium (cf. figs. 5 and 57).

There are nineteen chetigerous segments, in each of
which notopodial and neuropodial setze may be seen (fig.
56). The notopodial setze are of two kinds. Some are

* Journal Marine Biological Association, New Series, Vol. III.,

p. 49, 1893.

+ Zur Kenntniss von Avenicola maria, L., Nachrichten von der
Kénigl. Ges. der Wissenschaften, Gottingen, 1892.

192

capillary sete, about ‘2 to “3 mm. long, bearing along one
edge of their distal fourth a narrow lamina, which may be
slightly dentate distally (fig. 11C). In some sete the
whole of the lamina seems to be broken up into a series of
minute pointed processes similar to, but, of course, smaller
than, those of the adult setze. Some of these setee have a
narrow but shorter lamina on the opposite side. The
other notopodial sete are quite different (fig. 11 A, B).
They are only about ‘18 mm. long. Hach of them ends
in a long fine point and beyond the middle of its length
the seta bears a thin but broad lamina or wing on each
side upon which faint oblique striations are occasionally
visible. Hach notopodial pencil contains only one seta
of the latter kind accompanied by one to five of the longer
papillary sete. The shorter sete with a broad lamina on
each side soon disappear, they are not recognisable in
young specimens, 17 mm. long, from the sand.

The neuropodial crotchets are about ‘04—05 mm.
long (fig. 15). Hach has a thickening upon the shaft
lying just below the level of the epidermis. On examin-
ing the rostral region there are seen to be two or three
well-marked teeth behind the rostrum, and a small process
often ending in a fine point under the rostrum. These
structures are in focus along with the rostrum, and lie
approximately in the same plane. On careful focussing,
it may be seen that the teeth are not confined to the
region behind the rostrum, but that on the sides of the
latter there are small teeth, so that the rostrum projects
from the centre of a series of teeth situated around its
base. The sub-rostral process marks the position of the
smallest of these teeth. In their natural position the
crotchets lie so that the tip of the rostrum is directed
dorso-laterally. In most post-larval specimens about

5 mm. long each neuropodium bears only two to six

193

crotchets, the smaller number being present in the iirst
three or four neuropodia. In the branchiate Lytham
specimen 39 mm. long, the crotchets are rather move
numerous, there being eight or nine in many of the
neuropodia. The crotchets of post-larval stages differ
from those of adults in the relatively large size of the
teeth, and im the angle which the rostrum makes with
the shaft. In post-larval crotchets the rostrum is approxi-
mately at right angles to the shaft, while in older speci-
mens it makes a much greater angle, in large specimens
as much as 130 degrees (cf. figs. 15, 18).

As stated above, there are no gills in any of the seventeen
post-larval stages examined, except one. This one is
+9 mm. long, and the thirteen pairs of gills are present,
and all except the first two are branched. The largest
gills are behind the middle of the series, and this is pro-
bably the region where the gills are first formed. = In
other specimens no gills are indicated, but im the living
specimen 46 mm. long, unmediately behind the notopodia
of the penultimate and the two or three preceding chieti-
gerous segments, the blood-vessels form a well-marked
loop, as if preparatory to the formation of a gill, and there
is a very slight elevation of the skin in this region. Later
on, as shown in the Lytham specimen, the gill becomes
successively a papilla, a digitiform, and then a branched
structure. The gill arises, therefore, as a special respira-
tory structure, and is not a dorsal cirrus which secondarily
becomes a branchia.

The tail is very similar to that of the adult. The
terminal segment bears a number of circum-anal papille,
each of which carries a tuft of four or five sense-hairs,
which project posteriorly.

The skin is glandular. It contains numerous
scattered cells, each filled with yellow granules, If the

O

194

animal, and especially its anterior end, be subjected to
pressure, the yellow pigment seems to become diffused
through the whole skin, and the yellow granules in the
cells mostly disappear. Some of the pigment also exudes
into the water. Later such a compressed anterior end
becomes green, and this pigment resists solution in alcohol.
The skin also contains numerous mucus-forming cells, by
the activity of which the envelopmg tube is formed. A
specimen which was deprived of its tube was found
twelve hours afterwards enclosed in an elongate mass of
mucus formed by the epidermis.

The secondary annulation of the skin, which corres-
ponds with that of the adult, is shown in many post-larval
stages, except in the first two or three segments, where
the annuli are less clearly indicated. The metastomial
grooves are only faintly seen. They unite just behind the
middle of the achetous segment, and are there continuous
with a shallow mid-ventral groove which marks the
position of the ventral nerve cord.

The mouth is a crescentic or semi-circular aperture
at the anterior ventral edge of the peristomium (fig. 58).
The pharynx is protrusible, and bears small papille. It
leads into the ciliated cesophagus, which bears the two
glands, each of which is a sunple finger-shaped outgrowth
of the gut, 25—45 mm. long, directed forwards, and
showing in its posterior portion three or four slight
internal ridges which are the precursors of the larger
septa found im the glands of adults. The secretion of the
glands is already present in the form of droplets, some of
which are still in the glands, while others are in the
posterior portion of the csophagus. The stomach is
marked by elongate oval areas, between which are blood-
vessels. Chlorogogen cells are present, but are only dis-
tinguishable along the margin of the blood-vessels, and

not over the whole of each oval area as in the adult. Very
fine débris is present in the intestine of one or two speci-
mens, but in most the gut is practically empty.

The blood-vessels are well developed, and are
arranged as in the adult. The blood is reddish or pink
in colour. The heart is a simple tube, dilated at its upper
end, and contracting frequently. The two hearts do not
beat in unison. The wall of the ventral vessel contains
numerous spherical yellowish (some nearly colourless)
granules, probably chlorogogenous. The flow of blood in
the dorsal vessel is from behind forwards.

Cells are already abundant in the ceelomic fluid.
They are mostly oval, or spindle-shaped, and about ‘02 mm.
long. Many of them, especially the oval cells, already
contain yellow granules.

The musculature is similar to that of the adult.
Longitudinal muscles are well developed, the circular
ones only feebly so, and the oblique muscles are very
slender.

There are six pairs of nephridia opening near the
fourth to the ninth neuropodia, as in the adult. Each
nephridium is a eurved ciliated tube (fig. 31), the
lips at the antevior end of which are slightly everted, and
one is larger than the other. Attached to the larger lip
and hanging over towards the smaller are (except in the
first nephridium) from four to eight protoplasmic pro-
eesses* which are only visible in living specimens (fig. 52).
They are generally of unequal length and in the lying
specimen, 4°6 mm. long, the longest processes measured
only ‘05 mm. Lach process is shghtly swollen about the
middle of its length and tapers distally. It bears about
ten moderately strong, long cilia directed backwards

** See Goodrich, Quart. Journ. Micr. Science, p. 729-730, fig. 49,
Vol. 43, 1900. In his specimen the processes appear to have been
rather longer than in mine.

196

towards the aperture of the nephrostome. The leneth of
the nephridium is about ‘3 mm. The walls of its middle
portion already contain numerous excretory granules,
most of which are yellow, but others are almost colourless.
The ciliary action in the tube, especially in its posterior
part, 1s very vigorous at intervals. The first nephridium
is more slender than any of the others and its lumen,
especially in the anterior part, is very minute. Its
anterior end (nephrostome) forms a slight swelling on the
anterior face of the third diaphragm, due almost entirely
to the larger lip, between which and the smaller lip there
is a slit-hke opening. The larger lip bears a number of
well-marked cilia, but no ciliated processes like those on
the other nephridia could be seen. The relation between
the funnels of the nephridia of these post-larval stages
and those of the adult is unknown. Goodrich holds that
the adult funnel is not a nephrostome but a genital funnel
which is developed from the coelomic epithelium and is
added to the anterior end of the nephridium. The gonads
are not yet distinguishable.

The brain is divisible into a large anterior part (not
yet sub-divided into two lobes) consisting of neuropile with
a thick covering of cells, a posterior part which is bilobed,
each lobe having a fibrous core with a cellular covering,
and a middle region uniting the two. The ventral nerve
cord is more closely united with the epidermis than it is in

the adult. No giant fibres or giant cells are recognisable.

SystTEMATIC Postr1on AND CLASSIFICATION OF THE
ARENICOLID.®.
Benham” divides the Polycheta into two branches—
the Phanerocephala and the Cryptocephala. The chief

=

* Polycheta in Cambridge Natural History, Worms, Rotifers
and Polyzoa. 1896.

197

characters of the former are— the prostomium is distinct
and often bears, in addition to the paired eyes, sensory
tentacles and palps (as, for example, in Verezs); the body
segments are more or less alike and not divisible into two
sharply-marked regions, distinguishable by the different
arrangement and character of their setee and by internal
differences. In the Cryptocephala the prostomium 1s
compressed or hidden by forward growth of the peris-
tomium and thus becomes insignificant; the tentacles are
reduced but the palps become greatly enlarged and sub-
divided, forming the crown of gills; the body is divisible
into a “thorax” and ‘“ abdomen,” distinguished by the
form and arrangement of their sete and by certain
internal differences. Arenicola belongs to the branch
Phanerocephala which is divided into five sub-orders.

I. Neremprrormr1a—Prostomial tentacles and palps
well developed; pevistomial cirri usually present; para-
podia well developed with acicula, dorsal and ventral
eirr1; setve usually jointed; muscular pharynx with
chitinous jaws; septa and nephridia regularly repeated
throughout the body. Chiefly predaceous and carni-
vorous worms, e.g., Vereds.

Il. Sprronivormia._Prostomium without tentacles
and palps; peristomium with a pair of long elrTl; para-
podia project only to a shght extent, their dorsal cirr1 may
be large and act as gills, sete unjointed ; no jaws; septa”
and nephridia regularly repeated. Chiefly tubicolous or
burrowing worms.

III. Teresectirormia.—Prostomium forms a promi-
nent lobe (upper lp) with or without tentacles, but with-
out palps; peristomium may bear cirri or ‘ tentacular
filaments’; parapodia feebly developed, ventral cirri
absent, dorsal cirri may form gills, setee unjointed, uneini

(short, sharply-curved dentate hooks) usually present;

198

no jaws; septa incomplete except one strong diaphragm
in front; anterior to this the nephridia are large and
excretory while the posterior ones are mere funnels and
act as genital ducts. Tubicolous or burrowing worms.

IV. CaprrEtiiFrormia._—_No__prostomial processes;
parapodia do not project, setze unjointed, capilliform in
the anterior segments, hooded crotchets in the posterior
segments (this division does not correspond to marked in-
ternal differences), no cirri; no jaws; nephridia small and
may be more than one pair per segment; no blood-vessels,
but the ccelomic corpuscles are red. | Burrowers.

V. ScoLecirorm1a.—Prostomium rarely with sensory
processes ; peristomium without cirri; parapodia not well-
developed, setze unjointed, no uncini present; no jaws;
septa not regularly developed (some being absent);
nephridia often reduced in number but all alike.
Burrowers.

Arenicola belongs to the last sub-order, which contains
six families.

(1) OpHenipa#.—Comparatively short worms, many
of which have a pearly lustre; no prostomial processes ;
parapodia obscure, but dorsal cirr1 often present, e.g.,
O phelia.

(2) Matpanipa (or CiyMENID®). — Prostomium
truncated; body formed of long and few segments, never
provided with gills or other processes; the neuropodial
sete are hooked crotchets, each with characteristic sub-
rostral tuft. Inhabit sandy tubes, e.g., .V2comache,
Aaiothea, Clymene.

(3) ARENICOLID2#.—NSee below for definition.

