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TRANSACTIONS

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LIVERPOOL BIOLOGICAL SOCIETY.

VOL. XXXV.

SESSION 1920-1921.

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CONTENTS.

—_—__

I.—PROCEEDINGS.

Office-bearers and Council, 1920-1921 .
Report of the Council

Summary of Proceedings at the Meatinics
List of Members.

Treasurer’s Balance Sheet .

II.—TRANSACTIONS.

Presidential Address—‘ Sedimentation, Environment,

and Evolution in Past Ages.” By Prof. P. G. H.
BoswE tL, O.B.E., D.Sc. ‘

The Marine Biological Station at Port Erin, being the
Thirty-fourth Annual Report of the Liverpool
Marine Biology Committee, now the Oceanography
Department of the University of Liverpool. By
Prof. W. A. Herp, C.B.E., D.Se., LL.D., F.B.S.

“Notes on Dinoflagellates and other Organisms Causing
Discolouration of the Sand at Port Erm.” By
K. CATHERINE HERDMAN

“Note on Some Experiments on the Water Vascular
System of Echinus.” By Rutu C. BampBer, M.Sc.

*“On the Inheritance of Coat Colour in the Varieties of
Rattus rattus.” By J. W. CuTmMore

Report for 1920, on the Lancashire Sea-Fisheries Labora-
tory at the University of Liverpool, and the Sea-Fish
Hatchery at Piel, near Barrow. Edited by Prof.
JAMES JOHNSTONE, D.Sc.

“Aplysia” (L.M.B.C. Memoir No. XXIV). By
NeEwLic B. Eases, B.Sc.

PAGE
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29

59

64

71

73

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PROCEEDINGS

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OFFICK-BEARERS

1886—1887

Gx-Dresiwents :

1887—1888 J. J. DRYSDALE, M.D.
1888—1889 Pror. W. A. HERDMAN, D.Sc., F.R.S.E.
1889—1890 Pror. W. A. HERDMAN, D.Sc., F.R.S.E.
1890—1891 T. J. MOORE, C.M.Z.S.

1891—1892 T. J. MOORE, C.M.Z.S.

1892—1893 ALFRED O. WALKER, J.P., F.L.S,
1893—1894 JOHN NEWTON, M.B.C.S.
1894—1895 Pror. F. GOTCH, M.A., F.RB.S.

1895—1896 Pror. R. J. HARVEY GIBSON, M.
—1897 HENRY O. FORBES, LL.D., F.Z.S.
1897—1898 ISAAC C. THOMPSON, F.LS., F.R.
1898—
1899—1900 J. WIGLESWORTH, ue
1900—1901 Pror. PATERSON, M.D.,

1896

as
1899 Pror. C, S. SHERRINGTON, M.
ER.

Poe
er:

1901—1902 HENRY C. BEASLEY.

1902—

1903 R. CATON, M.D., F.R.C.P.

1903—1904 Rev. T. 8. LEA, M.A.
1904—1905 ALFRED LEICESTER.

1905—
1906—1907 Pror. W. A. HERDMAN, D.Sc., F.R.S.
US

1906 JOSEPH LOMAS, F.G.S.
1908 W. T. HAYDON, F.L.S.

1908—1909 Pror. B. MOORE, M.A., D.Sc.
1909—1910 R. NEWSTEAD, M.Sc., F.E.S.

1910—

1911 Pror. R. NEWSTEAD, M.Sc., F.R.S.

1911—1912 J. H. OCONNELL, L.B.C.P.

Loi12—

1913 JAMES JOHNSTONE, D.Sc.

1913—1914 C. J. MACALISTER, M.D., F.R.C.P.

1914—1915 Pror. J. W. W.
1915—1916 Pror. ERNEST GLYNN, M.A., M.D.

AND COUNCIL

Pror. W. MITCHELL BANKS, M.D., F.B.C.S.

STEPHENS, M.D., D.P.H.

1916—1917 Pror. J. S. MACDONALD, L.B.C.P., F.B.S.
1917—1918 JOSEPH A. CLUBB, D.Sc.
1918—1919 Pror. W. RAMSDEN, M.A., D.M.
19191920 HUGH R. RATHBONE, M.A., J.P.

Pror. W. A. HERDMAN, C.B.E., D.Sc.,

Hon. Crevsurer:
W. J. HALLS.

S. T. BURFIELD, B.A.,

R. CATON, M.D., F.R.C.P

J. A. CLUBB, D.Sc.

J. W. CUTMORE.

Pror. W. J. DAKIN, D.Sc., F.L.S.
G. ELLISON.

SESSION XXXIV, 1920-1921.

President :
Pror. P. G. H. BOSWELL, O.B.E., D.Sc

‘Mice- Presidents :
HUGH R. RATHBONE, M.A., J.P.

Hon. Secretary:
W. RIMMER TEAREH, A.C.P.

Council:

ERS.
Hon. Librarian:
MAY ALLEN, B.A.

ALWEN M. EVANS, M.Sc. (Miss)
Pror. J. JOHNSTONE, D.Sc.
W. S. LAVEROCK,
J. H. MILTON, F.G.S.
Pror. R. NEWSTEAD, M.Se., F.R.S.

M.A., B.Sc.

Pror. W. RAMSDEN, M.A., D.M.

Representatie of Students’ Section :

Miss M. BOWEN, B.Sc.

Vill. LIVERPOOL BIOLOGICAL SOCIETY.

REPORT of the COUNCIL.

—

Durinc the Session 1920-21 there have been seven ordinary
evening meetings. The annual excursion was held on June
18th, when a visit was paid to the Grosvenor Museum at
Chester, and a very enjoyable afternoon was spent.

The communications made to the Society at the ordmary
meetings have been representative of many branches of Biology,
and the various exhibitions and demonstrations thereon have
been of the utmost interest and value.

The form of the meeting on March 14th was somewhat of
a new departure. The President received the members and
a number of guests in the Zoology department, which, together
with the Geology and Oceanography departments, was thrown
open to inspection.

On May 6th, Prof. J. B. Farmer, F.R.S., D.Sc., of the
Imperial College of Science had intended to address the Society,
but was prevented by indisposition from doing so. It is hoped
that he will be able to be present at one of the meetings of
next session.

The Library continues to make satisfactory progress, and
additional important exchanges have been arranged.

The Treasurer’s statement and balance sheet are appended.

The members at present on the roll are as follows :—

Ordinary members ee - se pie ee 48
Associate members e ae oe ed 5S: 12
Student members, including Students’ Section, about 30

Total += Eds 2s 90

SUMMARY OF PROCEEDINGS AT MEETINGS. 1x

SUMMARY of PROCEEDINGS at the MEETINGS.

The first meeting of the thirty-fifth session was held at
the University, on Friday, October 15th, 1920.

1. The Report of the Council on the Session 1919-1920 (see
“Proceedings,” Vol. XXXIV, p. viii) was submitted
and adopted.

2. The Treasurer’s Balance Sheet for the Session 1919-1920
(see ‘‘ Proceedings,” Vol. XXXIV, p. xvi) was submitted
and approved.

3. The followmg Office-bearers and Council for the ensuing
Session were elected :—Vice-Presidents, Hugh R.
Rathbone, M.A., J.P., Prof. Herdman, D.Sc., F.RB.S. ;
Hon. Treasurer, W. J. Halls; Hon. Librarian, May
Allen, B.A.; Hon. Secretary, W. Rimmer Teare,
A.C.P.; Council, 8. T. Burfield, B.A., M.Sc., R. Caton,
M.D., F.R.C.P., J. A. Clubb, D.Sc., J. W. Cutmore;
Prof. W. J. Dakin, D.Sc., F.L.S., G. Ellison, Alwen M.
Hivans, M.Sc. (Miss), Prof. J. Johnstone, D.Sc., W. 5S.
Laverock, M.A., B.Sc., J. H. Milton, F.G.8., Prof. R.
Newstead, M.Sc., F.R.S., Prof. W. Ramsden, M.A., D.M.

4. Prof. P. G. H. Boswell, D.Sc., delivered the Presidential
Address on “ Sedimentation, Environment, and Evolu-
tion in Past Ages ” (see “ Transactions,” p. 3). A vote
of thanks proposed by Dr. Caton, seconded by Prof.
Johnstone, was passed.

x LIVERPOOL BIOLOGICAL SOCIETY.

The second meeting of the thirty-fifth session was held at
the University, on Friday, November 12th, 1920, Dr. Clubb
presiding.

1. Prof. Herdman submitted the report which he had prepared

‘for The Liverpool Marine Biology Committee drawing

attention to special portions and illustrating his remarks
by slides and specimens. (See “ Transactions,” p. 29.)

The third meeting of the thirty-fifth session was held at
the University, on Friday, December 10th, 1920. The President
in the Chair.

1. A paper by Miss E. Catherine Herdman on “ Dinoflagellates
and other Organisms causing Discolouration of the Sand
at Port Erm ” (see “ Transactions,” p. 59).

2. A paper by Miss R. C. Bamber, M.Sc., on “ Some Experi-
ments on the Water Vascular System of Echinus ” (see
“Transactions,” p. 64).

The fourth meeting of the thirty-fifth session was held at
the University, on Friday, January 14th, 1921. The President
in the Chair.

1. Prof. Herdman exhibited a butterfly’s wing displayed on a
card in a wonderful manner by a Japanese craftsman.

2. Mr. Burfield, B.A., M.Sc., exhibited several West African
specimens, together with the foetus of a whale (Megapter
longimana).

3. Mr. Cutmore read some notes on “ The Inheritance of Coat
Colour in the Varieties of Rattus rattus”’ (see “ Tran-
sactions, p. 71). |

4. Mr. E. Neaverson, B.Sc., gave an account of modern ideas
on the Evolution of Ammonites.

SUMMARY OF PROCEEDINGS AT MEETINGS. xl

The fifth meeting of the thirty-fifth session was held at
the University, on Friday, February 11th, 1921. The President
in the Chair.

1. In his unavoidable absence, Prof. Johnstone forwarded
the Report for 1920 on the Lancashire Sea-Fisheries
Laboratory (see “ Transactions,” p. 73).

2. Mr. R. J. Daniels, B.Sc., explained the result of the investi-
gations on the connection between sea-temperatures and
tides.

3. Mr. W. Birtwistle discussed the scales and otoliths of fish
in relation to their age and development.

The sixth meeting of the thirty-fifth session was held at
the University, on Monday, March 14th, 1921. The President
received the members and a number of visitors in the Zoology
department, in the Library of which refreshments were pro-
vided. By kind consent of Prof. Dakin and Prof. Johnstone,
the President was enabled to throw not only the Geology, but
the Zoology and Oceanography departments open to his guests.
Specimens and apparatus were exhibited, and the members of
the stafis of all three departments explained them to those
present.

The seventh meeting of the thirty-fifth session was held
at the University, on Friday, May 6th, 1921. The President
in the Chair.

By invitation of the President, Prof. Farmer of the Imperial
College of Science had consented to address the Society on
“ Alpines,’ but was, unfortunately, too ill to be -present.
At short notice, the President prepared and delivered an account
of a Geological Survey of the south of the Isle of Man conducted
by a party at Haster last. The lecture was illustrated by many
slides and proved of great interest.

Xl LIVERPOOL BIOLOGICAL SOCIETY.

The eighth meeting of the thirty-fifth session was held on
Saturday, June 18th. A visit to Chester had been arranged
mainly by Prof. R. Newstead, F.R.S., who met the members
and conducted them to the Grosvenor Museum. Here Prof.
Newstead and Mr. Alfred Newstead, F.E.S., Curator, described ~
the various exhibits, the Roman and Natural History sections
claiming special attention.

At a meeting held in the Museum it was unanimously
resolved, on the motion of the President, that Herbert R.
Rathbone, Esq., C.C., be elected President for the ensuing
session. Dr. Clubb was appointed delegate of the Society to
the British Association Meeting at Edinburgh.

Warm thanks are due to the Chester Education Committee,
the Chester Archeological Society, and the Chester Society of
Natural Science, as well as to Prof. Newstead and the Curator,
for the kind hospitality extended to the Society at the Museum.

ELECTED,

1908

1919

1909

1918

1913

1903
1919

1912

1886

1886
1920

1917

1910
1920
1902
1886

1896
1886

Xlll

LIST of MEMBERS of the LIVERPOOL
BIOLOGICAL SOCIETY.

SESSION 1920-1921.

A. Orpinary MEMBERS.
(Life Members are marked with an asterisk.)

Abram, Prof. J. Hill, M.D., F.R.C.P., 74, Rodney Street,
Liverpool.

Adami, Dr. J. G., F.R.S., Vice-Chancellor, The
University, Liverpool.

*Allen, May, B.A., Hon. Lrprarian, University,

Liverpool.
Baldwin, Mrs., M.Se., Zoology Dept., University,
Liverpool.

Beattie, Prof. J. M., M.A., M.D., The University,
Liverpool.

Booth, Chas., Cunard Building, Liverpool.

Boswell, Prof. P. G. H., O.B.E., D.Sc., PREstpENT, The
University, Liverpool.

Burfield, 8. T., B.A., M.Se., Zoology Department,
University, Liverpool.

Caton, R., M.D., F.R.C.P., 7, Sunny Side, Prince’s
Park, Liverpool.

Clubb, J. A., D.Sc., Free Public Museums, Liverpool.

Dakin, Prof. W. J., D.Sc., F.L.8., The University,
Liverpool.

Duvall, Miss H. M., M.Sc., Zoology Department, Univer-
sity, Liverpool.

Ellison, George, 52, Serpentine Road, Wallasey.

Elton, Charles, “ Wensted,” Grassendale Park, Liverpool.

Glynn, Prof. Ernest, M.D., F.R.C.P.,.67, Rodney Street.

Halls, W. J., Hon. Treasurer, 2, Townfield Road,
West Kirby.

Haydon, W. T., F.L.S., 55, Grey Road, Walton.

Herdman, Prof. W. A., D.Sc., F.R.S., Vicz-PREsIDENT,
University, Liverpool.

X1V
1893

1912
1902
1903
1920

1898
1918

1896
1915
1917

1904
1913
1915
1921
1903

1890

1894
1908
1886
1920

1903
1913
1915

1903
1905

1889

LIVERPOOL BIOLOGICAL SOCIETY.

Herdman, Mrs. W. A., Croxteth Lodge, Ullet Road,

Liverpool.
Hobhouse, J. R., 19, Ullet Road, Liverpool.
Holt, Dr. A., Rocklands, Thornton Hough, Cheshire.
Holt, Richard D., India Buildings, Liverpool.

Johnstone, Angus, 63, Church Road, St. Michael’s,
Liverpool.

Johnstone, Prof. James, D.Sc., University, Liverpool.

Jones, Philip, “ Brantwood,”’ St. Domingo Grove, Liver-
pool.

Laverock, W. 8., M.A., B.Sc., Free Public Museums,
Liverpool.

Macdonald, Prof. J. §., B.A., F.R.S., The University,
Liverpool.

Milton, J. H., F.G.8., Merchant Taylors’ School, Great
Crosby.

Newstead, Prof. R., M.Sc., F.R.S., University, Liverpool.
Pallis, Mark, Tatoi, Aigburth Drive, Liverpool.

Prof. W. Ramsden, M.A., D.M., University, Liverpool.
Rathbone, Herbert R., C.C., 35, Ullet Road, Liverpool.
Rathbone, Hugh R., M.A., J.P., Vick-PRESIDENT,

Greenbank, Liverpool.
*Rathbone, Miss May, 29, Upper Berkeley Street, London,
1

Scott, Andrew, A.L.S., Piel, Barrow-in-Furness.
Share-Jones, J., D.Sc., F.R.C.V.S., University, Liverpool.
Smith, Andrew T., “‘ Solna,” Croxteth Drive, Liverpool.

Southwell, T., School of Tropical Medicine, University,
Liverpool. :

Stapledon, W. C., “ Annery,” Caldy, West Kirby.
Stephens, Prof. J. W. W., M.D., University, Liverpool.

Teare, W. Rimmer, A.C.P., Hon. Srcretary, 12,
Bentley Road, Birkenhead.

Thomas, Dr. Thelwall, 84, Rodney Street, Liverpool.

Thompson, Edwin, “ Woodlands,” 13, Fulwood Park,
Liverpool.

Thornely, Miss L. R., Hawkshead, Ambleside.

LIST OF MEMBERS. xv

1888 ‘Toll, J. M., 49, Newsham Drive, Liverpool.

1920 Walker, Prof. C., D.Sc., M.R.C.8S., The University,
Liverpool.

1918 Whitley, Edward, Bio-Chemical Laboratory, University.

1920 Yorke, Prof. Warrington, M.D., School of Tropical
Medicine, University, Liverpool.

B. Assoctate MEMBERS.

1916 Atkin, Miss D., High School for Girls, Aigburth Vale.
Liverpool.

1915 Bisbee, Mrs., M.Sc., Zoology Department, The Univer-
sity, Liverpool.
1914 Cutmore, J. W., Free Public Museums, Liverpool.

1918 Evans, Miss Alwen M., M.Sc., School of Tropical
Medicine, University, Liverpool.

1916 Gleave, Miss EK. L., M.Sc., Oulton Secondary School,
Clarence Street, Liverpool.

1905 Harrison, Oulton, 3, Montpellier Crescent, New Brighton.
1920 Kewlev, Miss Helen C., 10, Park Road N., Birkenhead.
1919 Mayne, Miss C., B.Sc., 17, Laburnum Road, Fairfield.

1919 Sleggs, G. F., B.Sc., Zoology Dept., University, Liver-
pool.

1915 Stafford, Miss C. M. P., B.Sc., 312, Hawthorne Road,
Bootle.

1917 Swift, Miss F., B.Sc., Queen Mary High School, Anfield.
1912 Wilson, Mrs. Gordon, High Schools for Girls, Aigburth
Vale, Liverpool. |
C. University STuDENTS’ SECTION.
President : Miss M. Bowen, B.Sc.
Secretary ; Miss D. M. R. Allan, B.Sc.
(Contains about 30 members.)

D. Honorary MEMBERS.

S.A.S., Albert I., Prince de Monaco, 10, Avenue du Trocadéro,
Paris.

Bornet, Dr. Edouard, Quai de la Tournelle 27, Paris.
Fritsch, Prof. Anton, Museum, Prague, Bohemia.

Hanitsch, R., Ph.D., Oxford.

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TRANSACTIONS

OF THE

LIVERPOOL BIOLOGICAL SOCIETY.

PRESIDENTIAL ADDRESS.

By P. G. H. Boswett, A.R.C.Sc., D.Sc.

George Herdman Professor of Geology in the University of
Tver pool.

(Read October 15th, 1920.)

Durine the past session the Society has sustained the loss of
two of its most distmguished members. Hrnry CHARLES
Brastey died on December 14th, 1919, at the age of 83.
He occupied the Presidential Chair of this Society during the
session 1901-2, and was Secretary of the Liverpool Geological
Society from 1890 to 1900, and its President for the sessions
1887-9, 1904-6, and 1908-9.

His work on fossil footprints gave him a wide reputation,
and he accumulated an excellent collection of Triassic footprints
largely from Storeton and other quarries in this district. In
addition he obtained a fine series of photographs of various
footprints scattered throughout the museums of the country.
He published many papers on the subject in the “ Proceedings
of the Liverpool Geological Society,” and wrote reports for the
British Association Committee which dealt with the Investiga-
tion of the Fauna and Flora of the Trias of the British Isles,
of which Committee he was for a time Secretary. This work
was recognised by the award to him in 1906 of the proceeds of
the Barlow-Jameson Fund of the Geological Society of London,
and by the posthumous award of the recently-mstituted medal
of the Liverpool Geological Society.

4 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

His splendid collection of footprints was purchased last
year by Councillor C. Sydney Jones and presented to the
Liverpool Public Museum; his albums of photographs were
presented to the Liverpool Geological Society, and his other
geological material has been acquired by the Geological Depart-
ment of the University.

Mr. Beasley was imbued with the spirit of the fine old
British amateur geologists. Although active commercial duties
left him scanty leisure for geology, he pursued the Science with
unabated vigour until illness compelled him to relinquish the
work. His kindly and helpful disposition endeared him to his
friends.

On May 28th, 1920, at the early age of 42, Lronarp
DoncasTER, Derby Professor of Zoology in the University of
Liverpool, passed away. Perhaps the most brilliant of the
younger school of British zoologists, he was early attracted to
the problems of variation and heredity, to which he applied
the exact methods of cytological research. A believer in the
theory of Mendelism, he was led on to problems relating to
the determination of sex, his work upon which constitutes a
milestone in the progress of biology. His books upon “ The
Determination of Sex” and “ The Study of Cytology ” remain
a monument to his memory as well as an indication of what
we have lost by his early death.

We knew him as a colleague for barely a short session,
but his humanity, charm, and uprightness commanded our
affection and respect. To use Professor Herdman’s words,
his death was nothing less than a calamity to the University
of Liverpool and, one would add, to the cause of Science.

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 5

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION
IN PAST AGES.

When we review the two chief classes of rocks which
constitute the crust of the earth, the igneous or fire-formed
rocks, and the clastic or. sedimentary rocks, we cannot fail to
note the difference in the extent to which we know them.
The characters of the igneous rocks have been studied by
geologists in greater detail than those of the sedimentary rocks,
so much so, in fact, that the petrology of the former—their
origin, history, and the control of their mineral constitution
by physical laws—has reached the stage of philosophic treat-

- ment. In contrast to this, the very wealth of organic remains

found in most of the clastic or sedimentary rocks has in many
cases diverted attention from their mineral and mechanical
characters and has left the field of the petrology of sediments
relatively obscure. On the one hand we find that the branch
of geological science which deals with igneous rocks is becoming
more and more amenable to mathematical treatment ; on the
other hand, the study of sediments has only in recent years
become quantitative.

It is one of the tenets of geology that the present is the
key to the past. But im many cases we have no certain informa-
tion as to the conditions under which ancient sediments were
laid down ; criteria are lackmg because our acquaintance with
the mode of formation of similar deposits at the present day is
insufficient and mexact. This lack of knowledge is the more
to be regretted since, apart fron the features displayed by the
entombed fossils themselves, the nature and character of the
sediments provide the only clues to the environments in which
the organisms dwelt, and which may have caused or modified.
the evolution of lineages. The environmental conditions would
not always leave their impress upon the rocks, but it is probable
that many which did so have left traces that are insufficiently

6 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

recognized or even wrongly interpreted. Broader climatic
changes have affected deposits so markedly that the corre-
sponding conditions have doubtless been rightly adduced,
but the effects of the lesser changes are only now being
recognized.

Sedimentation —Certain fundamental considerations in
regard to the formation of sedimentary rocks first, perhaps,
deserve emphasis.

As an ideal case, let us imagine that a continental area
composed of an igneous rock, such as granite, is subjected to
denudation, the gradient of the rivers being sufficient to
transport the bulk of the resulting detritus to the seashore.
As the transporting power of the rivers is checked on their
entering the sea, pebbles and gravelly detritus formerly rolled
along their beds will be deposited. Along-shore and tidal
currents distribute the material right or left, and storms
pile it up as beaches, where it often becomes mixed with other
coarse material resulting from the direct erosion of the land
by the sea. The pounding of the waves completes the rounding
of the constituents already begun by the rivers, and a belt of
shingle extending from above high-water mark to varying
depths, often below low-water mark, is the result.

Beyond the shingle belt, the river carries its sand, which
in turn settles down when the velocity of the stream falls to a
few millimetres per second. In due time the sand is distributed
as a seaward belt fringing and interdigitating with the shingle.
Similarly a band of silt is deposited, and lastly, the finest portion
of the burden, the mud, sinks to the bottom. It was formerly
considered that the last constituent, the mud or clayey material,
was laid down only when the water was practically still, and
that its deposition therefore indicated fairly deep water well
below the mfluence of waves or shore currents. On the
contrary, deposition of mud, resulting as it does from the
flocculation of the river-borne clay particles by the dissolved

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 7

salts in sea-water,* proceeds part passu with the deposition of
sand and silt or even fine shingle. For this reason, the majority
of sediments, both ancient and modern, are of mixed “ grade ”
and carry more or less clayey and silty material. Perfection
of grading (that is, the attamment of perfect evenness of size)
is a true phenomenon and is rarely met with in geological strata
or present-day sediments. Only by the long-continued action
of wind and water currents, particularly wind, are clastic
materials sorted effectively.

In Fig. 1, representing ideal conditions, a, b, c, and d
indicate in section the belts of shingle, sand, silt and mud
respectively. It is instructive to consider the effect on their
distribution of earth-movements such as are continually in
progress. Omitting from present consideration the change m
the proportion of the various river-borne constituents resulting
from increased or diminished denudation due to the con-
sequential greater or less elevation of the country (see p. 10),
it is evident that upon subsidence of the area, a corresponding
series of deposits will be laid down upon the new sea-bed
represented by XX. In consequence of the creep of the sea
over the land, each belt of detritus a’, b’, c’, and d’ will occur
shghtly landward of the corresponding one below, and not
exactly vertically over it. A continuation of the subsidence
will result in a further series a”, 6”, c’, and d” occupying the
position indicated. Ifthe movement has been gradual and not
intermittent, the planes XX, Y Y, which are true time-planes,
may be obliterated, and the fact that the deposits a, 6, c, and d,
or a’, b’, c’, and d’, are contemporaneous, may not be obvious.

Subsequent elevation and possibly denudation may result
in such a series of rocks forming the surface of the land. In
the event of a, b, c, and d not containing fossils, or, what
provides equal difficulty, containing different fossil forms as a

* River-water containing salts of calcium and magnesium in solution
also flocculates mud and causes its deposition.

TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY

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SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 9

result of differing environment, a strong tendency will exist
for a, a’, a’, etc., to be grouped together on account of litho-
logical similarity. Such an occurrence is almost inevitable if
the deposits are in due course mapped geologically, for the
time-planes XX, YY are difficult to follow, and the planes
aa, 88 become more strongly developed because of the varia-
tion in lithology above and below them; they are, in fact,
the stratigraphical planes or bedding-planes as commonly
known, planes which are usually and tacitly assumed to be
true time-planes, but which actually cut across the latter.
Only under exceptional conditions of fossil preservation, and
then by accurate and detailed zonal study alone, can the true
contemporaneity of deposits be determined.

The complementary case of a rising shore is represented
ideally in Fig. 2, where the deposits are seen to be thrown
successively seawards as elevation occurs. Again the litho-
logical planes aa, 88 cut across the true time-planes XX, YY,
and the deposits a, b, c, and d, and a’, b’, c’, and d’, are
respectively contemporaneous. After subsidence, “ interform-
ational conglomerates,” such as that bounded by aa and ££,
may be formed.

In plan, the effects of this discordance between the two
sets of planes would appear as Fig. 3, where the letters have
the same significance as in Figs. 1 and 2. Since topography,
drainage, soil, and vegetation are largely dependent upon the
hthological character of the underlying rocks, the lines repre-
senting the traces of the planes 88, yy would probably be
mapped as the “ boundaries” of the “ formation.” The time-
planes, revealed by the contained fossils, would run obliquely
through the “‘ formation ” as XX, YY, etc. (the broken lines).
Nevertheless, the planes 88, yy are actually parallel to the
shore-line, whilst XX, Y Y are not.

From Figs. 1 and 2, it is evident that the steeper the shore,
the greater will be the discordance between aa, 88, yy, etc.,

10 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

and XX, YY, ZZ, etc. The shallower and flatter the bottom,
the more nearly are the two sets of planes coincident, but
they can never coincide whilst dry land and sea both exist
in proximity. If, therefore, we are able to discover in the
outcrops of strata the degree of discordance, we obtain evidence
of the character of the earth-movement at the time of
deposition.

If the subsidence is rapid, the landward shifting of a’, a’
and 6’, b” in relation to each other and to a, 6 is respectively
greater and they will become much attenuated, partly as a
result of the greater area over which a given quantity of débris
will be spread, and partly owing to the decreased erosion due
to the lowering of the Jand. The more rapid the subsidence
the more obvious will be the phenomenon of overlap, and the
greater the amount of transgression. The existence of overlap
when the downward movement is gentle and continuous is not
necessarily shown by lithology, but may be revealed by the
organic remains if the conditions were suitable for development
and preservation of life.

Rapid elevation will clearly give rise to penecontempora-
neous erosion of the series of deposits formed when the land
stood at a lower level, and the new series of deposits may
contain rolled fragments derived from the older series. The
plane of junction between the series a, b, c, d, and a’, 0’,
c, d’ may appear only as an ordinary bedding-plane,
although it is actually of the nature of a disconformity. As im
the case of rapid subsidence, the result upon the outcrop will
be discontinuity of particular lithological phases. But im all
probability the most noteworthy result of the elevation will be
the sudden increase in the quantity of detritus due to the
activity of the agencies of denudation upon the elevated land.
The rapidity of the movement will prevent the coarser materials
from being either well-graded or well-rounded. Evidence of
penecontemporaneous erosion may well be obscured in the

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 11

abundance of new sediment. If the elevation be gentle, the
increase of sedimentation will be gradual, and the phenomena
of penecontemporaneous erosion and seaward thickening will
be more evident.

The sequence of sediments considered above is an ideal one
and can arise only where gravelly, sandy, and clayey detritus
together with dissolved material is brought down from the
land. At the present day extensive areas of igneous rocks
form but a small portion of the land-masses of continents, and
the greater part of the continental margins is composed of
ancient sediments which have, in the normal course of events,
been differentiated more or less effectively into the lithological
series discussed above. Offshore deposits derived from such
sediments will necessarily vary according to the constitution
of their parent material. Clay may thus form the littoral
belt entirely, or it may even lie on the landward side of a
sand-belt. It is probable that the character of the local
Jand-mass determines more than any other factor the distribu-
tion of the sediments in the offshore belt, or even of those
beyond it.

If the above theoretical considerations may be adopted,
we should expect to find some evidence, among the extra-
ordinary variety of rocks in Britam, of such occurrences in the
geological past. For obvious reasons, examples may not be
numerous—evidence may not be preserved, or investigation
may not yet have been carried out in sufficient detail. Attention
may, however, be drawn to certain notable cases.

The crossing of the time-planes by the lithological planes
is well illustrated by the series of fossiliferous sands occupying
the uppermost portion of the Lias and the lowermost of the
Inferior Oolite in the West of England. The sands extend
from the Dorset coast to the Cotteswolds and have been
variously termed Bridport Sands, Yeovil Sands, Midford Sands,
Cotteswold Sands, etc., after the localities at which they occur.

12 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

The careful zonal work of Mr. 8. 8. Buckman* has shown that
their age varies from place to place, for they yield an ammonite
fauna in which many sub-divisions can be recognized. The
Lias, generally speaking, is a clay-formation, and the Inferior
Oolite consists chiefly of limestones. In the area considered,
a shallower phase characterised by the deposition of calcareous
sands set in towards the end of Liassic times and continued
throughout part of Inferior Oolite times. But this phase of
shallowing and deposition of detrital sandy material passed
as a wave southwards, maintaining a peculiar, unusual, and
easily recognizable lithology and petrography. The similarity
in grade and mineral composition of the sands from Bridport
to the Cotteswolds is indeed extraordinary. Expressed dia-
grammatically, the sands appear in plan as in Fig. 3,

COTTESWOLD SANDS

MIDFORD SANDS

YEOVIL SANDS

BRIDPORT SANDS

Fic. 3. Diagrammatic representation of the time-planes in the Lias-
Inferior Oolite Sands, from the Dorset Coast to the Cotteswolds.

where the belt aa, Bf is the lithological deposit as it is
mapped.
* Quart. Journ. Geol. Soc., Vol. 45 (1889), p. 440, and Vol. 66 (1910), p. 52.

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. = 13

The time-planes cross it as shown, the hemere* named
after the various ammonites which characterise the horizons
being indicated in the diagram. The portions of each sand-
belt between a pair of dotted lines may be taken as practically
contemporaneous.

The conditions thus indicate a gently rising and. tilted
shore-line, beginning as a shallow sea in the Cotteswold district
whilst the area of Dorset was submerged under deeper water,
and becoming progressively shallow over the belt towards what
is now the English Channel.

The transgression of a lithological phase across time
divisions marked by definite faunal assemblages may be
illustrated by another of the many examples from the strati-
eraphy of Britain. Professor E. J. Garwood, in his description
of the Carboniferous Limestone of the N.W. of England,} has
discussed the evidence for the incoming of shallow-water
conditions during the formation of the zones of Michelinia and
Productus corrugato-henusphericus in the district between Shap
and Ravenstonedale. Coral-bearing limestones, indicative of
clear-water conditions, give place to a sandy type of sedimen-
tation which begins at the base of Michelinia-zone at Shap,
and transgresses several taunal horizons in a southerly direction
until at Ravenstonedale it appears only at the middle of the
sub-zone of P. corrugato-hemisphericus, 100 feet above the base.
The sandy conditions also persisted to a later date (1.e., to a
higher horizon) in the former district. The actual thickness
of sandy sediment is, however, greater in the south (Raven-
stonedale) than in the north (Shap), despite the fact that it
occupied less geological time in accumulation as measured by
the faunal horizons.

* The term “‘ hemera”’ was introduced by S. 8. Buckman (1893): ‘‘ to
mark the acme of development of one or more species. It is designed as a
chronological division . . .” (Q.J.G.S., Vol. 49, p. 481.) The term
“zone ”’ is strictly a stratigraphical one.

T Quart. Journ. Geol. Soc., Vol. 78 (1912), p. 449.

14 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

The effect of gentle subsidence of the shore has been
shown to be the lapping of successive members of a rock-series
over one another, each thus encroaching on the land area.
Overlap of this type is found in the buried Mesozoic rocks
under the Wealden area, where the Lias extends beyond and
unconformably covers the Trias, and is in turn overlapped by
the Bathonian (and possibly the Bajocian) which creeps up
over the ancient and eroded surface of Coal Measures. Overlaps
of the Purbeck rocks by the Wealden, and of the Wealden by
the Lower Greensand also occur. In these examples, the
subsidence appears to have been fairly gentle, although there
is evidence of elevation and erosion at many levels, and the
successive members of the Jurassic maintain approximately
the characters they bear in the north-east of France. where
some of them crop out. Hach also extends only a short
distance beyond its underlying deposit, and little overstepping
of the Palaeozoic rocks occurs.

Somewhat different is the case of the great overlap which
began with the Gault, continued with the Upper Greensand,
and culminated in the great spread of the Lower Chalk sea,
termed “the Cenomanian Transgression.” The Gault and
Upper Greensand (Selbornian) sea, extending beyond the limits
of the Lower Cretaceous, Jurassic, Triassic, and other rocks,
washed the shores of the old Palaeozoic land now underlying
the east of England. The Upper Greensand sea swept rapidly
westward forming a plane of marme denudation and trans-
gressing the various divisions of the secondary strata until
it deposited its sands and gravels upon the Palaeozoic rocks
of the west (Haldon Hills, Devon). The Cenomanian sea
marked an even greater subsidence, which carried it beyond
the north of Ireland and north-west of Scotland. The deposits
of Greensand and Chalk (both of Cenomanian age) rest upon
Jurassic rocks in these areas, and whilst denudation may have
since removed them in part, they probably indicate by their

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 15

outcrops the relative rapidity of the subsidence. It is likely,
however, that the eastern area of Palaeozoic rocks subsided
even more rapidly, so that it was speedily overstepped by a
covering of Gault, Greensand, and Chalk.

The purity of the Upper and Middle Chalk and its freedom
from terrigenous matter is doubtless related to the low altitude
of the Cretaceous land-surface and the distance from large
rivers or from those with other than a gentle gradient. These
conditions followed naturally from the rapid and widespread
depression in Cenomanian times.

In the earlier portion of this paper (p. 9 and Fig. 2), an

99

‘interformational conglomerate”? was demonstrated as being
produced during elevation and subsequent subsidence of the
land. Such oscillatory action seems to have been connected
with the formation of the Blackheath Pebble-beds in Hocene
times. The extraordinarily wide area covered by this deposit
of rounded flint pebbles (derived obviously from the flints of
the Chalk) and its even thickness preclude the possibility of the
whole deposit being contemporaneous. It 1s doubtless a litho-
logical phase traversed by time-planes, but the absence of
fossils of determinative character makes proof impossible.
The overlap of the Thanet Beds by the Woolwich and Reading
Beds, and of the latter by Blackheath Beds, which rest directly
on the Chalk near its escarpment in Kent and Surrey, indicates
an initial subsidence of the area; but the pebble-beds are
essentially shallow-water deposits, and their wide extension
from the Chalk, back over the Woolwich and Reading Beds
in turn, indicates a gradual subsequent elevation, accompanied
in all probability by penecontemporaneous erosion.

The existence of similar spreads of pebbly deposits is in itself
evidence of instability. The Bunter pebble-beds of the Trias and
the Old Red Sandstone conglomerates may be cited, although
these deposits may be of the nature of intermontane detrital
accumulations rather than interformational conglomerates.

16 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

A striking example of the relatively rapid elevation of a
shore-line is furnished by the East Anglian Crag deposits
(Phocene). The Coralline Crag is indicative of deeper-water
conditions than those of the overlying Red Crag. The Red
Crag consists of shelly sands, obviously drifted into position
in shallow bays which may have been partly land-locked.
Judged by the fauna, the oldest Red Crag occurs around
Walton-on-the-Naze in Essex, and the deposits become succes-
sively newer as we travel northwards into the area of the
Norwich Crag. Mr. F. W. Harmer* has divided the Red and
Norwich Crags into a series of zones. Whether the term
“zone ”’ can be justifiably apphed to the divisions is a matter
of no import, for there are certainly different faunal horizons.
But the Red and Norwich Crag zones succeed one another
northwards, and never overlie one another. In short, the
elevation was sufficiently rapid to give rise to the conditions
indicated in Fig. 2. It was poimted out on p. 10 that an
accompanying phenomenon of rapid upheaval was penecontem-
poraneous erosion of the older and elevated members of the
sedimentary series. The Crags provide an example of this,
for broken and water-worn shells from the older Red oe
deposits occur in the newer zones.t

Envvronment.—It is well-known that the fossil remains
found in sediments vary considerably in abundance and in
character, probably as a result of the mfluence of the environ-
ment upon the organisms. So far as we know at present, the
evidence of environment retained in clastic rocks is generally
as detailed in the followmg paragraphs. Deductions regarding
the environments of ancient times depend upon the fundamental
principle of geology already enunciated, namely, that the
present is the key to the past.t That we are only in the early

* Quart. Journ. Geol. Soc., Vol. 56 (1900), p. 705.

+ P. G. H. Boswell. Proc. Geol. Assoc., Vol. 24 (1913), p. 330.

{ For a comparison of ancient climates and past conditions of sedi-
mentation with those of the present day see Professor W. W. Watts, Pres.
Address Geol. Soc., Vol. 67 (1911).

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 17

stages of the interpretation of past conditions seems to be
proved by the recent work of the American geologists, both
on the ancient strata and on the special characteristics of forma-
tions being built up at the present time. When the study of
modern sediments, aqueous and continental, has become
more intensive, we shall doubtless be able to discover criteria
at present unrecognized in the rocks of various ages, and to form
in consequence more exact ideas as to the mode of origin,
climate, and rainfall, relation to shore-lines and so forth.*

Indications of the environment at the time of formation
of rocks may be yielded along the following lines :—

(1) The Medium. Air or water, as indicated by the
fossils themselves.

(2) Depth of Water, as shown by the lithology of the
deposit and the character of its fauna. Considerations of light
and motion also arise here. '

(3) Climate (by comparison with the present day), as
indicated by (a) organisms; (b) lithology and petrology of the
rock. Deposits laid down under glacial, temperate, sub-tropical
and tropical conditions, in deserts or derived from deserts, and
under the effects of heavy raimfall, each bear well-marked
characteristics by which they can be recognized. These
characteristics may be physical, as in the formation of drei-
kanter and rounded grains under desert conditions, and of
striated and far-travelled rocks as a result of glacial action ;
or they may be chemical, as in the differmg degree and nature
of alteration of the constituent minerals of deposits formed
by glacial action, under arid conditions or those of moist heat.t

* Since the above was written, many papers read at a symposium on
sedimentation by T. W. Vaughan, C. Schuchert, H. E. Merwin, E. W. Shaw,
and others, have been published in the Bull. Amer. Geol. Scc., Vol. 31 (1920),
p. 401.

+ See, for example, Barrell, J., ‘‘ Relations between Climate and Ter-
restrial Deposits,” Journ. of Geology, Vol. 16 (1908), p. 159, and “ The
Climatic Factor as illustrated in Arid America,” by Ellsworth Huntington,
with a contribution by C. Schuchert on “Climates of Geological Time,”
Publication 192, Carnegie Institution, Washington, 1914.

B

18 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Not only do geological deposits yield evidence of ancient
climates, but paleeo-meteorological indications are sometimes
obtained. An iteresting case is provided by the veritable
cemetery of Phocene whales, sharks, etc., which occurs on the
Belgian coast and has been described by M. Van den Broeck.
According to Mr. F. W. Harmer* these cetaceans and fish were
drifted by the north-westerly gales prevailing in Pliocene times
into land-locked bays on the eastern shores of the ancient
“ North Sea,” and were unable to escape ; hence the enormous
accumulation of vertebrate skeletons in the deposits there.

Similarly, the extensive growth of the roots of Coal
Measure trees on one side, and their relatively slight
srowth towards the other in the Upper Carboniferous has
been quoted as evidence of the direction of prevalent gales in
those early days. |

(4) Salt-, brackish- or fresh-water. At present the best
evidence of these conditions is provided by the fossils them-
selves, having regard to their similarity or otherwise to modern
marine, estuarine or fresh-water forms. But attempts are being
made to apply other lithological criteria to the deposits in order
that deductions may be made in the absence of fossils.

Although the ocean has become progressively more and —

more salt throughout geological ages, and is assumed to have
originated, presumably as a saltless hydrosphere, about 100
million years ago,t it is noteworthy that in the Devonian period
there lived a pelecypod Archanodon, so markedly similar to
the freshwater mussel of to-day that there is little doubt but
that its habitat was fresh-water; under other conditions,
Cardiola, Murchisoma, Nucula, Pleurotomaria, and other
castropods, are found, bearing general characters similar to

* Proc. Geol. Assoc., Vol. 17 (1902), p. 421.

+ For a summary of the evidence and deductions relating to this matter,
see F. W. Clarke, ‘‘ Data of Geochemistry,” Bull. 695 (1920), U.S. Geol.
Survey. But on the evidence of the accumulation of helium and lead in
rocks bearing radio-active minerals, the Devonian is stated to have been
formed about 380 million years ago.

eS ce

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 19

living marine mollusca. In the Carboniferous Period which
followed, deposits have been styled fresh-water or marine
according to the characters of their mollusca, and it is evident
that at least in these periods, if not earlier, the mollusca had
adapted themselves to a fresh-water or a marine environment.

(5) Paleogeographical conditions. Much light may be
thrown upon the ancient geography of the period by a study
of the derived fragments and minerals in rocks, and by the
variation in size and proportion of the constituents. The
petrological character of the adjoining land-area, its relative
altitude, and the presence or absence of large trunk rivers, may
often be adduced from the character of the sediments. Ancient
deltas have thus been traced. Judging from the evidence
obtained by the “Challenger” expedition on the formation
of glauconite, the presence of that mineral in rocks is pre-
sumptive evidence of oscillatory marie conditions, on
the continental edge of great ocean basins where currents of
different temperature or salinity mingle, and possibly near the
mouths of rivers bringing little suspended matter into the
ocean, but a considerable quantity of dissolved salts. The
existence and direction of beneficial food-bearing or inimical
mud-bearing currents may also be indicated.

(6) Diastrophism. The evidence yielded by sediments of
secular movements of the earth’s crust, slow or fast, was
considered in some of its aspects in the earlier part of this
address. The enormously-increased denudation consequent
upon considerable elevation is reflected in the vast accumula-
tions of the Flysch and Mollasse which fringe the Alps and
represent the wreckage of a great thickness of that mighty
mountain mass after the earlier stages of its uplift. On the
other hand, the depression of the British area which gave rise
to the great Cenomanian transgression was followed by the
formation of the Chalk in a basin which subsided at least
1,000 feet during its deposition. The remarkably purity of

20 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

the Chalk, and its freedom from any quantity of terrigenous
sediment can best be explained (in view of the fact that it
contains shallow-water forms of life, and was bordered by
land as close as N.W. Scotland and Ireland, the Harz Mountains,
Scandinavia, and: a belt which separated it in part from the
Hippurite-sea of Southern France, the Alps, and Central
Europe) by postulating a relatively low level and condition of
peneplanation of the land, and distance from large rivers
bringing terrigenous sediment.

Not only may gentle movements leave their mark upon
the rocks, but earthquakes yield records which have of late
been recognized more widely in ancient sediments than hitherto.
Professor P. F. Kendall has adduced evidence of earthquake
disturbances durmg the Coal Measure Period, many of the
features of present-day earthquakes, such as rifts, fissures,
undulations, ridges, hollows, pipes, “ sand-blows,”
riding having been found.* Similarly, the marvellous accumu-
lation in the Old Red Sandstone of the distorted remains of
innumerable fish may be evidence of earthquake shocks,
submarine or terrestrial, such as those that to-day kill off large
quantities of fish, the bodies of which are found floating on the
surface. The Old Red Sandstone was deposited during a
period renowned for its mountain-building movements with
accompanying volcanic outbursts. Sir A. Geikie has suggested

and over-

that mephitic vapours poured out by the volcanoes were the
cause of the high death-rate and the large accumulation of
fish remains.

(7) The existence of other classes of organisms. Often it is
possible to adduce from the strata evidence as to the conditions
of food-supply, the struggle for existence, and the reasons for
the survival of certain families of organisms. Thus, the
supposition as to a relationship between the decline of the
trilobites, and the rise of the ganoid fishes, receives strong

* Proc. Geol]. Soc., No. 1031, (1919), p. 28,

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 21

support when trilobites have been found in the stomachs of
fossil fishes, and we are thereby tempted to trace a causal
connexion.

In the matter of the broader aspects of evolution, it was
suggested by J. Starkie Gardner* that the expansion, migration, -
and consequent evolution of the ruminants waited upon the rise
of the grasses, and only when the latter became widespread
in Eocene and Oligocene times was the food-supply of these
animals ensured and migration and expansion of the stock
possible. Again, Professor EK. W. Berry, in a suggestive paper
on “ The Evolution of the Flowering Plants and Warm-blooded
Animals,” recently published,t has put forward tentative views
to the effect that the rise of the birds was dependent upon the
production of a food-supply in the shape of the fruits of the
flowering plants, and thus followed that stage in the evolution
of plants. He also suggests that the differentiation of the
Eocene mammals was possible only because of the food value
of such fruits, and, noting the concentration of energy in
srain, points out that human development was not possible
without it.

In his recently-published monograph on “ The Environ-
ment of Vertebrate Life in the Late Paleozoic in North
America,’ = Professor I. C. Case describes the change which
took place in the fauna from the long period of slow evolution
in the singularly monotonous environment of the marie
Pennsylvanian to the rapid evolution in the diversified environ-
ment of the Permo-Carboniferous. He regards the sudden
expansion as due to climatic change accompanied by physio-
eraphic changes which led to an alteration in the level of the
continent. He points out that in land life adapted to arid
climatic phases we should expect to find a greater activity

* Proc. Geol. Assoc., Vol. 9, (1885-6) p. 448.
+ Amer. Journ. Science, Series 4, Vol. 49, p. 207 (1920).
t Carnegie Institution Publications, No. 283 (1919).

22 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

and higher development, with special adaptation to resist
violent changes of temperature, etc.

In his opening address to Section C (Geology) at the
British Association, Cardiff, 1920, Dr. F. A. Bather quotes
Professor Abel as maintaiming that the varying “tempo” of
evolution in the case of the sirenians and horses of the Tertiary
can be correlated with the food-supply. The sirenians under-
went a steady, slow change because although they migrated
from land to sea, they retained the habit of feeding on soft
water-plants. Horses, though remaining on land, evolved at
first rapidly, and then more slowly, but up to Phocene times
always more quickly than the sirenians. Such evolution might
be correlated with their change into eaters of gram, and their
adaptation to a life on the plaims where food of this character
was available. The whales, like the sirenians, migrated at the
beginning of Tertiary time from the land to the sea. But their
rate of evolution was altogether different, hence very diverse
forms resulted. At first they remained near the coasts, and
kept to the ancestral diet, with consequent slow change.
Then they took to hunting fish, and afterwards to eating
cephalopods ; from Oligocene times onward the change was
thus very rapid, and a great burst in evolution in Miocene
times resulted. Finally, many turned to minute floating
organisms as food, and from Lower Pliocene times to the present
day the change has been very slow.

Dr. Bather rightly emphasizes the fact that any attempts
to frame a causal connexion are bound to be speculative.

Numerous cases can be quoted from the geological record
of the gradual changes in a fauna resulting from a gradually-
changing environment. Two parallel examples may be
mentioned of the effect produced on molluscan life by a gradual
elevation of the sea-bed sufficient to cut off arms of the sea
and produce lakes which continued to shrink. In the first

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 23

example, the Permian inland seas, now represented by the
dolomitic limestones and gypsum beds of N.E. England, show
a fauna which bears affinities with that of the preceding period,
the Carboniferous, but as a whole becomes impoverished in
species and rarer in individuals. At the same time, distorted
and dwarfed forms slowly appear—apparently as a result of
the concentration of sea-salts which were eventually thrown
out of solution upon the lake bottom as a result of evaporation.

In another example, the isolation of the great lakes,
such as Tanganyika, and others, in Africa, resulted in gradually
shrinking lakes throughout the Miocene period to the present
day. The institution, however, of partial mternal dramage
systems into the lakes, together with tropical floods (in contra-
distinction to the aridity of the Permian), has led to the gradual
sweetening of the waters. The fresh-water genera of mollusca
with marine affinities, such as Paramelania and others, are
typical of the peculiar fauna of the lake, a fauna which,
although of Mid-Tertiary age, contains forms bearing resem-
blances to certain Jurassic fossils.

In other instances we are able to note the dying out or
migration of species with changing climate. The gradual
oncoming of the Glacial Period in Western Europe was heralded
by the southward migration of a flood of northern mollusca,
such as Cardiuwm grenlandicum, Neptunea antiqua, Natica
clausa, N. helicoides, Pecten (Chlamys) islandicus, Tellina
pretenuis, and others, into the area of northern Essex, and the
consequent movement of the warmth-loving mollusca south-
ward out of the British area.