(4) ScatipreGmMip#.—Arenicoliform or maggot lke;
gills, if present, confined to the first five segments; pro-
stomium small and either drawn out at its lateral angles
into short processes or bluntly rounded; parapodia con-

199

sisting of almost identical notopodia and neuropodia each
ramus bearing capillary and fureate sete; four dia-
phragms at the posterior end of the first, second, third and
fourth segments; heart median; a pair of slender, tubular
nephridia in each segment, except in a few of the anterior
ones. Burrowers, e.g., Scalibregma, Humenia.

(5) Cotoraamipa.—Prostomium bears a pair ot
grooved processes and several tentacles which act as gills
and are usually greenish, due to the colour (chlorocruorin)
of the contaimed blood; capillary setze in all segments
except the peristomium; those of the anterior segments
are directed forwards forming a protection for the head;
limits of segments not clearly marked; only one or two
internal septa present and a corresponding number of
paws of nephridia. Burrowers in mud, e.g., Sephonostoma.

(6) STERNASPID® containing the single genus Stern-
aspis; body short, anterior region thickened and carrying
on each side three rows of setze; on the ventral surface at
the posterior end there is a bilobed horny plate, round the
edges of which are some fifteen or sixteen tufts of long
sete, and dorsal to these two bundles of filamentous gills;
the ends of the genital ducts project freely.

The family ArrnicoLtipa® contaims two’ genera
Arenicola and Branchiomaldane. The latter is, however,
only provisionally and doubtfully placed here, and as its
anatomy and affinities are so uncertainly known it may be
neglected in this account. The definition of the family
may, therefore, be taken as that of the genus Arenicola,
which may be summarised as follows : —

Limnivorous Polycheta provided with numerous
pais of branched gills not present on the anterior seven
segments. Prostomium small or moderately well
developed, bounded posteriorly by the nuchal organ, no
tentacles or palps. Parapodia each consisting of a conical

200

notopodium bearing capillary sete and a. transversely
thickened neuropodium bearing a vertical row of crotchets.
In the chietigerous region, except in the first three seg-
ments, there are four annuli between successive cheti-
gerous annuli. Internally there are three diaphragms at
the anterior end of the first, third and fourth segments.
The pharynx has no armature. A pair of hearts present
placing the gastric vessels in connection with the ventral
vessel. ‘There are five, six or thirteen pairs of nephridia.
A pair of otocysts lies in the peristomium (absent in A.
cla paredit).

The genus is divisible into a caudate and an ecaudate
section,

I.—The characters of the caudate Arenicolidze may be
briefly stated thus: A distinct tail present; the parapodia
and gills do not extend to the posterior end of the animal.
The body is often swollen anteriorly. Gills pinnate or
derivable from the pinnate type, eleven to thirteen pairs,
the first (which may be small or even absent) on the
seventh or eighth chetigerous segment. Prostomium
consisting of a median and two lateral lobes, brain with
distinct anterior, middle and posterior regions. Funnel
of nephridium with dorsal lip well provided with flattened,
spatulate, ciliated, branched, vascular processes; ventral
lip ciliated, entire (7.e., not deeply notched as in the
ecaudate Arenicolide). Gonads small, ova discoidal,
vitelline membrane comparatively thin (1 to 8).

(a) A. marina, Linneus. Nineteen chetigerous seg-
ments. Thirteen pairs of gills; the first, which is on the
seventh segment, may be reduced (or suppressed). Otoeysts
opening to the exterior. Otoliths, numerous foreign bodies
(quartz grains, &c.) which may, however, be covered with
a layer of secreted chitinoid substance giving them a

rounded outline. Six pairs of nephridia opening on seg-

201

ments 4 to 9. One pair of cesophageal pouches, cylin-
drical, club-shaped or conical. | Diaphragmatic pouches

(on the first diaphragm) small, globular or flask-shaped.
Found on both sides of the Atlantic north of 40° N.
latitude.
(0) A. asstmilis, Khlers.* Twenty chetigerous seg-
meuts. Thirteen pairs of gills, the first of which is
situated on the eighth segment (the first gill is Hable to

be reduced or suppressed). Otocysts large, opening to the

exterior. Otoliths numerous, spherical or rounded
chitinoid bodies. Six pairs of nephridia opening on seg-
ments + to9. Several pairs of cesophageal pouches; the
anterior pair long, club-shaped or filiform, the others
much smaller and pear-shaped. | No pouches on the first
diaphragm. .

Recorded from the extreme south of the American
continent.

(c) A. assimilts, var. affinis, Ashworth.” Nineteen
cheetigerous segments. Thirteen pairs of gills, the first

(liable to reduction or suppression) on the seventh seg-
ment. Otocysts large, opening to the exterior. Otoliths
numerous, and composed either of foreign bodies (quartz
erains, &e¢.), or of spherical chitinoid bodies. Other
characters as in the type of the species (see above).

Recorded from Otago Harbour, New Zealand, the
Macquarie Islands, the Falkland Islands.

(d) A. claparedii, Levinsen.t Nineteen cheetigerous
segments. Thirteen pairs of gills, the first on the seventh
segment (this pair of gills is liable to reduction or sup-
pression especially in specimens from the west coast ot
North America). Lateral lobes of prostomium well

** For an account of these forms see Ashworth, J. H.—Q.J.M.S.,
Vol. 46, pp. 737-785. Pls. 36-37.

+ For an account of these species see Gamble, F’. W. and
Ashworth, J. H.—Q.J.M.S., Vol. 48, pp. 419-569. Pls. 22-29.

202

developed. No otocysts. Five pairs of nephridia open-
ing on segments 5 to 9. Two or more pairs of esophageal
pouches, the anterior pair long and slender or club-shaped,
the others shorter and usually pyriform. No pouches on
the first diaphragm.

Recorded from the Mediterranean and from the west
coast of the United States.

(ce) A. cristata, Stimpson.” Seventeen chetigerous
segments. Kleven pairs of gills, the first on the seventh
segment. Otocysts, closed spherical sacs each containing
a single large spherical chitinoid otolith. Six pairs of
nephridia opening on segments 5 to 10. One pair of

cesophageal pouches, cylindrical or club-shaped. Dia-
phragmatic pouches (on the first diaphragm) large and
finger-shaped.

Found in the Mediterranean, in the West Indies and
on the eastern shores of North America, south of latitude
40° N.

TI. The characters of the ecaudate Arenicolide are
as follows :——No tail, the parapodia and gills extend to the

posterior end of the animal. Body generally of an almost

uniform diameter. Number of gills variable (according
to age and species), gills branched unilaterally. — Pros-

tomium simple, conical, non-lobate. | Brain commissural.
Otocysts closed spherical sacs, otoliths spherical. Dia-
phragmatic pouches long and finger-shaped. Cisophageal
pouches, one pair, flask-shaped. Nephridia with dorsal
lip bearing somewhat cylindrical digitiform, often
branched, ciliated vascular processes, ventral lip deeply
notched in middle, the two halves semi-circular in shape.
Ova generally oval with thick vitelline membrane (5 to 6).

(a) A. grubii, Claparéde.*—First gill on segment 12

** For an account of these species see Gamble, F’. W. and
Ashworth, J. H.—Q.J.M.S., Vol. 48, pp. 419-569. Pls. 22-29.

203

(may be small). Five pairs of nephridia opening on seg-
ments 5 to 9. Twelve to twenty-eight pairs of gills.
Gonads small.

Recorded from the English Channel (Plymouth, the
Channel Islands and the French coast), Isle of Man,
Iveland (Valencia), Scotland (Loch LTinnhe), the

Mediterranean.

(b) A. ecaudata, Johuston.*— First gill on segment
LG. Thirteen pairs of nephridia opening on segments
5tol7. Nineteen to forty pais of gills. Gonads large,

twelve pairs; im females each ovary bears as many as
thirty digitiform vascular processes bearing ova; in
males each testis is produced into one or more large, thin
reniform lobes.

Recorded from Scandinavia, the English Channel
(Plymouth, the Channel Islands and the French coast),
Isle of Man, Ireland (near Fairhead, Antrim).

The Affinities of Arenicola marina.

Arenicola marina is the only caudate species found in
Britain. As a comparison of the characters given above
shows, its nearest ally is the southern A. ass¢milis, var.
affincs, from which it differs in only two respects. In the
latter species there are several pairs of cesophageal glands
and no pouches on the first diaphragm, while in A. marina
there is a single pair of wsophageal glands and a pair of
septal pouches. The type specimens of A. assemilis are
rather further removed from A. marina, additional and
striking points of difference being found in the number of
chetigerous segments (19 in A. marina, 20 in A. assimilis),
and the position of the first gill (on the seventh segment
in A. marina, on the eighth in A. assimilis).

* For an account of these species see Gamble, F. W. and
Ashworth, J. H.—Q.J.M.S., Vol. 43, pp. 419-569. Pls. 22-29.

204

A, claparedii is at once marked off from the common
lugworm and from all other known species of Arenicola by
the fact that it has no otocysts. Other points, such as
its well developed lateral prostomial lobes, the presence
of several pairs of cesophageal glands, the presence of
only five pairs of nephridia and the absence of septal
pouches, further separate this species from A. marina.
A. marina is also well removed from A. cristata by the
number of cheetigerous segments (19 and 17), and gills
(13 and 11 pairs), the position of the nephridia (opening
on segments 4-9 and on 5-10), and the nature of the
otocysts and otoliths.

Between the two ecaudate species and A. marina there
are only the points of agreement which are common to the
genus. The common lugworm differs especially from
A. ecaudata, and these two species may be regarded as

lying almost at the opposite ends of the series.

The Affinities of the Arveni1c¢o lime

The discussion of the affinities of the Arenicolide 1s
rendered somewhat difficult owing to the fact that the
details of the anatomy of one or two of the neighbouring
families are very unperfectly known. The three families
Arenicolide, Scalibregmide, and Ophelide have several
features in common, as they are limnivorous and present
certain of the peculiarities characteristic of such Poly-
cheeta. They have a spacious ccelom sub-divided
anteriorly by diaphragms and non-septate in the middle
of the animal; the alimentary canal consists of an
eversible pharynx followed by an cesophagus (bearing one
or more pairs of lateral glandular outgrowths), a dilated
stomach and a straight intestine usually with a ventral

groove, and the blood-vessels in the middle region of the

animal are so arranged as to leave the stomach consider-
able freedom of movement.

The Arenicolide agree with the Scalibregmide in the
points named above, in the general shape of the body, the
sub-division of the segments into annuli, the sculpturing
of the skin, the small lobed prostomium, and the presence
(in Sealibregma and Humenia) of gills of a similar type.
The brain and non-ganglionated nerve cord of the caudate
Arenicolide is similar to that of the Scalibregmidie.
There are also points of difference between these two
families which are of considerable importance. In the
Scalibregmidie the two rami of the parapodia are practi-
cally identical, but they are very different in the Areni-
colide. In the latter the neuropodium bears crotchets
only, and the notopodium bears capillary sete, while in
the Scalibregmidie both rami bear two kinds of sete,
capillary and fureate, the latter being characteristic of the
family. In some of the Sealibregmidee the parapodia
form laminate appendages bearing dorsal and ventral
eri, which are not found in Arenzcola (cirrl are oceasion-
ally seen in the posterior region of American specimens ot
A. cristata). The gills of Scalibregma and Humenia are
confined to the first five segments, on which they never
occur in Arenicola. The heart in the Scalibregmidee is
a median structure, while in Arenccola there is a pair of
hearts. The nephridia of the Scalibregmide are minute,
but numerous, the simple microscopic funnel leading into
a slender U-shaped tube; the nephridia of Arenzcola are
few in number and wide and sac-like, each having a large
funnel fringed with ciliated vascular processes. Several
of the Scalibregmidie bear complex segmental lateral
sense-organs which are not found in Arenccola.

The Arenicolide have a few characters in common
with the Ophelide, but the accounts of the latter family

206

are so fragmentary as to preclude detailed comparison.
Besides the points mentioned above as common to the
three limnivorous families, the Opheliide and Areni-
colide agree in the character of their nephridia and in
their non-ganghonated nerve-cord. The main points of
difference between them are (1) the shape of the body;
(2) the skin, which is not sculptured and sub-divided into
annul in Opheliide; (3) there are no branched gills and
no hearts in Ophelude; (4+) the parapodia, on many of
which, in Ophelia, there is a filamentous dorsal cirrus.

On comparing the Arenicolide and Maldanide the
differences are again more obvious than the resemblances.
They agree in the general form of their parapodia, in the
small number of nephridia and gonads, and in the simple
brain and ventral nerve cord with uniform covering of
ganglion cells. They differ in habit, the Maldanide
have few but long segments, they have no gills and no
otocysts, and the tail segment is specialised. The ali-
mentary canal of Maldanide is simple and bears no
special glands, and there are no hearts. The genus
Branchiomaldane presents features some of which are
intermediate between these two families.

The anatomy of the Chlorhemide is imperfectly
known, but there appear to be no points in which they
approach the Arenicolide. The former family differs
from the latter in its set, septa, nephridia, median heart,
the processes of the prostomium and the ganglionated
nerve-cord. The Sternaspide are still further removed
from the Arenicolidee by the peculiar arrangement of their
cills and sete, the presence of ventral shields, special
genital ducts, coiled alimentary canal and only a single

pair of nephridia.
It may be eoncluded that the Arenicolide form a

act family clearly distinguished from the neigh-

lo}

comp

207

bouring families, but having some affinities with the
Scahbregmide, Opheliidee and Maldanide.

PARASITES.

I.—A considerable number of specimens of Arenicola,
from the Lancashire coast near Blackpool, were found to
contain small ovoid bodies attached to, or imbedded in,
the muscles of the anterior region. These proved to be
Distomid cercariw which had migrated into this position
and encysted there. Hach is about half a millimetre
long and a third of a millimetre broad and is surrounded
by a moderately thick eyst-wall. In each specimen the
two suckers, the muscular pharynx, the two limbs of the
intestine, about a dozen flame cells and the rudiments of
two of the reproductive organs (testes %) may be distin-
guished. These would remain encysted in <Arenicola
until the worm was eaten by the final host (probably a
fish or a bird), in which the cerearia would be liberated
from the cyst and would grow into a ** fluke.”

I1.—In other specimens Coccidia are occasionally
very abundant in the walls of the stomach, intestine and
nephridia. They are much more common in A. grubia
than in A. marina. They are spherical or ovoid cells,
each about 0°14 mm. in diameter when fully grown, with
a vesicular nucleus containing a large nucleolus. <A few
eysts, 0'2 to 0°25 in diameter, each containing a few
thousands of rounded spores (sporozoites) have been met
with on the outer surface of the gut or attached to the
muscles of the body wall. Each spore is 3 to 4 in
diameter, and consists of a thin covering of protoplasm
enclosing a (comparatively) large nucleus.

As the lugworm is a common food of fishes (especially

of flat fish), a knowledge of its parasites is desirable, as

208

these may have an important bearing on the parasitic

diseases of some of our food fishes.

Directions ror Pracricat Work.

Arenicola should be dissected as soon as possible after
it is taken from the sand, and especially in warm weather,
as the animal soon dies and changes rapidly take place in
both the external and internal structures. Specimens at
least eight or nine inches long should be obtained if
possible; the large Laminarian variety is excellent for
dissection.

Specimens intended for dissection may be killed by
placing them in sea water in a jar and adding sea water
which has been shaken up with chloroform. By this
method the specimens are gradually narcotised, and they
usually die in a moderately expanded condition, — If the
process of killing be too rapid, as, for example, if the
worms were dropped into chloroform, the contraction of
the muscles 1s sometimes so strong as to cause rupture of
the body wall, in which case the ccelomic fluid is lost and
a considerable portion of the alimentary canal is forced
out through the opening, and some of the blood-vessels
may give way. As soon as the specimens are dead they
should be transferred to the dissecting dishes containing
sea water. If ordinary sea water“be not available make
up beforehand a sufficient quantity of artificial sea water
by adding about 55 grammes of sea-salt to each litre of
fresh water required.

External Characters.— Note the shape of the worm;
its division into an anterior abranchiate chetigerous
portion,’ middle branchiate chietigerous region and pos-

terior achietous and abranchiate tail; the segmentation ;

209

the annulation; the parapodia and sete*; the gills*; the
prostomium and nuchal organ; the peristomium and the
succeeding achetous segment; the external apertures, the
mouth, anus, nephridiopores, and apertures of otocysts.

Dissection.

Extend the animal under sea water with the dorsal
surface upwards, fixing it down by two pins through the
sides of say the first segment, and two through the sides of
one of the posterior branchial segments. Open the
animal by making an incision with fine scissors along the
mid-dorsal line, beginning about the middle of the
chetigerous portion. Raise the flaps gently with the
forceps and extend the cut anteriorly to within about an
eighth of an inch of the prostomium, and posteriorly
about an inch into the tail. The tail is difficult to open
satisfactorily,-unless great care be taken the alimentary
canal will be cut open with the body wall. ‘The flaps of
the body wall should be regularly pinned out right and
left so that the animal is moderately well stretched both
longitudinally and transversely.

If it is desired to examine the celomic fluid before
proceeding with the dissection the first incision should be
made while holding the worm in the hand over a watch
glass. The ceelomie fluid which at once escapes through
the cut must be examined immediately, as on standing
even a short time the corpuscles collect into clots.
Examine the fluid fresh and determine the sex of the
specimen. A few permanent preparations (for method
see below) are also useful.

At the breeding season the ova and masses of sper-
matids are so abundant as to partially obscure some of the

* The detailed examination of the sete and gills is _ better
deferred until later. See Sections VIT. and VITT. below.

1

210

organs, e.g., the nephridia. In this case the reproductive
products should be carefully washed away. A change of
sea water in the dish may even be necessary.

The internal organs may be examined in the following
order :-

I. Coelom (see above).

II. Musculature.—Note the longitudinal and cireular
muscles, the muscles of the pharynx, the setal muscles, the
oblique muscles, the three anterior septa, the two pouches
on the first septum, the rudimentary septa (the safety cord
accompanying the afterent vessel of the fourth nephri-
dium, and the small septa in two or three of the posterior
branchial segments), the caudal septa, the mesenteries of
the first and second segments.

III. Alimentary Canal.—Note the proboscis,
pharynx, esophagus, esophageal glands, stomach covered
with the vessels of the gastric plexus between which are
the areas of chlorogogen cells, intestine, anus. Later
(after section V.) the stomach and intestine may be slit
open and their contents washed out so as to show the
ventral ciliated groove and the subsidiary grooves. The
stomach and intestine may be pushed over to one side,
care being taken not to break any of the blood-vessels, so
as to leave the greater part of the body wall in this region
open to view.

IV. Vascular System.—Note the dorsal, intestinal,
gastric, cesophageal, ventral, sub-intestinal, neural,
nephridial longitudinal and dorsal longitudinal vessels,
the afferent and efferent vessels of the nephridia and gills
and the hearts. The sub-intestinal vessels are difficult
to see, and are only visible on carefully drawing the ventral
vessel a little further away from the wall of the stomach.
Note the chlorogogenous tissue on the ventral vessel.

\Y. Nephridia and Gonads.—Look out for any

211

departure from the normal in the number or structure of
the nephridia. After examining these organs in a
general way, carefully remove the oblique muscles which
cover one or two of the nephridia and examine these with
a lens, noting the various parts. Note the funnel, its
dorsal lip fringed with processes, its ventral simple lip, the
excretory portion of the organ, the bladder, the gonad (not
present on the first nephridium), the blood supply, &e.
At the breeding season the vesicles may be distended with
ripe ova or spermatozoa. Remove one of the nephridia
entire and transfer it, with as little disturbance as pos-
sible, to a glass slide and examine under the microscope.
If the worm has been freshly killed the strong action of
the cilia of the funnel will be well seen. Note the vessels
of the funnel, some of which have blind dilated endings.
Note also the gonad traversed by the gonidial vessel. The
excretory portion of the organ may be cut across; at the
cut edges the action of the long cilia borne by the cells of
this portion may be seen.

VI. Nervous System.—The greater part of the
ventral nerve cord may be easily seen on pushing the
alimentary canal to one side. It may be readily traced
forwards as far as the first diaphragm, but the rest of the
cord, the connectives, the brain and the otocysts are only
exposed after the first diaphragm has been carefully cut

away from the body wall. Very little further dissection
is required. Tt is often, however, an advantage to cut
away the pharynx, as sliown in fig. 46. The exposure of
the brain requires some care. ‘The otocysts are usually
rather yellowish bodies about the size of a small pin’s
head, their position is seen in fig. 46. Remove an otocyst

to a slide, cover it and examine it under the microscope.
The peculiar quivering motion of the otoliths will be seen

if the specimen has been only recently killed,

212

VII. Gills—Examine one of the gills about the
middle of the series. Note its attachment to the body
wall, its basal webbing, the main trunks and_ their
branches. Remove the gill to a slide and examine it
under a low power to see the mode of branching and the
blood-vessels. | Note the small size and simple character
of the first gill.

VIII. Setz.—Notopodial sete may be easily obtained
from a dissected specimen by taking hold with the forceps
of the inner end of the setal sac and drawing it inwards.
In this way the whole bundle of notopodial sete will be
removed. ‘To clean off the tissues of the setal sac and any |
adhering strands of muscle the preparation may be
warmed in 5 per cent. caustic soda. After washing in
water the setee may be placed in glycerine for a time and
then permanently mounted in glycerine jelly. Only
unworn sete should be selected for examination.

By treatment of an excised neuropodium with warm
caustic soda the muscles become gradually softened, and
by the aid of a pair of needles may eventually be separated
into an anterior and a posterior mass, between which the
cheetee lie. With care the entire band of neuropodial
cheete may be obtained. It should then be washed in
water, placed for a time in glycerine and mounted in
glycerine jelly. The various stages of formation of the
new cheetwe at the ventral end of the series may be seen.
There are usually two or three fully developed crotchets
which have not yet come into use. These should be
selected for observation of their characters as they are
uninjured by wear.

I have found it very useful to have dissections
of small specimens, 17 to 50mm. long, for the study
of young nephridia, which are too small to be easily

removed from the body wall, gonads, blood-vessels, &e.

Preserved specimens were generally used and the dissec-
tion was performed under 70 per cent. spirit.” The
specimen was opened in the usual way and pinned out on
a piece of weighted cork in a small glass dish, and the
alimentary canal carefully removed. The specimen and
the cork were then put into stain, either carmine or
Mayer’s acid hemalum, for 12 to 24 hours. After the
excess of stain had been removed the worm and the cork
were passed into 90 per cent., and then into absolute
aleohol. The body wall, which by this time was
moderately certain to retain its shape, was unpinned, and
after another change of absolute alcohol was placed in oil
of cloves and afterwards mounted in balsam. Fig. 25 was
drawn from such a preparation, in which the blood-vessels,
&c., are very clear. Useful preparations may also be
made by splitting the anterior portion of preserved
specimens into two by a median sagittal cut. Such
sections give a good idea of the position and relations of
the nuchal organ, diaphragms, proboscis, &e.