Evolution.—Many of the organisms that occur as fossils
can be grouped into series showing gradual transition from
species to species and even genus to genus. Indeed, it has
with truth been asserted that wherever the geological strata
yield a complete record, transition or continuous development
can be traced. Such transitions can be ascribed only to the

24 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

effects of environment. Several lineages (“species series ”’),
which are single genetic lines, have now been carefully worked
out. It cannot be said that in the present state of knowledge
the evolution of lieages can be definitely correlated with chang-
ing environment as indicated by the sediments contaiming them.
Certain cases (e.g., the Micrasters of the Chalk* or the Ammo-
nites of the Lias) show an evolution unaccompanied by any
apparent change in sedimentation or, so far as we can judge,
of the environment that would be reflected in the character
of the sediment.t

But in such cases where lineages show progressive change
in their constituent forms, and the sediments containing them
an apparent constancy of environmental factors, we cannot
yet assume that evolution has proceeded independently of
environment. Alternatively, we must face the fact that our
knowledge of sediments, particularly of those characters which
should be indexes of environmental change, is far from sufficient.
Our obvious course is to study more intensively the conditions
of sedimentation at the present day, and to apply the results
of such work to the rocks of the past.

In the present state of knowledge it would almost seem
that on the whole the environmental caus2s leading to minor
changes in development have left their record in the sediments,
but that the greater changes and the evolution of lmeages
cannot be correlated with known variations in lithology.

* A. W. Rowe, Quart. Journ. Geol. Soc., Vol. 55 (1899), p. 494.

7 Mr. S. S. Buckman, in his “ Inferior Oolite Ammonites ’’ (Monogr.
Pal. Soc., Supplement, p. xv. (1898), wrote: “It is a great mistake to
suppose that Ammonites were influenced by the character of the deposit,
though this error has been so widely taught that nearly every writer, myself
included, has argued as if it were a fact. When Dorset, Somerset, and
Gloucestershire are compared, it will be found that the same species lived
when the deposit was argillaceous, arenaceous, or calcareous, and flourished
equally well. Notably is this the case when the Middle Lias of Dorset and
of Somerset are compared ; or the Lias-Oolite deposits of Dorset, Somerset,
and Gloucestershire, and these again with the Continent.”

t In the case of organisms such as ammonites, evolution may have

taken place elsewhere, and migration have brought them into the position
in which they are now found.

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 25

Much light was thrown upon the deposits of ancient times
by the results of the “ Challenger”? Expedition in 1873-76,
albeit the work was confined very largely to deep-sea deposits.
From the geological as well as the biological, chemical, and
physical standpoints, the benefits which are likely to accrue
from a new “ Challenger” Expedition, such as that suggested
recently by the President of the British Association for the
Advancement of Science,* cannot be over-estimated. Apart
from the storehouse of new facts in nature always ready to be
drawn upon, we now realise more clearly than in 1872 what
problems require elucidation and what fields lack exploration.

Our knowledge, for example, of the terrigenous belt which
fringes the continents is madequate, and seems to be relatively
less than that of the depths of the oceans. Nevertheless, most
of the fossiliterous strata, which it is our duty and pleasure to
study, were actually deposited as ancient terrigenous belts.t
We need more exact information regarding the exact conditions
of sedimentation to-day, and their influence upon plant and
animal life. Hven the termmology of the subject cannot be
regarded as adequate or settled.t Few or no accurate and
quantitative descriptions of modern sediments exist.§

It may therefore be an advantage if tentative suggestions
are here put forward regarding pomts upon which a new
‘Challenger ” Expedition might throw much light, and about
which our present knowledge is insufficient. A re-examination

* Herdman, Professor W. A., Pres. Address, Rept. Brit. Assoc., Cardiff,
1920 (1921).

+ Compare for example, Professor W. W. Watts, Pres. Address, Geol.
Soc., 1911, p. Ixxvi.

{ For example, Professor W. A. Herdman suggested in 1895 the term
‘neritic’ to include those shallow-water, detrital deposits full of organic
remains, deposits which do not find a place in Murray’s “ Challenger ”
scheme.

§ In the ‘‘ Challenger’ reports, deposits of various-sized grains are
termed indiscriminately “sands”? or “muds.” The only quantitative
work which seems to have been accomplished is that by Dr. Sven Oden
recently on the mechanical composition of Globigerina Ooze, Radiolarian
Ooze, and Red Clay collected on the expedition. See Proc. Roy. Soc.,
Edinburgh, Vol. 36 (1916), p. 219.

Bl

26

TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

of much of the geological material collected on the former
expedition would doubtless yield valuable results, but there
can be no question as to the advantage of collecting material
more systematically and fully (so far as terrigenous deposits
are concerned), and noting as far as possible the exact con-

ditions of accumulation.

The following suggestions are not intended to be exhaus-

tive; they are rather those which occur to one interested

particularly in the petrology of sediments :—

GEOLOGICAL INVESTIGATIONS WHICH IT IS DESIRABLE THAT A
New ‘‘ CHALLENGER ” EXPEDITION SHOULD UNDERTAKE.

iy

A more comprehensive and detailed scheme of classification

of deposits, especially the terrigenous group.

The description of all deposits, so far as possible, on a

quantitative basis, i.e., by mechanical analyses, with
a terminology founded on such a basis. The full
determination, qualitatively and quantitatively, by
modern petrological methods of the mineral constituents
of sediments.

Investigation of the methods of mechanical precipitation

of sediments in sea-water, and the effect on size of grain
or ageregate of the salinity (including lime-contents,
etc.) and temperature (upon which the viscosity of the
water depends).

The relation of the sediment (grain-size and general

chemical character) to the depth of water m which
laid down; the consideration of what is the deepest
water indicated by any particular type of sediment, as
bearing upon the question of permanence or instability
of the continents and oceans, and on the origin of certain
rocks.

Further investigation of the effects of chemical precipita-

tion or replacement of deposits under varying conditions

SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 27

of depth, i.e., under varying pressure and temperature
in sea-water, and of varying content of silica, calcium,
magnesium, and carbon dioxide ; and on the formation
of dolomite,* colloidal silica (e.g., flint), ete.

6. Precipitation through such organic agency as that of
bacteria, as suggested in the case of limestones.t (In
this connexion, the present-day analogue of the Chalk
cannot be regarded as globigerina ooze). —

7. The relation of the character of sediments to rising and
sinking adjacent land areas from which they are
derived ; the criteria in each case—mechanical, mineral,
and chemical ; the effect on organisms ; the composition
of the sea-water in each case.

8. Further investigation of coral-reef formation. Evidence
of upheaval or submergence provided by the relief of
islands and the form of the coast-line.

9. The petrological character and possible origin of the
boulders on the sea-bottom—especially in the case of
the various “ narrow ” seas.

10. The possibilities of deep-sea boring, by Joly’s or other
apparatus, and the bearing of the evidence yielded on
Recent and Tertiary geological history and climatic
conditions, and on the question of the permanence of
the oceans.§

*See Watts, Professor W. W.. in discussion upon Professor E. W.
Skeats’s paper. Q.J.G.S., Vol. 61 (1905), p. 141.

+ G. H. Drew “On the Precipitation of Calcium Carbonate in the Sea
by Marine Bacteria, etc.’ Publication No. 182, Carnegie Institution,
Washington, 1914.

t See Peach, B. N., Proc. Roy. Soc., Edinburgh, Vol. 32 (1912), p. 262.
Cole, Professor G. A. T., and Crook, T., Mem. Geol. Surv., Ireland, ‘‘ Rock-
Specimens dredged from the Floor of the Atlantic’ (1910). Herdman,
Professor W. A., and Lomas, J., 7th, Sth, 9th, 12th Ann. Reports, Liverpool
Marine Biol. Committee, 1894-5-6 and 8. Also Proc. Liv. Geol. Soc., Vol. 8
(1898), :p. 205. :

§ On deep-sea boring apparatus, by which it is considered that a
depth of several feet might be bored in the sea-floor, see Joly, Professor J.,
Sci. Proc. Roy. Dublin Soc., New Series, Vol. 8 (1897), p. 509, and Vol. 14
(1914), p. 256. Also Evans, J. W., Rept. Brit. Assoc., Bournemouth, 1919
(1920), p. 179.

Cc

28 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

11. Investigation of the petrology of sediments in relation to
neighbouring land-masses, temperature of water, etc.
Distribution of minerals from volcanic rocks. The
‘stability of minerals.

12. Determination in sediments of allothigenous (primary)
and authigenous (secondary) minerals. The two
generations of minerals as indicated by size. The
formation of glauconite.

13. The landing of parties on such islands or places on the
mainland difficult of access (e.g., the island of Rockall),
and collection of specimens.

14. Considerations of the habitat and migration of organisms.
The possible evidence of environment yielded by
sediments. Relation to lime and other contents of
sea-water (lime-secreting habit, etc.).

The rocks of the earth’s crust and their organic remains
present problems that may be attacked by biologists and
geologists from very different points of view. Both would
doubtless now agree with Huxley in his dictum that “ The
primary and direct evidence in favour of evolution can be
furnished only by paleontology. The geological record, so
soon as it approaches completeness, must, when properly
questioned, yield either an affirmative or a negative answer:
if evolution has taken place, there will its mark be left; if it
has not taken place, there will lie its refutation.”

But in the study of sedimentation, of past environments,
and of the evolution of organisms, there is more than this.
Suess, in “ Das Antlitz der Erde,” has summarized the wider
conception in the striking sentences which follow. “It is the
organic remains, no doubt, which afford us our first and most
important aid in the elucidation of the past. But the goal of
investigation must still remain in the recognition of those great
physical changes in comparison with which the changes in the
organic world appear only as phenomena of the second order,
as sumple consequences.”

THE
MARINE BIOLOGICAL STATION AT PORT ERIN
BEING THE
THIRTY-FOURTH ANNUAL REPORT
DRAWN UP FOR THE
OCEANOGRAPHY DEPARTMENT OF THE
UNIVERSITY OF LIVERPOOL.
By Proressor W. A. Herpman, C.B.E., F.R.S.

The Port Erm Biological Station was transferred by the
Liverpool Marine Biology Committee to the University of
Liverpool on December 31st, 1919,* and from that date
became the marine laboratory of the department of
Oceanography. This change in responsibility and adminis-
tration has, however, caused no change in the scientific work
of the institution. Research workers and students are
admitted on the same terms as before, and the series of Annual
Reports and other publications will be issued in future by the.
University in continuation of those produced by the Committee.
Professor James Johnstone, who is now (from October Ist, 1920)
the Head of the department of Oceanography, has asked me to
draw up the present Report, as the Port Krin establishment has
been under my direction during the greater part of the past
year. On account of this bemg a year of transition from the
old dispensation to the new, when no general investigations
of special note were undertaken, and also in order to effect
such economy as is possible in printing, | have decided to
report merely upon the usual statistics of the Biological
Station, along with short summaries of some of the researches
carried on by those working in the laboratory.

*See last Annual Report, p. 3.

30 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

The increase in number both of those working at the
Biological Station, and of those visiting the Aquarium, is
remarkable. Last year (1919) we had 60 laboratory workers
and over 23,000 visitors; this year, there were about 100
researchers and senior students, and nearly 36,000 visitors to
the Aquarium. From Liverpool University we had Professors
Dakin, Johnstone, Ramsden, Harvey-Gibson, and Herdman,
Mrs. Bisbee, Mr. Burfield, Miss Knight, Miss Fry, and others ;
from Oxford, Professor B. Moore, Mr. E. Whitley, and their
assistants ; from Birmingham, Professor Gamble and students ;
from Manchester, Dr. and Mrs. Tattersall and students ;
from Reading, Professor Cole, Miss Eales, and a party of
students; from Aberystwyth, Mr. Douglas Laurie and
students; from Nottingham, Miss Bexon and _ students ;
Professor Stephenson from Lahore; and from Cambridge,
Mr. H. H. Thomas, and a party of senior students from
Newnham College. . ,

The work of the staff at the Biological Station has been
carried on as usual, and large collections of the plankton in
the bay have been made throughout the year.

As on previous occasions the statistics as to the use made -
of the institution throughout the year will be given in the
form of a “ Curator’s Report ”’ (see below).

It may be useful to those proposing to work at the
Biological Station that the ground plan of the buildings,
showing the laboratory and other accommodation, should be
inserted in this Report as on previous occasions (see p. 31).

CuRATOR’S REPORT.

Mr. Chadwick reports to me as follows on the various
departments of the work at the Station during 1920 :—

“ Ninety-six workers occupied our laboratories during
the past year, the majority being undereraduates from the
departments of Zoology and Botany of the University of

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32 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Liverpool. The Universities of Cambridge, Oxford, Birming-
ham and Manchester, and the University Colleges of Reading,
Nottingham and Aberystwyth, were also represented by
researchers and students. |

“Miss Knight, of the department of Botany of the
University of Liverpool, devoted the whole of July and
September to research upon the life-histories of certain
marine alge. Professor B. Moore, with his son Mr. T. Moore,
Mr. E. Whitley and Mr. T. A. Webster as coadjutors, continued
his research into the seasonal variation in the alkalinity of
sea-water, and was followed in the same line of research im
August by Mr. E. N. Allott, of the department of Chemistry,
University of Oxford. During the Easter vacation, Professor
Harvey-Gibson, assisted by Miss Knight, was engaged in
preparing drawings to show the diagnostic characters of the
species of Algee, for his forthcommg book on the subject.
In April, and again in September, Mrs. Bisbee devoted herself
to the physiology of Echimoderms, with special reference to
the direction of the currents in the madreporites of starfishes
and sea-urchins. Durimg the Kaster vacation, Miss C. Mayne
continued her work on the animal ecology of Port Hrin Bay, -
and Mr. G. I’. Sleggs devoted some time to further work upon
the common barnacle, Balanus balanoides.

“In addition to Professor Herdman’s special plankton
investigations carried on between March and September, the
ordinary official bi-weekly tow-nettings were taken by the
Assistant Curator throughout the year, with only very
occasional interruptions due to unfavourable weather. General
faunistic work was carried on vigorously by all our biologist
workers, and amongst the large number of species collected
were some exceptionally large specimens of Lucernaria sp.,
not previously recorded from Manx waters. These were
found by Professor Dakin and others on the boulder-strewn
beach of Bay-ny-Carrickey.

MARINE BIOLOGICAL STATION AT PORT ERIN. 30

“Miss Catherine Herdman, during both the Easter and
the Summer vacations, continued her investigation into the
occurrence and the changes in the Amphidiniums and other
Peridiniales in the sand of Port Erin beach, and succeeded in
discovering several new forms, which were exhibited alive at
the Cardiff meeting of the British Association.

Inst of Workers, 1920.
February 9th and 10th. Mr. E. A. Lewis.

Miss M. Knight.

During the Easter vacation (March
and Aprii).

Miss M. Knight.
Professor Herdman.
Miss E. C. Herdman.
Professor J. Johnstone.
Professor Stephenson.

Professor R. J. Harvey-Gibson.

Miss P. Fry.

Mr. H. Hamshaw Thomas.

Professor B. Moore.
Mr. T. Moore.

Mr. E. Whitley.

Mr. T. A. Webster.
Miss D. Bexon.
Miss I. Bayliss.
Miss B. Cockshott.
Mr. H. A. Storey.
Miss G. Clegg.

Miss H. Good.

Miss Horrobin.
Professor W. J. Dakin.
Miss L. Thorpe.
Miss E. L. Gleave.
Mrs. Bisbee.

Miss M. E. Roper.
Miss M. A. Pocock.
Miss I. M. Allen.
Miss R. Hilton.

Mr. G. F. Sleggs.
Miss C. Mayne.
Miss M. Hobbins.
Professor Ramsden.
Professor F. J. Cole.
Miss N. B. Eales.
Miss D. R. Crofts
Miss E. Trewavas.
Miss N. F. Soyer.
Mr. A. 8. Wright.
Professor Gamble.
Miss N. E. Boycott.
Miss O. M. Parsons.
Mr. J. G. H. Frew.
Mr. R. Douglas Laurie.
Mr. J. R. W. Jenkins.

Mr. E. E. Watkin.
Mr. R. A. Little.
Mr. W. M. Speight.
Mr. Burfield.

Miss N. Carter.
Miss G. F. Selwood.
Dr. W. M. Tattersall.
Mrs. Tattersall.

Mr. F. Neave.

Miss M. Bowen.
Miss M. A. Wilson.
Miss O. V. Jones.
Miss E. Lewis.

Miss G. E. Jeffcote.
Miss E. M. E. Gardner.
Miss D. Hanson.
Miss Hughes

Miss A. E. Chesters.
Miss Staidler.

Miss M. Simpson.
Miss D. Allen.

Miss K. M. Stoddart.
Miss Tregoning
Miss D. Hookins.
Miss M. Baggs.

Miss Clayton.

Miss Roper.

Miss M. A. Pike.
Miss M. Critchley.
Miss M. Murray.
Miss J. Graham.
Miss Hall.

Miss O. Bangham.
Miss Ashford.

Miss W. Kehoe.
Miss B. Atherton.
Miss J. J. Anderton.
Miss D. Stephenson.
Miss B. M. Illingworth.
Miss E. Angel.

Miss K. M. Huyton.
Miss H. V. Davies.
Miss D. M. Dawson.
Miss N. Dawson.
Miss M. Knowles.
Miss D. Bell.

Miss A. Butterfield.

34 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

During the Summer vacation (July Mr. W. Birtwistle.
to September). Miss I. M. G. Butler.
Miss M. Knight. Mrs. Bisbee.
Miss A. Bishop. Miss D. Hanson.
Professor Herdman. A
Miss E. C. Herdman. October 29th to November \st.
Mr. E. N. Allott. Miss M. Knight.

The Fish Hatchery.

“The stock of plaice collected for spawning purposes
during the autumn of 1919 consisted of 124 survivors of the
previous year’s stock—82 brought from Luce Bay by the
fishery steamer ‘ James Fletcher, and 110 caught off Niarbyl
and purchased from local fishermen, making a total of 316 fish.
Of this number 27 are known to have died before the end of
the year, so that the hatching season of 1920 opened with
289 fish.

“The season began on February 9th—an unusually
early date—when 15,750 eggs were placed in the hatching
boxes. A few of the fish must have begun spawning three
weeks earlier than this, for amongst the first lot of eggs
skimmed from the ponds a few newly-hatched larve were
found. The number of eggs skimmed on one day did not
exceed 100,000 until March 10th, and the largest daily numbers .
—378,000 and 399,000—were recorded on the 17th and 22nd
respectively. Upwards of 200,000 were recorded on March
13th, 19th, 20th, 23rd, 24th, and 30th. The total number
of eggs collected is 4,756,800, and of larvee set free 4,010,000.
Both these totals represent a substantial advance upon the
results of the previous year, and justify confidence that with
more settled conditions a much larger output of larval fish in
the near future may be expected.

“The Hatchery Record, giving the number of eggs
collected and of larvee set free on various days, is as follows :—

Larve
Eggs collected. Date. set free. Date.
25,200 ... Feb. 9 to 12 223,050... Hlebrize

25,200- 2) ~e 4d to. 18 18,900 .., March 8

MARINE BIOLOGICAL STATION AT PORT ERIN. 3D

Larvae
Eggs collected. Date. set free. Date.

109,250 ... Feb. 21 to March 1 91,400 ... March 19
518,700 ... March 3 to 10 428,400 cag
96,600 eit 71,400 30
231,000 Bo nity 173,300 ... April 1
153,300 tlle 387,450 sal 3
378,000 ONE 228,900 Sanat
252,000 sag 484,050 hee:
672,000 » 20 and 22 506,100 geal
483,000 23 and 24 200,550 Ase
258,300 > 25 to 27 567,000 erat:
688,800 ... ,, 29to April5 334,950 = 128
389,800 ... April 6 to 9 296,100 » 26
346,500 , 10 and 12 122,850 are
69,300 , 17 and 19 43,050 ... May 4
38,850 » 21 and 23 24,150 it da 8
21,000 » 27 to May 6 9,400 canal

4,756,800 4,010,000

Lobster Culture.

“ Fifteen berried lobsters—the same number as last year—
were purchased from the local fishermen. The yield of larve
was, however, much greater this year than last, for while in
1919 the total number was only 9,702, or nearly 647 per
lobster, this year the total was 28,720, or a fraction over
1,914 per lobster.
the disposal of the Assistant Curator rendered necessary the

The inadequate number of rearing jars at

hberation of a large proportion of the larve in their first and
second stages, 27,600 being dealt with in this way. LHleven
hundred and twenty were placed in the rearing jars, and of
this number 278, or about 1 in 4, were successfully reared and
set free as lobsterlings.

The Aquarvum.
“The Aquarium attracted 35,730 visitors durmg the
season, a number far larger than that of any previous year.

A new edition of the Guide to the Aquarium was first offered
51

36 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

for sale on July 19th, and though, owing to the greatly
increased. cost of printing, it was found necessary to raise the
price from threepence to sixpence, 843 copies were sold.
The display of local fishes was more representative than it has
been since pre-war days. Plaice hatched in three consecutive
years, and larval lobsters in various stages of development,
were exhibited, and attracted much attention.

(Signed) H. C. CHADWICK.”

REPORT OF THE EDWARD FoRBES HE. XHIBITIONER.

An “ Edward Forbes Exhibition ” was founded* in 1915,
at the University of Liverpool, in commemoration of the
pioneer marine biological work done in this district by the
celebrated Manx naturalist, who was born about a hundred
years ago. The object of the Exhibition is to enable some
postgraduate student of the University to proceed to the
Port Erin Biological Station for the purpose of carrying on
some piece of biological research, more or less in continuation
of the line of work opened up by Forbes, or an investigation
which has grown out of such work.

The Edward Forbes Exhibitioner for the year 1920 is
Miss Laura Thorpe, B.Sc., who spent several weeks during
the Easter vacation in an investigation of the food-contents
of the alimentary canal of various common molluscs and other
invertebrates of the seashore. Unfortunately, Miss Thorpe
sprained her ankle on a collecting expedition at Poolvaash
early in the time, and was laid up for some days and unable
to make any further observations on the beach, although
when able to work she was kept supplied with fresh material
by the other Liverpool students. Miss Thorpe has submitted
a detailed report upon all the species she was able to examine,
but as she proposes to continue her interrupted work during

*The Regulations in regard to the Exhibition will be found at p. 52.

MARINE BIOLOGICAL STATION AT PORT ERIN. 37

next Haster vacation, we have agreed to postpone a fuller
report to a future occasion, and merely to record now that
she found :—

Purpura lapillus feeding almost wholly on the rock-
barnacles (Balanus), the appendages of which were found in
abundance in the alimentary canal of the mollusc.

Patella vulgata feeding on the smaller algze, as remains of
red, green, and brown sea-weeds (such as Polysiphoma, Ptilota,
Rhodochorton, and Conferve) were identified, along with the
silicious cases of diatoms, such as Coscinodiscus and Hucampia,

and some sponge spicules both silicious and calcareous.

Inttorina littorea feeding at that time on green alge.
Trochus zizyphinus feeding on the alge Polysiphona and
Ectocarpus, along with remains of diatoms, the Hydroid Obelia

and sponge spicules.

OTHER RESEARCH WORK AT PORT ERIN.
LARVAL FisH AND PLANKTON Foon.

It was pointed out recently by Dr. Johan Hjort that as
the young fish larvee hatched in the sea in spring are dependent
for food, after they have used up the supply of yolk derived
from the egg, upon the diatoms and other minute organisms
of the phyto-plankton, which also make their appearance in
the sea in spring, it is most important that the young fish should
not be hatched before the diatoms have become abundant.
The phyto-plankton varies to some extent as to its abundance
and date of appearance from year to year, the maximum ranging
from March to May, and it is possible that in a late year, unless
the first larvee are correspondingly late, the fish may be hatched
out in quantity before their natural food is present in sufficient
abundance, and there may be an enormous mortality of larvee
which will affect the young fish population of that year, and
ereatly reduce the numbers in the commercial fisheries for

some years.

38 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

We have data for many years (from 1907) in regard to the
phyto-plankton in the sea off Port Erin, but it is not easy to
determine exactly when, in the open sea, the pelagic fish-eggs
have hatched out in quantity. We have, however, at the
Port Erin hatchery, the records, extending back to 1904, of
the numbers of eggs obtained from the spawning plaice in our
pond, the dates of hatching and the temperature of pond and
sea taken twice daily—and it is probable that these larve,
although hatched under a roof, afford some clue to what is
going on in the sea at the time. The whole matter is discussed
more fully in the Lancashire Sea-Fisheries Laboratory Report
for 1919, pp. 82-88, but as the enquiry was carried on at
Port Erin it requires this brief mention in the Annual Report,
and I wish to place on record that Miss Maisie Hobbins, B.Sc.,
while working at the Biological Station im April, gave me
great assistance in abstracting and comparing the records of
phyto-plankton and of hatching, of temperatures of pond and
sea, and of dates of spawning and temperature of water.
The plaice spawning in our pond at Port Erin was unusually
early in 1920, some fertilised eggs being produced in January,
and the temperature records show that the average for the
preceding winter months was high compared with recent
years. The mild winter seems to be accompanied by early
spawning of the plaice. There were, however, fewer hours of
sunshine than the average recorded for the spring months,
and this may have affected the photo-synthesis and reproduc-
tion of the phyto-plankton as the diatoms were late in appearing
in any quantity. It is possible, then, that the early-hatched
larvee found insufficient food in the sea and that the “ year
class ” of such fish for 1920 may not be largely represented in
the commercial fisheries of the future.

A careful comparison of our data for the thirteen years
(1907-19) shows that in nine cases (1907, 1910-12, and 1915-19)
the phyto-plankton in the sea preceded the hatching of the

MARINE BIOLOGICAL STATION AT PORT ERIN. 39

plaice larve, and that it was only in the remaining four years
(1908, 1909, 1913, and 1914) that there was apparently some
risk of the larve finding no suitable food, or very little, in
the sea. The evidence so far seems to show that if the fish larvee
from the hatchery are set free in the sea as late as March 20th
they are fairly sure of finding suitable food; but if they are
hatched as early as February they may run some chance of
being starved. This investigation is only started, but seems
promising. It should be repeated and extended in other
localities and in future years, and a comparison should be
made, if possible, between the results obtained in the laboratory
and the statistics for‘commercial fisheries when these are given
in sufficient detail and completeness.

PHOTO-SYNTHESIS AND NITROGEN FIXATION.

Professor Benjamin Moore, F.R.S., with Mr. E. Whitley
and Mr. Webster, have continued their very interesting and
fundamental investigations on photo-synthesis, including an
enquiry into the sources of the carbon and nitrogen compounds
formed in the growing green marine plant. Their results have
been communicated to the Royal Society and will be published
in due course, but Professor Moore and Mr. Whitley propose
to continue this lme of investigation further at Port Hrin
next year.

MICRO-FAUNA OF THE BEACH.

Miss HK. C. Herdman (Newnham College, Cambridge)
devoted many weeks, in spring and summer, to a detailed
examination of the micro-fauna and flora of the sand on
Port Erin beach. Beginning with the so-called “ Amphidinium
operculatum,”’ the occurrence of which in brown patches on
the sand between tide-marks has been recorded in previous
reports, she extended her investigation to other species of

40 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Dinoflagellates and some diatoms, and was able to supplement
and correct the views of previous observers. She found that
the organisms in question were more abundant at spring tides
than during neaps, that the different organisms remained in
their own patches and that there was no alternation between
Dinoflagellates and diatoms such as had been described. By
having successive samples of sand sent from Port Hrin, she
was able to exhibit the several forms of Amphidinium alive
under the microscope at the Cardiff meeting of the British
Association, and, after consultation with Professor Kofoid
from California, who is preparmeg a monograph on the group,
it was found that the various shapes which had been supposed
to be merely varieties of Amphidinium operculatum are really
at least three distinct species which are being described by
Professor Kofoid as A. herdman, A. asymmetricum and
A. sulcatum, and are all new to our British records. There
are also one or more species of Gymnodinium, a Polykrikos,
and a few unidentified colourless, naked Dinoflagellates ; but
as Miss Herdman is laying before the Liverpool Biological
Society a separate paper on her investigation, with figures of
the organisms observed, which will follow this report in the -
volume of Transactions, it is unnecessary to give further details
here.

ALGOLOGICAL INVESTIGATION.

Miss Margery Knight, M.Sc., who has made many visits
to Port Erin during the past year, and has devoted all available
time to a detailed study of the habits and life-history of the
common brown sea-weed Pylaella littoralis, has furnished me
with the following short summary of the results of her work :—

“ Pylaiella littoralis is found in abundance, either as an
epiphyte on Ascophyllum nodosum, Fucus vesiculosus, Fucus
serratus, or growing independently on smooth rocks or stones
in the pools at or below lhalf-tide level. The plant shows

MARINE BIOLOGICAL STATION AT PORT ERIN. 4]

two clearly differentiated forms of reproductive cells, viz. :
(a2) motile gonidia (asexual), and (6) motile gametes (sexual).
Observations on Pylaella during the spring and summer months
have revealed a periodicity or rhythmic alternation of these
reproductive cells, comparable with that found by Professor
Lloyd Willams in Dictyota dichotoma.

“There is also a very definite cycle of development of
Pylaella plants on the three ‘ hosts.’ At the time when the
first gametangial stage has been reached by the Pylaiella growing
on Ascophyllum nodosum, the young plants are just making
their first appearance on the now rapidly-growing plants of
Fucus vesiculosus. At a later period one can detect the embryo
plants of Pylaiella on Fucus serratus. The cycle is then
completed by the development of young plants on the new
shoots of Ascophyllum, whose maturer parts bear the now
battered and decrepit older generation of Pylavella.

“It is proposed to continue the research along these
lines :—

(a) Systematic observation of the behaviour of Pylaella
during the winter.

(b) Investigation of the cytological changes underlying
the alternation of sexual and asexual reproductive
cells.

(c) The relation of the epiphyte to the ‘ host’ plant.”

PLANKTON INVESTIGATION.

In the course of the plankton work, which is carried out
continuously at Port Erin, there has been this year one special
investigation which may be briefly described. It has been
much discussed in the past whether the plankton is so regularly
distributed that two hauls of the same net, taken at the same
place and, as nearly as possible, simultaneously, will give

492 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

almost identical results. With a view of testing the matter
further, on seven separate occasions, in April, May, August,
and September, when the conditions at sea seemed favourable,
I took from the motor-boat “ Redwing ” a series of four or six
hauls of the vertical Nansen net im rapid succession, from
depths of 8 to 20 fathoms up to the surface. Superficially,
at the time of emptying the catches from the net into their
bottles those of each series seemed very much alike, and even
when measured carefully in the laboratory some of the series
gave identical quantitative results—for example, six successive
hauls from 8 fathoms were all of them 0.2 c.c., and four out
of five from 20 fathoms were 0.6 c.c.; but qualitatively the
volume was made up rather differently in the successive hauls
of a series. The same organisms were present for the most
part in all the hauls of each series, and allowing for the well-
known seasonal variations the chief groups of organisms are
present in much the same proportions. For example, in a
series where the Copepoda average about 100, the Dinoflagel-
lates average about 300 and the Diatoms about 8,000, but the
percentage deviation of individual hauls from the average may
be as much as plus or minus 50, or even occasionally —
a good deal more. The estimated numbers of each organism
(about fifty species) in each of the thirty-four hauls have been
worked out, and the details will be published in the Sea-Fisheries
Report for 1920; but, pending further statistical treatment,
the impression one receives from looking at the figures is that
if on each occasion one haul only in place of four or six had
been taken, and if one had used that haul to estimate the
abundance of any one organism in that sea-area, one might
have been about 50 per cent. wrong in either direction—while
the probable error of the method allows of a range of only
from about 10 to 15 per cent. ‘This seems to indicate a greater
variation in the successive hauls than can be accounted for
by the probable error of the experiment.

MARINE BIOLOGICAL STATION AT PORT ERIN. 43
HVALUATION OF THE SEA.

This Biological Station was started by a body of men
who were engaged in faunistic work—that is, in collecting
and identifymg various groups of marine animals, and such
work is always necessary in exploring a new district, and
moreover, it is never finished but must always go on to some
extent, even when accompanied by more difficult experimental

research. Every year we keep adding something to the

published records of our fauna and flora. With the long
list of additions made in our last Annual Report (the accumula-
tions of some years) we brought the total number of species
for our Liverpool district up to about 2,500. But it is quite
possible that some common but minute species have been
overlooked ; in the present report several new kinds of Dino-
flagellates have been recorded, and last summer we added a
large species of Lucernaria, which had not been previously
noticed in the Irish Sea.

But in addition to such faunistic and ecological work,
the study of the conditions under which the animals live,
we have advanced in our research work at the Biological
Station into comparative anatomy and morphology, into
embryology and life-histories, and into physiology and_ bio-
chemistry. And now, in my final words, I wish to direct
attention to an extension of faunistic work which will, I believe,
become an important investigation at marine biological stations,
and is eminently suitable for team-work where a number of
zoologists and botanists are gathered together in co-operation.
It is the collection of material for a rough census or approxima-
tion to the numbers of different kinds of common animals and
plants found in a particular area, and their rate of growth
and reproduction, the study of the environment of each kind,
and the attempt to determine the conditions which limit their
distribution or affect their abundance. This is really no new

44 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

study, but it requires to be systematised and extended. We
have made some small contributions to portions of it in the
past in our own reports, and work of a similar nature is seen
in the Clare Island Survey, article “ Marine Heology ” by
R. Southern (1915), in Sumner’s “ Intensive Study of the
Fauna,” etc., in Bulletin of the Bureau of Fisheries for 1908,
in Orton’s “‘ Contribution to an Evaluation of the Sea,” etc.
(M.B.A. Journal, 1914), and in my “Spolia Runiana IV ”
(Linnean Journal, 1920). But the earliest, most important
and most complete investigation is that of Dr. C. G. Joh.
Petersen and his assistants in the Reports of the Danish
Biological Station for some years back, and especially the
Report for 1918. He uses a bottom-sampler, or grab, which
can be lowered down open and then closed on the bottom so
as to bring up a sample square foot or square metre (or in
deep water one-tenth of a square metre) of the sand or mud
and its inhabitants. With this apparatus, modified in size
and weight for different depths and bottoms, Petersen and his
fellow-workers have made a very thorough examination of the
Danish waters, and have arrived at certain numerical results
as to the quantity of animals in the Kattegat expressed in
tons, and have shown the dependence of all these animals,
directly or indirectly, upon the great beds of Zostera in the
Kattegat. Such estimates are obviously of great biological
interest and, even if only rough approximations, are a valuable
contribution to our understanding of the metabolism of the
sea, and of the possibility of increasing the yield of local fisheries.
It seems probable that the estimates of relative and absolute
abundance of such organisms may be very different in different
seas under different conditions. The work will have to be
done in each great area, such as the North Sea, the English
Channel, and the Irish Sea, independently. This is a necessary
investigation, both biological and physical, which lies before
the oceanographers of the future, upon the results of which

MARINE BIOLOGICAL STATION AT PORT ERIN. 45

the preservation and further cultivation of some sea-fisheries
may depend.

Our own contributions to the subject in the Irish Sea
so far deal only with a few of the shore and shallow-water
animals, and Miss Catherine Mayne, B.Sc., in several visits
to Port Erm has given me much assistance in counting and
measuring and weighing the more abundant animals and
plants, and in preparing a series of diagrams showing the
areas occupied by selected species on a typical square foot
on different parts of the shore. Some of these data were
made use of in a paper printed this year by the Linnean Society
(“Spolia Runiana IV ”’), from which I may take as examples
the following three very abundant animals, all free-swimming
when young but fixed in the adult condition, and all of value
as food of marketable fishes :-—

(1) The gregarious polychaet worm Sabellaria alveolata,
which builds masses of sandy tubes on the rocks at Hilbre
Island and elsewhere, and where 40 square yards may contain
over a million worms (See fig. 1, p. 51).

(2) The common rock-barnacle Balanus balanoides, from
the base of Bradda Head at Port Erin, where there may be
about 3,000 barnacles on a square foot of rock (Fig. 2, p. 53).

(3) The edible mussel Mytilus edulis, the most abundant
and most generally useful mollusc in our seas. The rocks
at Hilbre Island and elsewhere may be covered with a layer of
young mussels which are so closely placed as to be absolutely
continuous, while Professor Johnstone has calculated that a
mussel-bed in Morecambe Bay may have 16,000 young mussels
to the square foot, and may produce per unit of area nearly
a hundred times the amount of flesh for food that is produced
by cultivated land (Fig. 3, p. 56).

My object in referring to these still mcomplete investi-
gations is to direct the attention of our students and local
naturalists to what seems a natural and useful extension of

46 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

faunistic work, for the purpose of obtaining some approximation
to a quantitative estimate of the more important animals of
our shores and shallow water, and their relative values as either
the immediate or the ultimate food of marketable fishes.

**'L.M.B.C. Memotrs.”’

Although the Liverpool Marine Biology Committee has
now been dissolved, it is thought well to retain the former
title for this series of publications. They have become well-
known in laboratories and are referred to in literature as
the “ L.M.B.C. Memoirs,” and it would only lead to confusion
to change the title, although they are no longer published
by a Committee but by the Oceanography department of the
University.

Since our last report was published, no further Memoirs
have been issued to the public. H1mantuatta, by Miss L. G.
Nash, M.Sc., is ready to prmt; Miss HE. L. Gleave, M.Sc., has
nearly completed her Memoir on Doris, the Sea-lemon ;
Mr. Burfield, is writing the Memoir on Sacirra; Mrs. Bisbee
has made further progress with TupuLariaA, and still other
Memoirs are in preparation.

The following shows a list of the Memoirs already published
or arranged for:

I. Ascrp1a, W. A. Herdman, 60 pp., 5 Pls.

II. Carpium, J. Johnstone, 92 pp., 7 Pls.

III. Ecuinus, H. C. Chadwick, 36 pp., 5 Pls.

IV. Copium, R. J. H. Gibson and H. Auld, 3 Pls.

V. Aucyonium, 8S. J. Hickson, 30 pp., 3 Pls.

VI. LEPEOPHTHEIRUS AND LERN@A, A. Scott, 5 Pls.

VII. Lingus, R. C. Punnett, 40 pp., 4 Pls.
VIII. Puatce, F. J. Cole and J. Johnstone, 11 Pls.

IX. Cuonpruvs, O. V. Darbishire, 50 pp., 7 Pls.

X. Patetua, J. R. A. Davis and H. J. Fleure, 4 Pls.

XI. Anenicoia, J. H. Ashworth, 126 pp., 8 Pls.

XII. Gammarus, M. Cussans, 55 pp., 4 Pls.
XIII. Anuripa, A. D. Imms, 107 pp., 8 Pls.
XIV. Licata, C. G. Hewitt, 45 pp., 4 Pls.

XV. AntEepon, H. C. Chadwick, 55 pp., 7 Pls.
XVI. Cancer, J. Pearson,.217 pp., 13 Pls.
XVII. Pecren, W. J. Dakin, 144 pp., 9 Pls.

MARINE BIOLOGICAL STATION AT PORT ERIN. 47

XVIII. Exepong, A. Isgrove, 113 pp., 10 Pls.
XIX. Potycuaret Larva, F. H. Gravely, 87 pp., 4 Pls.
XX. Buccinum, W. J. Dakin, 123 pp., 8 Pls.
XXI. Eupacurus, H. G. Jackson, 88 pp., 6 Pls.
XXII. Ecutngperm Larv#, H. C. Chadwick, 40 pp., 9 Pls.
Sail, Topunx, G.C. Dixon, 100,pp.,.7 Pls.
HimanTuattia, L. G. Nash.
Doris, E. L. Gleave.
TuBULARIA, R. C. Bisbee.
AptysiA, N. B. Eales.
TEREBELLA, C. P. M. Stafford.
Bauanus, G. F. Sleggs.
SaciTta, S. T. Burfield.
ActiniA, J. A. Clubb.
ZOSTERA, R. Robbins.
HALICHONDRIA AND Sycon, A. Dendy.
OystER, W. A. Herdman and J. T. Jenkins.
SABELLARIA, A. T. Watson.
OstTRACOD (CyTHERE), A. Scott.
ASTERIAS, H. C. Chadwick.
Botry.Luoipes, W. A. Herdman.
NEMATODE, T. Southwell.

As the result of a slight fire in the Zoology Department
of the University, a portion of the stock of L.M.B.C. Memoirs
has been partially destroyed. There are a certain number
of damaged copies of some of the Memoirs which are stained
or singed externally, but are still quite usable, and are
suitable for laboratory work. It has been decided to offer
these at prices ranging according to the condition from one-
half to one-fourth of the published prices, as follows :—
Memoir I., Ascidia, 6d. to 9d.; VI., Lepeophtheirus and
Lernza, 6d. to 1s.; VII., Lineus, 6d. to 1s.; XIII., Anurida,
Is. to 2s. ; XIV., Ligia, 6d. to 1s.; XV., Antedon, 6d. to 1s. 3d.

Memoirs should be ordered from the University Press,
Liverpool.

Appended to this Report are :—

(A) The Laboratory Regulations—with Memoranda for the
use of students, and the Regulations in regard to the
“Edward Forbes Exhibition” at the University of
Liverpool ;

(B) The Financial Statement, List of Subscribers, and Balance
Sheet for the year.

48 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. .
APPENDIX A

LIVERPOOL MARINE BIOLOGICAL STATION
AT
PORT ERIN.

GENERAL REGULATIONS.

I.—This Biological Station is under the control of the
Oceanography department of the University of Liverpool, and
the Director of the Laboratory is the Professor of Oceanography.

IJ.—In the absence of the Director, the Station is under
the temporary control of the Resident Curator (Mr. H. C.
Chadwick), who will keep the keys, and will decide, in the
event of any difficulty, which places are to be occupied by
workers, and how the tanks, boats, collecting apparatus, etc.,
are to be employed.

II1.—The Resident Curator will be ready at all reasonable
hours and within reasonable limits to give assistance to workers
at the Station, and to do his best to supply them with material
for their investigations.

IV.—Visitors will be admitted, on payment of a small
specified charge, at fixed hours, to see the Aquarium and
Museum adjoining the Station. Occasional public lectures are
given in the Institution by members of the staff.

V.—Those who are entitled to work in the Station, when
there is room, and after formal application to the Director,
are :—(1) Annual Subscribers of one guinea or upwards to the
funds (each guinea subscribed entitling to the use of a work
place for three weeks), and (2) others who are not annual
subscribers, but who pay the Treasurer 10s. per week for the
accommodation and privileges. Institutions, such as Univer-
sities and Museums, may become subscribers in order that a
work place may be at the disposal of their students or staff for a

MARINE BIOLOGICAL STATION AT PORT ERIN. 49

certain period annually ; a subscription of two guineas will
secure a work place for six weeks in the year, a subscription of
five guineas for four months, and a subscription of £10 for the
whole year.

VI.—EHach worker is entitled to a work place opposite a
window in the Laboratory, and may make use of the micro-
scopes and other apparatus, and of the boats, dredges, tow-nets,

-&c., so far as is compatible with the claims of other workers,
and with the routine work of the Station.

VII.—Each worker will be allowed to use one pint of
methylated spirit per week free. Any further amount required
must be paid for. All dishes, jars, bottles, tubes, and other
glass may be used freely, but must not be taken away from the
Laboratory. Workers desirous of making, preserving, or taking
away collections of marine animals and plants, can make
special arrangements -with the Director in regard to
bottles and preservatives. Although workers in the Station
are free to make their own collections at Port Erin, it must be
clearly understood that (as in other Biological Stations) no
specimens must be taken for such purposes from the Laboratory
stock, nor from the Aquarium tanks, nor from the steam-boat
dredging expeditions, as these specimens are the property of the
Institution. The specimens in the Laboratory stock are pre-
served for sale, the animals in the tanks are for the instruction
of visitors to the Aquarium, and as all the expenses of steam-
boat dredging expeditions are defrayed from the funds, the
specimens obtained on these occasions must be retained (a) for
the use of the specialists working at the Fauna of Liverpool
Bay, (b) to replenish the tanks, and (c) to add to the stock of
duplicate animals for sale from the Laboratory.

VIII.—Kach worker at the Station is expected to prepare
a short report upon his work—not necessarily for publication—
to be forwarded to the Director before the end of the year
for notice, if desirable, in the Annual Report.

50 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

IX.—AlIl subscriptions, payments, and other communica-
tions relating to finance, should be sent to the Accountant,
the University of Liverpool. Applications for permission to
work at the Station, or for specimens, or any communications
in regard to the scientific work should be made to the Director,
Department of Oceanography, University, Liverpool.

MEMORANDA FOR STUDENTS AND OTHERS WORKING AT THE
Port ERIN BIoLoGIcAL STATION.

Post-graduate students and others carrying on research
will be accommodated in the small work-rooms of the ground
floor laboratory and in those on the upper floor of the new
research wing. Some of these little rooms have space for two
persons who are working together, but researchers who require
more space for apparatus or experiments will, so far as the
accommodation allows, be given rooms to themselves.

Undergraduate students working as members of a class
will occupy the large laboratory on the upper floor or the front
museum gallery, and it is very desirable that these students
should keep to regular hours of work. As a rule, it is not
expected that they should devote the whole of each day to work
in the laboratory, but should rather, when tides are suitable,
spend a portion at least of either forenoon or afternoon on the
sea-shore collecting and observing.

Occasional collecting expeditions are arranged under
guidance either on the sea-shore or out at sea, and all under-
graduate workers should make a point of taking part in these.

It is desirable that students should also occasionally take
plankton gatherings in the bay for examination in the living
state, and boats are provided for this purpose at the expense of
the Biological Station to a reasonable extent. Students desiring
to obtain a boat for such a purpose must apply to the Curator
at the Laboratory for a boat voucher. Boats for pleasure trips
are not supplied by the Biological Station, but must be provided
by those who desire them at their own expense.

MARINE BLOLOGICAL STATION AT PORT ERIN 51

Students requiring any apparatus, glass-ware or chemicals
from the store-room must apply to the Curator. Although
a few microscopes are kept at the Biological Station, these
are mainly required for the use of the staff or for general
demonstration purposes. Students are therefore strongly
advised, especially during University vacations, not to rely
upon being able to obtain a suitable microscope, but ought if
possible to bring their own instruments.

Students are advised to provide themselves upon arrival
with the “ Guide to the Aquarium ” (price 6d.), and should each
also buy a copy of the set of Local Maps (price 2d.) upon which
to insert their faunistic records and other notes.

Occasional evening meetings in the Biological Station for
lecture and demonstration purposes will be arranged from time
to time. Apart from these, it is generally not advisable that
students should come back to work in the laboratory in the
evening ; and in all cases all lights will be put out and doors
locked at 10 p.m. When the institution is closed, the key can
be obtained, by those who have a valid reason for entering the
building, only on personal application to Mr. Chadwick, the
Curator, at 3, Rowany Terrace.

Fie. 1. Sabellaria alveolata, from Hilbre Island, Nat. size.

52 - PRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

REGULATIONS OF THE EDWARD FORBES
EXHIBITION.

[Extracted from the Calendar of the University of Liverpool
for the Session 1920-21, p. 427.]

‘EDWARD ForBES EXHIBITION.

“‘ Founded in the year 1915 by Professor W. A. Herdman,
D.Sc., F.R.S., to commemorate the late Edward Forbes, the
eminent Manx Naturalist (1815-1854), Professor of Natural
History in the University of Edinburgh, and a pioneer in
Oceanographical research.

The Regulations are as follows :-—

(1) The interest of the capital, £100, shall be applied to
establish an Exhibition which shall be awarded annually.

(2) The Exhibitioner shall be a post-graduate student —
of the University of Liverpool, or, in default of such, a
post-graduate student of another University, qualified and
willing to carry on researches in the Manx seas at the Liverpool
Marine Biological Station at Port Erin, in continuation of the
Marine Biological work in which Edward Forbes was a pioneer.

(3) Candidates must apply in writing to the Registrar,
on or before 1st February. ,

(4) Nomination to the Exhibition shall be made by the
Faculty of Science on the recommendation of the Professor
of Zoology.

(5) The plan of work proposed by the Exhibitioner shall
be subject to the approval of the Professor of Zoology.

‘
MARINE BIOLOGICAL STATION AT PORT ERIN. | 53
(6) Should no award be made in any year, the income
shall be either added to the capital of the fund, or shall be

applied in such a way as the Council, on the recommendation
of the Faculty of Science, may determine.

(7) The Council shall have power to amend the foregoing
Regulations, with the consent of the donor, during his life-
time, and afterwards absolutely; provided, however, that
the name of Edward Forbes shall always be associated with
the Exhibition, and that the capital and interest of the fund
shall always be used to promote the study of Marine Biology.”

EDWARD ForBEs EXHIBITIONERS.

1915 Ruth C. Bamber, M.Sc.

1916 K. L. Gleave, M.Sc.

1917 C. M. P. Stafford, B.Sc.

1918 Catherine Mayne, B.Sc.

1919 George Frederick Sleggs, B.Sc.
1920 Laura Thorpe, B.Sc. °

Fic, 2. Balanus balanoides, on rocks at Port Erin. Nat. size.

54 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

APPENDIX B.

FINANCIAL STATEMENT.

On December 31st, 1919, the Honorary Treasurer of the
Liverpool Marine Biology Committee handed over the accounts
of the Port Erin Biological Station to the Accountant of the
University of Liverpool, with the followimg assets :—

ge eh

Balance in Treasurer’s hands a ss. oe

Memoir Fund (for printing) ... iF ... 229 4 4

Extension Fund (for buildings) —.... +, ee
Ministry of Agriculture and Fisheries Fund

(for Fisheries research) ... Bt: oe aes

CAPITAL ACCOUNT.

1. British Workman Public House Co., 99 shares £1 each,
fully paid.

2. The Trustees of the British Association (1896) Fund
also transferred to the University their fund of about
£1,000 to be held for the benefit of the researches
carried out at Port Erin in continuation of the work .
of the Liverpool Marine Biology Committee. This
has since been invested in £1,135 16s. 7d. Funding
Loan, 4%, 1960-1990.

The Isle of Man Government, by the terms of the
agreement, makes an annual grant of £200 im aid of the work
of the Hatchery, and the balance of that grant, amounting
to £95 12s. 5d., for the current year, was paid over to the
Accountant as from the date of the promulgation of the Act
in July. This amount was received in September, 1920,
and therefore does not appear in the present accounts.

The List of Subscriptions and Balance Sheet will be found
on the following pages. The accounts are made up to
31st July, 1920, the end of the University financial year,

MARINE BIOLOGICAL STATION AT PORT ERIN.

LIST OF SUBSCRIPTIONS TO 31st JULY

Brunner, Mond & Co., Northwich..

Druoomer, J. FP. l., 48, Hartington Gkiedemal
fionden, S.W. :.. .

Brunner, Roscoe, Belmont Hall, noe

Saveon rol,’ R. J. Nth The ae a
Liverpool ie

Graveley, I’. H., Indian ree, ‘aledtis

oll G: J. :

Erolt, Dr, A., Fopebinds, TEadion Higtah,
Hutton, J. As Woodlands, Alderley Edge

Isle of Man Natural History Society

Jarmay, Sir John, Hartford, Cheshire ie
Livingston, Charles, 16, Brunswick-st., Liverpoot
Manchester Microscopical Society... 2
Meade-King, R. R., Tower Buildings, hiverpool...
Mond, R., Sevenoaks, Kent...

Petrie, Sir Charles (The late)

Rathbone, Miss M. fe
Roberts, Mrs. Isaac, Thomery, 8. et & M., Te eee
Robinson, Miss M. E., Holmfield, Aigburth, L Eat
Roper, Miss M. H., Newnham College, Cambridge
Smith, A. 'T., 43, Castle-street, Liverpool...
Thomas, Dr.W. Thelwall, Rodney-street, Liverpool
Thornely, Miss, Field Head, Out Gate, Ambleside

Thornely, Miss L. R., Field Head, Out Gate,
Ambleside -

Toll, J. M., 49, Newsham-drive, nenpoal
Walker, ey Q., Uleombe-place, Maidstone
Watson, A. T., Tapton Crescent-road, Sheffield ...
Whitley, E., 13, Linton-road, Oxford

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56 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

SUBSCRIPTIONS FOR THE Hire oF ‘“‘ WorkK-TABLEs.’’

University, Liverpool she Bae oe :.. | SOR
Victoria University, Manchester ... ae 2 1) AO Se
University College, Reading ie ast ae be |
University College, Nottingham ... <r a: ote 0

£29080

Fic. 3. Mytilus edulis—Part of a mussel bed at Morecambe Bay.

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TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

58

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59

NOTES ON DINOFLAGELLATES AND OTHER
ORGANISMS CAUSING DISCOLOURATION
OF THE SAND AT PORT ERIN.

By H. CatHerine HerpMan,
Newnham College, Cambridge.

(Read 10th December, 1920.)

In the Annual Reports of 1911 and 1912, accounts were
given of greenish-brown patches on the sandy beach at Port
Erin. These were shown to be due to the presence, sometimes
in large numbers, of an actively motile Dinoflagellate described
as Amphidinium operculatum and sometimes of abundant
Diatoms. The discoloured patches of sand were seen to vary
in size and position from time to time and, in the individual
patches, it seemed that Dinoflagellates were replaced by
Diatoms and these, in turn, by more Dinoflagellates. It was
observed that the discolouration disappeared shortly before the
patch of sand was covered by the rising tide, and only
reappeared after that part of the beach was once more exposed.
No Amphidinia were present in tow-nettings taken in a few
inches of water over the position occupied by the discoloured
patches. It was therefore assumed that, at these times, the
organisms had gone down to the deeper layers of sand. The
variation in extent of the patches seemed to be greater, on
the whole, at neaps than at springs, and it was suggested that
possibly some correlation existed between the abundance of
Dinoflagellates and the state of the tides. A considerable
divergence of form was noticed between the individual
Amphidinia, but it was thought that they were probably all
varieties or possibly different stages in the life history of the
one species.

This summer, in July, August, and September, some
further observations were made on the occurrence and

D

60 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

distribution of the various organisms responsible for the
discolouration. The patches were examined daily from
July 28th to August 17th, and from September 6th to
September 28th, and were found to vary greatly in extent.
This variation showed a periodicity corresponding with the
tides, but in the opposite direction from that recorded in
1911 and 1912. The various organisms were present in
enormous numbers at spring tides, so that the greater part of
the south end of the beach was discoloured, while, at neap
tides, the patches were small, isolated, and much less clearly
marked. Another point on which this year’s observations do
not agree with those made in 1911 and 1912 is the alternation
of different organisms on the same patch of sand. Throughout
the time when the beach was examined this summer, although
neighbouring patches were produced by different organisms, ©
each patch was always characterised by one predominant
organism, so that it was possible to predict the cause of
discolouration in any sample of sand, provided its position
on the beach were known. Again, while most of the patches
disappeared about half an hour before that area of sand was
reached by the rising tide, a few of them were always visible
on the surface, even when covered by water. According to
the previous reports, the Amphidinia showed positive helio-
tropism. Experiments made this year all seemed to show that
the movements were negatively heliotropic, but it was evident
that they were affected more by variations in the amount of
water present than by different intensities of light.

Several species of Diatoms were found forming patches
which could generally be distinguished by their rather bright
brown colour and by the fact that, for the most part, they
remained on the surface at high tide.

The Dinoflagellata were represented by at least three
species of Amphidinium, one or more species of Gymnodinium,
Polykrikos, and a few unidentified, colourless, naked Dino-

NOTES ON DINOFLAGELLATES, ETC. 61

flagellates. Several of these forms were figured in the reports
of 1911 and 1912 as varieties or different stages of Amphidinium
operculatum, but they have since been described by Kofoid as
distinct species and, as they seem to keep definitely to their
respective positions on the beach for considerable periods
without changing, it is probably more satisfactory to regard
them as species rather than varieties. The differences in form
are made clear in the accompanying outline sketches (p. 62).

Amphidinuum herdman, Kofoid, corresponds to the
“short ” form figured in the report of 1911 as A. operculatum.
It differs from A. operculatum as described and figured by
Claparede and Lachmann in 1868 in the size and shape of the
operculum.

A. asymmetricum, Kofoid, is the same as the “long ”
form of A. operculatum described in 1912.

A. sulcatum, Kofoid, is not among the forms figured
in the previous reports, but occurred abundantly this summer.
It seems to be the only species of Amphidinium which remains
at the surface when covered by water. In the laboratory,
while A. herdmani and A. asymmetricum will live and multiply
on damp sand but do not flourish in the presence of too much
water, A. sulcatum will multiply in sea water alone to such
an extent as to form, in a few days, a thick slimy scum.

Gymnodimum sp. ? was present in considerable numbers
over a very restricted area. It was found only in and close
to a trickle of rather fresh water draining down from behind
the harbour steps. (See Sketch Map, p. 63.) It was always
associated with large numbers of Diatoms, and was found
on the surface at all times of the tide. It also multiplied in
water in the laboratory.

Polykrikos sp.% occurred fairly regularly on certain parts
of the shore though never in such abundance as to cause
discolouration. (See Sketch Map.)

Euglena spp.? The two species of Huglena each occurred

pi

62 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

in one isolated patch only (see Sketch Map) and were often

not present in appreciable numbers at neap tides.

They both

disappeared before the tide reached them. The discolouration

A = Polykrikos Sp?

Bi = A.asymmetricum.
(ventral view.

B2 = same (side view)

C1= A. Suleakum.
(ventral view)

C2 = same (side view.)

Di =A.herdmani.
(ventral view.)

2 =Same(side view.)

Et = Gymnodinium. sp?
(ventral view.)

E2= Same (side)

nm = Nucleus-

produced by them was distinctly greener than that caused by

the Dinoflagellates.

NOTES ON DINOFLAGELLATES, ETC. 63

Diatoms. Brown patches were caused by several species
belonging to the genera Navicula, Pleurosigma, and others.

Oscillatoria sp.? The only other organism which ever
appeared so abundantly as to cause discolouration was
Oscillatoria. This was almost always present in and around
the trickle of fresh water in the harbour, and occasionally
increased so as to form small dark green patches. (See
Sketch Map.)

yy

tj i.
i, in IY) O ff
. ; wy CBOE uth YW Go
Port Erin. Sandy beach. jy Lip Y a P ey
Distribution of organisms RAE :
at spring lides- a M Lighthouse .
D.
Di
Dic Upper limil of darnp sand.
D:
D:
D
: HWM.
LWM. D; Springs)
(Springs) a
ae
wy
Se —0o Well-
D:
D:
—=> ‘
{
aie
XK re 3)
ok >
Joe mS.
LK XK BS i
PET KSIOC (De D ,
Cake xk K P :
PS ELEE EOL EE D A
beh KKK LK HK D "
x Xx ee li A
K aK a
HA hoe KH KK KH a A:
AL KR KAL A K 4 Ay De Diatoms.
A OK oh KK LK D A’ O* Oscillatoria.-
D> Rao D A ET - Euglena I sp
eae pe eaens
mK = Arynphidinie b-icom.
Go \ aoe X= Asuleatussee on
f\ er a & =A. nerdmani.

P - Polykrikos-

l¥ serhanning tresh water,

64

NOTE ON SOME EXPERIMENTS ON THE
WATER VASCULAR SYSTEM OF ECHINUS.

By Ruts C. BamsBer, M.Sc.

[Read December 10th, 1920.]

In 1887, Professor Marcus Hartog* published a paper on
“The True Nature of the ‘ Madreporic System’ of Echino-
dermata, with Remarks on Nephridia,” in which he put forward
the view that “‘ we must needs regard the madreporic system
and the ‘ vasal’ part of the vasoperitoneal sac as constituting
a left nephridium, the right having failed to receive a duct.”

Previous to this, the generally accepted view was that
water enters the water vascular system through the madre-
porite, and is probably lost gradually by passing out through
the walls of the tube feet, etc.

Hartog supports his view by experiments which seem to
prove that there is an owtward current through the madreporite,
as would be expected if the water vascular system is an
excretory organ. Fresh specimens oi Hichinus were opened and.
the madreporic canals removed and slit longitudinally on one
side: they were then examined in the perivisceral fluid and he
reports a strong inrush of particles through the slit, and a
corresponding outward flow through the cut end towards the
madreporite. The madreporite of an Echinus and of several
starfishes, with part of the stone canals attached, were removed
and examined in sea water with powdered charcoal in suspen-
sion. No particles ever settled on the madreporites. Normal
and eviscerated specimens of Antedon were examined disc
upwards in sea water, with charcoal im suspension. No

particles were observed to settle on the discs except along the
imperforate ambulacral grooves.

* London, Ann. Mag. Nat. Hist., 1887, pp. 321-326.

WATER VASCULAR SYSTEM OF ECHINUS 65

Hartog concludes, “the above experiments show clearly
that the perforations of the madreporite in Echinus and
Asterias, and of the disc in Comatula, are purely excretory,
and serve to elimimate the excess of water taken up by the
body.” These experiments and the view they seem to support
met with much criticism.

Cuénot* claimed that ciliary action on the madreporite
would give Hartog’s results, without any outward current.
He considered “ qu’il n’y avait ni courant (entrée, ni courant
de sorti; tout ce que l’ou peut admettre, a la reeueur, c’est
qwil se produit une diffusion lente au contact des pores madré-
poriques entre le liquide des cavités environnantes et l’eau de
mer ballotée en tors sens par les cils.” He did not support
this view by experiment. Later}, he suggested that the cilia
liming the stone canal keep up the pressure in the water vascuiar
system by constantly tending to produce an inward current.

Ludwigt brought forward experimental evidence to prove
that there is an ward current through the madreporic pores.
He examined different adult Echinoderms, also Auricularia
larvae, in perivisceral fluid, with or without particles added,
and reported a distinct enward current through the madreporite
and down the stone canal.

MacBride§ also claims that the current is znwards. After
keeping Amphiura squamata living for several days in sea water
with carmine or lamp black in suspension, he found, on cutting
sections, that some particles were present in the pore canals.

In 1913, Mr. Burfield and myself, working at the Port Erin
Biological Station, repeated some of Hartog’s experiments and
added others, as follows :—

EXPERIMENT 1. The madreporite, with the stone ‘canal

* Cuénot, L. Leipzig, Zool. Anz., Vol. XIII, pp. 315-318 (1890).
+ Cuénot, L. Bruxelles, Arch. Biol., Vol. II, pp. 313-680 (1891).
{ Ludwig, H. Leipzig, Zool. Anz., Vol. XIII, pp. 377-379 (1890).

§ MacBride, E. W. London, Quart. Journ. Micros. Sci., Vol. XX XVIII,
pp. 339-411 (1896).

66 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

attached, was removed from a fresh Hchinus, and examined
in sea water with particles of carmine in suspension. The
particles were always driven back from the madreporite just
as they were about to settle. The behaviour of these particles
strongly suggested ciliary action on the madreporite.

EXPERIMENT 2. In order to test for any outward flow
through the madreporite apart from the action of cilia on its
surface, a fresh Echinus was obtained and its madreporite
carefully scraped. The madreporite with the stone canal
attached was then removed from the animal and examined in
sea water with the particles in suspension. All particles were
still driven off from the madreporite as though by an outward
current. .

EXPERIMENT 3. A madreporite with the stone canal
attached was placed in a vessel of sea water with particles
suspension, and left for several hours. It was then found that
a mass of particles had collected around the cut end of the
canal suggesting that there had been an inflow there, and
consequently, an outflow through the madreporic plate.

EXPERIMENT 4. Stone canals and ampullae were
examined in sea water under a binocular microscope. A
continuous circulation was distinctly seen by the movement
of the corpuscles in the fluid of the ambulacral system. In the
ampullae the direction of this circulation was very indefinite,
but in the stone canal there was a very distinct central current
towards the madreporite, and peripheral currents towards the
oral surface. The peripheral current seemed to be the result
of ciliary action on the lining of the canal.

Experiment 5. Coloured fluid was injected into fresh
specimens through the interambulacral areas. The punctures
were sealed with plasticine, and the animals kept m fresh
sea water for several days (different coloured fluids were used ;
e.g., methyl blue, methyl green or fuchsin in sea water ; also
carmine in perivisceral fluid). This experiment gave no

WATER VASCULAR SYSTEM OF ECHINUS 67

result. The animals were apparently not healthy ; the whole
of the interior stained, but there was no sign of any colour
being excreted anywhere.

These experiments seemed to support Hartog’s view, but
were by no means conclusive.

In 1915 I carried out other experiments, and have con-
tinued them either at Haster time or during the summer,
every year since then, at Port Erin. 7

It seemed doubtful whether evidence obtained from
dissected madreporites and stone canals could be relied upon;
therefore in the following experiments dissection has been
avoided as much as possible.

EXPERIMENT 1. Stone canals were examined under a
binocular microscope without being removed from the animal.
This is easily done by cutting a window on each side of the
animal and examining it in a glass vessel filled with sea water.
The currents seen agreed with our previous observations ;
there is a peripheral current towards the oral surface, apparently
caused by cilia lining the stone canal, and a central current
towards the madreporite. It is impossible to decide from
observation which of these is the main current, but the fact
that both are present perhaps accounts for the directly opposite
reports of Hartog and Ludwig. Observations made with a
binocular microscope leave no doubt on this point.

EXPERIMENT 2. lLaving specimens of Echinus were
examined in sea water with charcoal or carmine in suspension.
No particles were ever seen to settle on the madreporite,
although they settled freely elsewhere. A large number of
specimens have been examined in this way, and always give
the same result. As one observes the phenomenon the impres-
sion strengthens that the action is due to cilia on the surface,
and not to a steady outward current, in spite of our previous
experiment with a well-scraped madreporite.

EXPERIMENT 3. To test for surface ciliary action the

68 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

madreporite of a fresh Echinus was touched with a brush
dipped in formaline. The animal was immediately plunged
into fresh sea water to prevent the action of the formaline from
spreading beyond the surface of the madreporite. This
animal was then examined in sea water with particles in
suspension, and no longer gave any suggestion of an outward
current through the madreporite. Particles settled freely
over its whole surface.

Obviously any appreciable outward action is due to the
cilia on the surface of the madreporite or just inside the madre-
poric pores, and not to an outward current. This, of course,
does not disprove a very gentle or an intermittent outward
flow, such as one might expect from an excretory organ.
Feeding experiments were therefore attempted to settle
whether or not any excretory matter finds its way out of the
animal through the madreporic system.

EXPERIMENT 4. A dozen Echini were fed with dry
methyl blue. They were then kept under observation im
running water for several days. No colour appeared anywhere
on the surface, and on opening the animals it was found that
the methyl blue was simply coated with mucus, and was not
being absorbed at all. No results have so far been obtained
from any feeding experiment.

EXPERIMENT 5. Dry methyl blue was put mto the
coelom through a little puncture in the interambulacral area.
The puncture was sealed up with putty and the animal kept
in fresh sea water. After one night the whole peristome and
the buccal branchiae were bright blue, but no colour appeared
anywhere else on the surface, although the animal was kept
under observation for many days. Many specimens have
been treated in this way and always give the same result.
This experiment, like the feeding experiments, gave negative
results for the function of the madreporic system.

EXPERIMENT 6. To test for a possible cward current

WATER VASCULAR SYSTEM OF ECHINUS 69

many specimens of Hchinus were kept in fresh sea water
coloured with methyl blue*. The animals were opened at
intervals of one to five days, and every specimen showed colour
in the axial sinus; many had the axial organ stained very
deeply, two had a doubtful suggestion of colour in the stone
canal directly under the madreporite, but not a single specimen
showed any colour at all in the stone canal beyond this point.
On another occasion an Kchinus was kept in methyl blue and
sea water for two days, then opened. The stone canal and
polian vesicles were bright blue; there was no colour at all
present in the axial organ.

These experiments seem to prove that there is no con-
tinuous current in either direction in the madreporic system.
That fluid passes in through the madreporite seems certain,
but apparently it passes sometimes into the axial sinus, some-
times into the stone canal. Gemmellt found, by cuttimg thin
sections of fresh madreporites, that “the cilia on the surface
of the madreporite act tangentially, and tend to sweep away
any foreign particles. No pore-canal system as a whole has
its cilia acting oralwards, but in each pore-canal there is a
short superficial segment which shows the converse condition.”
Our observations agree with this report exactly, but do not
throw very much light on the apparently erratic action of the
whole system as shown in ixperiment 6 above. From work
on Asterias and Solaster, Gemmell found that the ciliation of
the axial sinus is in an aboral direction. Whether this is
true or not for Kchinus also has not been ascertamed to my
knowledge. But be that as it may, the ciliation of the madre-
poric system clearly does not account for our observed facts.
Probably,as Cuénot, MacBride and Gemmell have suggested, the

* Methyline blue is useless for this experiment owing to the fact that living
tissue reduces it to a colourless leucobase.

7 Dr. J. F. Gemmell. London, Phil. Trans. Roy. Soc., Series B., Vol. CCV,
pp. 213-294 (1914).

70 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

action of the cilia lming the stone canal serves to keep up the
pressure in the ambulacral system. If the pressure in this
system is high no fluid will be able to enter the stone canal
through the madreporite in spite of the action of its ciliary
lining.

Cuénot has also suggested that fluid may enter the body
cavity through the permeable axial organ, and this view seems
to be supported by these experiments. There is no evidence
to prove that excess fluid does not also leave both ambulacral
system and body cavity through the madreporic system.

Apparently the whole question is one of balance between
internal and external pressures. :

71

ON THE INHERITANCE OF COAT COLOUR IN THE
VARIETIES OF RATTUS RATTUS.

By J. W. Curmore.
[Addendum to Paper in Vol. XXXIII, p. 70.]

Since the publication of the first part of my article I have
completed my experiments on the Rattus group so far as
I could with the accommodation at my disposal.

From an analysis of the results I find :—

(1) That mating f. r. rattus (black) to R. r. frugivorus or
to R. r. alerandrinus (brown), gave an equal number of each
colour.

(2) That mating brown Hybrid to brown Hybrid, off
above, gave all brown offspring like themselves.

Bruack x Brown.

| |
Black 50 %. Brown 50 %. First Hybrid generation.
|
| |
Black Brown Brown
662 %- 334%. - 100 %. Second Hybrid generation.

(3) That mating black Hybrid to black Hybrid gave
eight black and four brown offspring. Six of the black young
showed a white mark on the chest, similar to those mentioned
by the late Professor Doncaster as mdicating the mixed
dominant character in his experiments with the common
brown Rat, R. norvegicus. Professor Doncaster suggested
to me that I should test these so marked; I am sorry it was
not convenient for me to do so. One of the black Hybrids
(the male) of the pair that produced both brown and black
offspring had a white spot on its chest.

So far as my experiments went no black offspring were
produced from brown Hybrids. I am sorry it was not con-
venient for me to test the brown young with white ventral

D2

t,

72

TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

patches. Brown ofispring were produced from black Hybrids
(see Table below and Chart above).

(4) That from the common brown Rat (norvegicus) mated

to the domestic white Rat (albino), gave results in accord
with the Mendelian laws of inheritance, and also in accord
with the results published by the late Professor Doncaster
in the Proceedings of the Cambridge Philosophical Society,
Vol. XII, Part 4.

(5) That from the pairs of norvegicus females mated to

rattus males I had no results.

Table of matings and results to show the inheritance of the three varieties,

Rattus r. rattus, R. r. frugivorus, R. r. alexandrinus.

Exp.
No.

iw)

or

Female
Parent.

rattus

alexandrinus

rattus

alexandrinus

Jrugivorus ...

rattus

rattus

Origin.

wild caught

wild caught

Of NO: Zoo

Of Now 2):

off No. 1

off No. 2

wild caught

...| rattus

Male Parent.

frugivorus ...

rattus

frugivorus

alexandrinus

.| frugivorus ...

rathus

Ob Nor 2

Origin.

wild caught

wild caught

off No: 1 “3:

Of INO 32: ee

off No. 1

..| wild caught

f
(

|
|

Result.

6 frugivorus
2 rattus

9 rattus

7 alexandrinus
1 frugivorus
13 rattus
12 frugivorus
1 alexandrinus

17 alexandrinus

13 frugivorus

8 ratius
4 alexandrinus

7 rattus

Sex.

33, 3
29

-| 8g, 19

43, 39
3

-| 73, 6

| 5d, 79

Ig
83, 98

| 5d, 89

-| 66. 22

43
33; 49

73

REPORT ON THE INVESTIGATIONS CARRIED ON

IN 1920 IN CONNECTION WITH THE LANCASHIRE

SEA-FISHERIES LABORATORY AT THE UNIVERSITY

OF LIVERPOOL, AND THE SEA-FISH HATCHERY
AT PIEL, NEAR BARROW.

EDITED BY
Proressor JAMES JOHNSTONE, D.Sc.,
Honorary Director of the Scientific Work.

(With Text-Figures.)

CoNTENTS. PAGE
Introduction (J. J.) ae 8 fae “ie 73
The Work of the Piel Laboratory (A. S. ) aay he in =e 95
Plaice Measurements made in 1920 (W. B.)_ ... ae oe days ALO
Herring Investigations in 1920 (W. B.)_ .. : ae i ‘2 iG
Temperature Variations and Tides (R. J. D. ne Be. wea
Seasonal Variations in the Composition of the Mussei (RB. JD: ) 146
Intensive Study of Port Erin Plankton ie A. H., A.S.,and H. M. L. *) 157
Variability in Port Erin Plankton (W. A. H.) .. ; 161
Sole Measurements in 1920 (J. J.) te see aes “ ae LO
Black littoral sands (J. J.) tk a tek oe sf eee LES

INTRODUCTION.

This Report, like those that have been issued since 1914,
must again be a small one. The reason for this is mainly
the greatly-increased cost of publication, but there are also
other difficulties peculiar to the circumstances of the time.
There is no doubt that the fishery industries are in a very
serious condition—perhaps even one of crisis—and so one is
obliged to try to discover in what ways the scientific research
now being carried on can be of immediate assistance. Obviously
the investigations that are mstigated by a statutory fishery
authority in this country must have, for their ulterior objects,
the attainment of results, or solutions, or information of some
kind that will be of material advantage to the idustry—that
is their justification as economic research. Now one may
E

74 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

submit that it ought to be the function of the industry, and of
the administrators, to state the nature of the problems tbat
confront them and to ask for such information as may be
attainable ; still it is, no less, the task of the investigators to
study the economic conditions that prevail and to endeavour
to acquire an attitude that will enable them to direct the
scientific research along commercially useful lines. In the effort
to attain such an attitude I, therefore, refer to the condition
of the sea-fishing industries—so far as the information at my
disposal goes.

The Trawl Fisheries.

There is little doubt that many of the conditions of the
year 1920 were indicated in 1913—all that the war has done
has been to accelerate a change that was apparent ten years
ago. In 1911 failing markets were being experienced—as
witness the Exhibition at Rusholme, in Manchester, in that
year. The steam-trawling trade was nearly stagnant because
the available home markets had fully been supplied then and
little could be done to develop an export trade in fresh fish.
So the “ Wish-as-food ” propaganda of that period took shape
and was the expression of a real difficulty in disposing of the .
fish that could be landed. It came as a kind of shock during
the war years when one realised that, for most English people,
fish was not a satisfactory substitute for meat !

The vicissitudes of the steam-trawling industry during
the years 1914-1921 would be of extreme interest if some one
personally conversant with these affairs would write them up
before the first vivid impressions fade. In 1918, 1919, and
even early in 1920 there was an appearance of fictitious pros-
perity : it was generally believed that large “fortunes” had
been made by the owners of fishing vessels, and there were
many attempts at the flotation ot new enterprises. The strike
of skippers of trawlers at Fleetwood in March, 1920; the
announcements made about that time of the “cost of pro-

SEA-FISHERIES LABORATORY. (i
duction,” and the failure to materialise of most of the new
flotations did much to dispel the illusion of prosperity. The
lowest earnings of Fleetwood skippers, I was informed, was
£17 a week, and the double of that was not uncommon. At
one port the lowest ratings on a steam-trawler had a weekly
wage of £2, a daily bonus, while at sea, of 6/-, a share of 2d.
in the £ on the earnings of the vessel, and free food while on
board and fishing. I don’t think these earnings, either of skip-
pers or deck-hands were too big when one considers what is
the nature of the work that is done, and I only quote the figures
here as illustrating some of the costs of landing the fish. Coal,
ice, and other consumable stores, had, it must be remembered,
increased in cost in much about the same ratio as wages and
bonuses. In June of 1920 a series of average costings taken
at several fishing ports showed that it took about 44d. to land
the average lb. of fish, while the latter sold at about 14d. to 44d.
Far more serious, however, was the incredibly bad means of
transport and distribution. When one compares the price
obtained for the fish on landing with the price at which it was
bought by the consumer in the retail fish shops it becomes
evident that an extraordinarily large proportion of the latter
price must have been absorbed by the expense of carrying
away the fish from the ports and distributing it to the con-
sumers, for it is probable that the retailers’ profits were not
enhanced in the same ratio as was that of the price paid by the
consumers. Even the pre-war transport was far from being
all that was desirable, and certainly that of the years 1919
and 1920 was very much worse—-so one heard repeatedly of large
‘quantities of fish that were unsaleable and had to be destroyed.
There were “ gluts” at many of the ports, and there was no
means of utilising these except the manure factory. The cold-
storage, about which one heard so much during the war years,
and in regard to which there was so much unfinished scientific
investigation, did not materialise. It appears now to be the

76 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

case that the process of “turning round” the trawlers and
drifters from war to fishing work was accomplished rather too
quickly. A large number of steam-fishing vessels were built by
the Government during the war and an attempt was made to
hand many of these over to the “ Mine-Sweepers’ Co-operative
Association ”-—a fine and generous project which deserved
better than to be launched during a time of slump and aban-
doned in little over a year. This scheme, and the futile
taking-over of the German “ Reparation trawlers ” are indica-
tions of the extent to which Ministers had “sized up” the
situation of the steam-fishing industry in 1919. So much, then,
for the conditions of the last two years—at the present time
(March, 1920) there is the certainty, either of an extensive
laying-up of trawlers when the Lent fishing season comes to an
end, or of a marked break in wages.

Smack-fishing was thoroughly decadent long before the
war period, and the years 1914-1919 hastened the rate of decline
so that (unless, perhaps, the price of coal remains at its present
value) this branch of deep-sea fishing will soon become extinct
in England. About 1885-1890 there were nearly 100 fine
smacks sailing out from Fleetwood and Hoylake: now there.
are 17, and it is said that even some of these are on the market.
The history of the old Fleetwood vessel “‘ Mary Ashcroft ” is
symbolic: She was built at Maldon, in Essex, in 1798, and
after fishing in the North Sea for about half a century she was
brought through the Caledonian Canal (in 1860) by Mr. Hugh
Ashcroft and Pilot John Hesketh to Fleetwood, from where
she fished till 1904 when she was wrecked on entermg White-
haven Harbour, and was then bought by Mr. Charles Pater,
of that port, for £20; raised, refitted,and sent again to sea to be
finally condemned ag unseaworthy in 1917. Thus ended an
honourable fishing career of 119 years during which those who-
worked this old vessel saw the great development of smacking,
which culminated in 1885, and saw also the beginning of the

ie

SEA-FISHERIES LABORATORY. 4X

process of decadence which is, apparently, now approaching
completion.

The Herring Fisheries.

The pelagic fisheries had even worse luck than that which
was experienced by trawling. There was never (in modern
times) a home market for more than about half (at the very
most) of all the herrings caught, and so the great drift-net
fishery depended largely upon an export trade. This has had
many ups and downs, but never so disastrous a period as that
of 1914-1920. The two great markets were Russia and Ger-
many, and the latter, of course, closed down on August 4th,
1914. With incredible difficulty the Russian market was kept
open till the end of 1916: in that year, for stance, a schooner
took 200 barrels of salted herrings from Port St. Mary to
Whitehaven, en route for Newcastle and Russia, and the freigh-
age was 4/— a barrel across the Irish Sea. One cargo, worth
£7,000, that did enter Russia cost £28,000 in freight and other
charges. Another cargo (at least) was frozen up in the Gulf
of Finland, and yet another had to be housed in sheds specially
built at the port of landing. A new route was opened up,
but in the end the political difficulties of the trade proved more
formidable than did the natural ones and the export into
Russia practically ceased. It is difficult to learn what was the
volume of the trade with Russia and Germany during 1919
and afterwards, but certainly its methods must have resembled
gambling rather than respectable business transactions. The
great Hast Coast herring fishery carried on during 1919 and
1920 only because the Government guaranteed a price to the
fishermen and took over the herrings packed.* This they
seem to have done without either courage or conviction, for,
early in 1921, it was announced that the guarantee would be
withdrawn, and at the time of writing the chances are that

* Which so far are largely unsold.

78 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

at least half of the Hast Coast herring vessels will be laid up
during the coming season. Nevertheless, m view of the
formidable menace of the rapidly-growing Norwegian and
Dutch herring export trade it is hoped that the decision may
be reconsidered. A contrast between the commercial policy,
in regard to fishery, of this country in 1815 and 1919 would be
very interesting did time and space permit one to make the
investigation. In 1815, after the reopening of the Continental
markets, the Government continued the bounties paid on vessels
fitted out for deep-sea fishing, and for herrings, cod and Img
cured for export, and it was only in 1830 that these “ doles ”
were completely withdrawn—by which time the export trade
had thoroughly been established. In 1921, however, after two
years of what has been, in effect, a bounty on the herring fishery,
the present Government has withdrawn the support it offered—
and this in the face of a formidable Continental competitive
trade which did not even exist in 1815.

The prosperity of the pelagic fisheries depends, then, on
an export trade, and it is in this respect that scientific and
industrial research come into consideration. The present

method of curing herrings—by “ gipping ’

> and preservation in
strong brine—was invented by a Dutchman in the 14th century,
and it is still essentially the same method that is practised in
Britain. It can be depended upon to keep herrings good for
about a year, perhaps (so that the 1919 pack guaranteed and
practically possessed by the Government must now be unsale-
able). Just as it 1s in the chemical trades the method of
“mass-production ” seems to be a peculiarly British one, Which
largely excludes the manufacture of commodities in small
quantities and prepared in numerous special ways. So while
a great variety of herring conserves are prepared abroad British
curers only export pickled herrings in large quantities, and but
a negligible bulk of canned fish. During 1916 and 1917 a great
deal was written and said about the establishment of an export

ae

SEA-FISHERIES LABORATORY. 719

fish-canning trade, particularly with regard to the practically
unutilised British sprats. A good deal of scientific research
work was initiated—and subsequently abandoned—but even
this never got beyond the tentative laboratory phase. The
application of laboratory methods to the investigation and
improvement of the routine factory processes was never
attempted—though such an extension is absolutely essential
if the investigations are to benefit the industry. But even this
display of interest in the canning trades had its effect, for there
was a kind of incipient boom about the end of the war and
several fish-canning enterprises on a large scale were projected,
and certainly those engaged in the embryo British fish-canning
industry were keenly alive to the value of experiment and
investigation. Now an export trade is the essential condition
for further development of the British herring, mackerel,
pilchard and sprat fisheries, and headway in this can best be
made by concentrating on canning. The pickled herring
remains good for about a year and then rapidly and steadily
deteriorates, while the herring or sprat canned in tomato
sauce improves up to five years, or if canned in oil, up to ten
years. In its keeping qualities, then, as well as in its much
ereater intrinsic and commercial value, the canned fish is
obviously the basis of an export trade. But the bulk of the
sprats and herrings at present canned in Great Britain are
inferior in quality, and both scientific and industrial research
is essential to the development of the trade.

As things are it is probable that something in the nature
of a bounty on fish canned for export may also be indispensable.
It would stimulate production, for an abatement of the Excess
Profits Duty (which would have been, in effect, a bounty)
might have led to greater output in 1917. Further, a
bounty would have stimulated trade by leading to an improve-
ment of the product—I assume that the payment of the “ dole ”
would be made contingent upon a satisfactory inspection by a

80 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

qualified official (as in the case of the branding of herrings by
the Scottish Fishery Board). Thus the pack could gradually
be made:better. I see no objections to such a policy except
those that are either doctrimaire, or bureaucratic, or simply
foolish ones. :

I think it is likely that the export herring trade of these
Islands will ultimately regam its pre-war magnitude—if that
is judged to be enough. Certainly it is unlikely greatly to
exceed the level it attamed just before the war. The great
markets (Germany and Russia) are after all limited ones, and
the South European and Hastern countries do not want pickled
nerrings (on the other hand there is an insatiable demand in
the East for tinned fish of the sardine type). Already there
is a great Norwegian trade, scientifically studied and organised,
possessing a national unity, which seems to be very difficult
to establish in this country, and turning out products of great
excellence. Holland strives mcessantly to regai her “ place
in the sun” which she possessed in the 16th century, and
certainly the growth of her herring fisheries during late years
has been remarkable. To rebuild the British herrmg export
trade must therefore be a task of some difficulty, and I am
convinced that in attempting it scientific and industrial research
will be necessary, while State support, in the form of bounties,
may be necessary.

The Inshore Fisheries,

It is not easy to obtain precise information as to the con-
dition of the small-boat and longshore fisheries, but it 1s pretty
clear that these also are on the decline. ‘Trawling for fish by
““nobbies ” seems to have fallen off in Lancashire waters :
thus, twenty years ago there used to be a small flotilla of
Southport and Morecambe boats at Pwllheli for the summer
fishing, but now one sees only an isolated vessel. There is little
doubt that the growth of the holiday resorts has tended to
transform the inshore fishermen into “ bumboatmen,”’ and

SEA-FISHERIES LABORATORY. 81

against this tendency it is very difficult to strive. Just now,
however, the efforts of the Fisheries Organisation Society seem
to be having good results, as witness the Co-operative Societies
at Fleetwood and Morecambe—enterprises that appear to me
to have all the elements of success. There is no doubt at all
that much more could be done to make shrimping and prawning
as carried on by these Societies more highly profitable. I was
told, at Morecambe, that there were, occasionally, “ gluts ”
of shrimps, and that some means of preserving the “ picked ”
product was very desirable. Here, then, there is an opportunity
for industrial research : say, the preparation of fish and (real)
Crustacean pastes; the “potting” of shrimps and prawns
in various ways in hermetically-sealed glass vessels, and the
preservation of picked shrimps by packing in sterilised bottles,
as in the case of fruits. It is quite likely that all these methods
may be sound ones from the commercial point of view, but they
have all to be tested, and for this purpose machinery must be
obtained. It would, no doubt, be difficult for the Co-operative
Societies to obtain the plant and work this during the necessary
experimental period. In short, a small experimental and
demonstration factory 1s wanted, and, since there is little hope
of obtaining this through the ordinary official channels, I make
the suggestion to the Fisheries Organisation Society. So far
as the inshore industry is concerned it is, hitherto, only the
latter Society that has been able to “ deliver the goods.”

Musselling and Cockling:.

The process of decadence is now nearly complete with
regard to the shell-fisheries. The general ascription of the cause
of enteric fever to sewage-polluted mussels and cockles has
closed many markets and some mussel beds. I regard what
has happened during the last dozen years as highly discreditable
to public administration. The evidence that outbreaks of
typhoid fever were set up by the contamination of mussels by
sewage was, in all cases, strong enough to justify remedial

82 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

measures, but I am pretty sure that in no case yet known would
it have been legal evidence, strong enough to cause a judge to

ascribe ilmess or death to the sewage contamination—at all

* events that has never been tested.

What mostly resulted from the investigations made by
this Committee was a crop of administrative procedure. It
was fairly easy for a local authority to set the machinery of
the Shellfish Regulations in action: much easier, for instance,
than to destroy the fly-breeding refuse in its own slums. That
procedure involved no investigation other than procuring a
sample and sending it to an analyst—or at the most making a
“ topographical survey.” Even the methods of analysis have
never been thoroughly tested and improved. There has been
no recognised “ standard of permissible impurity.” There has
been no adequate and systematic investigation of the general
distribution of “ coliform ” sewage bacteria in the sea. There
have been restrictions, and a confusion of administrative
methods in the experience of which it gradually became
evident that the local Fishery Authorities were practically
impotent in the matter since their powers of regulation were

inadequate, while the Central Authority was impotent for the

same reason and also because of its want of resources. The
authorities that do have the necessary regulating power—that
is, the local Sanitary Committee and the Ministry of Health—
have quite a different attitude with regard to the questions
at issue.

So far as this Committee is concerned it cannot be said that
it did not “ explore every avenue ” that promised escape from
disaster. But the result is that the shell-fisheries are decadent,
to say the least. Only in one part of the district (at Conway)
has there been any success in dealing with the matter, and this
success 1s to be traced to the outcome of scientific investigation
carried on by the Ministry of Agriculture and Fisheries with
the assistance of the Development Commission. So far as the

ee

SEA-FISHERIES LABORATORY. 83

mussel-fisheries of the Lancashire Coast are concerned there is
little hope of similar measures being taken, and I can only
suggest that the cleansing of polluted mussels for the markets
is a matter for controlled private enterprise. I see no reason
why this should not be successful, and no reason why the
Fisheries Organisation Society should not enable a mussel-
fisherman’s Co-operative Society at Morecambe to construct
and operate a mussel-cleansing tank.

The International Fisheries Investigations.

The above allusions to some of the difficulties under which
the fishing industries labour are really pertinent, for it does
not appear to me that fishery research just now has much
relation to the problems that more immediately concern the
fishermen and the owners of fishing vessels—whose existence
is the reason why there are fishery administrators and mmvesti-
gators at all.

I attended the meeting of the International Council for the
exploration of the sea, which was held im London, in March,
1920. This was the first post-war meeting, and it was very
fortunate that it was possible. Itis known that but for pressure
brought to bear upon the Government during the war years,
by the Board of Agriculture and Fisheries, the British contri-
bution would have been withdrawn. In that case there is little
doubt that the International organisation would have broken
up, and, as things are, it is pretty certain that it could not
have been resuscitated for some years to come. It is fortunate,
then, that the Council met when it did and took up the threads
dropped in 1914: still, one must confess, it was disappointing
to find that the representatives chose to look backwards rather
than forwards in March, 1920.

To the scientific men the fishery problems were still the
same as they were in 1914. Research, whether in fishery or in
mathematics, must be entirely personal if it is to have complete
success. Its mainspring is the curiosity and the desire to make

84 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

new knowledge and find out things in the mind of the investi-
gator, and it ought not to matter to him whether the results
he is trying to obtain are useful or not—the result is the thing.
One can easily “ organise ”’ scientific investigation to such an
extent that this motive falls into the background—fortunately,

is not
easily attainable! The problems upon which fishery investi-

as things are, such a degree of “ scientific organisation ’

gators were engaged in 1914, then, easily and naturally slipped
back again into prominence—and, of course, they still press
for solution, and have to be taken up some time or other in the
future.

What was really wanted in 1920 (and even at the end of
1918) was the point of view of the fishing industry rather than
that of the administrators. Obviously it was the production
of food commodities rather than the elaboration of legislative
restrictions that the circumstances of the time indicated. The
attitude of the fishmg industry was well known, though the
creat commercial interests were unrepresented at the Inter-
national Conference. It is remarkable that a much broader
“ statesmanlike ” (usmg the word in its older and
more creditable sense) view was taken by the industry than by:
the Statutory Fishery Authorities. I attended most of the
meetings held by the Reconstruction Committees of the
National Sea-Fisheries Protection Association in 1919 and 1920,
and, even then, the present situation and its difficulties were
(in great measure, at least) anticipated.* A coalescence of the
activities of the various National and Departmental Statutory
Authorities concerned with fisheries was strongly urged: it
was hoped that the Association would be able to persuade the
Government that fishery, in the international sense, was a
proper subject for arrangement at the Peace Conference ;
codification of fishery law was urged ; internationalisation of

and more

* For instances, in the ‘‘ Memorandum ”’ submitted to Mr. Prothero in
1918, and in the schemes of reconstruction prepared subsequently by the
industry and its advisers.

SEA-FISHERIES LABORATORY. 85
the Island of Heligoland was suggested; a programme of
scientific research was drafted; schemes of education and
technical training tor fisher lads were prepared—and so on.
But what has since happened has fallen very far short of these
ideals. There is still no suggestion, even, of education and
training for fishermen, and, on the whole, scientific research is
much less well provided for than it was in 1913. The Fisheries
Bill promised in the King’s speech in 1920 has not yet appeared.
I don’t suppose that fishery was even mentioned at the Peace
Conference, and as for vesting the Prussian Marine Biological
Station, and the revenues of the Island of Heligoland, in the
International Fisheries Council—that, perhaps, would hardly
have been regarded as “ practical politics.” To be sure it
might only have been the occasion for an irritatingly bureau-
cratic and wasteful administration ! Doubtless the reconstruc-
tion suggested by the fishing industry in 1918-20 will come
aboul—sometime—and when it does it ought to be remembered
what was its genesis.

Russia was not represented at the 1920 International
Meeting, nor were the Germans, although informal communi-
cation with some of the latter investigators had been reopened,
and it was known that the exploring vessel, “ Poseidon,” had
been working since September, 1919. France, which had
hitherto been unrepresented, sent a delegate and experts, and
it was expected that the United States of America would also
come in: this, however, has not yet been arranged, so far as
I know.

The various sections of the Conference resumed their
deliberations very much where the latter were suspended in
1914 except for one matter—the effect of the admiralty restric-
tions of 1914-18 upon the fish population of the North Sea.

Over-Fishing in the North Sea.
It had generally been agreed that there was over-fishing
in some areas—particularly the North Sea—though there were

86 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

exceptions to this attitude: that of Professor McIntosh, for -
instance, as expressed in his well-known book, “‘ The Resources
of the Sea.” One must not forget that “ over-fishing ”—or
rather, a progressive diminution in the quantity of socially
valuable fish taken from the North Sea—has not yet been
demonstrated beyond all shadow of doubt. But however that
may be it was agreed that there had been much less trawling
during the war years than was formerly the case, and so there
ought to have accumulated a “stock” of large plaice. This
was, of course, the species upon which most research had been
made before the war, and the Council had already “ adum-
brated ” certain tentative proposals (I thmk that is the best
way to put it) with regard to international regulations. It
was important, then, that the effect of the great decrease of
exploitation should be estimated: were there more large
plaice in the North Sea m 1920 than im 1913? The Danish
experts brought forward what, to my mind, was an uncon-
vincing argument that large plaice were more numerous in the
latter year than in the former one, and the English investigators
produced data which, i think, put the matter beyond dispute.
But whether the increase in the larger plaice was to be traced
to under-fishing in 1915-18, or to a natural periodicity was not
so certain—I return to this point later. Anyhow, another
year of “ intensive plaice investigation ” was decided upon and
arrangements for the conduct of this were drafted. The nature
of the possible restrictions to be submitted, later on, to the
various governments was not formally discussed, but it was
understood that these would probably take a certain form.
Upon the condition that the Council would come to the scratch,
as it were, and suggest some legislative restrictions depended
the future of the investigations—this was the attitude, it must
be remembered, at a time when a partial collapse of the British
steam-trawling industry had already been anticipated, and
when it was fairly certain that the exploitation of the home

a

SEA-FISHERIES LABORATORY. 87

seas had fallen off, and was likely to continue to fall off. The
restrictions that were in the minds of the delegates were, of
course, legal size-limits and perhaps a closure of part of the
“ Flemish Bight.’ There was no general agreement as to the
precise shapes of the restrictions—the Dutch delegates, for
instance, adopted their traditional, national attitude of evasion.
As to whether the restrictions that were in question could have
been enforced—that question did not appear to matter. The
discussion had, in fact, that kind of tone which one calls
“academic.” Obviously the closure against trawling, by steam
and motor-driven trawl-vessels, of a large area of the North
Sea well outside the territorial limits ; the prevention of landing
of plaice of less than 20 or 22 cms. im length, according to
the season, and the closure of the spawning area in the Flemish
Bight would involve a rather considerable international police
service. Whether it is practicable to provide this at a reason-
able cost, and to render it efficient, was not considered.

The Herring Fisheries.

The Council took up the question of the “‘ Herring Races ”
where it had been left in 1914. It was resolved that the bio-
metric investigations that were in progress then should be
renewed. It was decided to undertake an historical enquiry

into the fluctuations of the fisheries for herrings which have

been experienced in most EKuropean seas during the last three
centuries. The Norwegian and Danish fishery services under-
took the organisation of these investigations.

The Hydrographic Research.

The position of affairs was discussed in the hydrographic
and plankton sections, and although arrangements for the
resumption of the work, on much the same lines as it was
conducted before the war, were thought out nothing practical
has, so far, been done. As the Committee are aware, the.
periodic cruises made by the “James Fletcher” during the
pre-war years have not been resumed, nor have the regular

88 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

hydrographic investigations that were conducted by the British
national fishery services in 1914 been restarted on the pre-war
scale. Itis apparent now that these monthly, or even quarterly
cruises are impracticable because of the greatly increased cost
of maintaining the vessels in full commission. Proposals for
a greatly modified scheme of research were made by the
representatives of the Ministry of Agriculture and Fisheries,
and the principal feature of these was the collection of samples
and observations by means of transatlantic and cross-channel
passenger vessels. I think this modification of the older
programme is thoroughly practical and adequate. With regard
to the Irish Sea, for instance, it would mean sending assistant
naturalists once a month on one or more of the vessels working
between, say, Fishguard and Rosslare, Holyhead and Dublin,
Liverpool and Douglas, and Fleetwood and Belfast, and it
would, probably, be quite easy to make arrangements for that
purpose with the various Companies. The new programme
would mean cutting out the collection of samples of water from
the bottom and intermediate levels, since to obtain these
soundings are required. But it is likely that surface samples
and observations would give us most of the data that are
immediately wanted. I undertook, on behalf of the Depart-
ment of Oceanography at Liverpool, to look after such work
of this kind as would be possible in the Irish Sea and in the
Atlantic with respect to vessels sailmg from this port.

Plaice Investigations in the Irish Sea.

After the meeting of the International Council an arrange-
ment was made between the Ministry of Agriculture and
Fisheries and the Committee for the conduct of research into
the “plaice problem.” The grant of £1,650 made by the
Development Commissioners in 1914 was renewed for the
financial year 1920-21, and most of it was expended upon the
part maintenance of the “James Fletcher” when engaged
on this work and upon the payment of the salary and expenses

SEA-FISHERIES LABORATORY. 89

of Mr. W. Birtwistle, who was appointed as Naturalist in the
summer of 1920. Weekly samples of plaice were obtained
from the various fishing grounds during the period June-
December, 1920, and were sent to the Fisheries Laboratory
at Liverpool, and the usual length measurements were made
on board the vessel when fishing. In this way records of the
leneths, when caught, of some 26,000 plaice were obtained on the
fishing grounds, and detailed records of the length, sex, stage
of maturity, weight, condition and food of about 6,000 plaice were
made in the laboratory. Mr. Birtwistle and Mr. R. A. Fleming,
Technical Assistant in the Oceanography Department, carried
out these investigations. The work is tedious and uninteresting
because of its routine nature, but sincerity and accuracy in doing
it is essential if it is to have value. I am satisfied that
invariable care and _ scientific accuracy characterised the
investigation.

Another arrangement was made between the Ministry and
Department of Oceanography with respect to the same research,
and a sum of money was paid to the University for this purpose.
Two ‘“ichthyometric assistants,’ Mr. W. C. Smith and
Commander A. HK. Ruxton, were transferred from the Ministry’s
staff and were paid out of the sum granted. These workers
went to sea in steam-trawlers, smacks and small boats and
made observations and measurements of the fish caught in the
ordinary routine of commercial trawling. In this way very
valuable data were obtained from grounds unworked by the
“James Fletcher ”’—the offshore regions between Lancashire
and Isle of Man and the northerly grounds between the Island
and the Solway Firth. The fish studied was the plaice, but I
have gone over the records made by the measurers and have
extracted the measurements of soles caught by the smacks.
These are interesting since they form the first extensive series
of observations on the characteristic lengths of soles caught
offshore in the Irish Sea. I hope it may be possible to resume

F

90 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

this work in May of 1921, when the sole spawning season
occurs.

I have made a report on these results and have incorporated
in it a summary of the Irish Sea plaice investigations carried
on by the Committee during the years 1908-1913. This enables
one to make a comparison between the post-war year 1920
and the pre-war period. When that has been done it becomes
evident that the marked increase in the abundance of large
plaice which characterises the Irish Sea no less than the North
Sea grounds need not be due to the partial cessation of trawling
brought about during 1913-18 by the wartime restrictions.
In last year’s report Mr. Daniel summarised the results of the
very valuable series of trawling experiments made during the
years 1890-1920 by Captain G. Eccles. These relate to a very
typical “‘small-plaice” fishery ground, that off the Mersey
Estuary, and they show an evident periodicity in the abundance
of plaice in this region. Durimg the years 1895-6 plaice were
very abundant, and the same was the case during the years
1909-10. Again plaice were relatively very scarce durmg the
years 1905-6 and 1915-16, so that durmg the time in which
the Committee has been in existence there have been two.
cycles of abundance and poverty of plaice. I have shown,
also, that there are very marked differences from year to year
in respect of the proportion of baby plaice of six to twelve
months old that are taken in the shrimp trawl-nets. This
means that in some years great numbers of the plaice fry that
have hatched out in the Irish Sea die—probably because there
is, in those years, insufficient planktonic food in the water about
the time when the fry are pelagic—that is, before they sink
down to the sea-bottom as completely formed little flat-fish.