Preparations of the Ceelomic fluid may be made thus.
Immediately after the fluid is removed from the animal
spread a small drop evenly over the middle of a glass
slide so that it forms a very thin film. This may be
treated in either of the two following methods : —

(1) Invert the slide so as to bring the film over the
mouth of a bottle containing glacial acetic acid and hold
it there for several seconds. The vapour of the acid will

kill and “fix” the cells, ¢.c., will coagulate their proto-

*“If a fresh worm be used, after the dissection under sea water has
been completed, the specimen should be ‘“ fixed’’ in a saturated
solution of corrosive sublimate. In this case, however, the dissection
should be pinned out with cactus needles, and not with ordinary pins,
as the latter would produce a deposit of mercury in the neighbouring
tissues. After fixation wash in water and in 50 per cent. and 70 per
cent. spirit, until all traces of sublimate are removed. Then stain as
directed.

214

plasm. The slide may then be warmed gently over a
flame until the film begins to dry. It may then be
stained by placing a drop of safranin or dahlia over the
film. After a few minutes (three or four) the excess of
stain may be removed by washing with a little 50 per
cent. and 70 per cent. spirit. A few drops of absolute
alcohol are then run over the film, followed by oil of
cloves, and finally the preparation is mounted in balsam.

(2) The film may be allowed to gradually dry (a
matter of only a minute or two if it be even and thin),
but before it is actually quite dry a little saturated
solution of corrosive sublimate is gently run over it and
the whole slide immersed for a few minutes in this
solution. The slide is then washed in the usual way in
water and in the alcohols (several hours), and may then
be stained by any of the methods apphed to films or
sections, é.g., ivon-alum-hematoxylin, hemalum, safranin,
dahha, carmine. ‘These preparations show the various
ceelomic cells and also the reproductive products.

S€ C10 ms).

Specimens not above six inches long are large enough
for this purpose. Larger ones are more difficult to deal
with on account of the hardness of the musculature after
imbedding.

Specimens intended for sectioning must, of course, be
treated so as to remove all the sand from the alimentary
canal, and it is a matter of some little difficulty to ensure
this. The worms should be kept in dishes of clean sea
water, into which a small stream of water is allowed to
trickle or else the water in the dishes should be changed
at least twice a day. The dishes should be examined
several times a day, and the sand, which has been voided by
the worms, removed. After four or five days of this treat-

Ne (EA

ment the alimentary canal will contain very little sand.
This can usually be ascertained by examining the worms
by strong transmitted hght, when any sand present in the
gut will be detected. As soon ag all the sand has been
voided the worms may be placed in a dish containing a
smaller quantity of sea water. They may then be
narcotised by dropping absolute alcohol little by little on
to the sea water until the liquid contains about 5 per cent.
of aleohol. After a few hours the worms will be sufficiently
narcotised and may then be killed in an extended

condition. Before attempting to kill them ascertain by
touching them if they are thoroughly narcotised. Care

should be taken not to allow the worms to become quite
dead in the alecoholised sea water, as the tissues sufter.

A good killing and fixing mixture is sublimate acetic
(95 parts saturated sublimate solution and 5 parts glacial
acetic acid). Ags soon as the worms are dead transverse
incisions” should be made in the body wall at intervals of
+ to ? inch, so as to allow the re-agents to penetrate
rapidly and fix all the internal organs. If the operations
above described be carefully carried out the worms will
be killed straight, a great convenience when sectioning.

After a few hours in sublimate acetic the worms are
washed in running (fresh) water for a few minutes, and
then transferred to 50 per cent. alcohol (two or three
hours), to 70 per cent. and to 90 per cent. alcohol (two or
three changes). ‘To the latter a few drops of tincture of
iodine should be added to dissolve from the tissues of the
worm the last traces of sublimate. Fresh iodine should
be added as the liquid becomes decolourised, and this

** This should be done as rapidly as possible, as on contact with
metal a deposit of mercury is liable to be formed in the tissues. The
worms should be transferred from one vessel to another (where that is
necessary) by means of glass, horn, or paper lifters, and all contact
with metal avoided.

216

treatment continued until the straw-colour of the spirit
remains permanent. It may then be assumed that all
the sublimate has been removed. The worms may then
be transferred to fresh 90 per cent. spirit, and kept therein
until required for sectioning.

The segments required for sectioning are dehydrated
by passing through absolute alcohol (three changes), and
are then placed in either xylol or cedar-wood oil. The
writer has found the latter very satisfactory, provided that
care be taken to ensure the thorough removal of the oil
when imbedding in paraffin wax. That is, the specimen
is transferred from cedar-wood oil to the first vessel of
wax and afterwards to a second and third, before finally
imbedding. The time required in the bath, of course,
depends on the size of the tissue, but for a piece say half
an inch long by an eighth of an inch in diameter from
2 to 3 hours would be sufficient, except in the case of the
anterior end where a little longer time is desirable. Wax
with a melting point of 56° to 58° C. is best for Arenzcola.

The best results are obtained by staining the sections
on the slide by means of iron-alum-hematoxylin. If
this be too long a process the specimen may be stained in
bulk (before cutting into sections) with borax carmine, or
Mayer’s acid-hemalum. Some of the sections, especially
those in which it is desired to show gland cells (e.g., in the
stomach*) may, with advantage, be stained with Mayer's
acid hemalum or with Grenacher’s or Delafield’s
hematoxylin.

Transverse sections are useful for the study of the
general anatomy, alimentary canal, nephridia, &c.;
sagittal sections of the anterior end are helpful in the

* The histology of the alimentary canal of starved specimens
should be checked by the study of sections of small pieces removed
from a worm immediately after taking it from the sand.

217

study of the brain, nuchal organ, &e.; and horizontal
sections are almost essential for the study of the nervous
system, particularly the brain, otocysts, the ventral nerve
cord, and the giant cells. If sections of certain organs
only be desired, it is best to procure these from a worm
chloroformed and opened as soon as it is taken from the
sand. The organs are excised, separately preserved and
sectioned as desired. The following parts may be sug-
gested-—the otocyst, various portions of the alimentary
canal to show the condition of the gland cells, &e., when
the gut is full of sand (of course, the sand must be rapidly
washed out with sea water before preserving each part), a
nephridium with gonad,* and a heart (one not dilated with
blood, as when imbedded the blood becomes very brittle

and impossible to cut).

Post-Larval Stages.

These are not readily obtained. Occasionally living
specimens may be got from Plymouth in March and April.
These are, of course, best for examination, as some of the
structures described, such as the processes on the nephro-
stomes, can only be seen in living specimens. Preserved
specimens should be lightly stained in borax carmine, and
examined in cedar-wood oil, so that they may be turned
over as occasion requires. For preparation of sete cut out
two or three of the posterior chetigerous segmentst and
warm gently in a watch glass in 5 per cent. caustic soda.
Before the muscular tissue is dissolved transfer by means
of a pipette to water, and later to glycerine. After

* Whole mounts of the first nephridium, and one or two others
with their gonads are very useful. Stain with carmine and mount in
balsam.

+ From a spirit specimen. If the specimen be in oil remove the
latter by treatment with absolute alcohol before warming in caustic
soda.

218

soaking in the latter, the specimen may be picked out on
the point of a needle and placed in the middle of a melted
drop of glycerine jelly on a glass slide. The cover glass
(which may be warmed) should be gently pressed down on
to the specimen so as to bring the sete into one plane.
Sections of post-larval stages should be thin (not more
than 4 or 5u) if they are to be of much use.

219

ECONOMIC SECTION.

Arenicola, the ‘‘Lugworm,” is of considerable
importance to the fisherman, being largely used as a bait
for flat-fish, codling, haddock, &c.*

The worms are obitamed, at low tide, by digging in
the sand below the funnel-shaped opening and the coiled
casting which mark the head and tail ends of the animal's
burrow. Specimens obtained from near low-water mark
are larger than those found higher up the beach, and the
largest specimens are found in those parts of the beach
which are exposed only at low spring tides. Where there
is an abundance of organic matter in the sand the worms
are plentiful and usually of good size, so that fishermen
find it worth while to walk a moderate distance to such
sands, where they can more readily obtain a supply of
bait. Larger specimens usually bear exposure to the air
better than small young ones and the former may be kept
longer before use. At best however lugworms can only
be kept for a limited period, and should be used as soon as
possible after they are dug from the sand. In cold
weather they may be kept for a day or two without serious
detriment, but in hot weather they must be used within a
few hours. They are best kept in a cool place in a quan-
tity of moist sand sufficient to separate them from one
another. If they are allowed to lie together in a heap
they soon become soft and almost useless as bait. The
presence of a few burst or broken specimens expedites this
change, the ruptured worms lose their coelomic fluid and

usually some blood, which fluids seem to affect rapidly the

* In addition to the acknowledgments made in the footnotes on
three of the following pages, I wish to thank Mr. J. Johnstone, B.Sce.,
of Liverpool, Mr. H. C. Chadwick, of Port Erin, and Mr. Cyril
Crossland, B.A., of St. Andrews, for kindly sending to me information
on this subject.

worms with which they come into contact, so that in a
few hours, especially on a hot day, the whole of the worms
become soft and flabby, and soon die.

No attempts have been made, so far as the writer is
aware, to preserve lugworms for subsequent use as bait.
It seems doubtful, judging from the experiments which
have been made on the preservation, by means of chemical
substances such as boracic acid, of more hardy animals for
use as bait, whether such experiments on Arenicola would
be attended with any great success. Cold storage would
probably be more successful than chemical means of pre-
servation in the case of Arenzcola. Undoubtedly the best
plan is to use the worms as soon as possible after they are
dug, but during the brief interval between digging and
using them they should be placed in a moderate amount
of sand containing just enough moisture to make it
ccherent, and kept cool.

Lugworms are abundant on most of our sandy
beaches. In some places, however, e.g., near Aberdeen,
the force of the sea is so great that the worms cannot live
in the constantly shifting sands. In other places,
especially where organic matter is plentiful, e.g., near
some sewage outfalls, they may be found in large numbers
and of good size. The organic matter may be almost
entirely absent from the surface layer of sand, so that the
beach may have the usual yellow colour, but it may be
present in such quantities in the subjacent layer as to
produce in the latter a dark-grey or even almost black
colour. In this case the castings brought to the surface
by the worms are usually of the same dark colour, and are
conspicuous on the yellow beach. In thus passing through
their bodies the sand laden with organic matter, im
removing part of this during digestion and in discharging
the partially cleansed sand on the surface of the beach,

221

where it may be subjected to the action of the air and
water, these worms are playing an important part in the
removal of products, which, if left to accumulate, would
scon become objectionable.

The number of worms, and therefore of castings,
varies considerably in different sands. Davison* has given
an account of observations made in August, 1891, on the
Holy Island sands. He counted the castings in nineteen
measured areas, and found that the smallest number in
any one of these areas was 8°2 per square yard, while the
largest number was 42 per square yard. In both cases the
castings were fairly large. In other two of these nineteen
areas, Where the castings were very large (their average
weight, when dried, being three ounces and two and a
quarter ounces respectively), their numbers were 11 and
14-5 per square yards respectively.