So when one allows for this periodicity in the abundance
of plaice on the fishing grounds it is not at all certain that the
effect of the wartime restrictions on trawling was to increase
the natural stock of the larger sizes of plaice. It may merely

SEA-FISHERIES LABORATORY. 91

be the case (and this is what the Mersey statistics indicate)
that the years 1920-22 represent a natural maximum of abun-
dance, while the years 1914-15 represent a minimum.

Investigations in the Solway Firth.

The special grant for plaice investigation made by the
Ministry of Agriculture and Fisheries has enabled us to investi-
gate, for the first time, the fishery in the Solway. The upper
reaches of the Firth are a typical small-fish region while fairly
large plaice occur, in the autumn months, just north and south
of St. Bees’ Head. At the entrance to the Solway lies an
important plaice spawning ground, and ripe fish with clear,
running eggs were taken there at the end of February. The
shoals just south-west of Maughold Head, in Isle of Man, are a
good plaice ground during the first months of the year, but
later the larger fish leave there to spawn at the mouth of
the Firth. These investigations are in progress, and I hope
that we may be able to study this very interesting region
during 1921. In the meantime Mr. W. C. Smith has made a
provisional report on the Solway to the Ministry of Agriculture
and Fisheries.

Work on the Mussel.

Mr. Daniel has now nearly completed a year’s observations
on the seasonal changes that are undergone by the common
mussel. The investigation has been rather difficult since none
of the ordinary methods of chemical estimation of the “ proxi-
mate food principles,’ proteid, fat and carbohydrate, can be
strictly adapted to this shellfish. Modifications in the known
methods have to be elaborated in order that the investigation may
be as precise as possible. It has been found that the common
mussel is a very abundant source of the rare and expensive
substance, glycogen, the proportion of which in mussel flesh is
connected, in some way, with the spawning act of these shell-
fish. This investigation is far from bemg complete, and, so
far, a complete spawning cycle has not been studied. A

9°, TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

summary of the main results obtained so far is given in this

Report by Mr. Daniel.

So far, then, the work of the Fisheries Laboratory has
related partly to questions that interested us before the war
period (and which, of course, must still be investigated) and
partly to questions that are, in my opinion, of particular
interest at the present time. To the former category belong
the problems of over-fishing, size-limits, and the nature of
restrictions designed to prevent impoverishment of the fishing
grounds. These I regard as routine investigations which ought
to be pursued in order that data may be available in the future
when they become of pressing importance. So it 1s necessary,
from this point of view, to collect statistical information with
regard to such matters as the prevalent sizes of plaice, soles,
cod, and some other important species of fish : the composition
of the fish populations with regard to year classes and so on.
By and by all this information will accumulate and can be
worked up from new points of view.

To the latter category of investigations belong such as
will assist in production—when the time comes that an export
trade in fish may again attain large dimensions. These
researches ought to relate to the methods of preservation of
fish whether by refrigerating, curing, canning, or by other
means industrially practicable. In dealing with them there
are a host of questions which involve difficult and rather
abstruse chemical and bacteriological investigations, and,
unfortunately, it has not been possible yet to make a really
promising beginning with such work. There is also the very
important matter of the further utilisation of the enormous
abundance of mussels, cockles, shrimps and prawns that exist
in local waters. Tirst of all a renewed survey of the shellfish
beds on this coast is now necessary, and this ought to include
not only an examination of the foreshore from the point of

SEA-FISHERIES LABORATORY. 93

view of sewage pollution, but it ought also to include a natural
history survey. The present trade in mussels as food com-
modities appears to be coming to an end, and nothing can
prevent this but a rational attitude with regard to questions
of pollution and a satisfactory standardisation of public health
practice. This depends on research. Along with this must go
further investigation into the methods of cleansing sewage-
polluted shellfish, and the development of means of preserving
these animals in one form or other. The latter remark applies
also to the trade in shrimps and prawns. This is limited, as
a trade in fresh or potted fish, and some more permanent
methods of preservation must be devised.

One of the troublesome questions which the Committee
may have to consider in the near future is that of size-limits
with regard to plaice, and possibly other Irish Sea, fishes.
The matter does not seem to me to be urgent, for, just now,
there is a marked decline in trawling, both with regard to
steam vessels and smacks. Inshore fishing has also fallen to
a notable extent, and the effect (“if any ”) of this slackening
in trawling ought to be equal at least to that of any restrictions
on the size of fish that may legally be landed. It does not
appear, then, that there is any good reason for the imposition
of such restrictions—at the present time, at all events.

It is even doubtful (or at least, so I think) whether or not
restrictions on the sizes of plaice landed on the North-west
Coast of England would do any real good. If they benefited
anyone at all it would be the steam trawlers and smacks fishing
offshore in St. George’s Channel and in the Irish Sea. Whether
or not they would do so is not certain, and I don’t think the
benefit to the large vessels would be very apparent. Size-
limits of 20 or 22 ems. in the Irish Sea would certainly be very
difficult to enforce, and the present police organisation would,
I think, fail in such an attempt if the inshore men offered any
serious resistance.

94 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Further, I think it very doubtful whether the prevention
of landing of plaice less than 20 to 22 cms. long would result
in a marked increase in the prevalent size of the plaice caught
ofishore. To my mind such restrictions may have to be
accompanied by transplanting operations carried out on a fairly
large scale if they are to be justified. It is only that further
information may be obtained as to the nature of such trans-
planting that the plaice investigation is being contimued, for
we, probably, have all the statistical data that are required if
the only question at issue is whether size-limits should be
recommended, and if so, what limits. The whole question is
discussed, in detail, in the report which I have made to the
Ministry of Agriculture and Fisheries.

JAMES JOHNSTONE.

DEPARTMENT OF OCEANOGRAPHY,
University, LIVERPOOL
March, 1921.

SEA-FISHERIES LABORATORY. 95

SUMMARY OF THE WORK AT PITEL.

By ANDREW Scort.
Classes at Piel.

After an interval of five years, the classes in Navigation
and Marine Biology for fishermen were resumed in the spring
of 1920. The counter-attraction of high wages compared with
the value of the Studentships kept the steam-trawler men at
sea. Only the inshore men—the mussellers, cocklers, shrimpers,
etc.—applied for enrolment. Three classes were held between
23rd February and 20th April. The second class began
immediately after the first class ended. There was an interval
of about a month between the second and third classes. Most
of the men had been on various kinds of active service during
the war.

Mr. R. J. Daniel, B.Sc., had charge of the teaching work,
taking both the Navigation and Biology Courses. Dr. James
Johnstone, who had carried on the Biology Course from the
initiation of the scheme for educating the fishermen in the
hfe-histories of economic marine animals, had entered upon his
duties in the Oceanography Department at Liverpool University
and was unable to be present until the last class.

The students in the first class were all Morecambe men.
Those in the second class were selected from Morecambe,
Fleetwood, Blackpool and Southport. The third class was
again entirely composed of Morecambe fishermen. The
Studentships for the Blackpool and Southport men were pro-
vided by their own Education Authorities. The Education Com-
mittee of the Lancashire County Council provided all the others.

The following are the names of the men who attended the
classes :—

23rd February to 5th March.—HEdward Baxter, John
Baxter, R. Baxter, Rd. Baxter, Wiliam Baxter, James Swain,
Amos Willacy, H. Willacy, Reuben Willacy, Daniel Woodhouse,

F. Woodhouse and James Woodhouse—all from Morecambe.

96 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

8th March to 19th March.—John Alexander, Thomas Bell, —
John Bolton, Percy Bond, Mark Gerrard, Herbert Hodgson,
Arthur Johnston, Morecambe ; William Curwen, Herbert Raw-
cliffe, Ernest Wilson, Fleetwood ; Robt. Bamber, R. Cartmell,
Geo. Cornall, Blackpool; John Ball, James Rigby, Southport.

19th April to 30th April—W. Armistead, Richard
Bartholomew, Walter Bell, Samuel Bond, Thomas Bond,
Thomas Gerrard, Walter Gerrard, Thomas Mayor, George
Mount and J. Woodhouse—all from Morecambe.

A class in Navigation and Marme Biology for school
teachers was conducted by Dr. Johnstone and Mr. Daniel from
August 2nd to 13th. A number of names had been received
for this class, but only five gentlemen presented them-
selves when the work commenced. They were C. Saer, 8. A.
Palmer and C. E. Watson, Fleetwood ; Harold Milner, West
Bromwich, and E. R. Bird, 8. Lowestoft. The boarding-house
accommodation at Rampside and Roa Island is very limited.
It is almost impossible to secure rooms at short notice, especially
during the early part of August as that is the summer holiday
time at the large works in Barrow. In event of the August
vacation class for teachers being continued it would be well.
to try to complete arrangements as early as possible in the
spring.

Fish Hatching.

A return to this part of the work was made in the spring of
1920. Large plaice were collected in Luce Bay in October,
1919,-and conveyed to the tanks at Piel, where they afterwards
matured and provided a supply of eggs. For a time, at the
end of 1919 and the beginning of 1920, there was every possi-
bility that the Furness Railway would be unable to keep up
the supply of gas essential for working the gas-engine. The
lenethy strike of moulders at that period rendered it impossible
to renew defective parts of the plant, especially the cast-iron
retorts which had become badly cracked, allowing the gas to

SEA-FISHERIES LABORATORY. 97

pass into the furnace instead of into the gasometer. The Gas
Department of the railway did all it could to keep up the supply.
The store tanks had to be filled up every tide, and the circulation
cut down to a minimum to keep the fish alive as long as possible,
in event of a breakdown, and allow time to effect temporary
repairs. This probably accounts for a late spawning, as no
fertilised eggs were obtained until 24th March. The last fry
were set free on 15th May. Altogether 1,300,000 eggs were
collected and meubated. Sheghtly over 1,000,000 fry were
hatched and set free. No flounders were dealt with.

The Library.

One of the rooms was especially fitted up with cases of
shelving during the year so that all the books could be collected
together and made more easily accessible to workers. Miss
Allen, Departmental Librarian at Liverpool University, came
later on in the summer and rearranged the collection, and also
prepared a Card Catalogue of it. There is space for considerable
additions, and the catalogue will be easy to keep up to date.
Plankton.

573 samples of plankton, taken in connection with the
intensive study investigations, were received and quantatively
examined during 1920. The results are partly dealt with later
on in the report. Samples for comparison were collected from
time to time and examined.

Barrow Channel and the Oil Traffic.

Articles have appeared recently in the Press and elsewhere
drawing attention to the probable destruction of pelagic life,
including fish-eggs and larvae, by the rapid extension of the use
of fuel oil in place of coal in all kinds of mechanically-driven
vessels. It has been suggested that the accidental or wilful
discharge of oil into the sea may produce a surface film which
prevents the water absorbing air from the atmosphere so that
eventually the surface organisms may be asphyxiated. If the
microscopic food of the larval fishes were thus destroyed. the

98 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

larvae would starve to death. The destruction of larvae through
the want of sufficient food is not at all improbable, but this is
more likely to be brought about by an early spawning of the
adult fishes and a late arrival in the spawning area of the winter
and spring diatoms, etc. The investigations carried on by the
Lancashire Sea-Fisheries Committee and by the Liverpool
Marine Biology Committee, which extend over a period of
nearly thirty years, show quite clearly that the arrival and
abundance of the spring, summer, autumn and winter plankton
varies from year to year.

Barrow, within recent years, has become a very extensive
oil depot, and many millions of gallons arrive in tankers durmg
the year. Many of these tankers burn fuel oil. A considerable
export trade to distribute the oil is carried on by smaller
vessels. The oil-carrying trade has largely developed since the
laboratory was established at Piel in 1897. The whole of the
sea-borne traffic passes quite close to the establishment, and
any detrimental effect on the life in the channel would not
have escaped notice. Large beds of mussels occur in the
channel, and there is a general bottom fauna of zoophytes,
sponges, echinoderms, worms, crustacea, mollusca, tunicata and
fishes. Fully one-third of the periwinkles landed in the whole
of the Lancashire and Western District are sent away from Piel
Railway Station. These are collected along the sides of the
channel at low-water, and so far as the records show there is no
decrease in the output per man. In the period 1906-1914 the
mean annual man average was slightly under six tons. In the
period 1915-1917 it rose to nearly nine and a half tons. In
1920 the mean annual man average was nearly eleven tons.
Mussel fishing is prohibited owmg to danger of sewage con-
tamination, but the beds have not diminished in area or
apparent population. Formerly, very large succulent mussels
were obtaimable inside the dock area. These have practically
disappeared since the building and fitting-out of submarines

SEA-FISHERIES LABORATORY. 99

was started at the shipyard. This is generally attributed to
the escape of acids from the battery tanks. Dead conger-eels
and other fishes have been seen occasionally floating about im
the vicinity of the fitting-out berths. The fishery for sea-fish
in the channel is carried on throughout the year, but the results
are very variable. The fishermen suggest various reasons for
this such as too much steamer traffic, too much dredging, and so
on. It is quite certain that the success of the plaice-fishery
at any rate depends largely on the abundance of young mussels
up to half an inch mm length on the beds. As soon as the supply
is consumed the fish leave the area. The repopulation of the
beds is goimg on every year, but accidents occur, such as
sanding up and washing away by storms and tides, and a
fishery for plaice may only occur at irregular intervals. The
permanent bottom fauna, which can be seen very well at low-
water of a spring tide, has undergone no diminution. The
plankton of the channel corresponds with what is found offshore
and varies with the seasons. Fish eggs and larvae are fre-
quently found in the spring samples.

In 1919 and 1920 complaints were received from the stake-
net fishermen at Roosebeck that large quantities of thick oil
refuse were coming ashore and filling the tails of the nets as
the tide receded. Numbers of sea-birds were washing ashore
in a dead and dying condition. The matter was gone into and
the fishermen’s reports were found to be correct. The receding
tide for days at a time left the shores coated with oil, which
made everything very slippery. Quantities of thick, black
oily matter of a somewhat spongy consistency were also
washing up, and in this were immersed dead and dying black
ducks and divers. A point that was noted and also corrobo-
rated by the fishermen was the complete absence of dead or
sickly fish, and the shell-fish, mussels, periwinkles, etc., were
not being affected. It seemed to be quite clear that the oily
matter, although it was apparently destroying the sea-birds,

100 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

was not injuring the fish and shore fauna. The barnacles
everywhere between tide marks set free their larvae in the spring
of 1920 and 1921 in great abundance as in past years, and later
on the young barnacles attached themselves to the bottoms
of boats. The destructive action, so far as has been discovered,
was entirely confined to the birds. What probably happened
was that the birds regarded the floating masses as garbage of
some kind and dived into them, or they may have come up
accidentally into them after a dive some distance away. The
whole bird would at once be covered with the frothy oily matter,
which was very adhesive, and would finally become suffocated.
At that time vessels were being reconditioned, and the refuse
from the bilges, etc., was discharged into barges. It was then
conveyed out into Morecambe Bay where it was discharged,
and the southerly winds drove it ashore. The occurrence of
oil refuse on the shores of the channel was reported to Mr. J. M.
Mawson, the then representative of the Barrow Town Council
on the Sea-Fisheries Committee, and it came to an end. No
further complaints have been received from the local fishermen.

There are natural phenomena occurring every day at sea
which set up perfectly smooth places on the wind-roughened -
surface. Shoals of pelagic organisms may become massed
together by the action of wind and tides, and drift ashore as an
oily tract. The winter invasion of Noctiluca, described in the
Report for 1919 (p. 6), supplied a characteristic instance of wind
action and surface drift on pelagic life. The whole of the north
side of the water in the channel for a distance of nearly a foot
out presented the appearance and consistency of brick red-
coloured grease. It was due to a huge abundance of Noctiluca
drifted mto the harbour by a sheght southerly wind. An
uninstructed person might well be excused if he had reported
this as grease.

The correct management of an aquarium depends upon
one of two things. There must either be a constant circulation

SEA-FISHERIES LABORATORY. 101

through the tanks, or little or no circulation but an abundance

of growing vegetation. Aeration with a force pump has much
the same result as the action of growing vegetation. Should
the circulation stop through any cause, the animals in a tank
which has no vegetation die off in the ratio of their vitality.

Organisms such as Noctiluca have been kept alive in a perfectly
still tank fora month. An aquarium with growing vegetation
in it requires practically no circulation. We have a small fresh-
water aquarium that was started many years ago in connection
with the classes for school teachers. Vegetation was induced
to grow and it still continues in a flourishing condition. All
that is needed is a cupful of tap water added at intervals to make
up the loss from evaporation. Various organisms, such as

Hydra, Copepoda, Cladocera and Limnaea, have become estab-

lished and one generation succeeds another. A freshwater

stickleback placed in the jar in August, 1920, remains alive and

healthy after a lapse of eight months. Weeds and Diatoms,

in the presence of light, are the chief aerators of the sea. The

water is never perfectly still and the pelagic organisms are

constantly moving up and down in it. A surface film of oil

will not cut off the light sufficiently to prevent the algae and

Diatoms keeping up the aeration. Its lighter specific gravity

will also keep it clear of the pelagic organisms. When the film

of oil stranded on the sands, the Navicula, and other species of

Diatoms which form conspicuous brownish patches on the surface,
were not destroyed although the film was spread over them.

There is as yet, so far as Barrow Channel is concerned, no

indication that the oil trade and the extending use in the con-

sumption of fuel oil has had any harmful effect on the fauna

and flora. The chief engineer of one of the tankers making

frequent voyages to Barrow tells me there need be no discharge

of oil or fuel oil into the water. That would be regarded as

uneconomical by the owners and add to the running costs of the

vessel. The oil is recoverable from the refuse.

102 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

REPORT ON PLAICE MEASUREMENTS, 1920.

By W. BIRTWISTLE.

Although a few samples were examined in the early part
of the year, the main investigations did not commence until
June, and the bulk of the data was obtamed between this month
and the end of the year.

The measurements of length alone were all carried out
on board on live fish, either in the sailmg cutters or on the

99

fishery steamer “‘ James Fletcher,’ and the age and weight
determinations were made in the Fishery Laboratory of the
University of Liverpool from unselected samples of the ordinary
catches. The three main areas sampled were Nelson Buoy,
Mersey Estuary and North Wales.

Netson Buoy Area is the area enclosed by a line drawn
N.E. from Morecambe Bay Lightship to Walney, and a line
drawn §.8.E. from Morecambe Bay Lightship until Formby
Point is due East. Join these points for the southern limit.
It does not include the area enclosed by a line drawn from
Roa Island to Sunderland Shoulder.

Mersey Estuary includes all that area enclosed by a
line drawn from Formby Pomt to Pomt of Ayr (Wales).

Nortu Wates includes all that area between Point of —
Ayr and Pomt Lynas. It includes Beaumaris Bay to the
northern entrance to the Menai Straits.

Summary of Fish measured at Sea.

Area. Number. Period.
Nelson (Buoys. 22.>-c0- 8,046 June-Decemiber h..--.- see 6 inch Trawl.
North) Wales .22%......2- 5,656 January-December ......... Re
Mersey Estuary ...... 7,653 March-November ......... 3

MAT Ae: 1,249 November-Decembet ...... Shrimp Trawl.
Carnarvon Bay ......... 414 April= Augusta's. s.0-cescsneee 6 inch Trawl.
Menai Straits. ......... 1,152 January-December ......... 33
Cardigan Bay............ Li eyg April-September ............ be
inige Bay ch ajerackrnebe 194 Octobets caecoecs bees -
Morecambe Bay ...... 415 August-December ......... Stake Nets at

Flookburgh

Potal saense 25,956

a

SEA-FISHERIES LABORATORY. 103

Summary of Fish examined in Fishery Laboratory, Liverpool.

|
Area. Number. Period.
Nelson Buoy ......<...0 1,884 June-December .....:...... 6 inch Trawl.
North, Walesi..0....00... 1,616 June-December ............ i
Mersey Estuary ...... 710 May-November ............
_ A ee 866 November-December ...... Shrimp Trawl.
Menai Straits ......... | 829 January-November ...... 6 inch Trawl.
Carnarvon Bay ......... 34 ML pk cine setae sdeesastaven nese ders %
Motal 2... 5,939
|

Tasues I to V are summaries of Length-Frequencies of
fish taken on the various grounds by the 6 inch mesh Fish
Trawl.

Taste VI is a summary of Length-Frequencies of fish
taken in the Mersey Estuary Area by the 2 mch mesh Shrimp
Trawl.

TaBueE VII is asummary of the Sex-Age Group-Frequencies
taken in the North Wales, Nelson Buoy, Mersey Estuary Areas
by the 6 inch mesh Fish Trawl from June to December.

Tas_E VIII is a summary of the Sex-Age Group-Frequen-
cies taken in the Mersey Estuary by the 2 inch Shrimp Trawl,
from October to December.

TaBLE IX is a summary showing the variations in value
of the Length- Weight Coefficient K from the respective grounds
from June to December. In this table is given the number
of fish from which K has been calculated.

For indispensable assistance in the very laborious, routine,
biometric work of this and the followmg report I am much
indebted to Mr, A. Fleming, Technical Assistant in the Oceano-
eraphy Department.

104 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Tables I-V.

Summaries of the Length-frequencies of Plaice taken on
the various Fishing Crounds during 1920, by the 6 inch
mesh Trawl.

Table |. Carnarvon Bay Area.

April. May. June. July. August.
Length. —

No. | % | No. | % No. | % | No. | &% |e Nowaneen
14-5 mee a +.) S0-Geee. |
15-5 : = Maa ME LES) SE 2 | 10-00
16-5 .. = 5 | 4:904 1.2 2 | 10-00
17-5 t.} 2-70 a 1 | 0-98} 1 | 0-54] 4 | 20-00
18-5 1 | 2-70 a 159098 |e fe 2 | 10-00
19-5 be na 3 | 4-29] 4 |. 3-921 1. 1 0-54) Sea an
20-5 3 | S11] 4 | 5-71] 5.1 4:90] 2 | SEOs ie emenD
21-5 1°|°2-70|. 3 | 429] (7 .| 686) 3 | #e2/e sees
22-5 6 |1622| 2-| 2-86| 7 | 686] ° 9 | 4:86) one
23-5 1 | 2-70} 4 | 5-71|, 12 |11-76| 11 | 598) eoe
24-5 Pee eet) i. 10 | 9:80} 19 |10-27] 1 | 5-00
25-5 3°] 811| - 3. )- 4-291 8 | 7e8ab Te. | ieee Ex
26-5 2 (5-40). 3) 429) 12. 111-76) 23 ae ae
27-5 3 | 811] 10. | 14-29] 12 | 11-76] 25 | 13-51
28-54 4, | 2-70|- 28) |-19-43'|. 7. 6-86) Gases
29-5 2 | 540) 6.1.8:57] 1-1 098} 33 Jiueer
30-5 2 | 540{ 9 1286] 3 | 2°94). 41515 ee
31-5 se a V~| 1-43) ._.1. +). 0-984") Syl ese
32:5 2 | 540) 7 -1 10-00 |" = i 3 | 1-62
33-5 as ERIE fh ie 2 {oul08
34-5 3) 1) 4:90 17, ae 2 | Ae0s
35:5 1] 2-70 We Seas | ao agn eee 4
36-5 :. de | d-4321. iS 0-98
37-5 Po) 27024 1:43 |
38-5 - af set lige ot
39-5 : ¥ |
40-5 a. ‘4 ae ten
41-5 te O70! be, 0 a Se ay
42-5 Be Le: lal edge | 1 | 0-98
43-5 allt ext bigs Sf: Ae
44-5 ies ee
45-5 - ee
46-5 Se -
47-5 TAS ges
48-5 ey Wee
49-5 i =] 2°70
BOA Gh OX | sph
BLS ls dl 2-70
Totals ...| 37 bese 70 |100-03 102 |99-96| 185 | 99-97] 20 | 100-00

105

SEA-FISHERIES LABORATORY.

Redwharf Bay and Beaumaris Bay.

North Wales Area,

6 inch Trawil.

Table Il.

| Sooaaeoqqgoqooocooqoooocooecoo > S
sO] rHFUOSFRFSSHOHHSSSOHFOANOCOHHAAAHSH }
< ° SOMMAMAAMOCOOMHHAANGAAOOSOSOSCSOS S
r= |
= Se Chern .
Lae] a .
a) SAMAR ORHOORPrPrOOCOrPOHNMNH NAS RRR oS
| NH M MR AR eee ne
NWOWMONCAN N ANN S)
0 | BSSASOBHMBS eo; ep eNc0 cp
odie) NODMHANDON ie NAN >
pb ovale ieee! =r)
cS
fo) msOD OOD Hea to S| oo See ine)
Zz +
NOCHOMDOMFARHOTNNNS =
SOS Se aoe ame eg gens see gee ae es et cee : }
me ° TAA MMASSOHMHMOOATHS : oS
ah late? coy oe | Sa Ee ae Feb ee
el a |
© 5 8 INS OMMOHSCODAMMOMONHHSe HMA MMHNN = 2 ts ttt 3s tt tlt de
7 Sites Skink) Tie aie Re ie ee nk na Ue eM re eee aise ca Peo oro)
tots HH st Ot st Sa see
° See get eae Ree se ge eT ae Te Te r Hr aca ae
a oN “Lt rere ~ fey) Ter. 6) ged way) eid aa) cis aoe ~eorrere ~ oe a I~ S
3 ae |
Stleiws
= fe) ee i iro 4 ote | oH
7 Sy cea et en 6%, fee due Loma!
> HOR DOM MOSODHOHORHADAHAHOHODHOHR DDR ADDDNHNOD 4
SS (PR | sci t a ein Pd oon SIGN lea oN pel oN eB ICN es alae Marci Ce Heallall OG
Bs ° cS} AIEEE MMIDHNNARANAMMMMNANROMANG ASR OOnFOO!1S
ee
EB ee
oO fe} PHP LR HO ARAHAAM A OM MAM MO WOW OMI NW OD HOOD Ho OD CI 10
By a rs SNS Se 10
lo
HMOr-rmornstHOoOmMnDo HANDDSDONOHDOMDHDH ora) HHH Pe
BESO Macey © Slag eee ais ee ee ere ee BS QUCs > Gi ek= str SUS ae Sf oo eh eee
ES) SCADSMDOr HAHN 1019 SCNANANNMONnMA HO = O(a (S) () (S S
3
3
= .
fi fo) See Sel OCP eR me eM gnn Neocles oP) aot Se ee HEP RIO cao DREN oS CS Wg Rr, eel ad! 16
Z < Pigs
A a 1293918 19.13 10.19.15 19.19 19.1.2 1D 1G 19 1S 16-19 1D 18.15 10 1 18

pee ere OO So eS oe oy BS

We) oo oe Wl at

dil

HOAIANANMDHIOOMmOHOMAH HINO ODoOnA

———

a .

VOU AI OD 29 CD 6D 6 GD OD CD CFD CY SH SH SH SH SS ss ee f 1D 1D

106 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Table Il. North Wales Area. Redwharf Bay and Beaumaris Bay.
6 inch Trawl—continued.

_-—_

ea 1266 | 100-00} 820 | 99-95 | 222 Ae 765 | 99-98) 548 | 99-91] 1252 | 99-98

July. August. September. || October. November. | December, ||
Length. azn ear :
No. of No. | or | Ne. oe No. % No. oo No. Ta |
Pals. bape: : 1 | 0-183 |
14-5 4 0-32 I 0-12 . yee 1 0-18 2 0 i6
15-5 2 0-16 300 : 1 0-13 1 0-18 A
16-5 Ly 1-34 toe : 8 1-05 1 0-18 ong
17-5 ol 4-03 7 0-85 sist 19 2-48 | 12 2-11 10 0-80
18-5 86 6-79 | 45 5:49 6 2-70 | 62 8:10) |SaZ2 4-01 | 27 2°16
19-5 123 9-72 | * 95 1-58)" 4:95 | 125 | 16-3 44 8-03 | 29 2-al
20-5 7 9-24); 99 12-:07.| 24- | 10-81). 74 9-67 | 48 8:76 | 42 3°35
21-5 112 8:85 | 79 9-63 | 23 | 10-36| 80 | 10-46} 49 8-94); 40 | 3-19
22:5 95 7-50; 69 8-41) 21 9-46] 41 5:36] 55 | 10-04] 44 3°51
23°5 118 9°32| -77 9-40] 17 7:66 | 49 6-40 | 26 4:74| 62 4-95
24-5 125 Oe eS 07 | 1F 7:66] 38 4-97 | 35 6:39 | 58 4-63
25-5 110 8-69 | 53 6-46] 15 6-76 | 47 6-14) 36 6:57 | 70 5-60
26-5 83 656| 45 5-49 | 22 9-91 | 53 6-93 |- 3t 5:66 | 75 5°95
27-5 59 4:66} 30 3-65 | 17 7:66 | 41 5-36 | -31 5:66 | 113 9-02
28°5 41 3°24] 37 4-51) 12 5:40 | 36 4:70 | 29 5:30 |! 108 8-62
29-5 41 3:24] 36 4-39) 15 6-76 | 33 4-31} 24 4-38 | 113 9-02
30-5 25. | 1-97 |. 20 2°44) Il 4:95] 15 1:96 | 19 3-47 | 105 8-39
31:5 | 10 | 0-79] 20 | 2-44] 4 | 1:80} 8 | 1-05] 10 | 1-80] 82 | "Gem
32°5 3 boat OFA 12 | 1-46 2 0-90) 11 1-44) 15 2°74| 59 4-71
33-5 7 | 0-55) 13 | 1-58] 2 | 0-90) 7 | 0-911 16 |) 2:92)" Soest
34-5 12 0-95 4 0-49 2 | -0°90 4 0-52 4 0-73 | 35 2-79 |
35°5 8 | 0-63 i 0-85 500 500 8 1-05 af 1-28 ay 2°56.
36°5 6 | 0-47 7 0-85 1 0-45 3 0-39 7 1-28 | 18 1-44
37°5 q 0-32 3 | 0:36 599 1 0-13 5 0-91/ 12 0-96 |
38-5 . 1 0-12 ber Re 5 0-91 8 0-64 |
39-5 1 0-12 She | Sees 0-55 9 0-72.
40-5 pe 4 0-73 7 0-56
41-5 LI Ble el re 1 0-18 3 0-24
42-5 SST eng ce ot 4 0-73 6 0-48
43-5 1 | 0-08 / 1 |.0-18| 7 | 9GBI
44-5 aie 556 | ee ene “OE 4 0-32.
45°5 i 0-37 1 0-08
46-5 is 2 0-16
47°5 3 0-24
48-5 6 0-48
49-5 3 0-24
50°5 1 0-08
51-5 2 0-16
52:5 sae

SEA-FISHERIES LABORATORY.

107

Table til. Nelson Buoy Area. 6 inch mesh Trawl.
June. July. August. September.
Length. ee —
No. va No. % No. ON No. yf
14:5 pe uns ene se sud 2 0-09
15:5 11 1:25 <a ak 1 0:08 10 0-47
16-5 24 2-73 1 0-18 9 0:73 6 0-28
175 119 13-54 8 1:47 39 3°17 ou 1-74
18-5 170 19-34 52 9-58 102 8-30 74 3°47
19-5 166 18-88 67 12-34 123 10-00 139 6-52
20-5 145 16-50 39 7:18 162 13-18 203 9-53
21-5 81 9-21 33 6-08 138 11-22 246 11-54
22:5 48 5:46 20 3:68 108 8:79 274 12-86
23:5 45 5:12 25 4-60 110 8-95 239 TE-22%
24:5 30 3°41 37 6-81 87 7:08 191 8:96
25-5 16 1-82 44. 8:10 73 5:94. 154 7-23
26:5 9 1-02 39 7-18 55 4-48 114 5:35
27-5 1 0-11 51 9-39 49 3:99 90 4-22
28-5 3 0-34 38 7-00 57 4-64 96 4-50
29-5 2 0-23 32 5:89 38 3-09 75 3°52
30-5 sua a 16 2:95 oh 2-52 51 2-39
31:5 2 0:23 14 2:58 20 1-63 31 1-74
32-5 Moc Ne 5 0-92 9 0-73 28 1-31
33°5 at ait 8 1:47 fe AO on 37 1-74
34:5 se “ae a 1-29 4 | 0-33 14 0-66
35:5 2 0-23 2 0-37 3. | 0:24 5 0-23
36:5 1 0-11 2 0:37 VY | 30-08 5 0-23
37°5 oe a 1 0-18 1 0-08 1 0-05
38-5 eh meh 1 0-18 Qe LOG 1 0-05
39:5 2 0-23 sie Sas (Nate ane i
40-5 as ee oor ai | 4 aa
41-5 1 0-11 cr bs 1 0-05
42:5 I 0-11 1 0-18 | ms a
43-5 ws a nee a | sa: oe
44-5 sa | i
45:5 ee | ue
46-5 sia er
47-5 1 0:05
Totals ...| 879 99-98 543 99:97.) 1229 ~ | 99-98. | 2131 100-00

108 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Table Ill. Nelson Buoy Area. 6 inch mesh Trawl—continued.

| October. | November. December.
Length. | -— | -|

| No. WE No. | fs | 2 Net | y

| | | |
14:5 5 eee - |
15-5 ee | ; x. | ef
16-5 if: e 2 0-09 =
17-5 | 3 0-50 18 | 0-78 1 0-26
18-5 | 6 0-99 60 2-64 1 0-26
19-5 19 3-14 lll 4-88 6 1-56
20-5 Wt 29 4-79 167 7-34 8 2-08
21-5 tues ad 8-43 222 9-76 12 3:13
22-5 65 10-74 255 11-21 16 4-17
23-5 fae G7 11-08 294 12-92 32 8-33
24-5 81 13-39 290 12-74. 32 8:33
25°5 64 10-57 236 10-37 56 14-58
PES bye 47 UL 143 6-29 61 15-88
27-5 35 | 5-79 100 4-40 33 8:59
28-5 32 es ) 93 4-09 31 8-07
29-5 22 | 3-64 82 3-60 26° -. | 6am
30:5 | 19 |~ 3-14 59 2-59 16. | aes
31-5 32 | 5-29 40 1-76 22-9 No aes
32-5 | 9 | 1-49 36 1-58 is ~|° "3365
33-5 11 1-82 30 1:31 6 1-56
34-5 | 4 | 0-66 7 0-31 5 1-30
35-5 3 | 0-50 19 0-83 3 0-78
36:5 2 0-33 2 0-09 1 0-26
37-5 | 3 0-50 | 2 0-09 2 0-52
38-5 | B oe 1 0-04 A
39-5 1 0-17 | te
40-5 a “3 ee os mn se
41-5 io a | 1 0-04. 1 0-26
42-5 a | oe 1 0-04 5 ie
43-5 | | 4 0-18
44-5 a
45-5
46-5
47-5 |

Totals vcs6..2<: | 605 100-02. | 2275 99-98 384 99-97

SEA-FISHERIES

LABORATORY.

109

Table IV. Mersey Estuary. 6 Inch mesh Trawl.
March. April. June July.
Length. ? -

No. % No. % No. + % No. %

12-5 +3 a3 6 0-53 4 ||, 0:33 b
13-5 ae He 11 0-98 19 | 1:55 7 0-57
14:5 12 3-38 93 8-30 70 5-71 35 2-86
15-5 24 6-76 | 224 19-96 | 164 13-40 | 102 8-34
16-5 27 7-60 | 181 16-13 | 189 15-42 | 144 11-77
17-5 58 16-34 | 175 15-60 | 186 15:17 | 187 15-29
18-5 72 20-28 | 124 11:05 | 196 15:99 | 140 11-45
19-5 81 22-82 72 6-42 | 128 10-44 83 6-79
20:5 20 5-63 58 5-17 84 6-85 65 5-31
21-5 22 6-20 52 4-62 53 4-32 54 4-41
22:5 16 4-51 52 4-62 46. | 3-75 51 4-17
23-5 11 3-10 4.0 3-56 23 1-88 44 3-60
24-5 10 2-82 18 1-60 25 2-04 61 4-99
25-5 1 0-28 13 1-16 15 1-22 39 3-19
26:5 1 0-28 2 0-18 10 0-81 42 3-43
27-5 ‘es x 1 0-09 3 0-24 20 1-63
28-5 ae i. 6 0-49 25 2-04
29-5 2 0-16 29 2-37
30-5 ie - 19 1-55
31-5 8 0-65
32:5 a 12 0-98
33-5 oe 7 0-57
34:5 An 5 0-41
35-5 a 8 0-65
36-5 of 9 0-74.
37-5 ee. 4 0-33
38:5 is 3 0-24
39:5 a 1 0-08
40-5 3 Fi 0-57
41-5 1 0-08 5 0-41
42-5 1 0-08 2 0-16
43-5 ~ 1 0-08
4.4.5 2 0-16

45-5 sf =

46:5 i ve
47-5 1 0-08
48:5 1 0-08
Totals...) 355 | 100-00 | 1122 | 99-97 | 1225 | 99-93 | 1223 | 99-95

110

TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Table IV. Mersey Estuary. 6 inch mesh Trawl—coniinued.
August. September. October. November.
Length.
No. % No % No % No. %
12:5 ee sis ae 13 0-77 whe 558
13-5 7 0-54 40 a 0-42 wk Sob
14-5 37 2-88 5 0-67 86 5-12 Si 12
15-5 147 11-43 10 1-33 256 15:31 i S.
16-5 163 12-67 26 3°47 281 16-79 we ah
17-5 133 10-34 46 6-14 165 9-87 1 1-54
18-5 122 9-49 43 5-74 142 8-49 i 1-54
19:5 Tel 9-10 58 7:74 132 7:89 4 6-15
20-5 71 5-52 70 9-35 95 5-68 do sft
21-5 82 6-39 64 8:55 -| 96 5:74: 6 9-23
22-5 59 4-59 Wa 10-28 89 5-32 4 6-15
23°5 40 3-11 56 7-48 45 2-69 3 4-61
24-5 54 4-20 56 7 48 51 3-05 3 4-61
25:5 37 2-88 48 6-41 45 2-69 11 16-92
26:5 34 2-64 31 4-14 22 1-31 2 3-07
27-5 34 2-64 33 4-41 27 1-61 3 4-61
28-5 42 3°26 34 4-54 25 1-50 3 4-61
29.5 26 2-02 26 3°47 23 1.38 7 10-77
30-5 16 1-24 14 1-87 22 1:31 4 6-15
31-5 25 1-94 7 0-93 16 0 96 3 4-61
32-5 10 0:78 11 1-47 10 0-60 ae ts
33-5 12 0-93 9 1-20 10 0-60 2 3:07
34:5 6 0-46 10 1-33 6 0-36 1 1-54.
35:5 1 0-08 3 0-40 3 0-18 1 1-54
36:5 3 0-23 1 0-13 3 0-18 ee ae
37°5 1 0-08 4. 0-53 sicie ews 1 1-54
38-5 z 0-31 1 0-13 ee 2 3:07
39-5 ae oe 2 0-27 1 0-06 wes ds
40-5 1 0-08 1 0-13 1 0-06 1 1-54
41-5 1 0-08 we Lane a 1 1-54
42-5 ois an 1 0-13 A Me se
43-5 ons 1 0-13 : Bhs
44-5 900 sos ass 5 hoe
45-5 oF 1 0-13 ae ate
47:5 1 0-08 ie 1 1-54
48-5 gas | Boe site
Totals ...| 1286 SEP Oo) 749 99-98 1672 99:94 65 99-95
}

SEA-FISHERIES LABORATORY. 111

Table V. Menai Straits. 6 inch Trawl.

January. June. July. August.
Length. | © ————— - A J A J
No. vA No. a No. yi No. %
|

11:5 it 3-28 1 9-1 ud cc de
12:5 5 1-49 1 9-1 Se tee
13:5 34 10-15 1 9-1 2 3°51 Pp
14-5 31 9-25 2 18-2 7 12-28 5 15-62
15-5 42 12-58 2 18-2 13 22-80 5 15-62
16-5 35 10-45 2 18-2 9 15-79 6 18-75
17-5 21 6:27 Te 9 15-79 2 6-25
18-5 11 3:28 1 9-1 7 12-28 5 15-62
19-5 21 6:27 1 9-1 3 5-26 2 6-25
20-5 25 7-46 — 2 3°51 1 3°12
21:5 19 5:67 Ses 1 1-75 2 6-25
22-5 19 5-67 fe ene
23°5 22 6-57 1 1-75 ie
24-5 17 5-08 ve ve
25:5 5 1-49 ahs i
26-5 a 2-09 Se ae
27-5 2 0-60 es ae
28-5 3 0-90 Ze sis
29-5 5 1-49 1 1-75 oe
30-5 ese ae a
31-5 cai -
32:5 ce &:
33-5 sige a
34:5 ce =e
35°5 Je see
36-5 si 1 3-12
37°5 Sve sf
38-5 1p
39-5 e pe se
40-5 < 2 6-25
41-5 1 1-75 “a bs
42-5 ie
44-5 ase = a se ae aah 1 3°12
45-5 : ‘ wfacs os “ee ae
46-5 Sa
47-5 Bic ue
48-5 53.5]...1 1-75

Totals ...; 335 100-04 11 100-1 | 57 99-97 32 99-97

112 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Table V. Menai Straits. 6 Inch Trawl—continued.

|
| September. | October. | November. December.
Length. }—————_—————
| No o No. % No | % No. | %
|
12-5 a f 1 1-05 om | . | * a
13-5 1 2-63 1 1-05 2° --\5° 24S See 10-17
14:5 3 7:89 13 13-68 S° | |= eS 64 45 8-98
15-5 | + 10-53 18 18-95 10 12-05 61 12-17
16-5 2 5-26 11 11-58 1l 13-25 43 8-58
17-5 7 18-42 13 13-68 14 16-87 By 11-40
18-5 4 10-53 14 14-74 8 9-64 46 9-18
19-5 3 7:89 a 7:37 10 12-05 45 8-98
20-5 | 1 2-63 3 3°16 8 9-64 45 8-98
21-5 Se oy fon 2 2-10 2 2-41 51 10-17
22-5 ie 2263 3 3-16 4 4-82 26 5-19
23-5 3 7°89 a = 1 1-21 10 2-00
24-5 2 5-26 2 2-10 1 1-2] 10 2-00
25-5 |B Ss ee 00 1 1-05 1 1-21 5 1-00
26-5 ee aes om ame aan 5 4 0-80
27-5 em pi caer 1 1-21 ae os
28-5 Bee eli eect =: dee Be be
29-5 | 1 2-63 ok Z 1 0-20
30-5 Shh gees i mis oe
31-5 - bas Bs
32-5 fee Mel ates be Sei
Sao i= |. 2-68 1 1-05 oe es
34:5 ie Meee so3 1 1-21 see
35°5 Zz 526 | 2 2-10 1 1-21 Sate
36-5 Soe oe ies ate
37:5 1 2-63 aa oe: “he 1 0-20
38°5 = 1 1-05 ase
39-5 =< She =
40-5 + Ste oes
41-5 aoe Aer oe
42-5 ae Lae fen
43-5 eh. al 1-05
44-5 Bea Bef Te kale aoe
45°5 1 2 OB aoe aoe
46-5 ae aes Se
AT-5 | i Be e:
48-5 | 1 1-05
Totals ...| 38 99:97 | 95 2a 83 100-04 501 100-00

SEA-FISHERIES LABORATORY. L213

Table VI. Mersey Estuary. Shrimp Trawl,

May. October. | November. December.
Length. ———- —|-—- -—— ——__—
No. % No. % | No. | os No. 5
4-5 is see 1 0-21 Je det
5-5 ae ee 3 0-64 1 0-13
6-5 2 3°57 2 0-42 + 0-53
7:5 7 12-50 1 0-21 4 0-53
8-5 10 17-86 8 1-70 7 0-93
9-5 di 12-50 47 10-00 54. 761)
10-5 6 10-72 so 78 16-60 122 16-20
bid 2 3°57 5 19-23 74 15-74 150 19-92
12:5 3 5:36 3 11-54 53 11-28 148 19-65
13-5 I 1-79 a 15-39 35 7-45 107 14-21
14-5 3 5:36 3 11-54 36 7:66 59 7:83
15:5 + 7:14 2 7-70 31 6-60 36 4-78
16-5 1 1-79 2 7:70 22 4-68 22 2-92
17-5 ul 1-79 3 11-54 iy 3°62 11 1:46
18-5 1 U9 1 3°85 Lz 3°62 10 1:33
19-5 2 3°57 I 3°85 12 2-55 5 0-66
20-5 3 5:36 2 7-70 8 1-70 5 0-66
21:5 1 1-79 a 5 1-06 2 0-26
22-5 1 eri) nae 7 1-49 5 0-66
23-5 1 1:79 bse 4. 0-85 1 0-13
24-5 “is ade 4 0-85 ae =a
25-5 see 2 0-42 i
26-5 2 0-42
27-5 a de
28-5 ae
29-5 1 0-21
Potals ...). - 56 100-04 26 100-04 470 99-98 753 99-96

— ~ a

114 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Table Vil. Summary of age group frequency. Areas: Nelson Buo ;
North Wales, Mersey Estuary. Period: June to December: : |

I II III IV V VI VII VIII ik
Length. : _ ey
2] d| 2] do) 9] o| 2] s| 2] s|] 2] s| 2) S| elag
|
12-5 ee eA tase
13-5 | 2 DG Saale: }
14-5 9) 35) 455) 10 heal he ;
P5-5eeeds 1) Saleen) 27) Sa] al a ae .
16-5. 0 SS 45a\"515| 5) | 37 enelige:
Agee 0) |) 10 | 85107 | 16n) 14 te aoe
18-5 | 7 | 8 |125 |122 | 33 | 34 Bn hee |
19:5 | 10] 9 |122 |125 | 54 | 41 aa ltece H
20-5 | 14] 9 |133 | 89 | 70 | 52 2 soe lee
Pie’ |) Om 9401028267 || GIL) a7. soe le |
DER | PTE Te PSs | GBM Ee al vine ae .
23-5 1 io76"| F208! 4 86 2 Slee
24:5 is7) 46rlas W0sy Bal Re {
25-5 25123 nO2ul Say ate) we PT a 4 |
26:5 20 | 13 | 95 | 82/ 3] 5 ae §
27:5 17) LOMNOS S20 Sala ae 1
28-5 6a (Gale7 1 Gn) amas eae ft
29-5 Bull Ga oGi 2 2n aiien oes ae eee 3
30:5 2A DEON VAM a OM aI ah icc t
31-5 30) 250) Oia Rival desch. Ue eee ae .,
32-5 V7 ASE UST ral 1 cel Seen f
33-5 Onl 4a Sena a) a eae ae t
34-5 37) lel 25 gl Oe aes eee | ee }
35-5 The: eed MSS) lara MR Teton e |
36-5 AEE TL HE alors] ia , :|
37-5 eal OM al Pos eal ae oe |
38:5 eRe eee aes 1 5
39-5 aaalers 2 a
40-5 lal 2
41-5 i dat. ee
42-5 NS 3
43-5 a 3
44-5 I 2
45-5 Ss
46-5 1
47-5
48-5 3 2
49-5
50-5 1
51-5 1
52-5 |
Totals ...| 81 | 71 |962 |908 |1018/908 | 99 | 97 | 7/24] 1| 4 | 2

SEA-FISHERIES LABORATORY. 115

Table Vill. Age group frequency—October to December—
Mersey Estuary—Shrimp Trawl.

0 I II IIT IV
Length - : —
Pei oe lwieee hye dais Vesale 2
4-5 2 2 : Son aes ze Bh
5-5 1 2 ve oor Ae Pee eae
6-5 1 iL) iene Belen: i Ma
75 1 eae ee EE eal es:
8-5 2 8 Uae eaearen ese Phan | toe:
9:5 Qa. | 82) |-.46 ian Ree st a
10-5 BO 1 2 cea et
11-5 TA iearld POO AN osha cle ozs tal Bet
12:5 A BT 1 1 ea: ae
13-5 IP pero 3ay 52 1 1 dahl past
14:5 of | 28 4. 3 Lee
15:5 18 | 18 5 8 pees,
16-5 14 | 14 5 5 a
17-5 3 8 7 3 [Venti Se air ot
18-5 2 Bi eb 8 oe een ae
19-5 3 2 3 5 vi | gale
20-5 1 4 GAL. sre eNaenlt hs!
21-5 occa A gone: Nel een eae 3 A te | a
22-5 538 | SS aa 1 2 Cie alte haa epee
23-5 vont) cael Sane ia | SA Ne ea 1
24-5 2 [enreene DPD ae.
25-5 1 AE ie ee
; 26°5 1 es 1 gisye
ie 6275 a i
it 28-5
} 29-5 i
Se Worle se, | 10)°) 318 | 492- | 54 | 48 3 5 1

Table IX. Values of the Length-Weight Coefficient K. 1920.

No. | Nelson | No. | North | No. | Mersey | No. | Menai

Buoy. Wales. Estuary. Straits.
SUING) cione.no s 2 256 1-020 | 249 1-000 | 134 0-960 ane ha
CUE te ciain eins « das 297 1-059 | 148 1-015 | 286 0-973 48 1-020
AUGUSE .4....... 145 1:020 | 131 1-052 81 1-018 28 0-960
September ...| 405 1-079 | 147 1-047 dl 0-998 33 1-034.
October) i ~...:. 296 1-040 | 296 1-039 | 178 0-969 81 0-968
November...... 344 1-067 | 335 1-016 | 354 0-948 80 0-995
December ...| 127 1-200 | 211 1-084 | 434 0-941 525 ake

116 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

BIOMETRIC INVESTIGATIONS ON THE HERRING.

By W. BIRtTwIstTLe.

Two samples of herrings, taken by drift-nets off the South-
west of the Isle of Man, one in the third week in June and the
other in the first week in September, were sent to the University
of Liverpool for detailed examination. It was not possible to
deal with the whole of each sample in the fresh condition, so
they were kept in cold storage, and examined when circum-
stances permitted. About 60 fish of each sample were examined
fresh. Each sample consisted of nominally 250 fish = + cran,
and were quite unselected.

The usual characters were examined and recorded, viz. :—

1. Total length from extremity of snout to the vertical
line joming the tips of the lobes of the caudal fin in. the natural
position. [T.]

2. Total length to base of tail. ['T.cd.]

3. Length from tip of snout to beginning of dorsal fin.

[D.]

4. Length from tip of snout to beginning of pelvic fin.

5. Length from tip of snout to anus. [A.]

6. Lateral length of head. [I.ep.1.]

7. Number of keeled scales between anus and _ pelvic
fins. [K,.]

8. Sex recorded.

SEA-FISHERIES LABORATORY. 117

The condition of gonads was noted and was recorded by
Hjort’s notation. In addition scales were taken from each
fish for the estimation of the age.