At Musselburgh, on the Firth of Forth, there are
extensive sands laid bare at low tide in which the sub-
jacent layer contains a moderate amount of organic
matter. Here worms and castings of large size are
abundant near and for some distance above low-water
mark. There are (January, 1904) about twelve to fifteen
arge castings per square yard, the average weight of
(eight of) which when dried is three ounces. In the
course of a few minutes seven fine worms, the mean length
of which was thirteen inches, in addition to other smaller
ones, were obtained here. Although these sands have been
visited almost daily for a long period of years by fishermen
in search of bait, there seems to be no scarcity of worms,
although probably over a thousand per day are, on an
average, obtained.

Near Portobello the beach near low water is gravelly
in parts, and castings are scarce, but higher up the beach,

‘ Geological Magazine, Vol. VIIT., 1891, p. 489.

296

ld

about midway between tide marks, they are very
numerous. In one large area situated not far from a
sewage outfall I marked out a rectangular portion six
yards long and two yards wide, which was found to contain
404 castings, that is an average of 34 per square yard.
These castings were small, and the worms which formed
them probably did not exceed about five inches in length.
The conditions described above for Musselburgh are
closely reproduced on many parts of the Lancashire coast,
for example on the extensive sands in the Ribble estuary.

At Piel (near Barrow-in-Furness) the main source of
supply of Arenécola consists of an area fully half a mile
square lying to the north of the old steamboat pier. The
worms are most plentiful along the eastern side of this
area, that is adjacent to the railway embankment. They
do not extend down to low-water mark, even of neap tides,
as they would then be in the tide-way (the channel to
Barrow). The large area above described is beyond the
reach of tidal currents. There are other beds in which
Arenicola is plentiful, but they are not much visited by
fishermen in search of bait. The surface layer consists of
fine clean yellow sand to a depth of about six inches.
Below this it is black in colour and strongly charged with
organic matter. The number of castings in the large area
described above varies from ten to twenty-four per square
yard, on the best portions they average about twenty. The
largest worms obtained are about seven inches in length.*

Lugworms are usually found in the warmer parts of
the year (late spring, summer and early autumn) on
digging in the sand to a depth of one to two feet, but the
large Laminarian forms seem te burrow more deeply and
are found at a depth of nearly three feet. In frosty and

* T thank Mr. Andrew Scott, A.L.S., of the Lancashire and
Western Sea Fisheries Laboratory, Piel, for sending me this informa-
tion.

in stormy weather the worms sink more deeply, and are,
of course, more difficult to obtain.

Although lugworms have been so long used as bait,
and fishermen have searched the same areas of sand day
after day, there is usually no lack of them on most beaches.
Professor M‘Intosh* suggests that they have “ resisted the
attacks of man probably because a sufficient stock of ripe
examples and the very young are covered at all times by
the tide.” It is certain that plenty of old ones are covered
by the tide, judging from the large specimens to be taken
at low spring tides.t The habits of young ones are
unknown, except those of the post-larval stages which are
pelagic.

Arenicola produces enormous numbers of eggs, as is
seen from the condition of ripe females in the spring.
In these the celomic fluid contains many thousands of
full-sized ova.||

Unfortunately nothing is known about either the
oviposition or the early stages of development of the
common lugworm. We can only suggest, by inference
from the known facts of development of other species of
Arenicola, that the eggs are laid, probably entangled in
mucus, on or in the sand in shallow water, and the early

* Resources of the Sea, p. 14.

+ Reckoning only the specimens which are exposed at an ordinary
low tide their number is so great that the number removed at any one
time for bait really makes no appreciable difference. Take, for
example, the.area from which the Musselburgh fishermen dig their
bait. For a distance of about a mile from Hast to West there is a zone
from one to two hundred yards wide immediately above ordinary low-
water mark in which the castings average twelve to fifteen per square
yard. This area would, therefore, contain from three to four million
worms, and the removal of a thousand per day would produce little
effect upon the enormous number of worms accessible even at ordinary
low tides. How far seawards the worms extend below ordinary low-
water mark it is impossible to say, but no doubt there are here very
substantial reserves.

+ And also, in some localities, in late summer or autumn.

There were about 80,000 ova (a rough estimate made by the
dilution method) in the ccelomic fluid of one specimen examined.

224

stages of development are passed there. The larve grow
until the full number of adult body segments has been pro-
duced and then enter upon the pelagic post-larval stage.
This is the earliest known stage of development of the com-
mon lugworm. The young worms do not settle down to their
littoral habitat and characteristic mode of life until they
have attained a length of about 5 to 7 mm. Young speci-
mens 17mm. long have been found in the sand in June.
Although it is difficult to estimate their age, it may be
suggested that these specimens 17 mm. long and others up
to 44 mm. long taken near the end of June were probably
produced from ova laid in the preceding February or
March. If that be the case, then worms five or six inches
long are probably about a year old. Some of the large
deeply-pigmented specimens obtainable at low spring tides
are certainly much older, but on this point no information
is available. It may be taken that the smaller specimens
of Arenzcola used as bait are at least a year old. Con-
sidering the abundance of Arenzcola on many beaches, it
is astonishing that we know so little of its life history, and
that so few post-larval’stages have been taken in the tow nets.

The present state of our knowledge does not permit
one to make any suggestions with regard to the possibile
cultivation of lugworms in any given area in which they
are wanting. The writer has made several attempts to
fertilise artificially the ova of the common lugworm
removed from a ripe female, by adding spermatozoa
obtained from a mature male, but without success,
although both ova and spermatozoa appeared, when
examined microscopically, to be quite ripe and favourable
to the experiment. Others have also experienced these
failures when dealing with this and other species of
Arenicola.* Evidently, therefore, it is more difficult to

* I eventually? succeeded in fertilising artificially the eggs of
A. claparedii. For an account of the early stages of development of
this species, see under development.

DPN)

bring about artificial fertilisation in Arenicola than, for
example, in many Hchinoderms, and this fact would prove
a serious obstacle in the endeavour to cultivate Arenicola
with the idea of re-stocking exhausted sands. This
question is, however, not likely to become of practical
importance as, judging from reports from various parts of
the coast, the supply of lugworms is quite equal to, and
even more than, the demand, except, of course, in certain
restricted areas where conditions are unfavourable for
their life and growth.

As mentioned above, the sands around Aberdeen form
one of these unfavourable areas, so that lugworms are
either absent or scarce. In consequence they are imported
from the Moray Firth. The worms are gathered chiefly
near Campbeltown, near Fort George, Inverness-shire, and
sent by rail,” a distance of about 100 miles, the journey
occupying at least five hours, to Aberdeen. The worms
cost ten shillings per stone, and railway charges, &c.,
amount to ls. 2d. per stone.* This quantityt would bait
four small lines.” A baiting of mussels for the same
lines would cost about 3s. 6d., but as a rule the lugworms
would catch three or four times as many fish.” It is
almost impossible, in warm weather, to transport lug-
worms over such a long distance and to deliver them in
good condition at their destination. This probably
accounts for the fact that they are used in Aberdeen only
in the colder part of the year, from December to April.
No doubt, the comparatively high price restricts their use
for bait during the colder months. This is the only

** For this information I desire to thank the Secretary of the
Fishery Board for Scotland and the principal Fishery Officer of the
Aberdeen District.

+ Taking fourteen average lugworms, such as would be used for
bait, I find that their mean weight is rather over half an ounce each.
There would be about four hundred such worms in a stone (14 lbs.)

oa
Q

instance known to the writer, of lugworms being imported
and sold in quantities in the market.

Although lugworms are fairly abundant they are
apparently not as extensively used for bait as formerly.
This is probably because they are troublesome to obtain,
and may be kept only for a short time. These dis-
advantages account for the fact that in some cases
mussels are used in preference to Arenicola, which was
formerly employed, as these molluscs are readily obtain-
able in quantity, and may be kept for a reasonable period
with very little trouble. In other cases Nereids are used,
as these are also more hardy than Arenicola.

On the coast of Durham and Northumberland, for
example, Arenicola is not nearly so extensively used as
formerly. Nereids are, when procurable, used in pre-
ference to Arenicola, the order of preference being, for
“hard bottom ”—mussel, Nereis, Arenicola; for ‘“‘ soft
bottom ”——Nereis, Arenicola, mussel. The special fishing
for soles is not a feature of the present-day fishing in this
district as it was in the past. Possibly this accounts for
the fact that worms are, on the whole, less used, and that
the principal baits at present employed here are mussels
and limpets.”

Fullartont has made experiments which give inter-
esting information regarding the preference of fishes for
the four baits most commonly used on the Scottish coast.
The experiments were carried out in various parts of the
Firth of Forth, and in various depths of water. The line
used had 1,200 hooks, provided with different baits in
batches of forty hooks, so that a large variety of baits
could be used under identical conditions. The fish

** My thanks are due to Mr. Alexander Meek, B.Sc., of the
Durham College of Science, Newcastle-on-Tyne, for this information.
+ Seventh Annual Report of the Fishery Board for Scotland,

. 852,
p. 85 -

O07
ZZ

obtained by each kind of bait were carefully noted. The
following table is an abstract of the results obtained at
fourteen stations where lugworms, clams (Pecten oper-
cularis), mussels and limpets were used together. The
experiments extended from August 30th to December
26th, 1888.

eS tassel FISH CAUGHT,
ETOOH=: 'HADDOCK| Cop. |Wauttrrne{ Dap. | Toran.
NOn oS NOs SAeINosles No.| OMEN OSS
| : =i | | | L
Lugworm..... 3500 {130 | 3°7 | 39 | 1-1] 67 | 1°9)| 54*| 1:6 | 290) 8:3
| | |
Glam. cs-83- 3960 182 | 4-6| 44 | 1-1| 50 | 1:3] 53 | 1-3 329] 83
Miussel......... 4540 266 | 5:8 |) 75 | 1°6 94 |2.1)| 42 | 9 477) 10°5
Limpet........ 3320 | 92 | 2-7 | 15 | 5| 8| 2 28 | ‘8 | 143) 4:3
| | |

** Including four plaice.

From the table it is seen that Arenzcola is the most
successful bait for flat-fish, that it is about equal to
mussel for attracting whiting, but mussel is superior for
cod and haddock. Comparing Arenzcola and Pecten it is
seen that the former is rather more effective as a bait for
flat-fish and whiting, but the latter for haddocks, while
they are equal in their catch of cod. These two baits are
practically equal in value. Limpets are inferior to each
of the other three baits. It may be stated here that flat-
fish are not plentiful in the Firth of Forth. In the above
described experiments they form only one-seventh of the
eateh while haddoeks form more than half.

Haddocks form the majority of fish taken by the line
fishermen of Musselburgh, and other places on the Firth
of Forth. These men, who work over the same area as

that in which the above-named experiments were con-

YOS

hol ed

ducted, prefer lugworms as a bait for haddocks, in fact,
the results shown in the above table are not in agreement
with the general opinions of fishermen at several points
of the Scottish coast. Both in Aberdeen district and in
the Firth of Forth the order of preference seems to be
lugworms, clams, mussels. On the Lancashire coast and
in other parts of England, lugworms are preferred to
mussels.

Lugworms are used for baiting both long and short
lines, the custom varying in different localities. On the
Cheshire coast at New Brighton, at Piel, Lancashire, and on
the coast of Northumberland, short lines are usually em-
ployed, those of the New Brighton fishermen bearing only
about twenty hooks. In the Aberdeen district the lines
earry about three hundred hooks, and the Musselburgh
fishermen employ long lines bearing as many as twelve
to sixteen hundred hooks baited with lugworms.

The lugworm has a faint odour and an _ ethereal
extract proved to be attractive to certain fish, e.g., turbot
and rockling.* It is doubtful whether this scent is suffi-
ciently strong to play any part in attracting the fish which
are usually caught with lugworm bait, as most of these
fish—cod, whiting, plaice, flounder and dab—appear to
find the bait by the sense of sight.t

* F, Hvuaurs.—Journal Marine Biological Association, Vol. 2,
p. 92:

+ W. Bareson.—Journal Marine Biological Association, Vol. 1,
p. 241.