There was a marked difference between the two samples.
The samples taken in June had a mean length of 203 mm.,
measured from tip of snout to base of tail [T.cd.]. The fish
in this sample had only a moderate amount of fat in the ventral
cavity, and, with few exceptions, were virgin fish in the first or
second stage of maturity.

The investigation of the sex composition showed the
males to predominate by about 16 °%. No food could be found
in the stomachs.

The examination of the scales showed the sample to consist
of 55-8 % of fish with two completed winter rings, 37 % with
three, 5-8 % with four, 0-5 % with five, and 1-00 % with six,
so that the sample may be regarded as consisting almost
entirely of fish, with two or three winter rings on the scales.

The very trying work of scale-reading, including the
calculation of the percentage-growth rates was only made
tolerable by the help of Miss H. Mabel Lewis, Research Assistant
in the Department of Oceanography, and for her amiability
and patience I am much indebted.

The September catch, taken about 12 miles W.S.W. of the
Calf of Man, had a mean length of 234 mm., and was a good
sample of fish with considerable intestinal fat. Practically
the whole of this sample was in the fifth stage of maturity.
Males predominated by about 7%. Several specimens were
found with the stomachs full of Meganyctiphanes norvegicus.

Scale examination revealed the followmg grouping :—
5-9 % with two winter rings, 5-4 °% with three, 21-1 % with four,
32-1 % with five, 22:4 % with six, 7-6 9% with seven, 5-1 % with
eight, 0-4 with nine.

118 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Comparison by weight of the respective samples.

About 60 fish were taken from each sample and weighed
fresh. The results were :—

JUNE SAMPLE. SEPTEMBER SAMPLE.
Mean :

Length [7'] Frequency. Av. Wt. Frequency. Av. Wt.
mm. in grms. in grms
205 1 74 sae s
215 10 78 a se
225 20 88 2 103-5
235 26 97 1 96*
245 7 103 4 148
255 1 130 6 146
265 1 132 1 169
275 ee 18 198
285 a 18 215
295 7 228

ataiser sewn 66 57

* Spent.
Comparison of stages of maturity.

Sample. Fre- IF | JIE WT. }- TV. | V..cf Wile Va ieee
quency mined.
| es |
| 1% 1% 1 Mak 96-) | % || err

June” 222. ora betel ay 7-47 | 1-86 _| 0-47)" 25" jae 1-40
September 242 ss ... | 0-83 | 0-41 | 90-41 | 3-72 | 4-54
| | | |

Where a fish is between two stages it has been placed under
the higher stage.

Sex composition of the two samples.

Sample. Frequency. | 3 | 2 Undetermined.
eee | % %
MIIB +. ees ese oer 214 57-00 41-59 1-40

SEA-FISHERIES LABORATORY. 119

In the June sample three fish were noticed in a more
advanced state of maturity than the majority of the sample—
two in Stage IV and one in Stages IV-V. There is evidence,
from size and scale markings, that these fish belong to a group
similar to the fish in the September sample at Stage V. This
being the case, 1t would suggest that it has taken approximately
ten weeks for the herrings to advance from, say, Stage IV
to Stage V. And again in the September sample, two fish
show a less advanced stage of maturity than the majority,
being in Stage III. LHvidence from length and scale markings
suggests a possibility of their belonging to a group similar to
those in Stage II in June, so that if the assumption were
permissable, it would indicate that they had advanced from
Stage II to Stage III in approximately ten weeks.

Although the data are small, they at least indicate one
of many pomts which it is hoped will be found possible to
investigate durmg the present year. Another interesting
point arises, inasmuch as the fish curers stated that two weeks
previous to the September sample, nearly all the fish passmg
through their hands were Spents (= Stage VII) and taken
from the same grounds. Unfortunately we have no data, and
nothing can be said in confirmation of this.

They stated, however, that they were similar in size to
the September sample, and were uncertain how long this supply
of spent fish lasted.

That there are spawning grounds in the vicinity of Isle
of Man seems certain when a spent population is replaced by
another about to spawn, 3-72°% actually spawning, and
4-54 % finished spawning. Furthermore, conditions are
favourable on these grounds where there is abundant Laminaria,
rough ground and deep water of about 20 fathoms.

120 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Estimation of age by scale examination.

Scales were taken from each fish, cleaned and mounted
dry on a glass slide. .

The original intention was to count the winter rings only,
but later on it was decided to record the width of the respective
summer zones on the scales as percentages of the measured
part of the scale—i.e., the total distance between the “ base

2

line” and the outer edge of the striated portion of the scale.
This distance was measured by a micrometer eye-piece in
conjunction with a low magnification. In actual practice it
was found that the personal error might amount to +1%,
so that this error should be kept in mind when examining the
summaries. The results of these measurements show that in
separate year-groups the completed summer areas show a ~
considerable variation. For example, the two-ring scales of
the June sample show a variation in the first summer growth
from 38 °% to 74 °% of the measured part of the scale. By
examining the tables the other variations will be seen.
Whenever a doubtful scale occurred it was stained in silver
nitrate, and examined under polarised light. This materially .
assisted in the elimination of false rings.

EXPLANATION OF THE TABLES.

One typical scale belonging to each herring has been
measured, and these scales are grouped as “ two-rings,”
“ three-rings,” andsoon. The “f” columns show the numbers
of scales measured.

Thus, for the group of 2-ringed scales (J une) we have one
scale in which d, is between 36 and 40% of the distance T
(fig. 1); 3 in which d, is between 40 and 44 % of 7; 3 scales

SEA-FISHERIES LABORATORY. 121

in which d, is from 80 to 84 % of 7’; 10 in which d, is 84 to
88 % of 7, and so on. So also with the 3-ringed scales and
the higber groups.

The d’s are thus not absolute measurements but relative
ones—being percentages of the 7’s of each scale.

Fic. 1. Diagram of a 2-ringed scale.

TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

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TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

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SEA-FISHERIES LABORATORY. 125

We shall now summarise Tables I and I]——with interesting
results.

(a) June sample.

No. of Rings in a Scale.
2 3 4

J (SR 57-8 41-0 41-0

BOM Oars seein dics ve ew's 33-2 30-0 29-0

CR eR f aoe cine rises decease 91-0 71-0 70-0

PMA lens d ph dia atv cess : 22-0) 18-5
MG inn ckia'y cis je «sie ve 93-0 88-5

PAMERAE (ioe) vhivs Uiatichie dees a BAS 7-3

CMM ran Skee) cihiasste'ek ajc «| 95-8

(6) September sample.
| No. of Rings in a Scale.
ae 3 | Sas ia) OFS eae te 8

(xt. Cea eee 52:0 49-3 49-4 46:0 44-0 42-4 43
PE Ne a sissies. 36°8 2g-2 26-4 27°6 26-6 27-8 26-3
Cie Sea ae 88°8 78:5 75:8 73-6 | 70-6 1052) | GS
De case cscss| 15-2 13-6 12-7 13°9 Sl, ela
OU eens astsisy sis 93-7 89-4 86-3 84:5 83-3 83-0
AVS teaaae~ Ape ae 7-4 7-0 6-6 6-5 6-1
CL On ARE 96:8 93:3 91:1 89:8 89-1
Nae dedegs aga ae 38 38 od 3-1
Jp ae 97-1 | $49 | 93-2 | 92-2
ID 8 a cso | any, 2-1 2-8 2-4
ne | 97-0 96-0 94-6
ee. 3 chon. | rag aM | Lei
he | “ 98-1 96:3
PO eee eis s aig ES
Teena 98-2

In these summary tables the mean values of the d’s are
collected for scales that have two up to eight rings. The A’s
are the differences between these mean values, that is, they
are the mean widths of the zones of the scales added by growth
in each year. Thus, in the June 2-ringed scales 33-2 % of the
ringed portion is added on during the interval between the

126 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

laying down of the Ist and 2nd rings. But that is only the case
with the 2-ringed scales: in the 8-ringed ones only 26-3 % of
the ringed portion is laid down between the dates of formation
of the 1st and 2nd rings. This curious effect can be observed
throughout the tables (if one allows for the errors of the means
it is quite general). It seems as if the whole scale shrinks up
in the older fish and shrinks the more, the older the fish is.

Further, there is an obvious difference between the June
and September samples.

These results appear to have important bearings, but it
will be advisable that other investigations, which are in progress,
be made before a full discussion is attempted.

Table Ill. Showing Length— Ring frequency.

JUNE SAMPLE. SEPTEMBER SAMPLE.
ede Rings. Rings.
Length nie |
il D, 3 4 5 6} 1 Y 3 4 5 6 7 8 9
mm.
181-190 Ay 8 7 fe Netanya ros, Male tee ee aa one
191-200 Ea tot lu 2 1 hla spall esis call a8
201-210 paral 45) 129 Liege ey 1 Fane eee Lee su
211-220 Bes ee be | TAL Eee: 8 7 RO 1K ae
221-230 eae Ab oo, AS le Reel see 1 Ses ales 9 2, aoe
231-240 Sean ea 1 Wie Mlbee Pel oe 1 soe 3 1°25 | 38 a2 8 Gale
241-250 Se Ae MC actin abicts er 1 ead etre ete 2>| 225ml S ial ales 8 6 ]
251-260 gist dla woke: laremrtal|y aie. glee ||| “epresill® tateias| pucenn |e osaisen | aici lite | Al :
. 106 be 70) {peta 1 2 |. | 14>] 13:1 50! | 76. Sao 1
JUNE. SEPTEMBER.
mm. mm.
Mean length of fish with 2 ring scales = 202 Mean length of nsh with 2 ring scales =210
99 99 3 29 = 202 99 99 3 99 = 5)
9 29 4 22 =214 2” 29 4. 29 = 232
99 ” 5* 2 = 225 29 99 5 29 = 236
” cy) oe ” = 238 ” > 6 ° = 2837)
i, 53 Te 3 = 238
9? 9 8 9 = 240
99 29 g* 99 = 245

* | example.

SEA-FISHERIES LABORATORY. 127

ON IRREGULARITIES IN SEA-TEMPERATURE DUE
TO TIDAL OSCILLATORY STREAMS.

By R. J. Dantet, B.Sc.

It has been suggested by Professor D’Arcy Thompson*
that the annual temperature variation, at a fixed position in
the sea, can be represented by a Fourier Series. There ought
to be one principal component in such a series, and this ought
to account for the greater part of the variation above and
below the annual mean temperature. Then there ought to
be other components of 4,4,4, and so on, of a whole year, each
of which also accounts for some of the variation from the mean
annual value. Some, of course, of these minor components
may be expected to have small amplitudes; so small that
they may be neglected. An harmonic analysis of the annual
temperature fluctuation, at any fixed position, ought, therefore,
to give us a series of equations, each of which will represent
an harmonic oscillation, and the phase and amplitude of each
oscillation would be given by the analysis. If, then, the various
components be added algebraically the summation ought to
reproduce the observed annual temperature oscillation.

Of course, in making such an analysis, we ought to assume
the periods of the various components and then evaluate
their phases and amplitudes. That supposes a theory (or
explanation, rather) of the causes of variation in sea-tempera-
ture. Obviously the principal cause is the annual change of
declination of the sun. In the case investigated in this paper
the other causes are tidal oscillatory streams, by means of which
heat is transferred from the sea to the land, or wice versa.
These oscillations are assumed to have (1) a semilunar period
(the neap and spring tides), and (2) a semi-annual period

* Rept. II Northern area, North Sea Fisheries Investigations, cd.
3358, 1907, p. 185.

128 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

(equinoctial tides). An annual sea-temperature oscillation
ought, then, to decompose into three component oscillations :—
(1) Annual; (2) Six-monthly; (3) Fortnightly. On adding,
algebraically, these three oscillations there should result one
that is very similar to the observed oscillation. There ought,
of course, to be a “ residue ” unaccounted for by the analysis.

The explanation, it has been said, assumes that heat is
transferred between the sea-position investigated and the
adjacent land by means of tidal oscillatory streams, and it is
easy to see that this must be the case. In winter the extensive
sand-banks, uncovered by the ebb-tide, lose heat by radiation
and evaporation, so that they become colder than the sea-water
that flows over them at next flood-tide: therefore, that water
is cooled, and when it ebbs out seawards to the sea-position
under investigation it dilutes the warmer water there by colder
water. A reversal of these conditions occurs in the summer
months.

The question presented itself: could the annual tempera-
ture oscillation, at a pomt in mid-channel in the Irish Sea, be
subjected to Fourier analysis so as to bring out the three
periodic oscillations mentioned above and then leave a residue .
which might be traced to other periodic or unperiodic causes.
It is probable that Fourier analysis is not theoretically justi-
fiable, for the method assumes that the function (the annual
sea-temperature oscillation at a fixed station) is periodic—that
is, repeats itself exactly from year to year. But it does not;
and there are quite well-marked variations in (1) the dates of
maxima, mimima and means, and (2) amplitude from year to
year. These may, of course, be due to an oscillation, the period
of which is a number of years, but about that we do not know
yet.

Anyhow, it appears to be worth while to look for the
existence of a fortnightly component of sea-temperature
oscillation before plunging into Fourier analysis. This is the

SEA-FISHERIES LABORATORY. 129

object. of the present investigation. And it is obvious that
we must know all the principal causes of variation of sea-
temperature before we can, with confidence, say that the
difference between one year and another is due to, say, a greater
or lesser influx of Atlantic water into the area in question.

A series of readings of daily sea-temperature at certain
hight vessels in the Irish Sea have been given to us by the
Meteorological Office: at present we deal with the period
1907-12, 1914. The temperatures for January, 1915, are also
considered, after which month the records cease for the rest of
the war period. Chiefly, three light vessels are in question :—

‘Morecambe Bay: Lat. 53° 54’ N.; Long. 3° 31’ W.

Bahama Bank: Lat. 54° 20’ N.; Long. 4° 13’ W.

Carnarvon Bay: Lat. 53° 06’ N.; Long. 4° 49’ W.

Carn aryo :

SoC

Fic. 2. lLightships and hydrographic stations.

130 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Bahama Bank Ship and Carnarvon Bay Ship I consider to be
“ open-sea ”? stations, which are much less under the influence
of the land than is Morecambe Bay Lightship. This is about
16 miles distant from the mouth of Morecambe Bay,and the run
of the tidal streams is such as to transport water from the
Bay to the region between the Bahama Bank and the More-
came Bay light vessels. Therefore, the sea-region about the
latter position has a greater range of temperature than at
either Bahama Bank or at the middle of Carnarvon Bay.
It is to the influence of the land that we look for the explanation
of this greater range. Now the greatest differences of tem-
perature between sea and land are experienced during the
months January to March and June to September, and so we
find it advantageous to use either or both of these periods in
making comparisons between the various stations.

Two temperature readings are taken each day at the light
vessels—at sunrise and at 4 pm. It is the latter readings
that are taken into consideration here: the fact that they
are made at continually varying states of the tide 1s a condition
that may be neglected, as we shall see later. The readings
are Fahrenheit ones, but they have been converted into the .
corresponding Centigrade values.

The daily temperatures for the months January to March
are grouped in periods of ten days, and means are calculated.
These means are then plotted at the centres of the periods:
thus, the mean for January Ist-10th, 1907, is 6-27°C., and
this figure is plotted against January 5th. The ten-daily
points are then found, and a smoothly-running curve is drawn
through or among them. Mean temperatures for any day
are found from this curve. eS

If these smoothed curves are drawn for the first three
months of each of the years considerable differences will be
found. Thus, in January-March, 1912, there is 2 comparatively
great range, which is about 7° C. at the beginning of January

SEA-FISHERIES LABORATORY. 131

and the end of March, and which is minimal at 4:7°. Such a
curve cuts through those of years when the range is less.

When these smoothed curves for Bahama Bank and More-
cambe Bay light vessels are compared it is seen that their
general appearance, with respect to each other, are the same,
on the whole; and this is so even when the curves from the
same one light vessel, in different years, may be very different.
The Bahama Ship temperatures are higher throughout all the
years considered except 1907. In that year the temperature
at Morecambe Bay Ship was minimal (4:54° C.) on Jan. 31st ;
but it rose rapidly, and on February 16th it was higher than
at Bahama Ship, not only so but it was higher than at Carnarvon
Bay Ship, which is more southerly, and is in the core of the
water streams moving from south to north, and is less affected
by the influence of the land than 1s either of the other stations.

The general similarity, in shape, of the curves for More-
came Bay and Bahama vessels, and the higher range of the
latter are to be expected when one looks at their respective
positions. The latter vessel is just north of the line from
Maughold Head and Walney Island, along which line the tidal
streams that come through St. George’s and North Channel
meet, and form an area in which there is little oscillatory ebb
and flood, but a large, vertical oscillation. It has been found by
study of the salinities along the Maughold Head— Walney Line
(Hydrographic Stations I-III*) that this area is greatly affected
by the tidal streams ebbing out from Morecambe Bay. In its
eradual transference across, towards the Manx coast, this
water is greatly mixed with that which comes up from
St. George’s Channel because of the resultant tidal drift from
south to north. This mixed water, of course, gradually passes
out through the North Channel.t

* Bassett, ‘“‘ Report on Hydrographic Observations,’ Ann. Rept.
Lancashire Sea-Fish. Lab., 1907-14 ; Johnstone, 2bzd., 1908, p. 79.

+ Knudsen, Publications de Circonstance, No. 39, 1907.

132 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

While the position of Bahama Bank Vessel does not exclude
this effect of the bank water (as shown by a comparison of the
temperatures and salinities with those from Stations V-VII,
where the conditions are such as to let the Atlantic water become
a factor), the effect is much less evident than it is at Morecambe
Bay Light Vessel. The cause of the variations from the simple
harmonic curve in the graphs of sea-temperature at both
Bahama Bank and Morecambe Bay ships may be looked for,
therefore, in the local inshore conditions.

One clue to the causes of these variations may be found
in the various positions of the minima of sea-temperature.
Thus, the differences between the dates of the minima of the
smoothed curves for Bahama and Morecambe Bay Ships are
shown below :—

Morecambe Bahama Difference.
Bay. Bank.
Days
GOT Sarg ieee Et atide ctates January 31 February 20 20
LOGOS Fass nsaseoseeese-pesie ss February 14 March 8 23
NUD psadancoaossoconoqoodesodde March 1 March 6 5
WMO cconcssuctodsoqoassccasse January 30 February 3 4
ID) Cond gaogncdsacestosoadance February 9 February 11 Z
WON eine ew claoeaiia eee bgh es | February 9 February 4 5)
LOW A rectece se aaes icicles eactsses _ January 26 January 22 t

Thus, the difference in the dates at which the minima occur
may be from 2 to 23 days. The years 1912 and 1914 are the
only ones in which the minimum for Bahama Bank occurs before
that for Morecambe Bay. There was a marked deficiency in
both the air-temperature and the amount of sunshine until
February 10th in 1912 and until January 24th in 1914; and
apparently the temperature of the banks in Morecambe Bay,
which are laid bare by the tides, cooled the offshore water and
delayed the usual rise of sea-temperature in those years.
1907 and 1908 are, however, very exceptional years, for the
difference in the dates of occurrence of the minima were 20
and 23 days respectively; and they are also years which

SEA-FISHERIES LABORATORY. 133

show, on the whole, the greatest differences in mean temperature
at the two light vessels in question, though the exceptional
nature of the conditions is not so strikingly shown as in the
dates of the minima. Now it has been suggested that the
general weather conditions act on the coastal strip of water
between tide marks* to a much greater extent than on the
water of the sea; but the change in temperature of the banks
then acts on the sea (in some years, in the past, Morecambe
Bay has had much ice on the banks in the winter months).
This effect of the banks on the coastal sea-water is also shown
by the rapid rise in sea-temperature in 1907, during February
and March, when there was abundant sunshine and an air-
temperature higher than the normal for this time of year.

There are, however, many factors which are bound to
affect the temperature of the sea in such an area as Morecambe
Bay. These conditions must be very complex, and it can
only be during spells of exceptional weather, when one or a few
factors predominate, that it is possible to trace out connections
such as we are anxious to elucidate.

The heating and cooling of the sea-water in the Morecambe
Bay area must, however, be largely influenced by the flowing
and ebbing of the tides over about 100 square miles of sand,
uncovered every twelve hours. Now, since the spring tides
cover and uncover a larger area of sand-banks than do the
neaps, it was thought possible that there might be a correlation
between the deviations from the mean sea-temperature (as based
on the ten-daily averages) and the succession of neaps and
springs. Morecambe Bay Light Vessel is about 16 miles distant
from the mouth of the Bay, and its position is such that it is
not far from the main course of the floods and ebbs. (The
tide from the north part of the Bay, however, streams north
and south along Walney, and does not pass close to the ship.)
There is a mass of water, however, flowing past the ship, for nine

* Which is, of course, enormous in Morecambe Bay.

2
f
i

134 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

miles at springs and six miles at neaps, and this water has been
mixed with that which has been in contact with the sand-
banks. That this is so (that the influence of the tide streaming
off the sand-banks is indirect at the ship) is shown by the
fact that there is no evident connection between the sea-
temperature at the ship and the state of the tide, whether

aunsUusae nny, Februar March

Fic. 3. Temperature and tidal variations in January-March, 1907, Morecambe Bay
Light Vessel.

flowing or ebbing. There would be such a connection if the
influence of the banks on the ship were immediate and direct.
So one can use the daily, 4 p.m., observations of temperature,
even though the latter are taken at all states of the tide.

In applying these suggestions, the period January to

SEA-FISHERIES LABORATORY. 135

March has been taken, and, first of all, the data for separate
years have been considered : we begin with 1907. The heights
of the tide at high water at Liverpool—which is the nearest
standard port—are plotted for the p.m. tides of each day,
thus we obtain a curve, the maxima of which represent springs
and the minima neaps. This curve is drawn as the dotted
line in Fig. 3 and the straight line marked 0°C. may be
taken as representing mean sea-level at high water for the
period in question. ‘To compare the deviations from the mean
level at high water with the temperature variations we have
next to find the smoothed ten-daily temperature, and it is
assumed that in taking the means of overlapping groups of
ten days the smaller deviations of temperature, due to tidal
causes, are smoothed out. The straight line, “ 0° C.” in Fig. 3,
then represents the temperature graph as deduced from the
ten-daily smoothed averages, only it is straightened out,
so to speak, because all that we want to find is the deviations
of temperature from this smoothed value.

The smoothed temperature values are read off directly
from a graph, and then the differences between these and
the actually-observed daily temperatures are taken. These
actual daily temperatures run rather irregularly, and so I have
taken three daily averages: this gets rid of some of the more
violent irregularities, but ought not to hide the variations due
to the influence of the tides. Thus, the value for January 2nd,
for instance, is taken as the mean of three days January Ist
to 3rd, and it is plotted agamst the date January 2nd.

The difference between the smoothed mean ten-daily
temperature and the mean three-daily temperature can now
be found by adding or subtracting, as the case may be. The
former series 1s represented by a straight line and the latter
is represented by a graph, which runs above and sinks below
this straight line. It will be seen that there is a rather striking
similarity between the fluctuations of temperature and the

136 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

fluctuations in the height of high water at Liverpool*: the
former range between about 0-5° C. above and 1-33° C. below
the mean line. This is extraordinary when one assumes that
the differences are due, apparently, to the different areas of
banks covered by the tides at neaps and springs. One thing,
however, must be noticed: for approximately the first half
of the period the mean temperature for Morecambe Bay Light-
ship is below that at Bahama Bank. The foreshore in More- .
cambe Bay must therefore be exercising a cooling effect since
the influence of the sand-banks must be greater at the former
position than at the latter. We should expect, then, that
each high-water maximum would be opposed by a temperature
minimum, whereas the reverse condition is shown by the graph.
There is bound, however, to be a lag in the change of tempera-
ture, because it will take some time for the effect produced
inshore to be felt at the lightship. The second part of the
smoothed curves show that the foreshore is now warming the
water offshore, and the temperature fluctuations produced by
the tides and disclosed by the three-daily averages now corre-
spond directly to the curve of high-water levels—so there is
apparently no lag. That is, there is a complete reversal of the —
relative position of the fluctuations at the two lightships, and
yet the periodicity of rhythm of the three-daily temperature
fluctuations is apparently undisturbed. In spite of this
apparent anomaly we must, however, correlate the changes in
tidal level with the temperature fluctuations, though we must
not expect a very high degree of correlation since the rate at
which heat is transferred to and from the foreshore must
depend on other conditions, such as the winds.

If the temperatures for January to March, 1908, be treated
in the same way a similar rhythmic fluctuation is shown.
But this is not so regular as in the case of 1907. The maxima

* The difference between the times of high water at Liverpool and
Morecambe Bay is only about ten minutes.

SEA-FISHERIES LABORATORY. 137

and minima follow each other as before, the former lagging
from three to seven days behind the maxima of high water
of the same year. The correlation breaks down at one place :
the maximum high water of January 20th is opposed by the
lowest minimum temperature of the whole series and is suc-
ceeded by a maximum which holds till January 26th. The
weather reports disclose nothing that explains this anomaly ;

2i January. February, March,
ig. 4. Temperature and tidal variations January-March, 1910, Morecambe Bay
Light Vessel.

but if the temperatures for January are compared with those
of the same month at Bahama Lightship it is seen that there
is a sudden and remarkable increase in the difference between
the two stations, which rapidly disappears and suggests that
some abnormal condition affected the Morecambe Bay tem-
peratures. |

I

138 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

The curve for 1909 shows fluctuations which disturb the
rhythm, and when that of 1910 was examined it differed so
markedly from 1907 and 1908 that it appears proper to repro-
duce it here (Fig. 4). The fluctuations have a range of about
0-28° C. above and below the mean, and they are irregular
so that they fit in badly with the tidal curve of the same year :
thus, opposite the tidal maximum of February 12th the tem-
perature fluctuation nearly disappears. Weather conditions have
been discussed above, particularly in connection with the rapid
and unusual rise of temperature during March, 1907, at More-
cambe Bay Ship. The mildness of the early months of 1910,
particularly February, are indicated in the smoothness of the
ten-day average curve, which contrasts strongly with the
steeper curve for the Bahama region. In examining the
temperature changes from day to day, however, we are not
only dealing with general conditions, but also with the particu-
lar conditions for each day. In discussmg the smoothed
ten-daily curves it was found that in their early months 1907
and 1908 were “ strong’ years. Whatever were the conditions
on the Lancashire coast they were such that they not only
caused large differences between the temperatures, day by ~
day, at the two lightships, but they actually altered the shapes
of the two curves. It is during these years, therefore, that
one might expect the general conditions prevailing over the
ereat sand-banks to impress themselves on the temperature of
the water offshore from the Bay and make minor differences.
In 1910, however, the inshore conditions may not have been
so marked as to do this so far out as the lightships. It is quite
impossible, of course, to give due weight to all the factors
concerned, but some that undoubtedly operate can be men-
tioned, just to show the conditions that may hide the tidal
effects. The direction of the wind, for instance, will have
much influence. The winds themselves warm or chill the banks.
They may cut the tide or hold it back. They may raise the tide

SEA-FISHERIES LABORATORY. 139

to more than its. normal height: thus a stiff south-west breeze
south of Holyhead may cause the water on the Dock Sill at
Barrow to be a foot higher than the predicted tide, and a
north-east wind in the same southerly area cuts the tide in
Morecambe Bay even when, in the Bay itself, light westerly
breezes may be blowing. The amount of fresh water which
enters the Bay is also large: thus it is estimated* that the
rivers there carry down fresh water from about 1,080 square
miles of the wettest part of the British Islands. The quantity
of water that enters the Bay after heavy rains must alter the
temperature of the adjacent sea, especially after a time of
melting snow, and the volume of water setting out from the
Bay must also vary from this cause. These factors may
become more prominent ones in a “ weak” year.

‘These minor conditions are, to a great extent, incalculable
ones, and if a long series of years were considered, and com-
bined in some way, the irregularities that disturb the tidal
rhythm ought to “cancel out.” With this idea in mind all
the data available have been treated in the following way :—
One tidal graph must be made from all the years. Now
the times of high water vary from year to year, but we can
take the graph of high waters for 1907 and superpose the
similar graphs for the other years upon this by shifting the
latter backwards or forwards until the maxima and minima
nearly coincide. Unfortunately, the method is complicated by
the fact that springs and neaps do not occur with the same
intervals in different years, and it is therefore necessary to
compare the dates of the highest springs and the lowest neaps
throughout, say, January to March for every year in order to
find the actual difference in days between the maxima and
minima of 1907 and those of other years. If the average of
these differences is obtained then one can make the closest
fit for the high-water curve of each year with that of 1907.

* Report of British Rainfall Organisation for 1910.

140 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

The fit will not be exact, but the difference will not usually
exceed one or two days. The following precautions are
necessary in regard to the temperatures before the composite
high-water curve can be used. By comparing the daily
readings taken from the ten-daily curves the average daily
rate of change of temperature can be found. Thus, corrections
can be made.

Suppose that it is required to apply the graph of high
waters for 1908 to that of 1907. It was found that, m order
to get the best fit, the whole graph for 1908 had to be moved
forward by four days: thus, January 6th of 1908 will coincide
with January 2nd of 1907. Then we see, from the ten-daily
average charts that the average temperature for seven years,
for January 2nd, is higher than that for January 6th by
033° C., and so this amount has to be added to the value taken
for January 6th, 1908. Hach daily temperature must, of
course, be altered likewise before 1908 can be compared with
1907 and its tidal graph. The same method was applied to
each of the years, and the daily corrections were applied to the
particular readings. The corrected values for each day were
then added up and daily average fluctuations were thus obtained
for the years 1907-12 and 1914. These were smoothed by
taking three-daily averages, and the results were applied to
the high-water graph just as in the case of the individual years.
The result seems to be satisfactory, though the effect of the
resultant fluctuations is toned down, so to speak, and the greater
part of the range is no more than 0:28° C. above or below the
mean line. But in outlne the graph of composite fluctuations
follows that of 1907 so closely that one must look on it with
some suspicion. If the year 1907 is omitted and the com-
bination of all the others is tried the result is very different.
This curve for 1908-12 and 1914 shows little variation from
January Ist-5th. In February and March there are signs of
the same regular succession of maxima and minima that are

SEA-FISHERIES LABORATORY. 14]

shown by 1907, but the general effect is not convincing. What
the graph suggests is a possibility rather than a complete
demonstration. If the one poor year, 1910, is taken out there
is still no essential alteration. Therefore we see that 1907
exhibits so remarkable and characteristic a succession of
maxima and minima as to impress itself on the combined
temperature curves of the six following years.

The daily fluctuations in temperature for the months June
to September for the same years have also been examined.
The smoothed curve plotted from the ten-daily averages for the
summer of 1907 (the year in which the January-March tidal
periodicity of temperature is so plain) rises sharply from
11-:17° C. to a maximum of 17°44°C. on July 27-28th, and
it falls again as rapidly. The slope of the corresponding curve
for 1910 is less, and the maximum is 15°6° C. on August 4th.

If the daily temperatures for the summer 1907 at More-
cambe Bay Ship be treated in the same way as in the case of
the earlier months there is, it is true, a marked fluctuation
above and below the mean line. Minor and irregular fluctua-
tions are more noticeable in the summer months, as might be
expected since, at this period, the air-temperature and solar
radiation act with greater effect on the surface water and so
bring about bigger fluctuations.*

The curve, made as before, shows tidal maxima on
June 11th, August 10th, September 8th and September 22nd.
These are opposed to minima of temperature, which is the
condition one expects. The spring-tide maxima on June 26th,
July 11th and August 23rd, however, occur against parts of
the temperature curve, which are equivocal as regards the
occurrence of maxima or minima. The summer of the year
1907, then, does not fulfil the promise of its spring.

The whole series of years 1907-12 and 1914 were next

* See Robertson, ‘“‘ Observations of North Sea Surface Temperatures

and Salinities, 1904-5,’ North Sea Fisheries Investigations Committee Rept.
II (Northern Area), cd. 3358, 1907, p. 155.

142 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

thrown together in the same way, as has been indicated above,
for the period January-March. The temperature fluctuations
so obtained are not so well marked as they are in single years,
but the maxima and minima fit much better to the tidal
fluctuations with the exception of the period about August 24th,
when there is no very evident maximum to correspond to the
spring tides of that date. There are indications that this
summer rhythm is not due to any one particular year, as in
the case of the spring series of data.

Average Temperatures C.° for Ten-Day Periods.

SEA-FISHERIES LABORATORY.

Bay Lnghtship 4 p.m. Surface Observations, January-March

1907-12, 1914.

TABLE I.

143

Morecambe

)

January February March

1-10 | 11-20 | 21-30| 31-9 | 10-19 | 20-1 | 2-11 | 12-21 | 29-31
iC ieee 6-27] 5:88| 438] 4-59] 5-22| 611 7-28! 7-88] 8-99
ic ae 5-45| 4-76| 4:59| 5-17| 4:86] 5-06| 4-76] 5-28] 5-34
HOG! scsucs: 6-77| 5:66| 4-54| 4-70] 4:38] 4-10] 3-54] 4-65| 5-28
oe 5-34| 5-12| 4-32] 465] 4-70] 5-22] 5-28] 5-66! 6-77
feta. 6:32] 5:55| 5-72] 5-00| 534] 605] 638| 5-82] 6-05
ak. 6-67| 6-61] 5-93| 4-70| 4-70] 5-51] 5-99| 7-00] 7-11
Mie a. 6-05] 534] 5-00] 6-05) 6-38] 632] 6-43] 6-61| 7-06
es. RO Gas | come we Ak ce | sd A. hee
PRGpale vcs tkes 50-15 | 45-30 | 39-70 | 34-86 | 35 58 | 38-37 | 39-66 | 42-90 | 46-60
Average ......... 6-27| 5-66] 4-96| 4-98] 5-08| 5-48| 5-671 6-13| 6-66

Average Temperatures C.° for Ten-Day Periods. Morecambe
Bay Lightship 4 p.m. Surface Observations, June-September,

1907-12, 1914:

June July

1-10 11-20 21-30 1-10 11-20 21-30
BOOTS. oases! 11-22 13-12 13-23 14-44 15-94 17-89
TOUS acc e. 13-06 12-66 15-43 16-26 15-43 15-66
LS Seta 11-50 12-16 13-18 14-32 14-21 14-04
EOLOE a. 3s. . 11-67 13-33 14-26 14-32 15-60 15-32
LOT teat 0.< 14-82 14-09 13-60 15-00 16-32 17-73
ROE genes ca 13-38 13-60 13-83 15-43 16-38 16-11
BONA: rec ctes 11-55 13-99 15-00 15:77 16-77 16-05
Papal 2. a. 87-20 92-95 98-53 105-54 110-65 112-80
Average ...| 12-46 13-28 14-08 15-08 15-81 16-11

August September

31-9 10-19 20-29 30-8 9-18 19-28
BO To asso: 16-72 16-61 15-16 14-65 15-00 15-38
MOOS rec ..<2s 16-11 15-88 15-60 14-60 14-09 13-99
Jie UM Reena 15-43 15-94 15-55 14-65 14-26 13-49
ESTO Ave 15-55 16-11 15-55 14-94 14-88 14-49
BE ote: 17-89 19-00 17 83 17-56 16-94 15-32
Dinca Se 15-10 14-71 14-54 14-15 13-55 13-28
Oe aes 16-16 17-28 17-22 17-94 16:16 | 14-60
Total. .sves 112-96 115-53 111-45 108-49 104-88 100-55
Average ...| 16-14 16-50 15-92 15-50 14-98 14-36

144

TABLE IT.

TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Number of days that are to be added to, or subtracted from, the dates on wha
spring and neap tides occur at Liverpool in order that the years 1908-14
may be superposable on 1907 (January-March).

]
1907. 1908. 1909. 1910. 1911.
water. Diff. Diff. Diff. Diff.
Date. Date from Date from Date. from Date. from
1907. 1907. 1907. 19
Days. Days. Days Days
SS Jan 2 | Jan 5| 3 Jan ~ S76 4 Decis2s ee Jan os |
_ aes: a Siaces 13 5 > 16-17 8:5 | Jan. 5-6 | 2-5 - 9 1g
Max. -...-: »» 15-16 ie 20 4:5 a 24 8-5 39 13 2-5 53 16 0-5 |
_ ern > DBee | iss 28 | 4:5 x aba a-5 45 20 | os $9 25 | 1s
Lee We <I) Feb: 44 3 eb, “7 6 a 27 | 4 Feb: (C2 a
noses: se (is er eee ae » 15|-8 | Feb. 4433 uae oe
eee 5 | ae, | BO bee Ci abo ie » 12 | 29) 5a
re 5: 5p Pe OB OB F Ae A Mans “Dy oey » 19) 3 9)
i ee Mar) i2' | Mar, “41 2 5 8 | 6 , 25 | 5: | Maseee ee
ee oe Bee 8 a aes at) O55 | te 16.| 7-5 | Mar - 5 |) 3-5 9) 05!)
Oa ee 5 Jo-ton <5 12 | A :; 23°) 7:5 = 13 |. @-aeeee 16 | 08
ee ” BAW ss Fa Cd We ees a0) 7 3 19 | 4 3 24 | 1
Av. Diff. from 1907 ... 3:75 days | 7:3 days 3°45 days 0-9 days
Av. Diff. from 1907 in
nearest whole days 4 days 7 days 3 days 1 day
|
| 1907. | 1912 1914 | 1915
High | 4
water. | Diff. Diff. Diff.
| Date. Date. | from Date from Date from
| 1907. 1907. 1907,
| Days Days. | — Days
7 H, SRR Ake eee eee eee (eel EN 2 | Jan 6) 4 Dec, -29\ | .4 Jan 5 | om
Ne oe E ks bt dos. pn ent bo ni5 4 Be 8 §451524 5-5 shan 6 2; ee ll 3 ;
| a a poke Goce ee IT ety - 15 a 95 17 1-50
“OS Tit ah Se ne eee » 23-24), 291 5:5 | ,, 21.| 2-5 ee
SS ee ae eee Feb. 1] Feb. 5) 4 nS 29 | 3 Reb... 3,1 72am
BENE 5 sap seotiueds voankwstvussect es fe heoee 1214-5 eh le i 9| 9 |
2 ery Se 14 |) poet seen). ease 2 eee
isa ie Ree se ian be 35 22.5] as rt fae uf 197) oe * 24 | 2
al SS eae oie Sees eae see AT A 1 2 2 | Mar 5-| 3 as PE fal Bee Mar 4 2
gsi ar reee taste deaneaves | bs 12°) 3:5: || Mar.) 77a ei 10:| is
te nok bse cax'v one eavnmeoanot oy 10-16, | 5; 21 | 5-5 sf 14-)° 1-5 x 17 | 1-8
eR) Os 4. Pea ae Sy blle Si 90M eS . 1250) oe
;
eee ae, EHOW LOOT 5.55 cases aw ncen 9 paren 4-8 days 2-3 days 2-1 days {
| |
tl NE nt SoA ea i len |
Av. Diff. from 1907 in nearest whole |
NY cshceenphateitpacacssoweveosseeeeeee ders b- 5 days 2 days 2 days

SEA-FISHERIES LABORATORY.

TABLE ITI.

Number of days that are to be added to, or subtracted from, the
dates on which spring and neap tides occur at Liverpool im
order that the years 1908-14 may be superposable on 1907
(June-September).

145

1907. 1908. 1909. 1910.
High —_——— ona ~—
water. Diff. Diff. Diff.
Date. Date. from Date from Date from
1907. 1907. 1907.
Days. Days Days.
NU Cee June 4{|June 7] 3 May 28] 7 June 1] 38
igi Gy cewtenas 43 11 os is 4. June 4 7 # 8 3
ene Pee Oey 20-8 eis as ee La ie 4
jy et eee ie gel! 2! f9g)'|!'9 Pe EGS Gg Eaea) OMI) S
EIS eidewe cce.oe July 4) July 8 4 S 26 8 = 30 4.
JUS poe iy ae bs ll és 14 3 sulye AS 8 July 7 4
Erma e224 - BOUT gs 22573 if LI} 8 uf 16 |-.3
Wicisete sh edca es. os 20 Sy 28 | 3 Oe RE SS is 22 | 3
Vie ese cis sae Aug 2| Aug. > 6 4 Be 26 7 + 30 3
WEG acne kes ss ll we Uy 1 Aug. 2 9 Aug, -5 6
VEIN | atisicwsses a Lite al ese 20 | 2 55 LOAeEs 3 14| 4
ieee Dalicice «5 = 23 a 2g, 4 de 16 a “3 21 2
MESS Sits 02%. Sepia, 1 | Sept... 5¢) 4 » 20 7 99 29 | 3
Wax. acden ties s es 10 2 ay 31 8 Sept. 4 4.
I Meiece gens 5 Gales PSs) 2 Sept. 8] 8 95 13 | 3
IEE at ain'sidionn cos os BD | 35 26 | 4 i Lea eae le 5 19+ (423
Av. Diff. from 1907 ...... 3-06 days 7:7 days 3°44 days
Av. Diff. from 1907 in
nearest whole days ... 3 days 8 days 3 days
1907. 1911 1912 1914.
High
water. . Diff. Diff. Diff.
Date. Date from Date. from Date from
1907. 1907. 1907.
Days. | Days Days
Mine) | resdes <0 June 4|June 4] 0 June 8! 4 dune...) 43
MGS! csaees ta a: aE leis Ly eel ms LF) 6 5 8 | 3
VDT seis “A 19, 20} 1 $3 23 4 43 16] 3
MAE sete. es 2h | as 2 Wea 33 29 |, *3 3 27 |—1
AMBP Fe era's July 4] July 5] 1 July <9%| 5 July 2| 2
VES 2 Lacie tone - | ees ie 0 Re Leo) 6 -, Di 52,
MEMS <2 sass a 1 hes 20) | (I - 23.| 4 ie Ish iacl
Matias occ eeu: bs Bt |. 54 26 | 1 = 29 |.4 Sy 27 |—2
MIS Ti nase see: Aus 2 Ang.) bP 2 AOS Me Os Aug. 7 Eo) FE
Maser. 2) a 1 aia 10 |-1 - iSie 2 . Se
1 ge ee 5 ori s. TOP a ¥ 22) 4 - 16; 2
Maree o caigec | 9 OT as 24} 1 oe 28-5 3 22 | 1
1 ie Sept. 1 | Sept. 2 1 Sept. 5 4 = 30 2
WEEE He a dels eS Sule. Sorel oe be: Sept. ~ dial
is See eer Za UGa l=» 53 Ui linel “ EO) ccs 53 14 | 2
Maik) eo eeiny.: * ea gee 2a | ul 3 20h 33 i 22! 0
Ay. Dit from 1907 «23... 1-0 days 4-2 days
Av. Diff. from 1907 in
nearest whole days ... 1 day 4 days 1 day

146 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

SEASONAL CHANGES IN THE CHEMICAL
COMPOSITION OF THE MUSSEL (MYTILUS EDULIS).
By R. J. Dantez, B.Sc.

Introduction.

The paper is a preliminary notice of an investigation, at
present incomplete, into the seasonal variations in the com-
position of flesh of the common mussel {Mytilus edulis) from
samples obtained on the mussel-beds of Morecambe, Lanca-
shire. Since the methods of dealing with the samples obtained
are all-important in such work, it is this aspect which is dealt
with below. It is intended in the full report to include also
an account of the structure of the mussel. Although much
work has been done in this direction, notably by Sabatier* on
Mytilus edulis itself, and by List? on closely-allied species,
there seems room for a further description of this mollusc.

The positions of the Morecambe mussel-beds are well
shown in Chart IT, Report of the Lancashire Sea-Fisheries
Laboratory, 1912, as they were then. With one exception
the samples have been obtained from an area surrounding the
two “ gunnels,” or channels, which connect the Grange Channel
with Heysham Lake; it is mainly from these skears that
mussels are consigned for food, several of the samples dealt with
being taken from bags already packed for sale.

The importance of this fishery at Morecambe may be
shown by the fact that during the years 1900-1904, 7,838 tons
of mussels were removed from the beds, the value yielded in
any one year amounting to as much as £2,000.

The first sample was received on May 21st, 1920, and
since then other samples have been forwarded at mtervals
of approximately three weeks, by Mr. Edward Gardner,
Honorary Bailiff to the Lancashire and Western Sea-Fisheries
Committee, to whose kindly assistance I am greatly indebted.
The samples vary from 16-39 mussels, and are always

* Sabatier, Annales des Sciences Naturelles, 1877, Series 6, v., page 1.
t List, **‘ Die Mytiliden ” Fauna und Flora des Golfes von Neapel, xxvii,
1902.

SEA-FISHERIES LABORATORY. 147

despatched to Liverpool the same way, through the post in
tins. They usually arrive in good condition, with the valves
of the shells tightly closed.

Method of dealing with samples.

The outsides of the mussel-shells are first freed from
barnacles and any foreign matter, washed under the tap, and
dried with a towel. The mussels are prised open with a pair
of forceps, and a small wooden peg placed between the valves
to prevent them from reclosing. After shaking to get rid of
any water which may be lodged in the mantle cavity, the
mussels are reared up in small racks, with the posterior end
of the shell resting on a sheet of blotting paper; the latter
absorbs any mucus or excreta that may drain away. It is
necessary to open the shells carefully, because if the flesh is
punctured, blood and liquid flows from the animal itself.
The draining is continued until a dry glaze begins to show on
the surface of the flesh, a process which generally takes a little
over two hours.

Six mussels are then chosen at random and placed on
one side for special examination. The remaining mussels in
the sample, with their shells, are weighed in bulk, and after the
soft parts are removed, the shells alone are weighed. The
difference, of course, gives the wet weight of the soft parts.
In all cases the byssus threads are weighed in with the shells.
It is from this latter part of the sample that mussels are obtained
for sectioning to show the distribution of fat im the tissue.

The six mussels taken from the sample are each weighed
in their shells separately on a balance. The soft contents are
then scraped with care, by means of a scalpel, to a small
porcelain dish which has been previously dried and weighed.

The cleaned shell with any byssus threads are also weighed
separately, and it is then possible, by subtracting such weights
from those of the mussels with shells, to obtain the wet weight
of the flesh in the basin. This gives a more accurate result
than weighing the basin and flesh direct, because the removal

148 TRANSACTIONS: LIVERPOOL BIOLOGICAL SOCIETY.

of the beasts from their shells takes time, and evaporation is
constantly going on. The basin and its contents are then
placed in an electric oven at 105° C. and dried until a constant
weight is obtained. It is probable that all the water is not
removed by this method, since the mussels become covered
with a hard, impermeable skin.

From the differences of wet and dry weights the amount
of water in the tissue is obtained. The dried mussels are
powdered in a mortar and stored in small bottles. It is from
this powder that the percentages of fat and proteim are cal-
culated, two or three samples being run through together.

The following example is given to show the method of
tabulating the observations :— :

OcToBER 29TH, 1920.

Sample of 19 mussels taken from the Little Out Skear, close to
the Gunnel through into Heysham Lake.

Weight Weight
No. Length. Total weight with shell. of of
shell. flesh.
em. orammes. grammes. | grammes.

1 6-55 20-300 10-790 9-510
2 6:00 15-997 9-206 6-791
3 6-80 18-598 9-821 8 7aT
+ 5-95 16-721 8-557 8-164
5 6-15 15-044. 7-746 7-298
6 6-80 Av. 6-375 19-035 10-487 8-548
7 6-20 Totals 105-695 56-607 49-088
8 6-30 Averages 17-616 9-435 8-181
9 6-55 ae ——
10 6-80

1] 6-25

12 6-15

13 6-40 Weight 7-19 . 245:04 | 124-575 120-465
14 6-95

15 6-35 Average 18-850 9-580 9-270
16 6-70

17 5:95 Difference in averages 1-234 0-145 1-089
18 5-90

19 6-25 Av. 6-365

The difference in the averages of 1-6 and 7 to 19 in this case
are extreme when compared with most of the other samples.

akg

SEA-FISHERIES LABORATORY. 149

The Shell.

The length of each shell is found in ems., the measurement
bemg from the umbo to the extreme rounded portion of the
posterior edge. The shell is composed mainly of carbonate
of lime ; there is no trace of phosphate of lime. Iron is present
and seems to be connected with the blue colour of the shell.
This colour in mussel-shells is not uncommonly segregated
into stripes and bands, the remainder of the shell in such cases
bemg practically colourless. Pieces of shell with little colour
give feeble reactions when tested for iron, whereas the coloured
portions give very decided reactions. The shell also gives the
destructive flame reaction for strontium, and since this suggests
one of the ultimate destinations of strontium brought down
by rivers and streams, it will be interesting to examine other
molluse shells, and calcareous alge, to ascertain whether its
presence in these is general.

Shells with the periostracum have been taken from each
sample and powdered in an iron pestle and mortar. After
obtaining the water content by weighing powder before and
after drying, the samples have been stored, and now await
quantitative estimation of carbonate of lime and iron to see
if there are any significant changes in the percentages through-
out the samples.

Estimation of Fats.

In the estimation of fats, 0-5 to 1 gramme of the powdered
mussel-flesh was taken from each sample and the extraction
carried out in a Soxhlet apparatus, carbon tetrachloride being
used as solvent. Whatman’s fat-free extraction thimbles were
used, and these were cut down, so that when fitted into a
numbered weighing bottle, the lid of the latter could be
replaced in position. By excluding air as much as possible
in this way, subsequent weighings were done with greater ease
and accuracy.

The weighing bottle contamig a cut-down thimble, a
plug of cotton wool, and also a Swedish filter paper, was first

150 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

dried and weighed, the date of the sample having been written
in pencil on the thimble to avoid confusion. Mussel powder
was wrapped carefully in the filter paper and placed in the
thimble, the latter being then plugged by the cotton wool.
It was found in practice that this method prevented a passing
over of the powder itself during the extraction. The weighing
bottle, with its contents, was placed in the oven, and once a
constant weight was obtained the amount of powder in the
thimble was ascertained by subtracting the origmal weight
of the bottle, etc. |

To ensure as complete an extraction as possible, the Soxhlet
apparatus was kept working for three or four hours, although
the solvent appeared clear after the third or fourth siphoning.
The thimble, with its residue, was then placed back into the
weighing bottle and dried in the oven. The weight of the
residue was a check upon the accuracy of the extraction, smce
its weight plus that of the carbon tetrachloride extract should
equal the original dry weight of the powder taken for the
experiment. The error generally fell to within 0-5%, and
where differences were greater, the extraction was carried out
again.

This system of fat extraction is not without error; other
substances besides fats are probably extracted from the tissues.
Moreover, there will be oxidation of some of the fat present
in the powder during the heating and drying process. The
propriety of estimating fats in such a manner, instead of
estimating them as fatty acids, has been discussed by several
writers*.