DESCRIPTION OF PLATES.

Reference Letters.

A.B.S. = Achetous body seg-
ment.

Ac. = Aciculum.

adler, = Acrosome or apical body
of spermatozoon.

An. = Anus.

Ant.L. = Anterior lobe of brain.

Ale, = TOP UN BOE

B. = Blastophore (residual mass

of protoplasm).
Bl. V. = Blood vessel.
Br. = Gill.
br. Aff ) = Afferent and efferent
Br.Lf. 3
br. and N.Aff. = Afferent vessel

to gill and nephridium.

branchial vessels.

B.Sh, = Sheath formed of buccal
muscles.

Bucc.M. = Buccal mass.

Bucc.Pap. = Papille of buccal
mass.

Caud.Sep. = Caudal septum.

Ch. Seg.= Cheetigerous segment.

Chi.Gr. = Chlorogogen granules.

Chl. Tiss. = Chlorogogenous tissue.

Cel. = Coeelom. :

Cal. Hpith. = Coelomic epithelium.

Conn. Tiss. = Connective tissue.

Cut. = Cuticle.

Diat. = Diatom (as otolith).

D.L.V. = Dorsal longitudinal
vessel.
D.Mes, = Dorsal mesentery.

Dphm. = Diaphragm.

Dphm.P. = Pouch of first dia-
phragm.

D.V. = Dorsal vessel,

Hndth.N. = Nucleus of endo-
thelium.

Hip. = Epidermis. i

Hac.Gr. = Exeretory granules.

Het.Op.Ot. = External opening
of otocyst.

Gang.C. = Ganglion cell.

Gast.Lat. = Lateral

vessel.

gastric

G.C. = Giant nerve cell.
G.F’. = Giant nerve fibre.
Gl.¢. = Gland cell.

Gon, = Gonad.

Gon.V. = Gonidial vessel.
Ht.B. = Heart body.

Int.V. = Intestinal vessel.
M.Circ. = Cireular muscles.
Met.Gr. = Metastomial groove.
Mid.Com. = Middle commissure

of brain.

M. Long. = Longitudinal muscles.

Mo. = Mouth.

M.Obl. = Oblique muscles.

M.P. = Middle piece of sperma-
tozoon.

Musc. = Muscles.

N. = Nucleus.

N.Aff. = Nephridial afferent
vessel.

N.C. = Nerve cord.

N.EHp. = Nerve to epidermis.

Nfb. = Neurofibrille.

Ngl. = Neurogha.

Nim. = Neurilemma.

N.L.V. =Nephridal longitudinal
vessel.

Nm. = Neuropodium.

230

Nm.Ch. = Neuropodial cheetie.
Nm.Cirr. = Neuropodial cirrus.
N.O. = External opening of

nephridium.
Not. = Notopodimn.
Not.Curr. = Notopodial cirrus.
Not.Pr. = Protractors of Not.sS.
Not. Retr. = Retractors of Not.s.
Not.S. = Notopodial sete.
Nph.f’. = Funnel of nephridium.
Nph.F'.D. = Dorsal lip of do.
Nph.F'.V. = Ventral lip of do.
Npile. = Neuropile.
N.S.= Nervous sheath of otocyst.
Nuc.Gr. = Nuchal groove.
Nuc. fetr.= Retractors of nuchal
organ (and of prostomium).
N.V. = Neural vessel.
(i, = CGisophagus.
(. Conn. = Cisophageal connec-
tive.
G.Gl. = Gisophageal gland.
G.G1.V. = Blood vessel of do.
@.Lat. =
vessel.
Ot. = Otocyst.
Otl. = Otolith.
Ot.N. = Nerve to otocyst.

Lateral oesophageal

Ot.T. = Otocyst tube to exterior.

Par.V. = Parietal vessel.

P.B. = Polar bodies.

Per. = Peristomium.
Per.Cirr. = Peristomial cirrus.
Per.C. = Peritoneal cell.

Ph. = Pharynx.

Pignm. = Pigment.

Post.L..= Posterior lobe of brain.

Proc. = Process of giant cell.

Pr.Pr, = Protoplasmic processes
of nephrostome.

Prost. = Prostomium.

Prost. Epith. = Prostomial epithe-
lium.

S.C. = Sense cell.

Sila = Sense hairs.

Sp. = Spicule (as otolith).

Sp.N. = Spinal nerve.

Stom. = Stomodeum.

S.V. = Subintestinal vessel.

T. = Tail of.spermatozoon.

Tent. = Tentacle (prostomial).

U.L. = ** Upper lip” (part of
peristomium).

V. = Ventricle of heart.

Ves. = Vesicle of nephridium.

V.Gr. = Ventral ciliated groove.

V.M. = Vitelline membrane.

V.V. = Ventral vessel.

All the figures are drawn from <Arenicola marina,
except figs. 7, 8, 9, which are of Nercis pelagica, fig. 53 of
A, grubu, and figs. 69-79 of A. clapared:?.

Piate I.

Hie 1:
right side.

A Laminarian specimen, 190 mm. long, from
oo)

Proboscis fully protruded ; the buceal portion

first protruded during eversion is provided with numerous

backwardly directed papillae, the following pharyngeal

231

portion (smooth in the figure) is covered with closely set
rounded papille too small to be shown. —Prostomium,
segmentation, annulation, parapodia, gills and nephridio-
pores also shown. Natural size.

Fig. 2. Anterior end of a littoral specimen about
60 mm. long. Ventral aspect. In front the mouth is seen
surrounded by a series of papille. Behind the “ upper
lip” the three lobes of the prostomium are seen lying
retracted in the nuchal organ. Note the metastomial
erooves uniting in third annulus at anterior end of groove
over ventral nerve cord. Segmentation and annulation in
relation to the internal septa also shown. Compare from
second to third chetigerous annuli with fig. 1. x 6.

Vig. 3. Portion of * proboscis ” from fig. 1, to show
the buccal papille, which gradually merge into the
epidermal papille of the peristomium. x 9.

Vig. 4. Chitinoid caps from the tips of the buccal
papille. x 24.

Figs. 5, 6. Dorsal and ventral views of the anterior
end of a large littoral specimen, 340 mm. long. The
“ proboscis ” is half extruded. ef. figs. 1, 2.

Fig. 5. Dorsal aspect, showing the trilobed prosto-
mium fully extended, the origin of the two metastomial
grooves, the apertures of the otocysts, the sculpturing of
the skin, &e. Each of the first four annuli is subdivided
into two. ‘The first two annuli form the peristomium, the
third and fourth represent a body segment from which the
setee have disappeared. The first cheetigerous annulus and
the following annulus represent the first cheetigerous
segment. x 5.

Fig. 6. Ventral aspect, showing metastomial grooves,
groove over ventral nerve cord, and very small neuropodia
of first cheetigerous segment. x 5.

Figs. %, 8. Nerers pelagica. Dorsal and ventral

aspects of the anterior end for comparison with the two
preceding figures of Arenzcola.

Fig. 7. Dorsal aspect. Prostomium with pair of
tentacles, pair of much stouter palps and four eyes, the
peristomium bearing on each side four cirri (the basal
portions only are shown on the left), the first and second
body segments with their parapodia. x 6.

Fig. 8. Ventral aspect. Note prostomium with ten-
tacles and palps, peristomium bearing mouth on anterior
margin, the first and second body segments with their
parapodia. The structure at the base of the palps is part
of the peristomium forming the upper lip. x 6.

Fig. 9. Nereis pelagica. A parapodium, from the
74th chetigerous segment, divided distally into bilobed
notopodiwm and neuropodium, each of which bears a
sensory cirrus, au aciculum and a bundle of setee (jointed)
situated in a setal sac, the lips of which are well seen in
the neuropodium. x 20.

Fig. 10. The seventh notopodium and the small and
simple first right gill of the Laminarian specunen shown

in fig. 1. Compare with fig. 19 Sab?

Pirate II.

Fig. 11. Three notopodial setie from a_post-larval
specimen +35 mm. long. Most of the sete are of the type
shown in fig. LLC (x. 800), but in each notopodium there
is one seta of the kind shown in figs. 114, 116. (x 1,000.)

Fig. 12. Distal fourth of a seta (75 mm. long) from
a Laminarian specimen 250 mm. long. x 80.

Fig. 13. A portion of same seta (from the region
marked +) more highly magnified. On the lett the
broad lamina, with its finely dentate margin, is shown.

x S00.

Fig. 14. A portion (0°2 mm. from the tip) of a seta
(2.5 mm. long) from a littoral specimen 125 mm. long.
On the left the lamina, with its dentate margin, is shown.
x 800.

Fig. 15. Two crotchets from neuropodia of a post-
larval specimen 5'1 mm. long. The teeth on the sides of
the rostrum are indicated. The dotted line indicates the
level of the epidermis. x 1,000.

Fig. 16. Neuropodial crotchet from a young littoral
specunen 17 mm. long. x 500.

Fig. 17. Neuropodial crotchet from a littoral speci-
men 125mm. long. x 150.

Fig. 18. Ventral portion of neuropodium of Lami-
narian specimen 250 mm. long. On the left (which is

ventral) the various stages of formation of the crotchets

are seen. The crotchet on the right is fully formed.
Vin shows outline of the neuropodial sac. eit).

On comparing the four preceding figures there is seen
to be, as the worm grows, an increase in the length of the
crotchets, a decrease in the size of the teeth behind the
rostrum, and also a gradual change in the inclination of
the rostrum to the shaft, the angle increasing with the
size of the specimen.

Fig. 19. Right aspect of ninth and tenth chetigerous
segments of Laminarian specunen (190 mm. long). The
fourth gill has eleven main stems united at their bases by
a membrane. Five of these, and many lateral branches,
have been cut away to show the remainder. The ventral
stem alone, in which the lateral branches have the
simplest form, is shown entire. Lateral branches some-
what simplified. Fig. 21 shows one in detail. The
third gill has been almost entirely cut away. The
capillary sete are seen projecting beyond the lips of the

notopodial setal sac. Kach neuropodium resembles a

234

pair of tumid lips between which is the narrow opening
of the neuropodial setal sac which contains the crotchets.
The external opening of the sixth (last) nephridium is just
behind the dorsal end of the ninth neuropodium. x 6.

Fig. 20. Ventral stem of gill of younger Laminarian
worm. This stem is about half the length of that shown
in the preceding figure, and its lateral branches are still
comparatively simple. x 20.

Fig. 21. Lateral branch, from one of the dorsal stems
of the gill shown in fig. 19, bearing twenty-two gill
filaments. x 20.

Fig. 22. Fourth right gill of a littoral specimen

about 110 mm. long. The gill consisted of ten main
stems, eight of which have been cut away. The blood-
vessels are seen traversing the basal membrane. The

lateral twigs are fewer in number and not so richly
branched as in Laminarian specimens. xi 20:

Prac te

Fig. 25. Dissection of a large Laminarian specimen
(250 mm. long) cut open along the mid-dorsal line to show
the anatomy. ‘The alimentary canal is pushed over to the
left side, and most of the tail has been cut out. The
proboscis is about half extruded. The dorsal portion of
rach left gill is seen. The gastric plexus is shown full of
blood, and the heart about half expanded. ‘The funnel
only of the first left nephridium is seen, the rest of the
organ being covered by the esophagus. The funnel of
the third left nephridium is hidden by one of the
csophageal glands. The funnel of the fifth right nephri-
dium has pushed its way through the interval between two
of the oblique muscles. The blood-vessels of the sixth

right nephridium have been pushed forward one annulus,

235

so as to show the afferent branch to the nephridium. The
afferent vessel of the fourth nephridium is accompanied

by a solid cord of connective tissue. x 2.

Priate IY.

Fig. 24. Dissection of left side of fourth and fifth
cheetigerous segments of a Laminarian specimen, showing
second nephridium with blood-vessels, gonad, the muscles
and the ventral! nerve cord. Three of the oblique muscles
are interrupted to show the nephridium. x 4.

Fig. 25. Second right nephridium of a young littoral
specimen 44 min. long in dorsal aspect showing especially
the capillary network on the funnel and excretory part,
the processes on the dorsal iip, the position of the external
opening (dotted), and the gonad upon the gonidial vessel.
The edge of the ventral lip of the funnel is seen through
the dorsal lip. x 69.

Fig. 26. Fifth right nephridium of an adult male
showing the vesicle distended with spermatozoa in dorsal
aspect. The funnel of this nephridium was widely open,
as is usual at the breeding season. x 4.

Fig. 27. First left nephridium of a medium-sized
worm, in dorsal aspect. This nephridium is much more
slender than any of the others. The ventral lip of the
funnel is shown (dotted) through the dorsal one. The
gonidial vessel bears a number of blindly ending vascular
processes which are covered with chlorogogen cells. x 8.

Fig. 28. The anterior portion of the funnel of the
fourth nephridium in ventral aspect. The dorsal lip bears
numerous, almost semi-circular, lobed ciliated processes,
each of which contains a blind diverticulum of the large
blood-vessel which traverses this hp. On both lips there

is a network of blood-vessels, but they are shown only on

236

the ventral lip. Some of these vessels have blind dilated
endings. The ventral lp is simple and slightly everted.
x20:

Fig. 29. ‘Two of the processes of the dorsal lip, from
the second nephridium of a Laminarian specimen 190 mm.
long, to show the multi-lobate edge. x 20.

Fig. 30. Section of part of the excretory portion of
the nephridium, from a young specimen 65 mm. long,
showing two excretory cells with reticulate protoplasm
and excretory granules in the distal portion. The
granules become more numerous in older specimens, and
are apparently extruded from the distal portion of the cell
into the cavity of the nephridium. When this has recently
occurred the distal part of the cell is very clear and free
from granules. Hach cell bears one or two long flagella.
Below the cells is a thin film of connective tissue (vepre-
sented by a line) which is thicker in older specimens, and
outside this the thin layer of coelomic epithelium, which
covers the blood-vessels. x 650.

Fig. 31.— The last nephridium of a living post-larval
specimen 465 mm. long, in optical section. The larger
(right in the figure) lip of the nephrostome bears seven
protoplasmic processes (three are seen in the figure),
hearing long cila directed towards the opening. The
middle of the nephridium is slightly dilated and its walls
contain excretory granules. The whole nephridium is
ciliated. x 150.

Fig. 52. The anterior end of the same nephridium
drawn later. Optical section, showing the peculiar
ciliated protoplasmic processes of the nephrostome, the
cia of the nephridial tube, and the concretions in the
walls of its middle position. x 600.

Fig. 33. A process from the heart body of a speci-

men 250 mm. long (see figs. 59 and 40), to show the

237

endothelium, the muscle layer and the core of loosely
arranged peritoneal cells. In this and in several
other processes in the same heart there is a large collec-
tion of chlorogogenous granules in many of the peritoneal
cells. These are shown in red in the figure, but they are
naturally of a yellow colour. The granules are often
ageregated into small heaps, sometimes lying in a vacuole.
The outlines of the cells which are loaded with chloro-
gogenous granules are difficult to distinguish. The proto-
plasm of many of the peritoneal cells is vacuolated
and of others is granular, but the granules are very minute
and of a different nature from the chlorogogen granules.
x 00!

Fig. 34. Transverse section of a young specimen,
showing the nuchal organ, below which are the two
posterior brain lobes, an otocyst with its contained otoliths
and the tube leading to the exterior, the two cesophageal
connectives, the buccal mass with its sheath of muscles
and its retractors, the retractors of the prostomium and
nuchal organ, the muscles of the body wall, blood-vessels,
&e. The upper portion of the brain lobes and the outer
portion of each cesophageal connective contains nerve cells
(diagrammatically shown in the figure). The fibrous
portion of these structures is dotted. x 65.

Fig. 55. Transverse section of a young specimen at
the level of the openings of the glands into the esophagus.
The partitions which partially subdivide the gland, each
formed by a fold of the epithelium lining the gland and
enclosing a vascular sinus, are seen. Also the muscles of
the body wall and their blood-vessels; the oblique
muscles; the nerve cord; the vesicle and external opening
of the second right nephridium ; portions of two notopodial
setal sacs and the blood-vessels connected with the alimen-
tary canal. The ventral vessel and the two branches near

238

it are covered with chlorogogen celis. (See fig. 45.) The
nerve cord is divisible into a dorsal fibrous mass, in the
mid-dorsal line of which one giant-fibre is seen, and a
ventral portion composed largely of nerve cells the nuclei
of which are indicated. x 58.

Fig. 56. Transverse section of the same specimen in
the region of the last nephridium. ‘To the right of the
two vertical lines was drawn from a_ section passing
through the anterior part of the ninth chetigerous seg-
ment, while the portion on the left is from a section passing
through the tenth parapodium, and showing the notopo-
dium with its setal sac and protractor muscles and the
whole length of the neuropodium. We see also a portion
of a gill, with its afferent and efferent vessels, the funnel
(opening into the ecelom) and excretory part of the nephri-
dium, the stomach with its ventral groove and blood
sinuses, the subintestinal and the lateral gastric, the dorsal
and ventral vessels, the latter surrounded by chlorogogen
cells (fig. 45), the muscles of the body wall and their blood-
vessels; two oblique muscles; the nerve cord, the dorsal
fibrous mass of which contains two giant-fibres, and the
ventral portion with nerve cells, the nuclei of which are
shown. x 38.

PLatTeE V,

Fig. 37. Longitudinal section of the heart of a young
Arenicola 65 mm. long to show the heart body in an early
stage of its formation. On the posterior (right) side and
also on the antero-exiernal side (left of the figure), the
wall of the ‘heart is being invaginated at several points,
thus giving rise to the heart body. x 100.

ig. 38. A portion of the wall of the ventricle from
the point marked + in the preceding figure, and composed

aS Game

239

of three layers, an endothelium internally, a muscle layer
and a peritoneal covering. ‘The muscle layer is only
feebly developed in worms of this size, it becomes much
more highly developed in older specimens (see figs. 35, 40).
The protoplasm of the peritoneal cells is moderately homo-
geneous, in older stages it becomes either vacuolated or
granular and in many cases contains chlorogogen granules.
The wall of the heart is invaginated forming a club-shaped
process which contains a central cavity. The excessively
thin endothelium is partly obscured by a mass of blood
which closely invests the process. (Cf. figs. 33, 40). x 600.

Fig. 59. Longitudinal section of the much thicker,
muscular ventricle of a large specimen 250mm. long.
The invaginations of the wall are very numerous and
complex, filling up the greater part of the cavity and
forming the well-marked heart body. x 46.

Fig. 40. The tip of one of the invaginated processes
of the heart-body, from the previous figure, showing the
endothelium, the muscle fibres and the core of loosely

arranged peritoneal cells, some of which are vacuolated

and some granular. x 1260)
Fico. 41. Three blood corpuscles. The one on the
g |

right from an old specimen (250 mm. long), the two others
from a young specimen (65 mm. long). x LOOO.

Fig. 42. The terminal portion of one of the small
execal branches of the ventral vessel covered with irregular
dark brown chlorogogen cells. The latter do not extend
to the tip of the vessel. x 150.

ig. 48. Section of the covering of the ventral vessel,
the columnar cells loaded with yellowish chlorogogen
granules of various sizes. x 500.

Fig. 44. Coelomiec cells. In the upper part of the
figure a typical fusiform cell, on the mght four ameeboid
cells, three of which contain chlorogogen granules; on the

240

left three rounded cells, cne of which is vacuolated, the
other two contain chlorogogen granules. These may be
amceboid cells which had temporarily withdrawn their
pseudopodia. x LOO.

Fig. 45. A portion of the third diaphragm, from a
stained preparation, to show the numerous oval apertures
by which the septum is perforated. The diaphragm is
covered on both faces by a flattened endothelium between
which isa thin layer of connective tissue and inter-crossing)
muscle fibres. The endothelial nuclei of one face only are
shown. x 300.

Puate VI.

Fig. 46. Dissection of anterior end of large
specimen, with pharynx and the first diaphragm removed,
showing anterior and posterior lobes of brain; middle
cerebral region of each side connected by broad band of
nervous tissue; nerve to otocyst arising from cesophageal
connective; muscle strands from otocyst to body wall;
anterior portion of ventral nerve cord; first notopodial
sacs and muscles; the longitudinal muscles and the buceal
sheath. x 6.

Fig. 47. Horizontal section of prostomium of a
specimen 60 mm. long. The anterior and dorsal portions
of anterior lobes of the brain are formed largely of pyri-
form ganglion cells shewn diagrammatically in the figure.
Three coelomic spaces, lined by coelomic epithelium and
containing blood-vessels, are seen. On the anterior left
side of brain is an eye slightly exaggerated. The posterior
lobes of the brain underlie the nuchal organ, most of their
nerve cells are small and their nuclei only are shown.
The middle region of the brain, consisting largely of
neuropile (finely punctate), shows a transverse band of
fibres connecting the right and left halves, Attached to

241

the posterior end are the retractor muscles of the pro-
stomium and nuchal organ. x 70.

Fig. 48. Part of a similar section showing an eye
imbedded in the brain. In the upper part cuticle and
prostomial epithelium are shown, on the right a gland
cell and on the left a bundle of slender sense cells.
Beneath the epithelium is the anterior brain lobe and an
eye, which consists of a cup-shaped mass of reddish-brown
pigment spherules grasping a spherical lens. In the
right of the pigment mass is a nucleus and small amount
of protoplasm, probably the remains of the cell in which
the eye has been formed. x 550.

Fig. 49. Section of otocyst and tube leading to ex-
terior (from specimen 60 mm. long). The otocyst is
lined by epithelium continuous with that of the tube and
the epidermis. In the outer portions of the tube there
are fusiform sense cells, but in the otocyst itself the sense
cells are distinguished only by the presence of neuro-
fibrille (not shown in the figure). The proximal (and
narrowest) portion of the tube is ciliated. Below the
epithelium of the otocyst is the nerve sheath, connected
with the stout nerve from the esophageal connective.
This nerve, along the course of which are numerous ganglion
cells, also sends off branches to the skin. The otoliths are
irregular bodies, chiefly quartz grains. x 210.

Fig. 50. Camera-drawing of the cuticle lining the
otoeyst of a specimen 250 min. long. This is thicker than
in younger specimens. ‘The tube is almost blocked and the
otoliths are now assuming a rounded outline, due to the
deposition of layers of secretion. x 210.

Fig. 51. A small portion of epithelium from anterior
end of stomach, showing two large goblet cells. The
secretion of these cells has been coagulated on preservation
and now appears as a reticulum, x 210.

R

242

Puate VII.