The results from the above methods, however, if not
strictly accurate are all obtamed under the same standard
conditions ; and since this work is one of comparison rather
than intensive quantitative estimation, it is sufficient for the

* For papers see Hartley, J. of Physiology, 1907-8; Mottram, ibid.,
1909-10; Kumagawa and Suto, Bio-chemical Zs., 1908; Tamura, zbid.,
1913.

SEA-FISHERIES LABORATORY. 151

purpose. Fastidious method is beside the point in an investi-
gation such as this, where the errors of sampling may be very
appreciable.

Proteid Estimations.

Kjeldhal’s method was used in estimating proteid. The
amount of dried mussel powder taken was 0-5 grammes.
This was placed in a long-necked flask, with 20 c.c. of strong
sulphuric acid and a little sand added to stop bumping. The
flask was then heated cautiously until the frothing of the
material subsided. After cooling, a teaspoonful of sodium
sulphate was added to increase the temperature of boiling,
and a small piece of copper sulphate to assist in the oxidation.
The flask was then heated vigorously for an hour or more
until the contained liquid became a clear green. After diluting
the liquid with distilled water, it was added to an excess of
caustic soda and distilled, the ammonia evolved being collected
in 75 c.c. of decinormal sulphuric acid. The titration was
carried out with decinormal sodium hydrate, cochineal being
used as an indicator. -

Two or three samples were estimated at one time, a blank
experiment having first been made to calculate the error.

In order to obtain the percentages of proteid given below
the Kjeldhal nitrogen values have been multiplied by the
factor 6-25. This number has been used quite provisionally.
There is evidence from experiment that the factor ought to be
higher so far as the mussel is concerned, but since this part of
the work is incomplete, the more commonly accepted factor
has been used m the meantime. The proteid values given at
any rate show the tendency of the changes throughout the
_ season.

Estimation of Carbohydrates.

The large quantities of glycogen found in the mussel render
it highly desirable to obtain some method of estimation which
will give a sufficient degree of accuracy.

152 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Untortunately, direct method of estimation of glycogen,
such as Pfluger’s well-known short method, or Fraenkel’s
extraction with trichloracetic acid, are hardly applicable in
this case. Results thus obtained would be untrustworthy,
because the mussels have to travel under adverse conditions
for twelve hours or more, and probably during this period
some of the glycogen is converted into glucose by enzyme action.
Mussels required for sectioning and staining for glycogen have
been obtained by having them placed into absolute alcohol
immediately upon gathering from the beds, but this system
could not be extended very well to the estimation of amounts
of glycogen, because the original weight of the flesh treated
would not be known. Inverting the whole of the glycogen
into glucose by keeping mussels several days in chloroform
vapour, and estimating the glucose by reduction of Fehling’s
solution has also been tried. It is dangerous, however, to
adopt any method which has not been thoroughly tested, and
to do this one requires to work near the mussel-beds and thus
obtain fresh material. Since circumstances up to the present
have not allowed of such a procedure, the carbohydrates in
the meantime have been given as the difference on the other
percentages.

One pomt of interest which arose from the above work
is the small amount of trouble with which comparatively large
quantities of glycogen may be got from mussels, and it is
suggested as an easy and profitable source for obtaining the
substance for use in laboratories. The following experiment
is given in some detail to show the manner in which mussels
were dealt with for this purpose.

A number of mussels In poor condition, and therefore
likely to give minimal returns, were procured from the Wallasey
beds in the River Mersey on January 25th, 1921.

Thirty-three of the mussels were dealt with an hour or
two after gathering. The shells were wedged open, and aiter

SEA-FISHERIES LABORATORY. 153

shaking to get rid of any sea-water, the posterior adductor,
or large muscle, was cut, and the flesh scraped into a weighed
1,000 c.c. flask, through a glass funnel. While passing slowly
through the funnel the mussels were minced up with the blade
of a scalpel. The wet weight of this mass was found to be
337-9 grammes. Two hundred and thirty-two c.c. of 60%
caustic potash was introduced into the flask, a reflux condenser
fitted, and the whole heated on a water bath for three hours.
At the end of this time the tissue was broken down in a most
thorough manner. After cooling, the contents of the 1,000 c.c.
flask was transferred to a tall measuring glass and touched the
560 c.c. mark. The mixture was then diluted with water
until the total amount of liquid and tissue came to 1,400 c.c.
After stirrmg well with a glass rod, the mouth of the measuring
glass was covered with a petrie dish and the sediment left to
settle. This took place in about twenty-four hours, the residue
at the bottom measuring up to 170 c.c.

A siphon tube was then placed under the soapy film which
had formed on the surface of the liquid, and the clear part of
the latter siphoned off from above the sediment into a tall,
glass vessel capable of holding 3,000 ¢.c. This method of
siphoning, while allowing a small quantity of glycogen to
remain behind in the measuring glass, saves a good deal of
trouble in the subsequent filterings.

The glycogen was precipitated from the liquid thus
obtained by adding twice its volume of 95% alcohol. The
precipitate was allowed to settle and the liquid then decanted
off through a filter paper, contained in a glass funnel, and
fitted with a supporting metal cone. The filtration was
hastened by the use of a filter pump. The glycogen was then
washed by shaking with a little fresh alcohol and run on to
the same filter paper. To cleanse the glycogen more thoroughly,
it was dissolved by running boiling water through the paper,
and the opalescent liquid thus formed received into a fresh

K

154 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

flask. The bulk of water was reduced by heating on the
water bath, cooled, and the glycogen again precipitated with
alcohol and filtered on to a fresh weighed filter paper. It
only remained to give a final washing with ether, and dry the
glycogen on the paper at 100°C. The quantity of alcohol
used is large, but easily recoverable in a still. The subsequent
weighing gave a yield of six grammes of glycogen. The actual
amount of time taken during the operation was not great, since
the periods required for the sediment and glycogen to settle
may be employed in other work. The manner m which the
mussel tissue breaks down helps the process considerably, and
the haste required in obtaming glycogen for stance from
mammalian livers, where inversion takes place immediately
after death, is not necessary.

The only supply of mussels available for many laboratories,
however, will be those obtained from local shops, where they
may have laneuished for two or three days. Therefore, in order
to effect a comparison with the fresh sample, a second lot of
thirty-three mussels were kept until midday of January 29th
or4days. By this time most of the shells were gaping, and the
animals contaied had a flaccid appearance although still able
to show some little signs of movement. The weight of flesh
was less than in the first sample owing to the slow evaporation
of the water contents. The same procedure was gone through
as in the fresh mussels, and the amount of glycogen obtaimed
was 4-422 grammes, approximately two-thirds of the first
amount, but still m sufficient quantities to show that as a
cheap and easily-handled source of glycogen, the common
mussel is worthy of consideration.

Estimation of Ash. .

To obtaim the non-volatile mineral matter, about 0-5
erammes of dried powder was incinerated in a silica crucible.
After half an hour of heating to a dull red, the substance was
cooled and one or two drops of strong nitric acid added. The

SEA-FISHERIES LABORATORY. 155

heating was then continued over a fierce flame until a white
ash was produced. This residue, besides containing inorganic
matter from the tissue itself probably also includes a certain
amount of salt, deposited on the surface of the flesh by the
sea-water during the drying process, and also the sand and
mud lying in the gut of the animals. Since the amount of the
latter depends upon the vigour with which the animal was
feeding when caught, it is a variable quantity which is indepen-
dent of the actual body metabolism. The percentages have
therefore been reckoned on the wet ash free substance. This
does not make much difference so far as the fat and proteid
percentages are concerned, but alters the carbohydrate values
im some cases, since these are obtained by difference.

The percentage results are given below without comment
since the work is still proceeding :—

Morecambe Mussels.

Percentages based on Wet Ash Free Substance.

Proteid % Carbohydrate
Date. Water %. Oil %: N X 6-25. we

(by difference).
May (20 *- 258.3. 86-610 0-629 8-261 4-499
wune LO... 86-440 0-525 8-647 4-388
PU Oe boeken 85-884 0-867 8-791 4-458
BAL SER eee 81-321 1-267 10-960 6-452
I DOT veces e's 79-103 1-484 11-859 7-554
Sept: 13 cece 77-867 1-516 12-681 7-936
OCt es Bice cecaees 81-797 1-277 9-939 6-987
Ao OL separ 80-534 1-454 11-228 6-784
NOV, 25 .csceses 81-878 1-678 10-960 5-484
Deer UT \es..0023: 83-926 1-160 9-286 5-628

*In this sample the wet weight was obtained from the flesh after
removal from shell into dish, and not by difference of total weight—weight

of shell.

centages are affected accordingly.

The water contents therefore should be higher, and other per-

_ From the September sample onwards, transverse sections
have been cut through the region of the liver, with a view to

156 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

ascertaining the position of fat and glycogen in the tissues,
and tracing any changes which may occur.

The following technique has been adopted :—

Fat: (a) Tissue fixed in 4°% Formaline; frozen
sections cut and stained with Sudan IIT;
mounted in glycerine jelly.

(6) Fixative 10% potassium bichromate and
glacial acetic; paraffin sections stained
with Sudan III and Delafield’s haema-
toxylin.*

Glycogen: Fixative absolute alcohol; wax sections

stained with Lugol’s solution and mounted in~
xylol balsam.

* See Bell, J. of Pathology, No. 1, XIX, 1914

SEA-FISHERIES LABORATORY. 157

AN INTENSIVE STUDY OF THE MARINE PLANKTON
AROUND THE SOUTH END OF THE ISLE OF
MAN.—PART XIII.

By W. A. Herpman, F.R.S., ANDREW Scort, A.L.S., and
H. Maset Lewis, B.A.

Once again, from the pressure of other work, it has been
found impossible to undertake that general summary of our
accumulated data and re-consideration of our previous reports
which was promised. We can deal now, as before, only with
the observations and results of the past year—and these,
moreover, only in brief form in deference to the demand for
economy in printing.

The work during 1920 was carried on in exactly the same
manner as In previous years, and 573 samples of plankton were
collected in the neighbourhood of Port Erin, and have since
been worked up in detail. These bring the total number of
samples for the 14 years’ work, since 1907, up to 7,071.

In addition to an average of six gatherings per week
throughout the year in Port Erin Bay, in the specially important
months of March, April, July, August and September special
hauls were taken both in the bay and outside in the open sea
from the motor-boat “ Redwing.” The results have been
treated in the usual way, and the forms, lists, tables and graphs
are stored available for future reference in the Oceanographic
Department of the University ; where also the accumulated
collections of plankton catches are housed. A special investi-
gation undertaken by one of us (W.A.H.) from the “ Redwing ”
on the variation observed in successive vertical hauls is dealt
with as a separate paper in this Report (p. 161). The following
is only to be regarded as a summary of the outstanding facts
of the year 1920.

The vernal plankton maximum was again in May, and the

158 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

largest individual catch was 101-7 c.c. on May 17th. The
monthly average catch rises from 3-8 c.c. in January, through
9-8 c.c. in April, to 45:3 c.c. in May, and then falls to 31-6 in
June, 12-2 ¢.c. n August, 19-6 c.c. m September (due to the
Copepod maximum) down to the winter minimum 2-4 ¢.c. m
December. The Diatoms taken by themselves form the usual
double crested curve with a greater maximum im May, a
summer minimum in August, a second lower maximum in
September and the winter minimum in December. The
monthly average for May was over 21 millions (much greater
than in 1919) and in September nearly 14 millions. The
largest single catch of Diatoms was 66,168,350 on May 24th.
These numbers are more like those of 1918 than of 1919, when
the Diatom catches were unusually small.

The Dinoflagellate maximum was in June, when the
monthly average was 184,000. It had risen from about 5,000
in January, and fell to a minimum of 1,463 in October. There
was no marked second rise. The largest smgle haul of Dino-
flagellates was 617,900 on June 3rd, mainly composed of
Ceratuwm trupos, but the largest haul of Peridinaum (152,000)
was also on the same date—much earlier than in 1919.

The highest monthly average for the Copepoda (both
Nauplii and adults) was in September (74,328 adults and
86,956 Naupli)—much later than last year—and the largest
individual catch was 192,510 on September 27th. The monthly
maxima are this year in their normal order—Diatoms first,
then Dinoflagellates and lastly Copepoda. The great spring
increase In Diatoms was late in appearing, but once it did
appear was in abundance. |

Taking our usual seven dominant genera of Diatoms in
detail we find from the monthly averages that, as last yeaz,
Biddulphia and Coscimodiscus have their spring maxima in
March, while Rhizzosolenia is earlier than usual with its maximum
in May along with Chaetoceras, Thalassiosira and Lauderia.

SEA-FISHERIES LABORATORY. 159

The greatest Diatom catches are as follows :—

Coscinodiscus = 225,630 on March 22nd.
Biddulphia == 580,000 on April 20th.
Lauderva = 1,140,000 on May 11th.

Thalassioswa = 1,890,000 on May 17th.

Chaetoceras 10,741,000 on May 17th (5,967,000
on September 23rd).

Rhizosolena = 64,295,000 on May 24th.

Guinardia = 1,036,000 on June 14th.
Tn all cases this year the autumn increase is much smaller than
the spring maximum.

Reviewing the records of the six most abundant Copepoda
shows that most of them have their maxima late this year—
Acartia in June, Temora in July, Calanus and Orthona in
August, Pseudocalanus in September and Paracalanus in
November. The largest individual haul was 122,000 Pseudo-
calanus elongatus on September 27th. There were about
98,000 Orthona on November 11th and over 10,000 Paracalanus
on the same date. On the whole Copepoda were abundant
later in the year than in 1919.

Noctiluca was present from August on to the end of the
year, but only reached about 10,000 in a haul—in contrast
to over 26,000 in July last year.

Kchinoderm larvae were fairly abundant, up to over
9,000, at various dates from March to September. Sagitta
was most abundant in June and July, rare in other months,
though a few are always present. Polychaet larvae were
present throughout the year, but most abundant in the early
months, up to 56,000 on March 4th. Molluscan larvae, both
Gastropod and Lamellibranch, have also much the same dis-
tribution, but only reach the thousands in early spring and
again in late autumn. Ovkopleura was present throughout the
year, being most abundant in the warmer months and reaching
12,000 in May and 17,000 at the end of September. In most

160 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

months there were a few hundred in a haul. Rockling and
other fish eggs were present from January to October and began
to appear again at the end of December. On the whole these
distributions corroborate more or less the experience of previous
years.

When the special hauls taken durmg the Haster and
summer vacations in the open sea outside are compared with
those taken across the bay at the corresponding seasons, it is
found that in all groups the numbers per haul are usually
higher out at sea. The Copepods were in force outside rather
earlier than in the bay., the maximum for the adult Copepoda
being in August at sea and in September inside the bay. In -
other groups there is no great difference in time.

Finally, it may be remarked in connection with the point
discussed in our report last year as to the degree of correspon-
dence in time between the hatching of larval fish such as plaice
and the appearance in the sea of phytoplankton in abundance,
that 1920 may have been a year when microscopic food for the
first hatched young fish was scanty in amount. The fish-
hatching at Port Erin was unusually early (February) and the
Diatoms at least were not present in great abundance until
later than usual. It must be remembered, however, that in
addition to Biddulphia and Coscinodiscus, which reach their
maxima in March, various larval forms of Invertebrata such
as Polychaets and Mollusca are present in considerable abun-
dance in the early spring months and may serve in part, along
with the phytoplankton, as food for the young fishes.

SEA-FISHERIES LABORATORY. 161

VARIATION IN SUCCESSIVE VERTICAL PLANKTON
HAULS AT PORT ERIN.*

By W. A. Herpman, C.B.E., F.R.S.

(Emeritus-Professor of Natural History in the University of
Liverpool.)

The degree of uniformity in the distribution of the plank-
ton through the water of a sea-area which is under what seem
uniform physical conditions is still a vexed question. We are
still uncertain as to the degree of validity of our samples, and
as to how far they represent more than some proportion of the
contents of the actual water which was sampled.

The Sargasso Sea, surrounded by the North Atlantic Gulf
Stream circulation, and of relatively high temperature through-
out, is probably the largest area of apparently uniform
conditions that is known, and the results of the German
Plankton Expedition of 1889 show that the twenty-four plank-
ton catches obtained in that area were all small in quantity
compared with those from further North and further South
in the Atlantic. Schiitt, who reports upon these results, shows
that the average volume of the twenty-four catches was
3°3 ¢.c., but the individual catches ranged from 1-5 c.c. to
6-5 c.c. and the greatest divergence from the average was there-
fore + 3-2 c.c., the divergence in the other direction being
—18c.c. After somewhat arbitrarily deducting 20 per cent.
of this divergence as due to errors of the experiment, he
estimates the mean variation of the plankton in the area
investigated at about 16 per cent. above or below the average
of the hauls. Even this reduced figure does not, however,
indicate a very high degree of uniformity of distribution such

*] wish to acknowledge, with thanks, the help I have received in this
investigation from Mr. Andrew Scott, A.L.S., and Miss H. M. Lewis, B.A.—
from Mr. Scott in the examination and estimation of the catches, and from

Miss Lewis in making the calculations. I alone am responsible for the
work at sea

162 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

as might have been expected in the most “ halistatic ” known
area of the ocean.

These hauls were taken miles apart at considerable intervals
of time; the question next arises whether simultaneous or
almost simultaneous hauls taken through closely adjacent
bodies of water would show a greater degree of uniformity.
Hensen made a series of experiments, also discussed by Schiitt,
in which he hauled the same net twice in rapid succession in
as nearly as possible the same body of water, on forty occasions,
and eight times in succession once, and found that the average
error was about 13 per cent. ©

In all such work at sea it is obvious that much depends
upon the weather, the conditions under which the ship is
working and the care taken in the experiment. With the view
of getting further evidence from a new series of data, taken with
all possible care under favourable conditions, I carried out a
number of similar experiments at Port Erin during several
months in spring, summer and autumn of 1920. They con-
sisted of a series of four to six “ successive ” (that is, as nearly
as possible simultaneous) vertical hauls taken with the Nansen
net of No.20 silk. On each of the seven occasions (four in April
and one each in May, August and September) a day was selected
when the weather was favourable and a time when it was
known that the tide would not prevent the motor-boat
“ Redwing ” from maintaining her position on the marks during
the twenty to thirty minutes that the experiment occupied.
Two localities were used, the one just at the mouth of Port
Erin Bay with a depth of 8 fathoms, and the other a good
deal further out with a depth of 20 fathoms. The boat was
kept approximately stationary in the water, the hauls taken
as plumb as possible, and the rate of hauling up was fairly
constant at two minutes to 20 fathoms. The catches were
emptied from the brass bucket of the net direct into bottles
of 5 per cent. formaline, in which they remained until examined

SEA-FISHERIES LABORATORY. 163

microscopically in the laboratory—so no loss of material was
possible through straining or transferring from one vessel to
another.

The first four series (six in each) were taken in April
during the time of the ordinary mixed early spring plankton
_ before the phytoplankton maximum ; the next series, in May
(four hauls), was just at the time of the Rhizosolenia maximum
and shows a typical phytoplankton ; the August series (four
hauls) shows a scanty summer zooplankton; and the last
series, in September (four hauls), shows again an abundant
phytoplankton of autumn Diatoms and Dinoflagellates.

Two out of the thirty-six bottles were unfortunately broken
in transit from the Isle of Man, so that the total number
examined and now reported on is thirty-four, as follows :—

Fathoms. Hauls. Average.

April 3 & 6 0-20 c.c., mixed plankton.

es 6 20 5 0-56 ¢.c.,. 55 Bs

43 8 20 6 C252 Cie 3 ¥

dl 8 5 0-48c.c;, 55 -
May 25 ... 20 4 16-125 c.c., phytoplankton.
PUT yaks 20 4 0-50 ¢.c., zooplankton.
Pepi. 6%” "2. 20 + 6-10 c.c., phytoplankton, etc.

The nature of the plankton in each series was more or
less what was to be expected in the locality at that time of year,
and the volumes of the catches were also fairly characteristic
of the season. The apparent uniformity in the successive
catches of each series was obvious at the time of collecting.
It seemed to the eye to be the same catch that was emptied
from the Nansen-bucket into the bottle of formaline time after
time throughout a series. And this apparent uniformity of
volume is in most cases confirmed by the careful measurement
made afterwards in the laboratory—for example, the six
successive hauls from 8 fathoms on April 3rd all measure
0-2 c.c., four out of five of those from 20 fathoms on April 6th
are 0-6 c.c., and all four on August 7th from 20 fathoms measure
0-5 cc. The remaining four series show some variation, but

164 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY

the percentage deviation from the average of each series 1s in
no case great. The volumes of these series are as follows :—

Average.
April 8— 0-6, 0:6,/0-5, 0-5, 0:4, 0-5. .... 0-52°¢e.
» 13— 0-4, 0-6, 0-5, 0-4, 05... a, (0-48) Gre:
May 25—19-5, 15-0, 15-5, 14-5 ... 16-125 c.e.
Sept. 16—- 6:2, 7-5, 4:5, 6:2 6°10 c.c.

If, however, we examine the detailed results of the micro-
scopic investigation of the catches, we find that even in the same
series similar volumes of catches may be made up rather
differently, and may in some cases show surprising differences
in the numbers of a species in successive hauls, such as 10 and
100, 40 and 800, 4,000 and 18,000. The same organisms are
present for the most part in each haul of a series, and the
chief groups of organisms are present in much the same propor-
tion. For example, in a series where the Copepoda average
about 100, the Dimoflagellates average about 300 and the
Diatoms about 8,000. On another occasion we find Copepoda
about 1,000, Dinoflagellates about 4,000 and Diatoms about
100,000. These are in mixed catches; in a phytoplankton
(May 25th) the Copepoda may be in hundreds, the Dinoflagel-
lates in tens of thousands and the Diatoms in the millions.
But notwithstanding this appearance of similarity between
the hauls of a series, there is a considerable percentage deviation
in the case of some hauls from the average of their series—not
infrequently about plus or minus 50 per cent., in several cases
about 70 and in one case plus 129. The following table gives
the percentage deviations in the case of the volumes, and of
the estimated numbers of the four chief groups of organisms
present, viz., Diatoms, Dinoflagellates, Copepoda and the
Nauplii of Copepoda.

In all there are about 50 species of organisms that occur
with fair regularity throughout the series: 24 species of
Diatoms, 4 of Dinoflagellates, 8 of Copepoda and about 14 other
organisms or groups of organisms which are not of so much

Date
and
Depth.

April 3—
8 fathoms

April 6—
20 fathoms

April 8-—-
20 fathoms

April 13—
8 fathoms

May 25—
20 fathoms

August 7—
20 f.thoms

Septem ber16—
20 fathoms

SEA-FISHERIES LABORATORY.

No.
of

hauls.

Greatest
Vol. | per cent.
in c.c. |deviation
average.| from
average.
0-2 0
( —14
0-58
+ 3
—23
0-52
Gas
—l17
0-48
+25
—10
16-125
+21
0-5 0
—26
6-1
+23

165
Dia- | Dinofla-| Cope- | Cope-
toms | gellates | poda pod
ditto. ditto. ditto, | Nauplii.
ditto.
Soil) Tage, elite) o| Tetap
ie +24 #21 | ap
pate tres ape pea |
+4] +56 +49 +41
See ey ee
+17 +15 +22 +22
ze fa EGR) le Lope nS Lea
SET) +44 +33 +129
Es a ee eae eee
+15 +23 +60 +56
te —70 97 —13 —21
| +59 +17 +32 +10
eee ee al ee
+30 +36 +53 +37

importance and may be omitted.

Of the 24 species of Diatoms
as a general rule if a species occurs in one of the hauls of a series
it occurs in all, and in many cases in much the same proportions

in all; that is, there may be two or three or even more times
as many individual cells in one haul as in another, but all will
be in the tens, or in the hundreds, or the thousands, or millions.
The followmg are a few examples :—

April 3—

Biddulphia mobiliensis, 1,800, 1,800, 3,800, 4,000, 4,400, 5,400 ;
Coscinodiscus radiatus, 1,600, 2,600, 2,600, 2,800, 2,800, 2,200 ;
Lauderia borealis, 10, 20, 50, 40, 40, 20;

Streptotheca thamensis, 40, 30, 30, 40, 40, 60;

April 8—

Asterionella bleakeleyi, 12,000, 20,000, 16,000, 36,000, 28,000, 40,000 ;
Lauderia borealis, 200, 200, 240, 200, 120, 200 ;
Rhizosolenia setigera, 40, 40, 80, 80, 40, 40;

166 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

May 25—
Guinardia flaccida, 60,000, 62,000, 63,000, 54,000 ;
Rhizosolenia semispina, 1,620,000, 1 120, 000, at 600 ,000, 1,460,000 ;
Strevtotheca thamensis, 300, 100, 400, 200.

Many other similar examples might be given. On the other
hand in the case of other species or on other occasions there
was more variation, and such cases as 60 and 800 in adjacent
hauls can be found.

It is much the same with the four common species of
Dinoflagellates recorded. There again we find cases of con-
siderable constancy in the hauls of a series, such as :—

May 25—Peridinium divergens, 46,000, 62,000, 50,000, 44,000 :
and other cases of more variation—even in the same series,
such as :—

May 25—Ceratium furca, 6,000, 2,000, 8,000, 1,000.

Are we entitled from this to conclude that the Peridinium is
very evenly distributed through the water and the Ceratium
much less so? I doubt it.

The Copepoda, occurring in much smaller numbers, seem
also to indicate in many cases a fairly even distribution.
Sometimes they occur only in units, and yet each haul of the

series shows a few :—

April 3—Oithona similis, 8, 4, 3, 3, 5, 11;

3— Pseudocalanus elongalus, 10, 85, "130, 110, 79, 80;
13—T'emora longicornis, 10, 5, 10, 10, 10;
13—Oithona similis, 20, 20, 20, 20, 20),

99

99

Other cases again seem to indicate considerable variation
in adjacent hauls. Which of these contradictory impressions
received from an inspection of the results of the hauls is true
to Nature? If the Oithonas on April 13th had been quite
irregularly scattered through the water, is it likely that we could
catch exactly 20 in each of five successive hauls? On the
other hand, if they were evenly distributed, how can we account
for one haul (April 6th) catching 40 and the next 140, or for
the series on May 25th—20, 80, 460, 290 in the four successive
hauls @

SEA-FISHERIES LABORATORY. 167

Some of the other common organisms outside the above
main groups show equally contradictory evidence. The pelagic
worm, Sagitta bipunctata, is present in nearly every haul in
numbers varying from one to twenty-seven, but in some
series one or two specimens are present in every haul, while in
another case successive hauls in one series varied from one to
eleven. Other similar examples might be given from some of
the larval forms present. The impression one receives from
an inspection of the lists and numbers as they stand is that
if on each occasion one haul only in place of four or six had
been taken and one had used the results of that haul to estimate
the abundance of any one organism or group of organisms in
that sea-area one might have arrived at conclusions about
50 per cent. (or m some cases a great deal more) wrong in either
direction. |

Is such a vague result of any value as a basis for calculations
as to the population of the sea? And is it possible that such
irregular numbers are compatible with the hypothesis of an
even distribution of the plankton throughout a sea-area of
constant character? The answer to such questions depends
to some extent upon the possible range of error under the
conditions of the experiment, and upon the possibility of allow-
ing for that experimental error, and of reducing it by more
refined methods of collecting. It may be justifiable to claim,
as the result of a good deal of work at sea, that the conditions
of these experimental hauls at Port Erin were as free from
lability to error as any similar vertical hauls from a boat in the
open sea are likely to be. The occasions were chosen so that
the weather and state of the tide might be favourable, and every
care was taken to have the conditions of the successive hauls
in each series as much alike as possible. I feel confident that
the possibility of error in the collecting was reduced to a
minimum. There is also the possibility of error in the micro-
scopic examination and estimation of the contents of the

168 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

catch. This only applies in the case of the more minute
organisms which were present in great abundance, such as the
Diatoms and Dinoflagellates, where samples of the catch have
to be taken for counting, and estimations made. In the
case of the Copepoda and Sagitta and other larger organisms
this source of possible error is excluded, as these forms were
picked out directly from the entire preserved catch with the eye
or a hand lens and were all counted. Sampling and estimation
were not applied to the macroplankton, and yet the irreeularity
is as great there as in the case of the estimated microplankton.

The experimental error to be expected in the case of the
chief groups of organisms, and also in the case of a typical
common species of each, has been calculated with the followmg
results.

The total number of Diatoms on April 3rd varied im the
six hauls from 3,880 to 10,020, the mean or average being
8,055. Two of the hauls are below the average and four above.
The smallest haul is as much as 52 per cent. below the average
and the largest haul is 24 per cent. above. The question is—
do these variations in the catch come within the limits of the
probable error of the experiment ?

If we assume that the estimation of the number of Diatoms ©

im each haul is correct, then the possible errors are those

inseparable from all such collecting at sea—slight movements

of the boat, unknown currents in the water, irregularities m
the verticality of the line, etc. In this case of the Diatoms
on April 3rd the “ probable error” is found to be = 1,458,
and the “range” is the mean + the probable error, that is from
6,600 to 9,500.* Comparing this range with the estimated

* Obtained as follows :—We may assume that the small unavoidable
causes of error are not correlated, and that no single one has much greater
effect than any other; also that they tend to make the individual catches
more than the mean as often and as much as they tend to make them less

SEA-FISHERIES LABORATORY. 169

results of the hauls, we find that three of the series are within
the range and three are outside it, and two of the latter (3,880
and 10,020) are very considerably beyond the limits of the
probable error of the experiment.

The Diatoms for the other hauls give much the same result
when treated in the same manner—that is, roughly 50 per
cent., or rather more, of the observed variation in the catches
is not covered by the calculated range of error of the experiment.

In the followmg tables the three principal groups of the
plankton, Diatoms, Dinoflagellates and Copepoda, and also three
prominent organisms—one from each of these groups—are
shown for all seven series of hauls treated as in the case of
the Diatoms of April 3rd discussed above, and giving in each
case the figures necessary to make a comparison between the
range of variation in the catches and the calculated range of
error :—

than the mean. Then the first process is to find the ‘‘ standard deviation.”
Take, for example, the six successive hauls on April 3rd :-—

|
No. of organisms. — Frequency. Deviation from A2
Mean.
3,880 1 —4,175 17,430,580
6,670 ] —1,385 1,918,225
8,770 | 1 + 715 511,225
9,220 1 +1,165 1,357,224
9,770 | 1 +0715 2,941,224
10,020 | 1 +1,965 3,861,225
48,330 | 6 0 28,019,703
Mean = 8,055

: > Az © me
Find a/ 6 = 2,161 = standard deviation.

Next find 0-6745 x standard deviation = probable error = 1,458.
The range of error = mean + probable error = 8,055 + 1,458
= 6,600 to 9,500 (approximately).
The convention is to regard this as the catch, that is the variations
between 6,600 and 9,500 are not of any significance—any number

between these limits is equally permissible, that amount of variation being
possibly due to the unavoidable errors of the experiment,

L

TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

170

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SEA-FISHERIES LABORATORY.

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TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

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SEA-FISHERIES LABORATORY. 1768

To the question what light does a series of four to six
successive hauls throw upon the validity of a single haul, say
the first of that series, the answer seems to be that as regards
mere size (volume) and general nature (such as phytoplankton,
zooplankton or mixed) of the catch the series confirms the
representative nature of the single haul in a general way and
within limits. For example, in two out of the seven series
all the catches (six and four respectively) were alike in volume,
_ the additional hauls taken exactly confirming the evidence of
the first. In the remaining five series there was some diver-
gence from the average amounting in the most extreme case
to + 23 and — 26 per cent.; so that as far as this experiment
’ shows if a single haul had been taken, in place of a series, it
might have given a result about 25 per cent. different in either
direction (either above or below the average of the series).

Then again, in regard to the nature of the plankton, without
going into the exact statistics of the species or even of the groups
of species, it is evident to the eye at the time of collecting,
and this is confirmed by the microscopical examination, that
any one haul is very fairly representative of its series. If one
shows a phytoplankton catch, the others do also.

But if one next proceeds to deal quantitatively with the
groups of species that make up the catches, it is found that the
individual hauls in a series may differ widely. The preceding
tables show that both in the main groups of the plankton and
in those species which have been taken out as examples fully
50 per cent. of the variations from the mean of the series
extend beyond the range of error, and are therefore not due
to possible imperfections in the experiment. Thus more than
half the differences between the hauls of a series remains
unaccounted for, and may naturally be interpreted as evidence
of an unequal distribution of the plankton in closely adjacent
areas of water, or in the same area in successive periods of time.

Whether our present methods of collecting and of estimat-
ing are sufficiently accurate to enable us to determine the

174 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

amount of this inequality in the distribution, so as to be able
to put probable upper and lower limits to the number of each
organism per unit volume of water may be doubtful. But
even if the data are not yet sufficiently numerous and reliable,
we must still work on in the hope that improvements in method
and accumulation of evidence may in time enable us to make
some approximation to an estimate of the population of various
sea-areas.

I would go further and say that even if we had no hope of
attaining to greater accuracy, our present planktonic results are of
some value. Although estimates which may be 25 or even 50 per
cent. wrong in either direction may not justify us in calculating
exactly the number of organisms and of potential food present
per area or volume of water, they do give us a useful approxi-
mation. Even if 100 per cent. out, doubling or halving the
estimated number is a relatively small variation compared with
the much larger increases and reductions amounting to, it may
be, ten thousand times in the case of Diatoms, ten to fifty times
in Dinoflagellates and five to twenty times in Copepoda, which
we find between adjacent months, and even greater differences
if we take groups of months, in a survey of the seasonal
variations of the plankton in European seas.

SEA-FISHERIES LABORATORY. 175

ON MEASUREMENTS OF SOLES MADE IN 1920.

By JAmMEs JoHNSTONE, D.Sc.

In June of 1920 a system of observations on board smacks
and steam-trawlers, working in the Irish Sea, was put in
operation by the Ministry of Agriculture and Fisheries. Two
“fish measurers,’’ Commander A. E. Ruxton and Mr. W. C.
Smith, were stationed at the ports of Fleetwood and Whitehaven,
and, later on, a postgraduate student of the Zoology Depart-
ment at Liverpool University, Mr. G. F. Sleggs, B.Sc., was
engaged on similar work. The object of the observations was
to obtain data with regard to the sizes and general distribution
of the plaice caught by the first-class trawling vessels on the
offshore grounds of the Irish Sea. The measurers usually
worked on smacks sailing out from Fleetwood and Liverpool,
and, though their specific work was to observe the catches
of plaice made, they also measured all the soles caught. The
results are very interesting and are also quite novel, for there
were, previously, no measurements of the soles trawled on these
offshore grounds. Since these fish were the principal objects
of the fishing of the smacks the region where they occur was
pretty well worked and nearly 6,000 soles were measured.
Unfortunately it was impossible to arrange for the work to be
commenced earlier than the last day in May, so the spawning
period of the fish was not fully covered.

The grounds trawled over are shown on the sketch chart
(Fig. 5). The irregularly-marked regions represent, rather
roughly, the parts of the sea worked on the various voyages
of the smacks with which the measurers went. The Roman
numeral gives the month and the suffix gives the number of
hours during which trawling went on.

The principal sole-fishing ground is well shown : it extends
N.W. from Morecambe Bay Light Vessel up towards Maughold

Head and then over towards the coast of Cumberland. Further

South-west there was also a good deal of trawling, and some __

catches made in Carnarvon Bay are recorded. June was the
best month on the whole, and then the two smacks, with

i
'

fo a ah ae
rk a

“3 C ) <A
YN A +, oN

I~

were made,
which the measurers went, caught about 14 soles per hour’s

trawling. In July the number was 9, and it was 7 in August
and 6 in September.

SEA-FISHERIES LABORATORY. 177

The sizes are shown in the table below. There is little
change, with relation to the months, for the “ shortest-half-
ranges,” that is, the most prevalent sizes of soles caught are :—
June, July,- August, September. So far, then, as one can
judge there is not much indication of a rapid period of growth,
as in the case of plaice caught in the same regions, during the
summer and early autumn.

a
4

Measurements of Soles caught in the Irish Sea, 1920.

Mean June. July. - August. September.

Vi.gs | VIL-67 VIII.) VIIa, [VITT¢4) TX, | EX.g4 | TK) | TX'.gg | TXg5 | TX. 79
1 a 1 2 1 oe 3 a ae
5 1 1 wai 1 a 1 <= mae
1 ven 1 2 2 2 uo 3 sat 6

20 1 2 5 2 2 5 = a fe 8
37 2 om 12 2 aes 3 ay 11 - 32
42 13 Ae 28 i 1 13 1 16 10 | 41
57 27 1 59 22 3 11 1 26 5 | 49
68 42 I 82 21 5 13 3 26 8 54
85 47 1 81 37 7 11 2 38 6 | 75
62 47 3 108 it 8 18 - 28 8 | 83
91 (ng) 3 114 46 9 13 2 48 4 | 76
73 58 2 109 46 17 17 1 40 "My oe
67 81 Le 135 at 18 13 1 29 6 | 52
72 58 1 97 45 6 16 er 35 8 | 45
49 60 1 87 38 5 8 1 14 6 29
27 46 1 80 23 11 10 1 17 FA ey
25 18 I 51 19 4 3 ae 6 5 16
11 12 ig 38 18 5 2 2 8 a ee!
10 13 1 20 20 4 1 a 3 2 |: .4
iu 3 13 4 as 1 Ua 1 as 3
7 9 1 7 5 5 2 1 aoe See 3
4 2 1 5 2 5 aes Jew 1 l
2 2 3 3 cee ie 1 aoe
ane 1 2 1 1 ace 1
5 1 us 2

1
el ig2tt,| 821 619 28 1,187 | 454 121 168 16 | 361 84 671

178 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

ON BLACK LITTORAL SANDS IN LANCASHIRE.

By James Jounstone, D.Sc.

On most places in the littoral zone on the coast of Lanca-
shire the sand below the surface is more or less black. On
the Formby shore, for instance, on the landward side of the
channel between the shore and Taylor’s Bank there is (or
used to be) a cockle-bed, but below the upper two or three
inches of clean, yellow sand the substratum is very black.
At Piel (in Barrow) there is a dense bed of lugworms on the
west side of the railway embankment, and here also the sand
beneath the surface is black to grey in colour, the superficial
layer being yellow. Close to the embankment there are little
gutters contaming a few inches of water, and on the sides of
these the upper, yellow layer of sand is only about an mch
in depth, while below that, and as deep down as one can dig
with a spade, at all events, the sand is dense black. Further
out towards the low-water mark the upper, yellow layer becomes
thicker and the sand underneath becomes grey in colour, and
the greyness becomes rather lighter as one goes out away
from the shore.

The dense, black sand close inshore smells offensively of
decaying seaweed and sulphuretted hydrogen when it is turned
over. When I first collected a sample I dried it in a steam
oven and was, for the moment, surprised to find that the
colour had disappeared long before the sand became dry.
Even in the cold it disappears rather quickly, a mass of the black
substance becoming light yellow in about an hour. But under-
neath the upper layer of a quarter of an inch in thickness the
dense, black colouration was persistent. It was evident that
one has to do here with a deposit of moist ferrous sulphide
which rapidly oxidises.

SEA-FISHERIES LABORATORY. 179

Samples of the black sand were put into tall, narrow
glass tubes and covered with salt-water, fresh water, 5%
forma ‘ine and 70 % methylated spirit. In all cases the same
thing happened: the upper 5 mm. or so of sand bleached
rapidly to the normal, light yellow colour and then the action
slackened. Very slowly the discolourised layer thickened, but
after some six months it was little over about 5 mm. in thick-
ness. Some of the black substance was put into a 12 x 3 cm.
tube, the latter bemg filled to within an inch of the top. The
water in the sand was drained off for about ten minutes and
then the upper part of the tube was dried and filled with melted
paraffin wax, the latter bemg coated over the outer edge so as
to make an air-tight seal. After eight months the sand
remained perfectly black and there was no trace of bleaching.
A little white substance, rather like a bacterial growth, formed
on the surface, but this was not bleached sand: it has not yet
been examined.

Another, and similar, tube was filled in the same way,
but was sealed with an ordinary, unluted cork. The sand
oradually dried, but it did so unequally in such a way that air
was able to penetrate along irregularly dried paths. These
paths bleached to the usual light yellow colour while the other
parts remained black. Gradually, however, the whole became
orey or yellow, but on the margins of the “ paths ” an ochreous
substance, evidently ferric oxide (He,0,;), began to appear.
After eight months the whole contents of this tube had not
completely bleached, or reddened.

A little of the blackest sand was placed in a glass tube of
2 ems. bore and about i2 cms. long. Hydrogen was generated
from zine and sulphuric acid, washed in strong H,SO,, bubbled
through a strong alkaline solution of pyrogallic acid, agam
passed through strong H,SO,, and finally dried in a calcium
chloride U-tube. The tube containing the black sand was
gently heated and the O-free, dry gas was passed through it

180 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

until the sand was quite dry. It was then dark grey in colour.
When shaken out on to a sheet of paper it rapidly bleached
to the normal colour. It even bleached when kept in a
desiccator.

When examined under a microscope the sand is seen to
contain black granules adhering to, and mixed among, the
erains, but the latter are not “coated.” When it is treated
with dilute HCl it bleaches at once and SH, is evolved. The
solution, when filtered, gives all the tests for iron. When the
sand is ignited strongly it also bleaches, but the iron is not
then so easily dissolved out, though it can be, of course.

The blackening and subsequent bleachmg are easily
imitated. Some very clean, white sand was ignited, cooled,
and then put into an evaporating basin and covered with a
0-5 % solution of ferrous sulphate. A little ammonium chloride
and ammonium hydrate were added, and SH, was bubbled
through the wet sand. The latter rapidly blackened. It was
then quickly washed in boiled-out water and put into a, tall
glass tube with a little overlymg water. In a few hours the
upper layer bleached and the result resembled that obtained
from the naturally discoloured sand. Just the same effects
were produced when the mixture of clean sand and dilute
solution of ferrous sulphate was treated with ammonium
sulphide. The bleaching occurred in much the same way, but
the decolourised, upper layer was yellow because of the presence
of sulphur. Evidently, then, these littoral, black sands
are the result of the formation of ferrous sulphide. Every-
where on this coast (and especially im the North Lonsdale
region) the sea-water in the interstices of the sand contaims
soluble iron salts. Everywhere there are organisms (lugworms
and cockles, for mstances) which form excretal substances,
and in any case they die in the sand sometime or other. The
putrefactive process gives rise to SH, and some ammonia
salts, and then the trace of iron present in the water is precipi-

SEA-FISHERIES LABORATORY. 181

tated as ferrous sulphide. So one often finds a dead cockle-
shell in clean sand with some black sand in the shell cavity.
_ Wet ferrous sulphide very easily oxidises, of course, and there-
fore the upper layers of sand are always clean. But the black
stuff underneath exists under conditions that are nearly
anaerobic and so the oxidation is confined to the upper layer.
Near the shore there is a continual access of organic matter,
in the form of land drainage, which penetrates into the sand
and renders the process of formation of ferrous sulphide a
continuous one. Further out, over the littoral zone, there is
not so much of the organic matter for it is the more easily
distributed by the tide, and so the bleached layer is thicker and
the underlying discoloured stratum is not so black.

The same process, as was pointed out by J. Y. Buchanan,*
occurs on the sea-bottom in deep water and is responsible
for the formation of blue and black muds. Such sulphide-
containing muds and sands do not (or, at least, need not) be
found among sedimentary strata, for oxidation would generally
have led to the bleaching. But, m such strata, the presence
of much iron in the form of Fe,O; may usually indicate that
the sediments from which they have been formed have been
the seats of putrefactive processes.

* See ‘Accounts Rendered,’’ Cambridge University Press, 1919,
pp. 183-158.
L2

SEA-FISHERIES LABORATORY. 169

results of the hauls, we find that three of the series are within
the range and three are outside it, and two of the latter (3,880
and 10,020) are very considerably beyond the limits of the
probable error of the experiment.

The Diatoms for the other hauls give much the same result
when treated in the same manner—that is, roughly 50 per
cent., or rather more, of the observed variation in the catches
is not covered by the calculated range of error of the experiment.

In the following tables the three principal groups of the
plankton, Diatoms, Dinoflagellates and Copepoda, and also three
prominent organisms—one from each of these groups—are
shown for all seven series of hauls treated as in the case of
the Diatoms of April 3rd discussed above, and giving in each
case the figures necessary to make a comparison between the
range of variation in the catches and the calculated range of
error :—

than the mean. Then the first process is to find the “standard deviation.”
Take, for example, the six successive hauls on April 3rd :-—

No. of organisms. | Frequency. Deviation from A2
| Mean.
3.880 1 —4,175 17,430,580
6,670 ] —1,385 1,918,225
8,770 1 + 715 511,225
9,220 1 +1,165 1,357,224
9,770 il +1,715 2,941,224
10,020 1 +1,965 3,86] ,225
48,330 6 0 28,019,703

Mean = 8,055

: > A2
Find a/ —@ = 2,161 = standard deviation.

Next find 0-6745 x standard deviation = probable error = 1,458.
The range of error = mean + probable error = 8,055 + 1,458
= 6,600 to 9,500 (approximately).
The convention is to regard this as the catch, that is the variations
between 6,600 and 9,500 are not of any significance—any number

between these limits is equally permissible, that amount of variation being
possibly due to the unavoidable errors of the experiment,

L

TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

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TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

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SEA-FISHERIES LABORATORY. 173

To the question what light does a series of four to six
successive hauls throw upon the validity of a single haul, say
the first of that series, the answer seems to be that as regards
mere size (volume) and general nature (such as phytoplankton,
zooplankton or mixed) of the catch the series confirms the
representative nature of the single haul in a general way and
within limits. For example, in two out of the seven series
all the catches (six and four respectively) were alike in volume,
the additional hauls taken exactly confirming the evidence of
the first. In the remaining five series there was some diver-
gence from the average amounting in the most extreme case
to + 23 and — 26 per cent.; so that as far as this experiment
shows if a single haul had been taken, in place of a series, it
might have given a result about 25 per cent. different in either
direction (either above or helow the average of the series).

Then again, in regard to the nature of the plankton, without
going into the exact statistics of the species or even of the groups
of species, it is evident to the eye at the time of collecting,
and this is confirmed by the microscopical examination, that
any one haul is very fairly representative of its series. If one
shows a phytoplankton catch, the others do also.

But if one next proceeds to deal quantitatively with the
groups of species that make up the catches, it is found that the
individual hauls in a series may differ widely. The preceding
tables show that both in the main groups of the plankton and
in those species which have been taken out as examples fully
50 per cent. of the variations from the mean of the series
extend beyond the range of error, and are therefore not due
to possible imperfections in the experiment. Thus more than
half the differences between the hauls of a series remains
unaccounted for, and may naturally be interpreted as evidence
of an unequal distribution of the plankton in closely adjacent
areas of water, or in the same area in successive periods of time.

Whether our present methods of collecting and of estimat-
ing are sufficiently accurate to enable us to determine the

174 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

amount of this inequality in the distribution, so as to be able
to put probable upper and lower limits to the number of each
organism per unit volume of water may be doubtful. But
even if the data are not yet sufficiently numerous and reliable,
we must still work on in the hope that improvements in method
and accumulation of evidence may in time enable us to make
some approximation to an estimate of the population of various
Sea-areas. .

I would go further and say that even if we had no hope of
attaining to greater accuracy, our present planktonic results are of
some value. Although estimates which may be 25 or even 50 per
cent. wrong in either direction may not justify us in calculating -
exactly the number of organisms and of potential food present
per area or volume of water, they do give us a useful approxi-
mation. Even if 100 per cent. out, doubling or halving the
estimated number is a relatively small variation compared with
the much larger increases and reductions amounting to, it may
be, ten thousand times in the case of Diatoms, ten to fifty times
in Dinoflagellates and five to twenty times in Copepoda, which
we find between adjacent months, and even greater differences
if we take groups of months, in a survey of the seasonal
variations of the plankton i European seas. |

SEA-FISHERIES LABORATORY. 175

ON MEASUREMENTS OF SOLES MADE IN 1920.

By James Jounstone, D.Sc.

In June of 1920 a system of observations on board smacks
and steam-trawlers, working in the Irish Sea, was put in
operation by the Ministry of Agriculture and Fisheries. Two
“fish measurers,’ Commander A. KE. Ruxton and Mr. W. C.
Smith, were stationed at the ports of Fleetwood and Whitehaven,
and, later on, a postgraduate student of the Zoology Depart-
ment at Liverpool University, Mr. G. F. Sleggs, B.Sc., was
engaged on similar work. The object of the observations was
to obtain data with regard to the sizes and general distribution
of the plaice caught by the first-class trawling vessels on the
offshore grounds of the Irish Sea. The measurers usually
worked on smacks sailing out from Fleetwood and Liverpool,
and, though their specific work was to observe the catches
of plaice made, they also measured all the soles caught. The
results are very interesting and are also quite novel, for there
were, previously, no measurements of the soles trawled on these
offshore grounds. Since these fish were the principal objects
of the fishing of the smacks the region where they occur was
pretty well worked and nearly 6,000 soles were measured.
Unfortunately it was impossible to arrange for the work to be
commenced earlier than the last day m May, so the spawning
period of the fish was not fully covered.

The grounds trawled over are shown on the sketch chart
(Fig. 5). The irregularly-marked regions represent, rather
roughly, the parts of the sea worked on the various voyages
of the smacks with which the measurers went. The Roman
numeral gives the month and the suffix gives the number of
hours during which trawling went on.

The principal sole-fishmg ground is well shown : it extends
N.W. from Morecambe Bay Light Vessel up towards Maughold

176 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Head and then over towards the coast of Cumberland. Further
South-west there was also a good deal of trawling, and some
catches made in Carnarvon Bay are recorded. June was the
best month on the whole, and then the two smacks, with

No ON a _

\
,
7
r

STG

Fig. 5. Grounds from which the measurements of Soles
were made.
which the measurers went, caught about 14 soles per hour’s
trawling. In July the number was 9, and it was 7 in August
and 6 in September.

' SEA-FISHERIES LABORATORY. 177
The sizes are shown in the table below. There is little
change, with relation to the months, for the “ shortest-half-
ranges,” that is, the most prevalent sizes of soles caught are :—
June, July, August, September. So far, then, as one can
judge there is not much indication of a rapid period of growth,
as in the case of plaice caught in the same regions, during the
summer and early autumn.
Measurements of Soles caught in the Irish Sea, 1920.
Mean June July. August. September.
length SUES EEE Sane
i eae Walligy| VIE s| VIERS,, [VIE s| EX | ER ia EX ay | ER ga] TX igg | TX re
(19-5 ae ee * wae aon 1 af 4 : vad dee aes
20-5 1 1 ee bee sia 1 2 1 be 3 ae 2
21-5 7 5 es Te Wb. ot oes) i ae ape cect ea ee
22-5 11 1 aie ete 1 2 2 2 : 3 “ 6
3:5 | 23 | 20 1 2 5 2 2 ill kee Pee. s
24-5 46 37 2 Sais 12 2 wig 3 sss 11 gen) |e
25:5 83 42 13 a 28 7 1 13 1 16 10 4]
26.5 92 57 27 1 59 . 22 3 11 1 26 5 49
B75 | 94 | 68 | 42 1 82 21 tele 3 | 26 8 | 64
me5 | 13. | 85 | 47 1 81 37 7 DBL > |. 38 6) 36
29-5 102 62 47 3 108 db 8 18 ie 28 8 83
~ 30-5 85 91 Ue =o 114 46 9 13 2 48 4 76
31-5 110 73 58 2 109 46 17 17 1 40 ll 61
32:5 108 67 81 Geis 135 44 18 13 1 29 6 52
33:5 85 72 58 1 97 45 6 16 sia 35 8 45
34-5 58 49 60 1 87 38 5 8 1 14 6 | 29
35:5 55 27 46 1 80 23 11 10 1 17 a, |e
B65 | 42 | 25 | 18 1 51 19 4 Se 6 5 | 16
Rei eawh itor 12 | 38 18 5 2 2 8 2 7
38-5 24 10 13 1 20 20 + 1 asi 3 2 4
39.5 18 7 3 ne 13 t ose 1 nee 1 des 3
40-5 | 10 i 9 1 7 5 5 2 wih: oe. 3
41-5 5 4 2 1 5 2 5 peta 1 1
a) 6 Bo: 2 2 3 3 a ee a5 Lg eee
43-5 4 cis fess 1 2 1 wo Lice: Hae
44-5 2 a BAe fe Joe ee ae ee | a ae
— 45:5 2 5 i: 1 s Pee
A 46-5 1 eee eee os eee
47-5 1 1 34) ’ |
vi 48-5 eee eee eee |
Totals ...| 1,211| 821 | 619 | 28 | 1,137 | 454 | 121 | 168 | 16 | 361 | 84 | 671
Catch re | | |
perhour| 14 | 13 9 3 10 8 7 5 1 | 11 | 2 fae

178 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

ON BLACK LITTORAL SANDS IN LANCASHIRE.

By James Jounstone, D.Sc.

On most places in the littoral zone on the coast of Lanca-
shire the sand below the surface is more or less black. On
the Formby shore, for instance, on the landward side of the
channel between the shore and Taylor’s Bank there is (or
used to be) a cockle-bed, but below the upper two or three
inches of clean, yellow sand the substratum is very black.
At Piel (in Barrow) there is a dense bed of lugworms on the
west side of the railway embankment, and here also the sand
beneath the surface is black to grey in colour, the superficial
layer being yellow. Close to the embankment there are little
gutters contaming a few inches of water, and on the sides of
these the upper, yellow layer of sand is only about an imch
in depth, while below that, and as deep down as one can dig
with a spade, at all events, the sand is dense black. Further
out towards the low-water mark the upper, yellow layer becomes
thicker and the sand underneath becomes grey in colour, and
the greyness becomes rather lighter as one goes out away
from the shore.

The dense, black sand close inshore smells offensively of
decaying seaweed and sulphuretted hydrogen when it is turned
over. When I first collected a sample I dried it m a steam
oven and was, for the moment, surprised to find that the
colour had disappeared long before the sand became dry.
Even in the cold it disappears rather quickly, a mass of the black
substance becoming light yellow in about an hour. But under-
neath the upper layer of a quarter of an inch in thickness the
dense, black colouration was persistent. It was evident that
one has to do here with a deposit of moist ferrous sulphide
which rapidly oxidises.

SEA-FISHERIES LABORATORY. 179

Samples of the black sand were put into tall, narrow
glass tubes and covered with salt-water, fresh water, 5%
forma‘ine and 70 % methylated spirit. In all cases the same
thing happened: the upper 5 mm. or so of sand bleached
rapidly to the normal, light yellow colour and then the action
slackened. Very slowly the discolourised layer thickened, but
after some six months it was little over about 5 mm. in thick-
ness. Some of the black substance was put into a 12 x 3 cm.
tube, the latter beme filled to within an inch of the top. The
water in the sand was drained off for about ten minutes and
then the upper part of the tube was dried and filled with melted
paraffin wax, the latter being coated over the outer edge so as
to make an air-tight seal. After eight months the sand
remained perfectly black and there was no trace of bleaching.
A little white substance, rather like a bacterial growth, formed
on the surface, but this was not bleached sand: it has not yet
been examined.

Another, and similar, tube was filled in the same way,
but was sealed with an ordinary, unluted cork. The sand
oradually dried, but it did so unequally in such a way that air
was able to penetrate along irregularly dried paths. These
paths bleached to the usual light yellow colour while the other
parts remained black. Gradually, however, the whole became
orey or yellow, but on the margins of the “ paths ” an ochreous
substance, evidently ferric oxide (Fe,0;), began to appear.
After eight months the whole contents of this tube had not
completely bleached, or reddened.

A little of the blackest sand was placed in a glass tube of
2 cms. bore and about 12 cms. long. Hydrogen was generated
from zine and sulphuric acid, washed in strong H,SO,, bubbled
through a strong alkaline solution of pyrogallic acid, again
passed through strong H,SO,, and finally dried in a calcium
chloride U-tube. The tube containing the black sand was
gently heated and the O-free, dry gas was passed through it

180 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

until the sand was quite dry. It was then dark grey in colour.
When shaken out on to a sheet of paper it rapidly bleached
to the normal colour. It even bleached when kept in a
desiccator.

When examined under a microscope the sand is seen to
contain black granules adhering to, and mixed among, the
orains, but the latter are not “coated.”” When it is treated
with dilute HCl it bleaches at once and SH, is evolved. The
solution, when filtered, gives all the tests for iron. When the
sand is ignited strongly it also bleaches, but the iron is not
then so easily dissolved out, though it can be, of course.

The blackening and subsequent bleachmg are easily
imitated. Some very clean, white sand was ignited, cooled,
and then put mto an evaporating basin and covered with a
0-5 % solution of ferrous sulphate. A little ammonium chloride
and ammonium hydrate were added, and SH, was bubbled
through the wet sand. The latter rapidly blackened. It was
then quickly washed in boiled-out water and put into a tall
olass tube with a little overlymg water. In a few hours the
upper layer bleached and the result resembled that obtained
from the naturally discoloured sand. Just the same effects —
were produced when the mixture of clean sand and dilute
solution of ferrous sulphate was treated with ammonium
sulphide. The bleaching occurred in much the same way, but
the decolourised, upper layer was yellow because of the presence
of sulphur. Evidently, then, these littoral, black sands
are the result of the formation of ferrous sulphide. Every-
where on this coast (and especially m the North Lonsdale
region) the sea-water in the interstices of the sand contains
soluble iron salts. Everywhere there are organisms (lugworms
and cockles, for instances) which form excretal substances,
and in any case they die in the sand sometime or other. The
putrefactive process gives rise to SH, and some ammonia
salts, and then the trace of iron present in the water is precipi-

SEA-FISHERIES LABORATORY. 181

tated as ferrous sulphide. So one often finds a dead cockle-
shell in clean sand with some black sand in the shell cavity.
Wet ferrous sulphide very easily oxidises, of course, and there-
fore the upper layers of sand are always clean. But the black
stuff underneath exists under conditions that are nearly
anaerobic and so the oxidation is confined to the upper layer.
Near the shore there is a continual access of organic matter,
in the form of land drainage, which penetrates into the sand
and renders the process of formation of ferrous sulphide a
continuous one. Further out, over the littoral zone, there is
not so much of the organic matter for it is the more easily
distributed by the tide, and so the bleached layer is thicker and
the underlying discoloured stratum is not so black.

The same process, as was pointed out by J. Y. Buchanan,*
occurs on the sea-bottom in deep water and is responsible
for the formation of blue and black muds. Such sulphide-
containing muds and sands do not (or, at least, need not) be
found among sedimentary strata, for oxidation would generally
have led to the bleaching. But, in such strata, the presence
of much iron in the form of Fe,0O, may usually indicate that
the sediments from which they have been formed have been
the seats of putrefactive processes.

* See ‘Accounts Rendered,’? Cambridge University Press, 1919,
pp. 183-158.
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183

L.M.B.C. MEMOIRS

No: XXIV:> ‘APLYSIA

BY

NELLIE B. EALKES, B.Sc.

LECTURER IN ZOOLOGY, UNIVERSITY COLLEGE, READING.

CONTENTS.
PAGE
Introduction ... he aes ae ee be Eos 2% apn 184
History mG re om ae oe eis aes oes << 2 288

Habitat ste ie ae cai oe os pi ese x.) ae
Food ... fas a <a ass tid’ se wat ee a3 19
Life-History ... aege hei wad on es as fee sae GE

Enemies i nie Ee eee eee ue ae ae: eee pe
Fossil Remains = doe ae sis bos ake aoe cigs ae
External Characters ... wt sei ae sis at “ag “ie ee
The Shell bes a os See a se 3 aa. 202
Histology of the Foot and its Glands a: ae ase ox, 208
Histology and Physiology of the Mantle Glands... se a 20D

The Digestive System oF vias sc ae Sue Sts awe +200
Glands of the Gut ae bes See ae eae wae a. als
Mechanism of Digestion ot aes ie. R25 ae aoe! 214

Blood Vascular System 215
Respiratory System ... oe es oe. ae i: ee wey 20
Excretory System 225
Muscular System... “ns as es oe = Le Jet) Qe
Nervous System 229
Sense Organs 238
Generative System 24]
Literature sae ies ee are 255
Explanation of the Plates ... Eo eet wee bes nae we 0 20

184 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

INTRODUCTION.

The Mollusc of which the present Memoir is the subject
belongs to the Euthyneura, a sub-class of the Gastropoda.
The Kuthyneura are hermaphrodite, and usually, except in
primitive forms, have undergone detorsion so that the visceral
nerve cords are uncrossed. In many cases a secondary external
symmetry has been acquired. The Euthyneura are divided
into two orders, Opisthobranchiata, including Aplysia, and
Pulmonata, including land forms such as the Snail. In Opis-
thobranchiata the ctenidium is situated posterior to the heart,
and. there is usually a widely-open pallial cavity. The cteni-
dium is covered by the overhanging mantle in the sub-order
Tectibranchiata, containing Aplysia, but this mantle skirt is
absent in the Nudibranchiata.

The family Aplysiidae has six genera, viz. :—Aplysia,
Dolabella, Dolabrifer, Aplysiella, Phyllaplysia, and Notarchus.
Of these only Aplysia is British, and of the three best known
European species, Aplysia limacina, A. depilans, and A.
punctata, only the Jast named inhabits the waters round our
shores. *

The popular name for Aplysia is the Sea-hare; it has
been called this since the days of Plmy owing to its resemblance
to a sitting hare when contracted, and to the similarity between
the auriculate tentacles and the ears of the hare. The name
Aplysiat was first given to the Sea-hare in the 13th edition of
the “ Systema Naturae ” of Linnaeus (1791), though the 12th

* Tt was formerly supposed that the large Aplysiae, taken in Torbay
by Major Hunt in 1875 (‘‘ Trans. Devonsh. Nat. Assoc.,” 1877). were
specimens of A. depilans, but the characters of the species were not then
sufficiently well defined to determine this with certainty. Major Hunt
later (1904) considered them unusually large specimens of A. punctaia, and
for many years only this species has been known on British coasts. Similarly
the very small rose red species of Thompson has been shown to he the
young stage of A. punctata.

+ The Aplysia mentioned by Aristotle is not a Mollusc, but a Sponge.
The word means “that which cannot be washed” or possibly “* washed
with.”

APLYSIA. 185

edition (1767) has Laplysia, an obvious misprint for L’ Aplysia.
In the 10th edition, the animal is called Tethys limacina, but
the name Tethys now belongs to a genus of Nudibranchs.

As a type for dissection Aplysia is of considerable value.
Not only is it the largest British Gastropod, but it exhibits
intermediate characters between the primitive and more highly
specialised forms. Thus, though it has partially acquired a
secondary external symmetry, its mternal organs are still
markedly asymmetrical and afford numerous links in the chain
of evidence that detorsion has taken place. The pallio-visceral
nerve cords, long but uncrossed, resemble the Streptoneura in
the first character and the Euthyneura in the second. There is
as yet no indication of the concentration of the nervous system
which is so marked a feature of the more specialised Tecti-
branchs and Nudibranchs, although other members of the
family (e.g., Phyllaplysia, Notarchus) show it. Further, the
tendency towards disappearance of the shell and mantle cavity
can be understood after a study of this form.

EISTORY.

Aplysia has been known from very early times, the first
authentic description of it being that of Pliny in the first
century A.D. By the ancients it was generally regarded with
abhorrence, due, no doubt, to its grotesque appearance and
the nauseating odour of the large Mediterranean species.
Whatever the cause, this entirely innocuous creature became
invested with poisonous and magical properties, and only one
writer of early times (Nicander, ¢. 150 A.D.) says a good word
for it, quoting it as a specific in certain diseases.

Pliny,* who called it Lepus marinus, the Sea-hare, gives
an account of the popular superstitions regarding it. He

* Pliny describes three species, two in the Mediterranean and one in
the Indian Ocean. Of these the last is probably a Dolabella.

186 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

describes it as being poisonous to the touch, producing vomiting
and subsequent death, unless the antidote of “ asses’ milk
and asses’ bones ground and boiled” be given to the victim.
Other observers thought the “onely aspect and sight thereof”
was poisonous, while another version of this superstition was
that if a human being touched an Aplysia, that person died.
Others said that the Sea-hare died, ‘“ which latter,” says
Johnston, “ would be the more probable result.”

Johnston, in his “ Introduction to Conchology,”’ quoting
from Cuvier’s “ Histoire des Mollusques,’ claims that the
celebrated Locusta used Aplysia “to destroy such as were
inimical to Nero; it entered into the fatal potion which she
prepared for the tyrant himself, and which he had not the
resolution to swallow ; and Domitian was accused of having
given it to his brother Titus.’
for this story, which was probably quoted by Cuvier from the
1550 edition of the “ Antiquarium lectionum” of Coelius
Rhodiginus, and does not occur in the original (1516) edition.*

2

There is, however, no foundation

Apuleius, one of the first to investigate the internal
anatomy of Aplysia, was accused of magic and poisoning, and
the principal point of evidence brought forward at his trial
was that he had induced two fishermen to procure a Sea-hare.
To him belongs the earliest description of the teeth of the

4

first triturating stomach. He says they are “similar to the

ossicles or ankle bones of the hog, connected and joined.”

4

Aelian says Aplysia “ resembles a snail from which the shell
has been taken,” but Dioscorides found the shell under the
mantle folds and compared Aplysia with a Cuttle-fish.

In 1554, Rondelet, in his “ De Piscibus Marinis,” gave two
fairly good figures of Aplysia under the name Lepus marinus.

*T am indebted to Dr. Charles Singer for unravelling this difficulty.
In the 1550 edition, produced by Camillio Ricchieri (Rhodiginus}, the
statement about Locusta appeared for the first time, and was evolved,
Dr. Singer says, ‘‘ out of his inner consciousness by putting together the
ideas of poison by Aplysia in Pliny and the exploits of Locusta.”” Bechmann,
in his ‘‘ Beitrage zur Geschichte der Erfindungen,” Leipzig, 1786-1805,
quotes also from the 1550 edition of Rhodiginus and copies the same errors.

APLYSIA. 187

He explains that it should not be confused with other fishes,
because “it is very poisonous and would be fatal to anyone
who ate it.” Rondelet makes the mistake of putting the
genital groove on the left side of the body instead of on the
right side. This mistake was copied by Aldrovandus, but
corrected by Gesner, both of whom reproduce Rondelet’s
figures. Gesner removes Aplysia from the fishes and places
it amongst the soft-bodied animals.

In 1684, Redi made the first recorded investigations of
the internal anatomy of Aplysia since the time of the unfortu-
nate Apuleius. He called it the marine Slug from its resem-
blance to the terrestrial Lomax, and described the internal
anatomy of both animals. Nearly a century after Red,
Bohadsch, a Bohemian fugitive who took up his residence in
Naples, wrote a book on marine animals, published in 1761.
In this book he describes two species of Aplysia, which he calls
Lernaea, gives good figures of them both, and a long and
fairly accurate description of the nternalanatomy. Hestudied
their habits and observed the exudation of a milky as well as
a purple fluid. The opaline gland, which secretes the milky
fluid, has since been called by his name. He dissected the
alimentary canal, nervous system and sexual organs, and
came to the conclusion that Aplysia was related to the land
snail.

The first authentic mention of Aplysia in British literature
is in Pennant’s “ British Zoology,’ Vol: 4, published in
1777. He figures a small specimen and classifies it amongst
the Worms. It is true that Borlase, in his “ Natural
History of Cornwall ” (Oxford, 1758), says that he was brought
a Sea-slug on March 24th, 1752. He states that the animal
had eyes on its antennae and exuded a purple dye. He
thought it was a Holothurian and compared it with the
undoubted Holothurian in Rondelet, Part 2, p. 125. The
purple suggests Aplysia, but it is strange that if his specimen

188 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

was a Sea-hare he did not know of Rondelet’s description of it.
Sowerby, in 1806, recorded Aplysia from St. Michael’s Bay,
Cornwall, and investigated its purple dye.

In 1767, Linnaeus, in his “ Systema Naturae,”’ adopted the
name given to Aplysia by Bohadsch, viz.: Lernaea. (Editions
8 and 9.) In the tenth edition he revised its nomenclature
and called it Tethys, in the 12th edition Laplysia,* and in
the 13th edition Aplysia. To one species of Aplysia he gave
the name Aplysia depilans.

Lamarck, in 1812, attempted a classification of Inverte-
brate animals and recognised the affinities between the Bullidae
and Aplysiidae. In 1817, Macri, a Neapolitan, disposed once —
and for all of the fables concerning Aplysia, and stated in most
emphatic language that 1t was quite harmless.

In 1817 appeared Cuvier’s “ Mémoires pour servir a
Vhistoire et a ’anatomie des Mollusques,” containing ““ Mémoire
sur le genre Laplysia”’ (first published in 1803). This Memoir
contains a full account of the Mollusc with good figures.
Cuvier made the first chemical mvestigation of the purple,
though he made the bad mistake of supposing that it was the
gland now known to be the kidney, which exuded that fluid.

From 1820 onward Aplysia has been studied from every
standpoint by many observers, so that a fairly complete
knowledge of its anatomy, histology, and embryology (excluding
the metamorphosis) has been obtamed. ‘The literature, how-
ever, contains many inaccuracies, copied without verification
by different writers, and no reliable monograph, with the
exception of that by Mazzarelli, has appeared.

The most important works on the anatomy of Aplysia
during the nineteenth century are those of Delle Chiaje, Sander

* Laplysia appears to be a printer’s error for L’Aplysia, and was
corrected by Gmelin in the thirteenth edition. Aplysia means “ that
which one cannot wash.’’ It has no meaning for the Mollusc which now
bears it, and was chosen quite arbitrarily by Linnaeus. The Aplysia of
Aristotle is a sponge which could not be freed from gritty and dirty matter.
Aristotle does not mention the Sea-hare.

APLYSIA. 189

Rang, Milne Edwards, Spengel, Blochmann, Cunningham,
Vayssiére, Lacaze Duthiers, Mazzarelli, Guiart, and Blatin.
Very little work has been done in this country; nearly all
these authors investigated the larger Mediterranean species.
Milne Edwards (1847) and Blatin and Vles (1906) contributed
to our knowledge of the circulation, Cunningham (1883) worked
out the relations of the kidney and the pericardium, to Spengel
(1881), Lacaze Duthiers (1888), and Guiart (1901) we owe a
comprehensive account of the nervous system, and Mazzarelli’s
important monograph, published in 1893, has already been
noticed.

The first observations on the development of Aplysia
were due to van Beneden, who, in 1841, described the veliger
larva* with its nautiloid shell. In 1874, Lankester published
a paper on the development of Aplysia, and eight years
later Manfredi summarised the information on the subject.
Blochmann also worked on the embryology. Mazzarelli
published several papers on the development, and corrected
Lacaze Duthier’s curious mistake in supposing the primitive
kidney to be an analeye. Morerecently, Georgevitch (1900) and
Carazzi (1900) studied the embryology, and the latter, in 1905,
worked out the cell lineage in the early stages. Carr Saunders
and Margaret Poole, in 1910, made a careful investigation of
the work of previous authors. The metamorphosis of the larva
into the adult condition is not yet known.

The large size of the Mediterranean species of Aplysia has
made them suitable for histological and physiological study.
The histology of the mantle glands was investigated by
. Blochmann in 1883; in 1888, Robert studied the microscopic
structure of the hermaphrodite gland; and Cuénot, in 1890,
described the blood and lymphatic glands. Mazzarelli has
written several papers on the histology and physiology of
Aplysia, the chief being on the reproductive system and the

* Sars, however, had discovered this larva.

190 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

pallial glands. Botazzi worked on the physiology of the
nervous system and muscles, Jordan on the physiology of
movement, MacMunn, Moseley, and Briot on the “ purple,”

and Ariola on digestion.

HABITAT.

Aplysia punctate inhabits the shallow-water zone of the
sea down to a depth of about forty fathoms (Lo Bianco). Its

range extends from the Mediterranean to the Arctic Circle. It -

is, however, extremely susceptible to the effect of foul or badly
aerated water, so that it occurs most abundantly on those
parts of the coast where the tide runs rapidly and the water is
uncontaminated by sewage or decaying matter. The best
place to look for it is on the beds of Zostera at very low tides.
Its appearance is often sporadic, and whereas it may be very
abundant in a certain year at a definite spot, the same place
may not yield a single specimen when searched again the
following year. The same applies to the collection of specimens
withthe dredge. At different places along the coast remarkable ©
incursions of Aplysia have occurred at intervals, as described
by Major Hunt m Torbay, and by other observers on the
Welsh and Manx coasts. Such an incursion was recorded by
Chadwick at Port Erin in July, 1916, when, after a severe
storm, hundreds of Aplysiae were thrown up on a small area
of shore within Port Erm Bay. They were in poor condition
and lay amongst pieces of decaying weed. Most of them
disappeared after a few days.*

* The cause of the sudden appearance of Aplysiae in such numbers
is not known. It is probable that many die after breeding, but on this
occasion Chadwick saw no cordons of eggs. Possibly the stormy weather
tore off masses of weed, on which the animals were feeding, from the rocks
in deep water, and the Aplysiae were thrown up with the weed. Compare
also similar incursions of Aphrodite.

APLYSIA. 191

FOOD.

The food of Aplysia consists of seaweeds of various kinds.
When full grown it lives on green and brown weeds such as
Ulva lactuca, species of Fucus, etc., and the colour and markings
of its skin bear a close resemblance to the weed (vide External
Characters). The animal can adapt itself to its surroundings,
and undergoes remarkable colour changes which very quickly
enable it to imitate the particular weed on which it is feeding
at the time. Thus very small specimens feed on red weed
like Delesseria and are coloured rosy red, larger specimens
feeding on weed from the Laminaria zone are brown, while those
feeding on Fucus are olive brown. (Vide Life History.)

If the contents of the crop be examined, Foraminifera,
little Ophiuroids, and small Gastropods may sometimes be
found, but these have probably been consumed accidentally
along with the weed and do not form the bulk of the food as
Cuvier implied in his account of the Sea-hare.*

LIFE-HISTORY.

During the spring the Aplysiae come up into shallow
waters to deposit their cordons of eggs amongst the weeds
between tide marks. From the eggs hatch, in about a fort-
night, free-swimming veliger larvae, which lead a pelagic
existence. ‘The metamorphosis into the adult form is not
known. The youngest Aplysiae found are about a quarter
of an inch in length, and are brought up in the dredge attached.
to red weed. These young forms are of a deep rose-red colour
and feed upon the weeds which they so closely resemble.
Apart from the differences in the shape of the tentacles they
are in external form like the adult, though differing from them
so markedly in colour. These small red specimens were

* Cuvier, G. ‘“‘ Mémoires pour servir & histoire et a4 ‘anatomie des
Mollusques.”” Paris, 1817.

192 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

formerly regarded as a distinct species (A. rosea of Rathke,
A. nexa of Thompson). Garstang,* however, showed that
they were the young stage of A. punctata, and that when kept
in a tank and fed on different weed they changed colour and
became first brown and finally olive green, the inference being
that these colour changes represent the protective colouration
exhibited by the animal as it passes through the Laminaria
and Fucus zones respectively, during its migration from deep
water to its breeding grounds, as it becomes mature. ‘

After the period of oviposition in the spring it is not
known what happens to Aplysia. Mediterranean fishermen_
assert that it becomes full grown in one season, lays its eggs, .
and dies. Confirmation of this statement is indicated by
observations made at the Plymouth Laboratory. Dr. Orton
thinks that Aplysia is probably an annual, and that it attains
the length of 6-8 inches in a single season. Dr. Orton’s records
also point to an early and a late brood of young, the first
reaching the red stage about July, and the second about
September at Plymouth. Thus the wintering forms spawn in
the spring, and the young produced may reach maturity and
spawn in the autumn. It is also possible that the same
individual can produce two broods during its life-time.

There are, therefore, the following stages in the life-
history :—

1. Pelagic veliger (larval) stage hatching from shore-laid
egos.

2. Metamorphosis (unknown),

3. Rose-red stage in red alga zone on sea bottom.

4. Brown stage in Laminaria zone.

5. Olive green stage in Fucus zone. This is the mature
stage when spawn is produced.

6. If the individual survives egg-laying it may return
to deeper water.

* Garstang. “‘ Journ. Mar. Biol. Assoc.”? 1889-1890.

APLYSIA. 193

BENEMIES.

Despite the ancient fables concerning them (vide History),
Aplysiae are absolutely harmless and appear to possess few
enemies. No other animals are known to attack them,* and
they are singularly free from parasites or epizoic organisms.
There is no record of any parasite, but on young specimens
in the “red” stage, small colonies of Obelia and Pedicellina,
etc., are occasionally found attached to the mantle.

In all stages Aplysia is protectively coloured, and the
resemblance to the weed on which it is feeding is so close that
detection may be difficult except when it is moving. If
attacked it has two means of defence.t It can exude a rich
purple dye, which forms an effective screen under cover of which
it can escape, from glands situated on the under side of the
mantle, and an acrid fluid from the sub-pallial opaline or poison
gland. It might be supposed that the dye would have been
employed by the ancients, to whom Aplysia was well known,
but there is no evidence that they utilised this particular
animal. The unstable character of the dye coupled with
abhorrence of the creature that produced it were quite sufficient
to prevent its use.

FOSSIL REMAINS.

There are no authentic fossil remains of Aplysia, whose
soft body and delicate shell do not lend themselves to pre-
servation. The supposed fossil shells of Aplysia from the
Pliocene are probably flakes from Pelecypod shells. (Zittel,
Text-book of Palaeontology, Vol. 1, p. 568.)

* Rondelet states that the Mullet eats the Sea-hare. As, however,
he also says that Aplysia feeds on “ water, mud, and filth,” he cannot have
investigated very thoroughly either its habits or its anatomy.

} As Sir Charles Eliot says of the Nudibranch: “It cannot fight and
it cannot run away.”

194 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

EXTERNAL CHARACTERS.
(Figs. 1-7.)

If possible, Aplysia should be examined alive before any
attempt is made to dissect it. No one who has seen only the
preserved animal can have an adequate idea of the appearance
of the living animal, for not only does it lose its colour and the
velvety nature of the skin, but it dies in a contracted condition,
rarely measuring more than a third of its length when alive.

(4

When preserved it assumes the “ sitting-hare”’ position, but
it seldom does so during life. Then it resembles a large slug
with a face like that of a rhinoceros of grotesque and solemn
aspect. The body is relatively broader and the visceral hump
higher than in the Slug.

The colour of the full-grown animal varies, but it usually
resembles very closely the particular weed on which the
specimen is found. In many it is a rich olive green or brown,
with small black spots and irregular greyish flecks. A black
spot is due to granules of pigment in the skin, a white or
greyish mark to absence of pigment, whereas the green or
brown colour is caused by colouring matter dissolved in the
cells of the epidermis and underlying layers. Preservative,
especially methylated spirit, quickly extracts the soluble
pigment, and to a lesser extent also the granular pigment.
Hence the grey appearance of preserved specimens. Gautier
and Villard* have shown that the soluble colouring matter
possesses the same spectrum as chlorophyll, and that it can be
traced back to the chlorophyll extracted from the food by the
liver cells. If this is so, Aplysia can be said to imitate the weed
by making use of the pigments extracted from the weed.

Not only, however, does Aplysia imitate the colour of the
weed, but also its shape. For example, a specimen feeding

* Gautier and Villard. ‘‘ Recherches sur le pigment vert jaune du

a des Aplisies.” C. R. Soc. Biol., Paris, T. LVI, p. 1037-1039,

APLYSIA. 195

upon frilled Chondrus crispus possessed frilled parapodia
like the fronds of the weed. The resemblance was so perfect
that unless the Aplysia was moving, it was impossible to
distinguish it from its surroundings.

The greyish flecks on the skin differ in shape and size at
different ages and in different specimens. When first they
appear they are spots, few and far between. After a time
ovate flecks arise, arranged radially round the original spot,
like the zooids of a compound Ascidian. The radial spots
finally fuse with one another and with the first spot to form
an irregular patch. These spots bear a close and unmistakable
resemblance to the irregular colonies of Polyzoa found growing
on the weed.

The body is soft and slimy to the touch owing to the
mucus which is secreted abundantly by the epithelial glands
of the skin.

Externally the animal appears bilaterally symmetrical,
but the symmetry is superficial and does not extend to the
internal organs. It has been acquired by detorsion of a spirally
coiled type. The body may be divided, for purposes of
description, into three regions :—

(1) Cephalic region.
(2) Foot and its appendages.
(3) Mantle and Visceral Hump.

1. Cephalic region. The anterior portion of the body,
consisting of the head and neck, is very highly contractile.
This region is frequently bent ventralwards when Aplysia is
moving sluggishly over the weeds. (Fig. 2.) The head bears
the mouth, two pairs of auriculate tentacles, a pair of sessile
eyes and the male copulatory organ. The tentacles are
contractile, but not, as in the snail or slug, invaginable. The
anterior pair are short, with an open groove on the outer side
formed by the curling of the edge. At the base they are
stout, and confluent with paired labial expansions which form

196 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

a kind of “‘ buccal veil,” shaped like two quadrants of a circle,
and sloping slightly inwards to the mouth aperture, which is
a vertical slit lying between them. This buccal veil can be
thrust out, partly invaginated, or flattened to form a shield.
(Fig. 3.) The anterior tentacles are tactile organs.

The posterior tentacles or rhinophores (Fig. 4, rh.) are
longer and less fleshy than the anterior pair. Like these, they
are crooved along their outer edges, but the grooves are closed
proximally so that they bear a certain resemblance to hare’s
ears. When the animal is moving they are directed forwards
and outwards, when at rest they stand almost upright. They
function as olfactory organs.

Immediately anterior and slightly lateral to the base of
the rhinophores lie the paired eyes. Each eye is a bluish
black speck situated on a circular patch of white (unpigmented)
skin. The eye is so small that it often cannot be found m a
much contracted specimen. It is usually flush with the
surface of the head, but in a well expanded Aplysia it may
be elevated on a small papilla. (Fig. 3.)

On the right side of the body at the outer side of the base
of the right anterior tentacle is the aperture through which
the male copulatory organ or penis is protruded. ‘This aperture
is connected, by means of a shallow open groove, the spermatic
groove (Fig. 4, sem. gr.), with the common genital aperture.
The groove is unpigmented. On pressing it open with forceps
the groove is seen to consist of two projections from the body
wall which meet but do not fuse. Along the tube so formed
the spermatic fluid passes forwards from the common genital
duct to the penis during copulation.

The neck is long in Aplysia punctata, and is of the same
diameter as the head.

2. The Foot. The foot or pedal sole is the organ of
locomotion. It is an elongated, flattened, muscular structure
which occupies the whole of the ventral surface of the animal,

APLYSIA. 197

extending forwards in front of the buccal veil and backwards
as a projection or “ tail”’ posterior to the visceral mass. Its
anterior end is almost rectangular, the posterior pointed. There
is no division into regions as in many Gastropods. Anteriorly
the foot is separated from the body by a backwardly directed
cutter (Figs. 2 and 22, gt.), which makes a cleft about half an
inch deep between the foot and the buccal veil. The vertical
slit-like mouth 1s continuous ventrally with this gutter, but
behind the mouth the gutter narrows and ends blindly. (Vide
elands of the foot.)

From the postero-lateral portion of the foot, in the region
of the visceral hump, arise a pair of upwardly directed out-
growths, the parapodia or swimming lobes. These are mobile
fleshy structures and cover the visceral hump when the animal
is at rest. Anteriorly the flaps are free, their bases being
about an inch apart, but posteriorly they are fused completely
in this species. The line of attachment is thus a horseshoe,
with the open ends directed forwards. (Vig. 4, para.; Fig. 7,
para. b.)

The foot is much narrower than in the land snail, and the
whole of it is rarely used for creeping. Usually one portion
of it is flattened and the remainder has the edges curled
towards one another. When Aplysia crawls up the stalks
of seaweeds only the anterior part of the foot is flat, the posterior
portion curls itself round the stalk by approximation of the
lateral edges. (Figs. 21-23.) The narrowness and elongation of
the foot are well adapted for this purpose. (Compare the broad
flat foot of a Doris.) It is stated by various observers that the
foot can also be used for crawling in the inverted position on
the surface film as in many Nudibranchs. During creeping
and swimming the foot exhibits waves of movement due to
muscular contraction. These are not so well shown in Aplysia
as in the Snail, and different observers give conflicting accounts
of the direction of the waves. They appear to pass backwards

198 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

along the edges of the foot, and the type is called
retrograde.

Aplysia can also swim by means of sinuous movements
of its parapodia, or can, according to Guiart, jerk itself suddenly
backwards like a Cephalopod by rapid closing of the parapodial
lobes. This last movement is probably connected with respira-
tion and with the excretion of faecal matter.

3. Maitle and Visceral Hump. (See Fig. 7.)
[Hold the parapodia apart with the fingers. ]

Between the lobes of the upstanding parapodia and overlying
the visceral hump can be seen a mushroom-shaped mass
consisting of the mantle enclosing the shell. In the typical
Gastropod the mantle encloses the projecting visceral mass,
and mantle and visceral mass are permanently lodged within
a conical or spirally coiled shell (Cf. Patella, Buccinum, etc.).
Between the mantle and the body is a space, the pallial cavity,
which contains the ctenidia, and into which the anus, the
kidney, and the genital glands discharge. At first sight the
condition in Aplysia appears to vary from this type, but is
really a modification of it, due to reduction of the mantle and
shell and to the reflection of the mantle flaps over the shell.
In many Gastropods the mantle edges become either tem-
porarily or permanently reflected dorsalwards over the surface
of the shell (e.g., Cypraea, Physa, etc.). In Aplysia this has
become permanent by the fusion of the mantle flaps in the
mid-dorsal line. The fusion, however, is not quite complete,
as a circular aperture (Fig. 7, sh. ap.), which varies in size in the
different species of Aplysia, is left in the centre. In the young
individual the space is very much larger than in the adult.
(Cf. Fig. 21). Through the mantle aperture can be seen the
delicate, transparent, horny shell. As might be expected,
the enclosure of the shell is causing its gradual disappearance.
In some allied forms it has disappeared altogether. The six

APLYSTIA. 199

genera of Aplysiidae can be arranged in a series on this point,
thus :—
Dolabella. Shell with deep anal incision and short
spire.
Dolabrifer. Boat-shaped shell.
Aplysiella. Shell slightly covered.
Aplysia. Shell covered, circular aperture in mantle.
Notarchus. Shell much reduced, shell sac closed.
Phyllaplysia. Shell absent.

As the result of the inclusion of the shell by the mantle
and of the compression of the visceral hump during the
acquisition of secondary symmetry, the mantle cavity, or cavity
between the mantle and the body wall, is much reduced.

The mantle, shell, and visceral hump form a projecting
shelf, fixed on the left side but free on the right side of the
animal. The mantle is uniformly thin dorsally, but at the right
postero-lateral corner it becomes thick and fleshy and curves
upwards in the form of a spout or siphon known as the anal
spout or funnel. This is shaped somewhat like the auriculate
tentacle as it is open along its outer side, but it is much thicker.
The edges are often frilled. On the posterior wall of this
spout lies the anus, which has a radiate appearance due to the
“sphincter muscle which regulates the opening and closing of
the aperture. When the parapodia are closed the anal spout
- frequently projects between them, but it can be completely
withdrawn. (Cf. Figs. 4, 5, an. f.)

[Lift the free edge of the mantle shelf. ]

Beneath the mantle shelf hes a crescent-shaped space,
open dorsally and anteriorly where the parapodia are free,
but shut in posteriorly where they are fused. The concave
side of this crescent and its floor are formed by the body wall,
its outer or convex side is bounded by the right parapodium,
and the incomplete roof consists of a glandular projection of

N

200 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

the mantle. This space is all that remains of the pallial cavity.
It contains the single ctenidium and the osphradium or water-
testing organ, and into it discharge the reproductive apparatus,
the kidney, the anus, and certain glands to be described later.

The Ctenidium. The ctenidium (Fig. 7, ct.), as m most
Tectibranchs, is a lobate plume-like structure which is attached
by a broad base to the postero-lateral portion of the floor of
the pallial cavity. Its free portion projects backwards and
slightly outwards into the cavity, but it can be rotated on its
axis or even thrust upwards above the edge of the mantle
shelf, the last-named position occurring when the water
becomes deficient in oxygen. Along the antero-dorsal convex
side of the ctenidium runs a mid-rib, formed by the efferent
branchial vessel. On each side of it are ranged the pinnules
ofthegill. The afferent branchial vessel forms a similar mid-rib
on the postero-ventral concave side of the ctenidium., (Vide
Circulation.)

The Osphradium. (Spengel’s Olfactory Organ.) Immedi-
ately anterior to the attachment of the ctenidium and lying
in the body wall is situated an organ whose function is to test
the water approaching the ctenidium. This, the osphradium,
is visible as a yellow patch in the living animal, but is often
difficult to find in a preserved specimen. (Vide Sense Organs.)

Genital Aperture. The common genital aperture (Fig. 7,
c. gen. ap.) is a small crescentic opening situated at the right
anterior end of the pallial cavity on its floor, at the level of
the anterior limit of the projecting mantle shelf. Its position
can be readily determined as it lies at the junction of the
pigmented and unpigmented skin of the neck and pallial cavity
respectively. Moreover, from it arises the obliquely placed
seminal groove which extends forwards to the penis at the
base of the right anterior tentacle.

Nephridial Aperture. The nephridial aperture (Fig. 21,
ren. p.) is situated on the under side of the overhanging roof
of the pallial cavity immediately posterior to the point of

APLYSTA. 201

attachment of the ctenidium. It is a small slit-like aperture,
and can be found by gently stroking the surface in this region
with the handle of a scalpel.

Glands of the Pallial Canty. Two sets of glands, both
probably defensive in function, open into the pallial cavity.
These are the purple gland and the opaline gland.

The purple gland (Fig. 7, p. gl.) is situated on the under
side of the free edge of the mantle shelf and occupies a clearly
defined area. In the resting condition it is yellowish or brown
in colour. The numerous ducts of the large unicellular glands
give a pitted appearance to this region. If a living Aplysia
be irritated by forcibly holding up the mantle skirt or by
removing the animal from sea-water, a rich, reddish purple
dye mixed with abundant mucus issues from the mantle glands.
The discharge is not instantaneous, but takes place within a
few seconds. The dye mixes very slowly with the sea-water
and forms an effective screen under cover of which the soft-
bodied and otherwise helpless Mollusc can escape from its
foes.
The Opaline Gland (Vayssiére), Poison Gland (Cunning-

ham), Grape-shaped Gland (Cuvier), Gland of Bohadsch

(Mazzarelli) lies beneath the floor of the anterior part of the
pallial cavity, into which it discharges by numerous apertures,
which tend to fuse in small groups in some individuals
(Fig. 7, op. gl.). In well preserved specimens the orifices may
be rendered visible by stroking the surface with the handle
of a scalpel. In the largest of the Kuropean species, Aplysia
limacina, the ductlets unite and discharge through a single
external aperture, and in this species, too, the gland has the
appearance of a bunch of grapes. Cuvier’s name, grape-

shaped gland, is applicable therefore to this species only.

[Reflect the parapodia, msert scissors into the circular
aperture in the mantle on the summit of the visceral dome,
and make radial cuts towards the edge of the mantle, thus
exposing the shell. Cut along the edges of attachment of the

' mantle and remove the flaps entirely. ]

202 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

THE SHELL. (Fig. 6.)

Redi describes the shell of Aplysia as “ most delicate and
quite smooth, so that it seems to be polished and looks like
transparent talc.” The shell in Aplysia is in process of
disappearing. It is completely hidden from view by the
upward growth of the mantle, and in allied forms such as
Phyllaplysia has disappeared altogether. It has lost the
three-layered condition of the shell of most Molluscs, what is
called the shell being only its outer horny layer. Beneath
this, but separated from it and often broken in pieces, lies ail
that remains of the calcareous layers.* The shell has become
flattened like the visceral hump which it covers, and has lost
all trace of the spiral coiling which occurs in the larval stage.
The columellar muscle has disappeared though remnants of it
still remain, and the shell is held in place by the upgrowmg
mantle folds.

In shape the shell is depressed, with a rounded growing
margin situated anteriorly and a pomted umbo with recurved
edge. The umbo and recurved edge form the rostrum (Fig. 6,
ros.) of some authors. The umbo is posterior, and is directed
downwards. The shallow arch of the shell is greatest near
the umbo. The shell is slightly asymmetrical owing to the
presence of a concavity (an. wm.) on the right border into
which the anal spout fits. This concavity is much deeper
in Dolabella. Rings of growth are visible on the shell.

[Lift up and remove the shell. ]

Beneath the shell lies the thin transparent mantle, through
which can be seen the organs of the visceral hump. The latter
are moulded to the shape of the shell, a recurved projection
of hepatic tissue fillmg the concavity of the shell near the umbo.

* The calcareous matter readily dissolves in acid, and will therefore
not be found in a specimen preserved in an acid fixative.

APLYSIA. 203

A portion of the mantle is marked off by its opacity
from the remainder. This portion is in the form of a band
about an eighth of an inch wide which closely follows the
contour of the shell. It is the shell-forming region of the
mantle, and owes its opacity to the greater height of its
unciliated columnar cells and to their abundant contents.
(See Fig. 21, sh. f.)

Through the transparent skin can be seen the kidney, the
liver, and the spongy tissue overlying the purple gland.
(Cf. Figs. 15, 21.) The kidney is a triangular gland which is
asymmetrically placed on the left side of the visceral mass.
Its surface is channelled by the blood-vessels belonging to the
afferent renal system. On the right of the kidney lies spongy
tissue, forming the thickness of the mantle shelf at this point.

Between the spongy tissue and the kidney, in the acute angle

between the two, a stout band of muscle (Fig. 15, ret. mant.)
makes its appearance. This band, when traced in sections,
is found to arise from the base of the right parapodium. It

threads its way between the pericardial cavity and the anterior

aorta, and is inserted on the under-side of the mantle beneath
the right side of the shell. This muscle probably functions
as a retractor of the visceral hump. A similar but much
smaller muscle occurs on the left side, arising from the left
parapodium. (Vide Muscular System.)

Posteriorly the space beneath the mantle is occupied by
the liver.

HISTOLOGY OF THE Foor AND ITS GLANDS.

The pedal epithelium consists of slightly pigmented cells
interspersed between which are goblet-shaped mucous gland

_ cells. The pedal sole is ciliated throughout, and there is an

abrupt line of division between these cells and the smaller and
less compact, strongly pigmented, unciliated cells of the lateral
body wall. Beneath the epithelium the cells are very irregular,

204 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

with abundant Jacunae or blood spaces, and numerous muscle
bundles. The muscles are arranged longitudinally, as flattened
bands bounding the body cavity (haemocoele), and diagonally,
as irregular interlacing strands. (Fig. 21, l. ped. m.)

The glands of the foot are either diffuse or concentrated
glands. To the former class belong the isolated unicellular
gland cells, which are distributed over the whole surface of the
foot. To the latter class belong three sets of glands.

The unicellular gland cells lie in or just within the ciliated
epithelial layer of the foot. (Figs. 21, 23, ped. gl.) They
resemble those which occur on most parts of the external surface
of the animal, but are more crowded in this region. Hach -
consists of an enlarged flask-shaped cell, the neck of the
flask forming the duct for the discharge of the fluid secreted
by the bulbous portion.

The concentrated, aggregate or compound glands are three
in number, viz.: the anterior pedal gland, the supra-pedal
gland, and the paired posterior pedal glands. There is no trace
of a middle pedal gland or pore. The anterior pedal gland
(Figs. 9 and 22, ant. ped. gl.) forms a compact and closely
packed glandular area at the anterior end of the foot. The
gland cells, though derived from epithelia! cells, have pushed
their way, as in all the compound glands, into the loose tissue
lying beneath the epithelium. The cells are still flask-shaped,
but the néck oi the flask has become much elongated. The
anterior pedal gland discharges on the antero-ventra! portion
of the foot. ,

Towards the posterior portion of the anterior pedal gland,
larger gland celis appear. These gradually separate themselves
off from the ventral gland and discharge dorsally into the
gutter between the buccal region and the foot. These gland
cells constitute the supra-pedal gland. (Fig. 9, sup. ped. gl.)

Opening on the posterior end of the foot, about half an inch
from the tip in a full-grown specimen, are a pair of posterior

APLYSIA. 205

pedal glands. These differ from the anterior and supra-pedal
glands in that each gland possesses a cellular duct into which
the large gland cells discharge. The duct is of wide calibre,
and its walls consist of large squarish cells bearing long flagella.

(Fig. 24, post. ped. gl.)
HisTOLOGY AND PHysloLoGy OF THE MANTLE GLANDs.

(a) The Purple Gland. As has already been described
under External Characters, a rich purple dye is secreted by
unicellular glands situated on the under side of the free edge
of the mantle. Secretion takes place only when the animal
is irritated. A large quantity of mucus issues with the dye,
which mixes slowly with the sea-water and forms a screen under
cover of which Aplysia can hide itself or escape.

The dye is not a permanent colour in the form in which
it is given off by the animal. It is therefore not adapted for
use as is the dye obtained from Murex, Purpura, etc., though
it probably resembles it fairly closely in chemical composition.
There is no record in early literature which shows that the
ancients either knew of or attempted to use the dye obtained
from Aplysia. Their feelings of disgust towards this harmless
Molluse probably prevented the discovery of the dye in those
species which produced it.*

Under the influence of light the purple changes colour
and becomes reddish ; acid increases the intensity of colour,
alkali does not affect it at first, but on subsequent exposure
to light it becomes rose pink. When a piece of cotton or silk
material is stained with the dye the colour remains purple for
a variable period, but ultimately changes, especially if left
in the light, to a dull brown. The same colour change takes
place, but much more rapidly, when the purple is mixed with
alcohol.

* Aplysia punctata and A. limacina exude purple, but A. depilans only
a milk-white fluid. The last named is a common Mediterranean species,
and is probably the one described in the early literature.

206 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

(b) The Opaline or Poison Gland. This gland, situated on
the floor of the pallial cavity and discharging into it by
numerous apertures, consists of enormous unicellular vesicles,
whose contents in stained preparations closely resemble those
of the mucous glands of the skin generally. The gland is well
developed in specimens not more than a third of an inch in
length, occupying a relatively greater area than in full-grown
individuals. (See Fig. 21, op. gl.) .The fluid excreted by the
gland is milky and acrid in nature, and in the Mediterranean
species possesses a nauseating odour which was well known to
the ancients, and was largely responsible for their abhorrence
of the Sea-hare. The foetid smell has not been noticed in the
British species. While the purple is very readily exuded by
Aplysia under irritation, the milky secretion of the opaline
gland is only rarely discharged, and then less copiously than
the purple. The secretion is probably both protective and
excretory. Mazzarelli states that the opaline gland may also
exude purple, but this has not been confirmed by other
observers.

THE DIGESTIVE SYSTEM.
(Figs. 8-12.)

[Cut through the floor of the pallial cavity, being careful
‘not to injure the visceral nerve cords or the paired ganglia ©
which Jie immediately beneath. The cut should be made
between the common genital aperture and the opaline gland.
Continue backwards keeping to the right of the anus. Cut
forwards in front of the common genital aperture obliquely
towards the middle line between the tentacles. This involves
cutting across the external seminal groove. Turn back the
flaps of body wall, but do not cut any connections in the
abdominal region. The opaline gland now hes on the right
of the cut, while on the left, by turning up the sub-pallium,
can be seen the reproductive apparatus, the parietal and
visceral ganglia, and the anterior aorta. The visceral mass
is in the centre. Now cut between the parapodium and the
visceral hump, following the course of the horseshoe formed

APLYSIA. 207

by the base of the parapodia round to the left. By slitting
up the connective tissue which holds the visceral mass in place
the whole of the latter can be lifted and turned backwards
and forwards without disarranging the organs. |]

The digestive organs of Aplysia consist of a buccal mass
bearing an odontophore and receiving the discharge of two
salivary glands ; an oesophagus which dilates into an enormous
crop ; two “ triturating stomachs ” ; a small chamber, the true
stomach, into which open the ducts of a voluminous digestive
gland or “liver”; a caecum; intestine and rectum. The
mouth is anterior, the anus postero-lateral and on the right
side of the body. (Vide External Characters.)

Buccal Mass or Pharyngeal Bulb. This is a pear-shaped,
highly muscular organ which can be partly thrust out during
feeding in order to grasp the weed upon which Aplysia browses.
At the anterior narrow end lies the mouth, a median vertical
slit-like aperture without lips or distinct outline. The opening
is beset with from twelve to twenty longitudinal ridges which
allow of considerable expansion in this region. (Fig. 9, buc. /.)
The epithelium of the labial region is ciliated and glandular.
The mouth leads into the cavity of the buccal mass. This is
shown in section in Fig. 9. Its swollen posterior end forms a
cul-de-sac on the ventral side and lodges the odontophore.
Dorsally is given off the oesophagus, and the ducts of the
salivary glands enter the bulb.