Fig. 52. Plan of the nerve cord of a young specimen
about 25 mm. long to show the position of the giant cells.
Transverse lines mark the posterior limits of the segment,
the numbers of some of which are given at the side. The
cells are drawn too large (x 40) in proportion to the width
of the cord ( x 25), and the latter is about twice too broad
in proportion to its length (x 12). The first giant cell is
situated in the achewtous segment which lies behind the
peristomium. There was no giant cell in the sixteenth
chetigerous segment of this specimen. Gnant cells are
not distinguishable in the small anterior tail segments, but
a few are present in the more posterior segments. One is
shown in the twelfth caudal segment.

Fig. 55. Transverse section of the nerve cord of
Arenicola grubii. The section shows the dorsal fibrous

part of the cord, in the mid-dorsal region of which are
three giant fibres, the nuclei in the sheaths of which are
shown. In the ventral portion of the section note the
numerous small nerve cells, the nuclei of which are shown
on the right and left; a bundle of pyriform ganglion cells
whose processes are directed into the fibrous part of the
cord; and a giant nerve cell. The protoplasm of the latter
is reticulate and its nucleus vesicular. The cell gives off
a large process which, after sending branches into the
fibrous part of the cord, enters the right lateral giant fibre
at the point where there is a transverse connection between
the two lateral giant fibres. The neurofibrille of the
process are shown. This drawing of the giant cell and its
process was obtained by superposing camera drawings of
the four consecutive sections in which these structures
occur. x 210.

Fie. 54. Transverse section of nerve cord of Areni-

c

243

cola marina, showing a giant cell and its process in which
the neurofibrille are seen; also sheath of neurilemma
enclosing the cord; fibrous part of cord partially sub-
divided by a median sheet of neurogla; two giant fibres ;
nuclei of small nerve cells situated in ventral part of cord ;
root of a spinal nerve on the right; epidermis; circular
muscles; longitudinal muscle bands, the fibrils and nuclei
ot which are seen; two oblique muscles and the coelomic
epithelium. x 500.

Fig. 55. Horizontal section of fourth chetigerous
segment of a specimen 45 mm. long passing through the
ventral nerve cord, to show the giant-cell and the spinal
nerves. <A pair of nerves is given off from the cord oppo-
site each inter-annular groove and in addition a nerve or a
small bundle of nerves to the cheetigerous annulus. x 165.

Vig. 56. A post-larval specimen 3°9 mm. long taken
in the tow-net near Lytham. ‘The animal is seen from the
left side, and shows the eyes on the prostomium, the seg-
mentation and annulation, the parapodia, the two kinds of
notopodial sete, the gills, and the otocyst. x 950.

Fig. 57. Dorsal view of anterior end of a post-larval
specimen 5'4 long, to show the prostomium, the nuchal
organ, the peristomium in which he the otocysts (outline
dotted), the achztous body segment and the first cheeti-
gerous segment. The peristomium and the achetous
segment are divided into two, thus forming four annul,
corresponding to the subdivision of this region in adults.
Cig. 0. x 200:

Fig. 58. Ventral view of the corresponding portion
of a post-larval specimen 35mm. long. The mouth is
situated on the anterior edge of the peristomium and the
two cesophageal connectives are seen uniting in the third
annulus. Cf. fig. 6. -x 100.

Fig. 59. The prostomium and nuchal organ drawn

244

from a living post-larval specimen 46mm. long. The
prostomium bears six eyes, two of which, those first formed
in the larva, are larger than the others. Seattered over
the surface of the prostomium are groups of fine sense
hairs. Only those on the margin are shown in the figure.

x) 100.

Puate VITI.

Figs. 60—65. The formation of spermatozoa.

Fig. 60. One of the earliest stages found in the
celomic fluid consisting of sixteen cells (spermatogonia).
x 900.

Fig. 61. Optical section of a similar stage showing
eight of the spermatogonia arranged round a vesicular
residual mass of protoplasm—the blastophore. x 500.

Figs. 62, 63. Later stages produced by continued
division of the spermatogonia. x 4500.

Fig. 64. Two cells—spermatids—trom a stage much
later than the preceding. At one end (the left) of each is
a small mass of protoplasm which later forms the apical
body of the sperm, following this is the nucleus and a
clear substance from which the middle piece of the sperm
is derived, while on the right the protoplasm is being
drawn out to form the tail. x 2000.

Fig. 65. A discoidal mass of almost ripe spermatozoa.
x 900.

Fig. 66. A ripe spermatozoon. The head is divisible
into an apical body, the nucleus and the middle piece,
which is notched behind to receive the tail. x 3000.

Fig. 67. A ripe egg from the body cavity. The flat
face is shown. ‘The nucleus is large and vesicular, the
yolk granules in the protoplasm are rather more numerous
around the nucleus, the vitelline membrane is thin (1p)

x LOO.

Fig. 68. Side view of a ripe ego. x 100.

Figs. 69—79. Segmentation of the egg and larval
stages of Arenicola cla paredit.

Vig. 69. Two-cell stage. he two polar bodies are
shown. Four and a half howrs after addition of the
spermatozoa to the sea water containing the eggs. x 210.

Fig. 70. Four-cell stage, seen from the anterior pole.
eG:

Bie (1, Night-cell stage, seen from the anterior
pole. The first four ectomeres (la, 1b, lc, 1d) have been
cut off from the lower cells. x 210.

Fig. 72. Sixteen-cell stage, seen from the anterior
pole. Mach of the first ectomeres has divided into two and
the second quartette of ectomeres (2a, 2b, 2¢, 2d) has been
eut off from the lower cells. Of the latter only one (24)
is shown in the figure. 2d is the largest cell in the egg
and forms a conspicuous landmark. x 210.

The cleavages shown in the three preceding figures
occupied about two hours

Fig. 73. The Jarva (blastula) at the end of 24
hours, seen from the posterior pole. The four quartettes
have been formed, the first three of which are ectomeres.
One of the fourth quartette (4d) is the mesoblast cell and
it has already sunk into the segmentation cavity. The
three other members of the fourth quartette (4a, 4b, 4e)
and the four lower cells (44, 46, 4C, 4D) are endoderm
cells. In this specimen each of these seven primary endo-
derm cells, except 4c, has again divided, so that there are
thirteen endoderm cells at the posterior pole of the larva.
xe LO:

Big. 74. Larva about six hours later than the pre-
ceding. Ventral aspect. ‘The pre-oral band of cilia is
shown just in front of the stomodzal invagination. The
larva is at this stage constantly rotating in the vitelline

246

membrane. The latter shows a thin area through which
later the larva forces its way. x 210.

Fig. 75. Larva three days (72 hours) after fertilisa-
tion of the egg. Dorsal aspect. Both ciliated bands are
now present, and there are two eyes on the prostomiun.
Ten minutes after the drawing was made the larva forced
its way through the thin area in the upper portion of the
vitelline membrane. x 210.

Fig. 76. Larva one day after hatching. Dorsal
aspect. ‘T'wo short spade-shaped sete are present. The
anterior and posterior ciliated bands and the eyes are also
shown. The specimen was slightly compressed by the
cover-glass and therefore appears a little broader than it
should be. x 210.

Fig. 77. Larva twelve days. after hatching. Seen
from the right side. The prostomium bears two eyes and
several small groups of sense hairs. Sete are present in
three segments, in the first two of which both notopodial
and neuropodial sete may be seen. The notopodial sete
are of two kinds. The alimentary canal is complete from
mouth to anus, the middle portion is dilated with yolk.
The eelom is obvious post-orally. The anterior girdle of
cilia has entirely, and the posterior one almost, disappeared.
The anterior portion of the ventral band of cilia still
remains. x 210.

Fig. 78. A (notopodial) seta from the larva shown in
hie. VO |< LOO:

Fig. 79. Two sete from the larva shown in fig. 77.

Fig. 794. One of the neuropodial crotchets. The
dotted line indicates the level of the epidermis. x 1000.

Fig. 9B, The distal portion of one of the notopodial
sete. The other seta in the same notopodium is sunilar
to the one shown in fig. 78. x 1000.

J.H. Ashworth, del.

M‘Farlane & Erskine, Lith. Edin?

=

Piate If |

7

Bi

YY

y
4

AN ; ' vs Pass a * ' : i
Fig. 13 x goo. {F814 «800. ChiSeg,!° Fig.19x 6.
J. H. Ashworth, del. A x ia NI G; O LA M‘Farlane & Erskine, Lith Edin’

Gast.Lat. |

J.H Ashworth de

fe it
Pe | Wem
re er er
a } lore kK
aE

ree

ri
Lorine

ee I<

an

en GERSGESSERE
(Gs
Br. ae N.Aff.

y nee Ges
‘irmsweeneess uy REDE O ES RA OREE cor

ea eee

ah i i =

Pig 25 ne

ARENICOLA.

- Ohh Liss

Sooo
sa =

Saray | soueangans')
PvE ee! is
.. Tem Brsntstsy/] UE IY Beal he

PSs RT E//|
7 PEED TP Ee a
AUT TE Pare
KEEErtrreA

Vy)
m ~

HULL =
Eo CE

i) \eitearee Henin

SE <semarphs/
=i SGRBRRTTA Ce
irs meee

rt

7
a 7, |
TLLbis ae
Reo

| tal
pee ~~
on
=

by

=

=
nie
aw

VUZE

A

Ny

|| NEEREEEEEETE SS
" ray
em

NEGRSERSD GSE)

A

S258EEsrse

g ey

7

Tp 1M
mn DS oe |
D.L.V.-------- q j
“cre, eed fy ———- Ae
\ Yam) ee,
\) i \pesaii ay
desta Int. V.
ison Noe. S. 7
ane a === |
and Septum. eos)
Rt
5 Ree” Ye TIS D.L.V.
Noe. S72 i
Bris
Caud. Sep.------

An
~~ “MéFerlsne & Erskine Lith.Edint

ad
—

”

Fig. 24x 4.

Not.Retr.

a
2 itt \)

Ly 2 >
as aK y
\ ' a
“ 7 - =
0 ' 7
om ry
ae a
>’ WR

}>)
iP
M061. }IS

OU
Exe. Gr. M‘Farlano & Erskine, Lith Edin™
J H-Ashworth, del. |

ARENICOLA.

16.38 x 600.

M‘Farlane & Erskine, Lith. Edin?

Chu, Tiss.

bavi
By)

a

p)

Uy
Oks

@
§,. 41 x i000.
ARENICOLA.

Fig.

J.H.Ashworth, del.

¢
y
by

Nic. Gr.

uc Beri

J.H.Ashworth, del.

BLY.

pile.

Ss eon
Fig. 47x 70.

ARENTCOLA.

4
13
3
4
)

Prare Ve

~~~-.Muse.
“Gang.C.

Fig. 49 x 2io.

*~Coel.Epith.

~~ Diat.

“OEL.

M‘Farlane & Erskine, Lith. Edin

Puate VIL.

Not.S2--

Lap S.

Nuc.67--4
sb a
Ea < eR
Eyes AS OE.

Fig. 59 x 100.

|

aa
Vie

jo sea!

7]

Mm. Ch!

Fig. 57 x 100.

Ch.Seg? M,Ob1 GE

i, MLong. Ep.
Coel.Epith. Nim. org. ie

MM. Cire

Gi we. Fig. 56 x15.

J.H. Ashworth, del AR E NI C 0) oe. Krein oe

Fig. 54 x 300.

Puate VIII.

Fig. 79. x iooo ,
J.H.Ashworth, del. ARE NI (§ O A . MSParlane & Erskine. Lith Ediu™

]

Ta

Bp etme
eed

4

t ims
rar

- OUNA

3 2044 072

,

«
.
.
4
.
:
.
.
«
.
.