The whole apparatus is held in place by means of stout
ligaments whose position and appearance vary with the state
of contraction of the animal examined. Some are transverse,
some obliquely placed ; all are attached to the body wall round
the buccal orifice. They form the extrinsic muscles of the
buccal mass. Viewed from the side the buccal mass presents
the following groups of intrinsic muscles :—

1. Paired fan-shaped antero-lateral muscles, originating
from the mouth region and spreading out to be inserted on the
swollen posterior wall of the buccal mass.

208 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

2. Paired postero-dorsal muscles, connected dorsally in
the middle line and continuous in direction with those of the
oesophagus.

3. A single, stout basal mass of muscle situated on the
ventra! side of the odontophore. |

4. A circular band of muscle acting as a sphincter round
the buccal orifice.

[Open the buccal mass by a median longitudinal incision
along the dorsal side. ]

An internal view of the bulb shows that it consists of a
thick walled chamber, from the postero-ventral portion of
whose floor arises a pulley-like structure, the odontophore.
The food entering the mouth is forced upwards over the top
of the odontophore and leaves the bulb by the dorsally situated
oesophagus, coming under the action of the radula or tooth
tibbon as it does so. The interior is divisible into five
regions :—

1. The oral region beset with longitudinal ridges as
already noted. This part, which is eversible, ends abruptly
posteriorly where the sphincter muscle causes a slight con-
striction and the jaws are fixed.

2. The mandibular region. On the walls of this region
are affixed paired flat horny plates, the so-called mandibles.
(Fig. 9, mand.) Dorsally the plates are connected by semi-
cartilaginous tissue so as to appear to be continuous ; ventrally
they merge into the epithelium of the mouth. They are
composed of dark brown chitinous rods packed side by side,
but with one free end curved and projecting slightly into the
cavity. The rods have been called “stick cells.” The
mandibles have no masticatory function, but help to stiffen
the buccal orifice and to form a plate against which the radula
can work.

APLYSIA. 209

3. <A region of irregular folds which are more complex
dorsally where they form a channel which is gradually cut off
from the main cavity by two lateral inwardly projecting folds,
thus forming the pharyngeal canal. (Fig. 22, ph. can.) The
edges of the pharyngeal folds bear a few scattered “ stick
cells,’ differing slightly in shape from those of the jaws.
(Fig. 22.) This region is abundantly supplied with mucus
from the salivary glands which discharge into the cavity of the
buccal mass. (Fig. 22, 7. sal. d.)

4. The odontophore. This arises as a cushion-like
projection from the floor of the posterior cul-de-sac of the
buccal mass, and has the shape of a pulley fixed on its postero-
ventral side. Over the surface of the pulley les the radula,
whose posterior immature end is lodged within a pouch known
as the radular sac.

The cushion or rotella is a highly muscular organ supported
by paired “ cartilages ” of a spongy nature and covered with
the epithelium of the buccal cavity. It is held in place by
muscle bands, which attach it to the wall of the buccal mass
and allow the whole apparatus to be thrust forward or with-
drawn. The cartilages also can be moved one on the other so
as to give a lateral movement, but this is only possible in a
very small degree.

Over the posterior, dorsal, and anterior faces of the rotella
is stretched the radula or rasping organ. (Fig. 9, vad.)2\ This
is a broad ribbon consisting of a basal or sub-radular membrane
in which are set numerous chitinous teeth arranged in close
and regularly placed transverse rows. A delicate protective
layer of connective tissue covers the posterior part of the ribbon.
The radular teeth are minute denticles whose cusps are directed
backwards. The central tooth of each row differs from the
lateral teeth, which are all alike. (Fig. 10.) In Aplysia
punctata there are fifteen lateral teeth on each side so that
the radular formula is 15.1.15. The number of laterals,

210 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

however, may differ in various individuals according to age.
The broadest and oldest part of the radula is that spread over
the anterior face of the rotella. Here the teeth are dark brown
in colour while those further back are paler and softer. The
posterior portion of the radula is hidden within the radular
sac (Fig. 9, rad. s.), where the new rows of teeth are formed
to replace those worn out by constant use. This replacement
goes on throughout the life of the animal.

5. The pharyngeal canal. Dorsal to the odontophore
the cavity of the bulb becomes laterally compressed and an
incipient separation of the channel so formed occurs. This is
the pharyngeal canal and the ingrowing projections that will
later cut it off from the buccal cavity are the pharyngeal
crests. (Fig. 22, ph. can. and ph. cr.) These crests bear
groups of “ stick cells ” similar to those forming the mandibles.
The canal passes insensibly into the oesophagus.

Ocesophagus and Crop. The oesophagus is the posterior
continuation of the pharyngeal canal. (Fig. 8.) At first it
is a narrow thin-walled tube which passes through the nerve
ring. After emerging from the ring it swells nto a voluminous
chamber, the crop (Fig. 8, cr.), which becomes spirally coiled
when the hunchback attitude is assumed by the animal.
The walls possess a thin muscular coat, and internally have
rugose folds. The liming endothelium is ciliated but not
glandular. The crop is called the first stomach by earlier
writers. It is capable of great expansion.

The Gizzard. This is sharply marked off from the preceding
region by an annular constriction which occurs at the point of
junction, and by a pronounced difference in musclature. The
gizzard consists of two portions. It is thick walled, possessing
a dense coat of circular muscle fibres covermg the anterior
portion and of longitudmal fibres in the posterior portion.
When slit open the two chambers are seen more plainly.
These are called by some authors the first and second triturating

APLYSIA. 211

stomachs (Fig. 8, ant. giz. and p. giz.), and by those who call
the crop the first stomach, the second and third stomachs.
The lumen of both chambers is very small, for, in addition to
the thickness of the wall, the inner lining is beset with semi-
transparent horny teeth. These are probably of little use
for grinding purposes, but compress and strain the food so as
to prepare it for the action of the digestive juices. In the
first triturating stomach are from twelve to twenty teeth.
(Fig. 11, a. 6.) These are large and stout, with diamond-
shaped bases set in sockets in the walls. They are readily
detachable. Their shape varies; some are almost perfect
pyramids, others like the Cap of Liberty, with backwardly
directed points. Between the teeth the walls of the gizzard
are thrown into folds. In the second portion of the gizzard
the teeth are much more slender. (Fig. 11,c.) They are long
and tapering, with pointed tips and ovoid bases, and are about
twelve in number.

Stomach and Caecum. At this point the alimentary canal
becomes embedded in the digestive gland. A pair of valves
(Fig. 12, 1. stom. v.), muscular and covered with long vibratile
cilia, regulate the passage of the food from the posterior
portion of the gizzard into the morphological stomach. Up to
the present no change of a digestive nature has taken place
in the food, and in sections of the preceding portions of the
canal, the histological elements of the weed are plainly visible.
Digestion proper is initiated in the stomach (Fig. 8, stom.),
which forms an ill-defined chamber, the ‘
Zuccardi. The stomach receives the discharge from the
“liver ” by a variable number of ducts (usually three on the
right side and one on the left). The ducts are almost equal
in diameter to the stomach itself. They are strongly ciliated
so as to drive the hepatic fluid forwards into the alimentary
canal. It is probable that the bile is not only digestive but
also excretory. The liver is more properly an hepato-pancreas,
but functions also as an accessory kidney.

‘camera biliare ” of

Wd TRANSACTIONS LIVERPOOL BIQLOGICAL SOCIETY.

From the stomach the food is directed by a strongly ciliated
fold, which plugs the entrance to the intestine, nto the caecum
(Fig. 12, caec.). This arises as a diverticulum of the stomach.
In specimens about twelve millimetres long it is a mere knob
on the surface of the latter, but in the full-grown Aplysia it
reaches from the heart of the liver mass to the surface, its
blind end being swollen and slightly bent on itself.* The .
cavity of the caecum is divided longitudinally by a ciliated
clandular fold, which terminates a short distance from the
blind end, thus allowing the two portions on each side of the
fold to communicate with one another. The fold is known as
the typhlosole or caecal valve (Fig. 12, caec. v.). The left
portion of the fold is continuous with the cavity of the stomach,
the right with the intestine. The food, as was shown by
Mazzarelli and Zuccardi, after being mixed with the hepatic
fluid, passes down the left side of the caecum, up the right
side and so into the intestine. The stomach and the caecum
‘constitute therefore, physiologically, the true stomach of
Aplysia, but morphologically the true stomach, arismg from
the larval stomach, is represented by the ‘ camera biliare’.
only, and the hepatic caecum represents a new formation.”

The Intestine. This receives the food from the caecum
and passes forwards through the visceral mass, emerging on its
anterior surface. (Fig. 12, wt.) It then takes a sharp bend
to the left, and, still lymg on the surface, though sunk in a
depression which exactly fits it, passes backwards along the
ventral face of the visceral mass, loops back on itself, then
bends upwards and to the right along the dorsal side of the
visceral mass towards the anus, which is postero-lateral in
position. Its diameter narrows gradually, and its walls become
thinner and less muscular. It is ciliated throughout.

The Rectum. The terminal portion of the intestine which

* In dissection this blind end should be looked for and the caecum
traced back from it. Otherwise it may be removed with the liver substance
and its connection with the stomach wrongly supposed to be another bile duct.

APLYSIA. 213

ascends the anal papilla may be called the rectum, though it
is not differentiated from the remainder of the gut. (Fig. 8,
rect.) Near the anus it becomes more muscular, however,
and at the point where it discharges to the exterior, a sphincter
muscle, formed by interlacing muscle bands in the surrounding
tissue, occurs. Waste products are forcibly expelled by the
alternate relaxation and contraction of the anal sphincter,
and the ciliary action of the respiratory chamber, aided, if
necessary, by sudden approximation of the parapodial lobes,
removes the faecal matter from the neighbourhood of the
animal.

GLANDS OF THE GUT.

These comprise the salivary glands and the “ liver.”

Salivary Glands. There are two elongated salivary glands
in Aplysia, and they discharge, as has already been described,
into the buccal cavity. Hach gland is attached by connective
tissue to the side of the crop and passes forwards, rarely taking
part in the spiral coiling of the latter. Just behind the nerve
ring the glandular tissue stops, and the flat, thin-walled duct
passes through the ring as in all Kuthyneura, runs parallel to
the oesophagus, and plunging into the muscles on the dorsal
side of the bucca] mass opens into the buccal cavity. (Migs.
22 and 23.)

In sections the glandular portion shows a simple aggre-
gation of secretory cells round a central duct. The duct is
ciliated. The salivary secretion consists largely of mucus,
and is not digestive. The nerve supply is drawn from the
buccal ganglia (Fig. 17, r. sal. n. and J. sal. oes. n.), and the
blood supply from the gastro-oesophageal artery. (Fig. 13,
g. 0S. Gd.)

Liver. The liver, digestive gland or hepato-pancreas is a
compact, voluminous gland which makes up the greater part
of the visceral mass. With the gonad it forms, as it were, a
packing for the coils of the alimentary canal. In a specimen

214 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

which has been long preserved the components of the visceral
mass are extremely difficult to separate. In the fresh con-
dition, however, this is possible. The outline of the liver is
smooth and rounded. It shows no trace of spiral coiling, but
is divided into irregular lobes.

Microscopically the liver (Fig. 21) consists of simple
oroups of cells lining central spaces, the spaces uniting to form
ciliated channels, the bile ducts.’ The latter are of wide
calibre and discharge by four orifices into the stomach. The
hepatic cells conta dark brown or greenish granular pigment
and frequently drops of oil. The bile fluid is im part digestive
and in part excretory.

MECHANISM OF DIGESTION.

The food, which consists of seaweeds of various species,
is grasped by the protruding lips and jaws and rasped off in
small pieces by the action of the radula. To do this the whole
odontophore is thrust forwards so that the radular ribbon
works against the flat surface of the jaws. The backwardly-
directed teeth of the radula scrape off particles of the weed,
and the mucous secretion of the salivary glands mixes with
the food and moistens it. The food is then stored in the
crop. Relaxation of the sphincter muscle between the crop
and the gizzard allows the food to pass into the latter in small
quantities at a time. Here the horny gizzard teeth squeeze
and strain the fragments. The rate of entrance into the
stomach proper is regulated by means of the strong flap-like
valves which guard the aperture. In this chamber the digestive
juice from the liver is poured on the food, which then travels
slowly down one side of the caecum, up the other side, and so
into the intestine. By this time digestion is practically
complete, the digested matter is absorbed, and the waste
products, in the form of loose irregular pellets, are expelled
through the anus.

APLYSTA. 215

BLOOD VASCULAR SYSTEM.
(Figs. 13-15.)

The blood vascular system in Aplysia consists of a two-
chambered heart, arteries, venous sinuses and lacunae. The
heart is enclosed within a pericardial chamber, and is situated
on the left side of the animal, ventral to the kidney and over-
lying the visceral mass somewhat obliquely. It is in close
proximity to the ctenidium as in all Molluscs. The pericardium
is a portion of the coelom and communicates with the renal
cavity, which is also coelomic, by a reno-pericardial aperture.
The arteries constitute an asymmetrical system of vessels
supplying the tissues with blood from the heart. There is no
capillary system, but the arteries discharge into large spaces
within the tissues known as lacunae. The lacunae are devoid
of epithelial lming, the blood coming into apparent contact with
the muscles and connective tissue fibres. From the lacunae
the blood travels back to the general body cavity surrounding
the gut and other organs. This body cavity is not, therefore,
a true coelom, since it contains blood, but a haemocoele. From
the haemocoele the blood is collected in wide vessels with
definite walls, the venous sinuses. These occur only near the
ctenidium and kidney, with which they communicate, and are
not to be found in other parts of the body. The blood traverses
either the kidney or the ctenidium on its way back to the heart,
so that the blood entering the heart is mixed blood, the greater
part being oxygenated blood from the ctenidium and a small
portion being blood purified from nitrogenous waste, but not
oxygenated, from the kidney. |

The blood is colourless and contains amoeboid corpuscles.
The oxygen carrier is haemocyanin dissolved in the plasma.

It is at first sight difficult to see how a constant circulation
can be maintained on account of the great spaces in the body.
The blood fills them very rapidly causing sudden turgidity,
O

216 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

which was formerly thought to be due to the imbibition of
water. The reverse process, viz., the emptying of the spaces,
is brought about chiefly by the strong muscular contractions
of the animal, the blood being forced out of the tissues by
compression.

[DissEction. Remove the shell so as to expose the
kidney lying on the surface of the flattened visceral hump.
Dissect away the left anterior portion of the kidney: the heart
is situated directly beneath it. Trace the arteries from the
heart. The course of the arteries can best be followed by
injecting, drop by drop, a strong aqueous or gelatine solution
of Prussian blue into the three main trunks whose apertures
can be found by slitting up the large arterial trunk arising
from the ventricle of the heart. For a complete injection
use Prussian blue gelatine and inject either into the efferent

branchial vessel trom the ctenidium or into the spongy tissue
of the foot. ]

The Pericardium (Fig. 14, pe.) is a spacious chamber,
representing a shut-off portion of the true coelom, which does
not contain blood. It communicates with the cavity of the
kidney by means of a small reno-pericardial duct situated close
to the entrance of the renal vem into the auricle, 1.e., on its
anterior wall. The walls of the pericardium are supported
by tough interlacing fibrous bands. The nerve supply is
derived from the parietal ganglion. (Fig. 16, pe. n.)

The Heart does not fill the pericardium. It projects from
its floor into the cavity and runs obliquely across the body,
the ventricle being slightly anterior to the auricle, and both
lying anterior to the ctenidium. (Hence the name Opistho-
branchiata. )*

The Auricle (Fig. 13, aur.), which is on the right, is thin-
walled, delicate, and transparent. Fine interlacing strands
of muscle and fibrous tissue give it the appearance of beautiful
lace. The auricle receives blood from the ctenidium and the
kidney by two efferent branchial veis and a renal vein

* Great contraction may cause the heart to appear almost transverse.

APLYSIA. 217

respectively. The ventricle (Fig. 13, venir.) is smaller than
the auricle and has thick, opaque muscular walls. There is a
constriction between auricle and ventricle, marked internally
by two crescentic flaps or valves. (Fig. 14.) Neither auricle
nor ventricle possesses an endothelium so that the muscle
strands are bathed directly by the blood.

From the antero-ventral portion of the ventricle arises
the arterial trunk which supplies the whole body with blood.
It runs obliquely across the floor of the pericardium, and is
attached to the latter. Auricle and ventricle must be pushed
back to expose it. The sides of this aorta are sacculated, and
an internal examination shows that the sacculae are divided
off from the central cavity by fibrous strands. The function
of the sacculations, which form the crista aortae (Fig. 13,
cr. ao.), 18 not known. It is supposed by some to be a lymph
gland in which the leucocytes of the blood are manufactured :
by Grobben it was regarded as a gland for pericardial excretion
(Ci. Keber’s Organ in Lamellibranchs.). Mazzarelli pointed
out that it is not alone in contaiming leucocytes in its wall, for
both auricular and ventricular walls produce them.

On slitting up the crista aortae a semicircular valve is seen
guarding the entrance from the ventricle in order to prevent
regurgitation of blood into the ventricle. Three apertures or
paths of exit for the blood are visible :—

1. An anterior opening lying ventral to the auricle.
This leads to the anterior aorta.

2. A smaller aperture at the level of the ventricle and
leading to the gastro-oesophageal artery. In some Opistho-
branchs this artery arises as a branch from the posterior or
abdominal] aorta.

3. A posterior aperture leading to the abdominal aorta,

ARTERIES.

The arterial system shows great asymmetry. Three
arterial trunks arising from the heart are present, viz.: the

218 . TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

anterior aorta, the gastro-oesophageal artery, and the posterior
or abdominal aorta. The anterior aorta supplies the mantle,
the foot and its appendages, the head and tentacles, the nervous
system, the pallial and sub-pallial glands, and the reproductive
organs; the gastro-oesophageal artery sends blood to the
alimentary canal; the abdominal aorta supplies the liver and
those portions of ne gut and FCpraduchine organs lying within
the visceral mass.

The Anterior Aorta (Fig. 18, ant. ao.) leaves the pericardium
on its right antero-ventral face immediately posterior to the
parietal and visceral ganglia. At this pomt a sharp bend
forwards occurs, and its first branch is given off to the vesicle-
of Swammerdam (Fig. 13, spth. a.). The aorta then passes
to the right of the parietal ganglion and ventral to the nerves
issuing from that ganglion. An artery runs dorsalwards to
supply the mantle (dors. a.). From the right side of the aorta
arise branches to the opaline gland and genital organs (gen. a.).
The trunk gradually assumes a more median position, and no
more branches occur until the nerve ring is reached. The
artery does not, however, as in the Snail, pass through the
nerve ring, but runs between the pedal and parapedal commis-
sures, ventral to the former (i.e., outside the rmg) and dorsal
to the latter (Figs. 13, 23.). Asymmetrical arteries to foot
and body wall are given off, and the now median artery runs
forward ventral to the buccal mass, which it supplies with
blood. Finally it forks and terminates in the labial tentacles
and anterior portion of the foot.

It must be remembered that in an animal possessing such
a high degree of contractility as Aplysia the appearance of the
arterial system varies greatly accordmg to the amount of
contraction exhibited by the specimen dissected. Thus the
aorta at the level of the nerve rmg may form a semicircle in a
contracted specimen, whereas in an expanded specimen the left
pedal artery hooks sharply over the parapedal commissure.

APLYSIA. 219

A. Anterior Aorta. (Unless otherwise stated the branches are
unpaired.)

1. Artery to the Spermatheca. (Fig. 13, spth. a.) This
small artery is easily overlooked, but is demonstrated by
injection. It arises from the aorta on its left side just as the
latter leaves the pericardium, runs along the duct of the
vesicle and branches fanwise over the surface of the sperma-
theca.

2. Dorsal Artery. (Fig. 13, dors. a.) This arises from
the aorta close to its exit from the pericardium and runs
dorsalwards, looping round the retractor muscle of the mantle
to supply the mantle and its glands.

3. Gemtal Artery (gen. a.). This large artery springs
from the right side of the aorta and runs straight backwards
dorsal to the branchial nerve (from the parietal ganglion) to
supply the genita] organs. In some specimens of Aplysia
punctata it gives off one or more branches to the opaline gland,
but in others, and in A. depilans, the branch to the gland
arises independently from the aorta. The genital artery
follows the course of the large hermaphrodite duct in a backward
direction and sends branches to it. It then passes through the
loop formed by the accessory genital glands, supplying them
with blood, and on emerging from the mass runs beside the
little hermaphrodite duct, without, as is also the case with
the nerve, taking part in the sinuosities of the duct. The
artery finally reaches the hermaphrodite gland.

3!. Artery to the opaline gland in specimens where this
arises separately from the aorta and not as a branch of the
genital artery.

4. Pedal Arteries (ped. a.). A pair of pedal arteries arise
from the aorta at the level of the nerve ring. That on the
right is posterior in its origin to that on the left. As already
stated the pedal arteries pass backwards ventral to the para-

220 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

pedal commissure whereas the aorta is dorsal to it, so that
they appear to hook over the commissure. Both pass back-
wards obliquely towards the foot. Arriving at the surface of
the foot at about the level of the crop they plunge immediately
into it and branch into anterior and posterior trunks. The
former has the shorter course; the latter can be traced almost
the whole length of the foot just under its inner surface.
It is not possible to trace the branches by dissection, but in
sections of small specimens they are seen to merge gradually
into the large and ill-defined lacunae of the foot. A large
branch to the parapodium (para. a) is given off from the
posterior branch of the pedal artery. :
5. Cephalic Arteries (ceph. a.). Cervical of Mazzarelli.
The paired cephalic arteries arise, like the pedal, asymmetrically
from the aorta. Their distribution 1s different on right and left
sides. As in the case of the pedal arteries the right cephalic
artery is posterior to the left mm origin. The right artery
passes forwards or outwards, according to the degree of con-
traction of the animal. It sends a small branch to the blood
sinus surrounding the ganglia (ne. a.). Arrived at the penis
it branches into three. The first branch supplies the penis
(pn. a.); the second runs ventral to the penis and beyond it,
to the body wall (b. w. a.), the rhmophore (rh. a.) and the eye
(opt. a.) ; the third branch sends blood to the spermatic groove
(sem. gr. a.). The left cephalic artery also runs ventral to the
pedal ganglion, sending to it a small artery. It then goes
direct to the body wall, rhinophore and eye of its side.

6. Radular Artery (rad. a.). This small unpaired artery
arises from the dorsal side of the aorta and runs directly into
the radular sac which les immediately above it.

7. Pertbuccal or Anterior Tentacular Arteries (peribuc. a.).
Paired symmetrical arteries encircle the buccal mass in the
region where the muscle is thickest. From each artery arises
a branch to the labial tentacle (ant. tent. a.).

APLYSIA. 221

8. Anterior Pedal Arteries (ant. ped. a.). Coronary of
Blatin and Vles. These paired symmetrical arteries form the
anterior termination of the aorta. They curve round the
lateral portion of the extreme anterior end of the foot and also
supply the anterior pedal gland.

B. Gastro-oesophageal Artery (g. oes. a.).

This large artery supplies that portion of the gut between
the oesophagus and the sizzard. In many forms it springs
from the abdominal aorta, but in Aplysia it arises independently
from the middle of the pericardial portion of the arterial trunk.
To trace its branches the main artery should be injected with
a coloured solution. On reaching the surface of the crop the
artery forks, the two arms of the fork running to right and left
of the crop along its surface and branching repeatedly, forming
a beautiful raised pattern when injected. A small branch is
given off to each salivary gland and runs along its inner side.
Backward branches ramify over the gizzard.

C. Posterior or Abdominal Aorta (abd. ao.).

This emerges from the left postero-ventral portion of the
pericardium and passes backwards to supply the organs con-
tained within the visceral hump. The artery runs dorsal to
the anterior coil of the intestine and soon gives off on the left
side a large branch to the liver. The hepatic artery divides
into superficial (s. hep. a.) and deep (d. hep. a.) branches which
ramify within the liver tissue. A second branch, also arising
on the left side, has numerous hepatic and intestinal branches
(hep. int. a.). It supplies the caecum (caec. a.), the artery
running along the concave side of the curve and giving off
branches over the surface of the caecum. The remainder of
the posterior aorta supplies the gonad and little hermaphrodite
duct (gen. al.).

DP, TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

LACUNAE AND VENOUS SINUSES.

The lacunae are irregular spaces in the tissues into which
the arteries empty themselves, there being: neither capillary
system nor system of veins. The lacunae are best shown in
those parts of the body, such as the foot, the parapodia, the
tentacles or the mantle, where the tissues are of a spongy
nature. Here there are interlacing bands of fibrous and
muscular tissue united by connective tissue. Between the
bands are numerous irregular spaces, the lacunae. The only
compact tissue in these regions is the surface epithelium. The
lacunae are not bounded by any epithelium, so that, as in the
case of the walls of the heart, the muscles and connective
tissue fibres are apparently bathed by the blood. By means of
this lacunar system a rapid flow of blood into the tissues can be
effected, causing sudden turgidity and expansion. This was
thought to be due, by earlier writers, to the imbibition of
water.

Tn the visceral hump the lacunae are much smaller owing
to the compactness of the organs in this region. It is note-
worthy, however, that the connective tissue holding the parts
of the visceral hump in place is fenestrated so that the blood
can pass through.

The course of the blood from the lacunae back to the
heart can be traced by injection or by sections of small spect-
mens. If, for example, a few drops of Prussian blue solution
be carefully injected by means of a hypodermic syringe into
any portion of the foot or lateral body wall, the fluid readily
passes through the lacunae and emerges into the general body
cavity in the form of little spurts from gaps between the
longitudinal muscle bands of the foot and sides of the body.
(Fig. 21, ped. lac.) It can similarly be shown that the blood
from the mantle, the body wall generally, the tentacles, the foot
and parapodia is discharged by irregularly-placed apertures

APLYSTA. 293

into the large body cavity in which lie the gut and its glands,
the nervous system and the reproductive organs. This cavity,
the apparent body cavity, 1s therefore not a true coelom, for it
contains blood, but a haemocoele. Only the cavities of the
pericardium, of the renal sac, and of the hermaphrodite gland
are coelomic.

The portion of the haemocoele into which the blood from
all parts of the body, with the exception of the kidney. and the
ctenidium, is discharged is known as the ventral abdominal
sinus. Like the lacunae in the tissues this sinus has no
bounding epithelium. From this sinus the blood is sent either
to the kidney or to the ctenidium on its way back to the
heart. To facilitate the propulsion of the blood, venous
sinuses with muscular walls collect it from the common sinus
and empty themselves into the kidney or the ctenidium. These
muscular sinuses are not extensive, but occur only in close
connection with the kidney and ctenidium. Their walls are
fenestrated. Five of these sinuses constitute the main afferent
branchial sinus, the remainder form the renal sinus.

The chief factors of the afferent branchial sinus are :—

1. A small smus (Fig. 14, sin. 1) receiving blood from
the left anterior body wall. It runs backwards along the edge
of the sub-pallium on the left side of the body, ventral to the
kidney and pericardium, and posterior to the ctenidium bends
to the right to enter the main sinus.

2. A large sinus (sim. 2) opening from the ventral
abdominal sinus (anterior part) into the left of the main
afferent branchial sinus.

3. A large sinus (sin. 3) bringing blood from the posterior
part of the ventral abdominal simus, viz., from the visceral
hump. It enters the main sinus on its posterior wall.

4. A small smus (son. 4) from the right body wall.
Through its fenestrated walls it receives also from the ventral
abdominal sinus.

224 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

5. A small smus (sin. 5) receiving from the right anterior
portion of the ventral abdominal sinus.

The union of the sinuses forms the large branchial sinus
or afferent branchial vessel (aff. br.), which lies immediately
beneath the floor of the pallial cavity posterior to the ctenidium.
The sinus enters the ctenidium on its outer concave side and
extends the whole length of this surface. On slitting up this
portion of the sinus, large gaping orifices are seen through
which the blood passes to the lamellae of the gill. There is
here, as in the tissues generally, no capillary system.

From the ctenidium the blood is collected by two efferent
branchial vessels which lhe along the inner, convex portion
of the gill (eff. br.). Like the afferent vessel the efferent vessels
communicate with the lamellae by wide openings. The
efferent vessels discharge into the auricle of the heart.

All the blood from the ventral abdominal sinus does not
enter the ctenidium for purposes of aeration. _ At the level of
the heart there enters the kidney on its dorso-lateral face
a short sinus bringing blood from the left portion of the
haemocoele. (Fig. 15, ren. sin.) A small quantity of blood
from the left body wall and the anterior part of the left
parapodium also enters the renal sinus, and on the right side
of the kidney several small smuses from the mantle and
pericardial roof open. (Fig. 15, ren. mant. sin. and ren. perv.
sin.) The renal sinus discharges into the lamellae of the
kidney, from whence the blood is collected by an efferent
vessel (Fig. 14, eff. ren.) and taken to the heart. There is
- thus a renal portal system in Aplysia. The blood is collected
on the ventral side of the kidney, and, purified now from
nitrogenous waste matters, leaves by a short efferent renal
vessel situated on the right side of the kidney. The efferent
vessel opens into the base of the efferent branchial vessel, just
as the latter is about to open into the auricle.

bo
to
ce)

APLYSIA.

RESPIRATORY SYSTEM.

Aeration of the blood is brought about through the
medium of the single asymmetrically placed ctenidium, whose
position and external structure have already been described
under External Characters. For its blood supply and innerva-
tion see the sections on Blood Vascular System and Nervous
System respectively.

In microscopic preparations the ctenidium shows a regular
epithelium, in some parts ciliated, in others, especially near
the insertion of the ctenidium, strongly glandular. Beneath
the epithelium lies a loose tissue consisting of connective tissue
and muscle fibres. The centre of each pinnule is a blood
space whose walls are hounded by the tissue just mentioned.
There is no capillary system, but the afferent branchial vessel
opens by “ gaping orifices” into this cavity, and the efferent
vessel collects in a similar way.

EXCRETORY SYSTEM.
(Figs. 14, 15, 21.)

The excretory system of Aplysia consists of a single
asymmetrically placed kidney situated on the left side of
the body, overlying the heart and visceral hump, and covered
by the shell and mantle. In shape it forms a triangle whose
base is directed forwards over the heart, the apex of the
triangle curving towards the right posteriorly. It will be
noted that the kidney has separated itself from the visceral
mass, and lies close under the mantle. In all Euthyneura
the single kidney represents the morphologically right (topo-
graphically left) member of an original pair of which the
fellow has entirely disappeared in Aplysia.

The kidney is a coelomic sac lined by a glandular epithe-
hum which is produced inwards in the form of parallel lamellae.
The renal sac communicates with the pallial cavity and with
the pericardium. The former opening, the renal pore, is the

226 TRANSACTIONS LIVERPOCL BIOLOGICAL SOCIETY.

aperture through which the renal excretion is discharged.
(Fig. 21, ren. p.) It lies in the wall of the pallial cavity at
the root of the ctenidium. Its walls are muscular. There is
no ureter, but the renal sac empties its excretion directly
through the renal pore. The reno-pericardial duct connects
the cavities of the renal sac and pericardium, and is thus a
means of communication between the renal and pericardial
portions of the coelom. It brings about a secondary connection
between the pericardium and the exterior. The duct is not
visible to the naked eye and is difficult to demonstrate by
injection in Aplysia punctata, as Cunningham was able to do
in the larger Mediterranean species. Sections, however, show
that the duct is situated close to the entrance of the efferent
branchial vessel into the auricle.

Internally the kidney consists of fairly regular parallel
lamellae, which are pendent from its dorsal surface and are
held in place by fibrous bands arising from the floor of the
renal sac. The lamellae sometimes branch. They run
obliquely across the cavity. A single layer of non-ciliated
cells forms the wall of each side of the lamella, and between
two walls is a blood sinus. Blood enters the kidney by a
dorsally placed afferent renal sinus, collecting from the left
anterior portion of the ventral abdominal sinus, and to a
lesser extent from the left body wall and left parapodium.
Small smuses enter the right anterior border of the gland from
the mantle from the part roofing in the kidney. These sinuses
branch repeatedly over the surface of the renal sac, lying in
channels excavated on its upper surface. The blood passes
through the lamellae to collect again in a large sinus, the
efferent renal sinus, on the floor of the gland. The efferent
renal vessel leaves the ventral side of the kidney on its right
side, and discharges into the efferent branchial vessel just as
the latter enters the auricle. (Vzde Blood Vascular System.)”

The kidney is innervated from the branchial ganglion,
(Fig. 16, ven. n.)

APLYSTA. rar

The kidney is not the only organ of excretion. The
sacculations forming the crista aortae, certain cells of the liver
and of the connective tissue, and the opaline gland are probably
all concerned with the elimination of waste matter.

The Crista Aortae (Fig. 13, cr. ao.) lies on the aorta close
to its origin from the ventricle of the heart. Leucocytes occur
in its walls and are thence transferred to the blood stream, so
that the region is also alymph gland. Itis claimed by Grobben,
however, that waste matter from the blood is drawn off here,
and that the crista aortae is homologous with the pericardial
gland of other Molluscs.

The liver contains two kinds of cells :—(a) Protoplasmic
cells rich mm granules, secreting a digestive ferment, and
(6) cells poor in protoplasm, but usually full of brown oily
globules, excretory in function. The former stain deeply, the
latter hardly at all.

The connective tissue surrounds the whole of the body
organs as a thin layer and permeates between the coils of

convoluted organs, e.g., accessory genital mass, forming a

(Sle y)
packing for the coils. It also fills the spaces between the
muscle fibres of the foot and parapodia, but not completely,
for frequent gaps, the lacunae, occur. These lacunae are
part of the blood vascular system. In the large haemocoele
(ventral abdominal sinus), in addition to the layer covering
the gut, nervous system, etc., layers of connective tissue
occur between the gut and body wall. (These have been
omitted from Figs. 21-23.) In many parts, especially where
the organs are compact, as in the visceral hump, the connective
tissue is fenestrated to allow of the passage of the blood through
it. The tissue consists of colourless corpuscles embedded in
a semi-gelatinous matrix. Some of these corpuscles (cells of
Leydig) contain concretions of chally matter, and function as

accumulative excretory cells.*

* Note that in a specimen preserved in acid fixative all traces of these
concretions disappear.

228 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

MUSCULAR SYSTEM.

The muscles in Aplysia are usually arranged in elongated
bundles. The individual fibres are tubular, and are not trans-
versely striated. (Fig. 21,1. ped. m.) The chief groups are :—

1. The muscles of the gut, extrinsic and intrinsic.

2. The retractor muscles of the mantle, penis, ete.

3. The muscles of the kidney, ctenidium, etc.

4. The muscles of the foot and body wall.

The extrinsic muscles of the gut comprise those holding
the buccal mass in place and the sphincter muscles at mouth
and anus. ‘The first named consist of numerous straight bands
radiating from the buccal mass towards the foot and body
wall. The remainder of the gut is held in place by connective
tissue only. The whole alimentary canal possesses an intrinsic
muscular coat of fibres varying in thickness in the different
regions. It is thickest and most complicated im the wall of
the buccal mass and gizzard. (Vide Alimentary Canal.)

Stout bands of fibres arising from the parapodia act as
retractors of the mantle and so of the visceral hump. There
are two of these bands on the right side arisig from the right
parapodium, and one on the left side arismg from the left
parapodium. The right anterior muscle threads its way
between the vesicles of the opaline gland, passes upwards
between the pericardium and the left wall of the pallial cavity,
through the spongy mantle tissue to the surface of the mantle
lying beneath the shell. It arrives at the surface between the
kidney on the left and the free edge of the mantle containing
the purple glands on the right, spreading out to be mserted
directly on the mantle epithelium. (Fig. 15, ret. mant.) The
posterior right retractor muscle passes upwards from the right
parapodium in the region of the anus. The left muscle is
smaller than those on the right side, but is similar in distribu-

tion and origin. (Fig. 21, ret. mant.)

APLYSTA. 229

The retractor penis arises from the muscles of the foot.
It consists of numerous bands which join up only at the base
of the penis sheath to form the stout hollow pillar of muscle
which traverses that organ. (Hig. 19, ref. pn.) In the kidney
and ctenidium small muscular projections arise from the walls
to support the lamellae. (Hig. 21.)

The musclature of the foot is very characteristic. - On the
inner surface bordering on the haemocoele, flat longitudinal
bands occur and run the whole length of the foot. (Fig. 21,
1. ped. m.) Between the bands the haemocoele enters into
communication with the lacunar system of the foot. In the
spongv tissue of the foot and parapodia the muscle bundles
are intricately woven to form a network. The meshes of the
network are partly filled with connective tissue of a gelatinous
nature, but numerous lacunae occur. ‘The muscles are directly

bathed by the blood.

NERVOUS SYSTEM.
(Figs. 16, 17, and 23.)

The nervous system is of great interest from the compara-
tive point of view because it exhibits the intermediate condition
between the streptoneurous and euthyneurous types. The
Streptoneura possess long visceral cords twisted into a figure
of eight, the Kuthvneura usually have uncrossed cords, and the
majority show a tendency to shortening of the visceral cords
and concentration of the chief ganglia around the oesophagus.
Aplysia has long,
whose ganglia is at first sight somewhat obscure and has

untwisted visceral cords, the homology of

given rise to considerable confusion in the literature on this
Molluse.

The nervous system of the typical Gastropod consists of
the following ganglia :—Paired cerebral, paired stomato-gastric,
paired pedal, paired pleural, paired parietal, and unpaired

230 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

visceral ganglia. The cerebral, pleural, and pedal ganglia
form a nerve ring surrounding the oesophagus. The two
cerebral and two pedal ganglia are united by means of cerebral
and pedal commissures respectively, the former dorsal and the
latter ventral in position. Connectives link up the cerebral
and pedal, cerebral and pleural, and pleural and pedal ganglia.
The cerebral ganglia are connected with the ventrally placed
stomato-gastric ganglia, which are united by a commissure.
The visceral nerve cords originate from the pleural ganglia,
and along the course of these cords, which are united posteriorly
he the remaming gangha, viz., two parietal ganglia and a
single visceral or abdominal ganglion. In Aplysia all these
gangha, with the exception of the left parietal (the mfra-
intestinal ganglion of Prosobranchs), are present as distinct
ganglia. There is evidence that the left parietal ganglion has
fused with the unpaired visceral ganglion. The right parietal
(supra-intestinal ganglion of Prosobranchs) and the visceral
ganglion form an apparent pair owing to the shortening of the
pleuro-visceral connectives along which they lhe.

The regions innervated by these ganglia are similar to
those in other Gastropods. The cerebral ganglia are the main ~
sensory centres supplying the tentacles (touch, smell, taste),
the eyes and the so-called auditory organ. The stomato-
gastric ganglia are the seat of the extensive sympathetic system
which ramifies over the surface of the gut. The pedal ganglia
are motor centres innervating the foot and its appendages.
From the pleural ganglia origimate the pleuro-visceral connec-
tives (visceral cords), the ganglia along the course of these
cords supplying the mantle and its glands, the gill and the
osphradium, the genital organs, heart, kidney, etc.

In a fresh specimen the nerves appear yellowish white
in colour, and the ganglia are a bright yellow or orange. The
whole of the nervous system, both central and peripheral,
is surrounded by a sheath of connective tissue between which

APLYSTA. Ta

and the nervous tissue lies a blood sinus. In the anterior
regions of the body it is sometimes difficult to distinguish
between nerves and the delicate muscle tendons that hold the
gut in place. The presence of the blood sinus surrounding
the nerve, however, at once distinguishes the latter.

[DissEction. Make a median incision through the body
wall between the rhinophores so as to expose the buccal bulb.
Extend the cut forwards and backwards until the cerebral
ganglia are visible. Wind the pleural ganglia and trace the
pleuro-visceral cords back to the adjacent parietal and visceral
ganglia, which are situated dorsal to the alimentary canal
and at the level of the posterior curve of the crop, exactly
beneath the anterior wall of the pericardium. This involves
making an oblique incision towards the genital aperture.
Continue the cut through the floor of the pallial cavity between
it and the base of the tight parapodium. |

A. Cerebral Ganglia and Nerves. (Fig. 16.)

The cerebral ganglia (c. g.) lie on the dorsal side of the
oesophagus at its point of origin from the buccal mass. So
large are the nerve cells in these and the other chief ganglia
that the surface possesses a granulated appearance. The
antero-lateral surface of each cerebral ganglion is somewhat
swollen, and is seen in sections to consist of a distinct ganglion,
the optic ganglion of Mazzarelli, which is markedly dispro-
portionate to the minute eye of the animal. The two cerebral
ganglia are united by a single cerebral commissure, and are
linked up with the pleural, pedal, and stomato-gastric or
buccal ganglia by cerebro-pleural, cerebro-pedal, and cerebro-
buccal connectives respectively.

From the cerebral ganglia arise the following pairs of
nerves, the distribution of right and left sides being similar
except in the case of 5 :—

1. A small tegumentary nerve (teg. n. 1). This arises
from the antero-ventral portion of the ganglion and runs
forward to the skin between the tentacles. A branch of the
nerve innervates the buccal orifice, and the dorsal side and
P

939 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

muscles of the bulb. A chain of small ganglia occurs along the
course of this branch.

2. Anterior tentacular nerve, the nerve of the Jabial
tentacle (ant. tent. n.). This arises from the ventral side of
the cerebral ganglion, emerges beneath the third nerve, and
runs forward as a stout nerve beside the buccal mass. It has
two branches. The first or superficial branch is external to
the second or deep branch. The superficial branch runs close
_ under the skin of the labial tentacle, forking round the lobes
of the tentacle. Knotty thickenings often occur along it, but
these do not contain nerve cells. The internal or deep branch
divides into three, of which two supply the ventral and lateral
portions of the buccal cavity and are ganglionated, while the
third runs along the fleshy base of the labial tentacle.

3. Posterior tentacular nerve, the nerve of the rhino-
phore (rh. n.). Its origin is close to that of 1 and 2, but it
immediately ascends dorsal to them so that it appears to be
the first nerve when the ganglia are exposed. Its course is
straight to the rhinophore. When it reaches the body wall
a small nerve branches off to supply the inner side of the
tentacle. The main nerve is ganglionated at the base of the
auriculate portion of the rhinophore, and from this ganglion
a single nerve proceeds along the inner or folded side of the
tentacle, branching to supply the lobes of the ear-like apex.

4. The optic nerve (opt. n.). The presence of a com-
paratively large optic ganglion, attached to the cerebral
ganglion, would suggest a well developed eye and stout optic
nerve. Such is not the case, however. The eye is sunk in
the skin at the base of the rhinophore, and its nerve is extremely
slender. The optic nerve is closely attached to the nerve of the
thinophore.

Nerves 3 and 4 pass dorsal to the penis on the right side.

5. Tegumentary nerve (teg. n. 2). It springs from the
postero-lateral portion of the cerebral ganglion, and supplies

APLYSIA. Zoo

the skin on the side of the body anterior to the rhinophore.
On the right side it sends a branch to the penis.

6. The “ auditory” nerve (aud. n.). This slender nerve
arises from the posterior side of the cerebral ganglion, and
passes backwards between the cerebro-pleural and cerebro-
pedal connectives to the statocyst, which lies in a shallow pit
excavated on the surface of the pedal ganglion.

B. Pleural Ganglia and Nerves.

The pleural ganglia (pl. g.) are situated laterally to the
cerebral ganglia with which they are connected by the short
and stout cerebro-pleural connectives. Pleuro-pedal connec-
tives are also present, but there are no pleural commissures.
From the pleural ganglia arise the long pleuro-visceral con-
nectives. That on the right side passes straight to the parietal
(supra-intestinal) ganglion lateral to the right salivary gland.
The left, connective dives ventral to both salivary gland and
oesophagus, emerging into view again at the posterior end of
the crop, where it swells to form the visceral ganglion, lying
adjacent but slightly postero-ventral to the parietal ganglion.
Both connectives run dorsal to the aorta. The amount of
contraction of the animal may cause some variation in the
relative positions of the parts in this region. From the pleural
ganglion arises a slender nerve to the body wall. In some
specimens there are two nerves on the left side and one on the
right (feg. n. 3 and teg.n. 4). The nerve emerges from the
anterior portion of the ganglion and passes straight outwards.
Tt has an anastomosis with the posterior tentacular nerve (A3)
and with the tegeumentary nerve (C5). Although nerves arise
from the pleural ganglia in Streptoneura (e.g., Patella), their
presence is rare in the Euthyneura, where the infra-intestinal
ganglion takes on the work of supplying the reduced mantle.
The fact that the visceral ganglion supplies both viscera and
mantle region is evidence that this ganglion represents infra-

234. TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

intestinal and visceral ganglia, and Guiart claims to have
found traces of this fusion in Aplysia. Both Guiart and
Mazzarelli deny that any nerves arise from the pleural ganglia
in Aplysia. Pelseneer, however, figures a pleuro-pedal plexus
in Aplysiella petalifera.

C. Pedal Ganglia and Nerves.

Each pedal ganglion (ped. g.) lies close to the pleural ganglion
of its side. A stout cerebro-pedal connective runs between
it and the cerebral ganglion, and a pleuro-pedal connective
between it and the pleural ganglion. From it arise the
numerous nerves supplying the foot and parapodia. Theanterior
portion of the ganglion bears a hollow sac, the “ otocyst”’
(Fig. 23, ot.), which receives a slender nerve from the cerebral
ganglion (nerve A6). The pedal ganglia are united by two
commissures, known as the pedal and parapedal commissures
respectively. The former is a broad commissure which lies
ventral to the oesophagus and thus completes the cerebro-pedal
nerve ring. (Hig. 23, ped. comm.) The parapedal commissure
(para. ped. comm.) is long and slender, and is ventral not only
to the oesophagus but also to the aorta. . The aorta, therefore,
passes through the space between the two commissures. The
parapedal commissure gives off a small nerve on the left side
to the connective tissue in this region.

The pedal nerves may vary in number and distribution
in different specimens. Those on the right side are always
larger and more numerous than those on the left, since they
are distributed to such asymmetrically placed structures as the
penis, genital groove, etc.

1. Anterior pedal nerve. This large nerve arises from
the ventral side of the pedal ganglion and divides into four
branches, all of which supply the foot. The first or deep branch
is hidden by the second and third in dissection and runs forward
to the anterior portion of the foot.

APLYSIA. 235

2. Small tegumentary nerve.

3. Tegumentary nerve. This large nerve supplies the
retractor muscles of the head, the skin, and, on the right side,
the muscle strands attached to the penis. It anastomoses with
the posterior tentacular nerve (A3).

An additional small tegumentary nerve, occurring on the
right side only, supplies the skin and penis. .

All the above nerves run forwards. The following run in
a posterior direction.

4. Parapodial nerve (Fig. 16, para. n. 1.). This is a
large nerve which arises from the ventro-lateral side of the
pedal ganglion and passes straight backwards ventral to the
longitudinal muscle bands and somewhat obliquely to innervate
the parapodium. It branches on its outer side only.

5. Small tegumentary (teg. n. 7). This nerve springs
from the inner dorsal side of the ganglion, crosses dorsal to 4,
and runs beside the crop. It has three branches, viz., to the
body wall anterior to the genital aperture, to the parapodium,
and to the sub-pallium. On the right side it has an anastomosis
with the vulvar nerve (D1) from the parietal ganglion and also
with the nerve from the pleural ganglion (B1).

6. Small parapodial (para. n. 2). This goes straight to
its destination and does not branch until it reaches the muscles
of the parapodium. : |

7. Middle pedal nerve (ped. n. 2). It passes straight
backwards, crosses ventral to 8, and plunges into the middle
portion of the pedal sole.

8. Posterior pedal (ped. n. 3). This large nerve imner-
vates the posterior portion of the foot, branching on the
surface of the muscle bands. An additional nerve, distributed
to the foot, may be present on the left side.

D. Parietal Ganglion (par. g.).
The parietal ganglion (supra-intestinal) lies beside, but
slightly antero-dorsal to the visceral ganglion, at the level of

236 TRANSACTIONS LIVERPOOI BIOLOGICAL SOCIETY.

and dorsal to the posterior curve of the crop. This is the last
remains of streptoneury in Aplysia. The unpaired nerves
arising from the ganglion are liable to variation. The main
ones are :—

1. Small vulvar nerve (vul. n.), which springs from the
antero-lateral portion of the ganglion and runs transversely,
branching into two to innervate the sub-palJlium and the
vulvar orifice. Before branching, however, it has an anastomo-
sis with the small tegumentary nerve (C5) from the pedal
ganglion.

2. Branchial nerve (br. n.). This arises from the posterior
portion of the parietal ganglion. It is a stout nerve which goes
to the base of the ctenidium, where it swells into the branchial
ganglion. Just before entering the branchial ganglion a nerve
passes out to supply the purple gland. From the ganglion
are supplied the osphradium, the ctenidium, and the kidney.

3. A small nerve to the floor of the pericardium (pe. n.).

4, A small nerve to the spermatheca (spth. n.).

K. Visceral Ganglion (vise. g.).
(Represents the infra-intestinal and visceral ganglia fused.)

The following nerves arise from the ganglion :—

1. A small nerve to the gastro-oesophageal artery
(g. oes. n.).

2. Astoutnerve (an.n.) from the outer side of the ganglion
whose course is straight to the anal region dorsal to the visceral

mass. One branch ascends the anal spout and supplies the
muscular walls of the anus and the fleshy siphon, another
branch passes ventral to the rectum to the genital duct and
accessory glands.

3. Genital nerve. This passes ventral to the duct of
the spermatheca, runs parallel to the large hermaphrodite
duct, and on the ventral surface of the albumen gland
swells into a small ganglion (gen. g.). From the ganglion

APLYSIA. 237

branches supply the genital duct and accessory genital glands.
The largest branch emerges on the dorsal side of the accessory
mass, passes dorsal to the rectum and innervates the little
hermaphrodite duct and gland.

4, A small nerve to the floor of the mantle cavity.

¥. Stomato-gastric or Buccal Ganglia. (Fig. 17.)

The buccal ganglia (buc. g.) are small ganglia lying on the
ventral side of the buccal mass. They are slightly anterior
to the cerebral ganglia with which they are connected by
cerebro-buccal connectives (c. buc, conn.). A buccal commis-
sure 1s present.

[DissEction. After dissecting the nerves from the
cerebral, pleural, and pedal ganglia, detach the’ nerves as
near as possible to the organs they innervate. Dissect off
the connective tissue from the gut so that it can be pinned back
on the left side. Cut through the muscle bands that hold
the buccal mass in place and turn the latter over to expose
its ventral surface. The buccal ganglia are now visible. Or
cut through the oesophagus about half an inch from the buccal
mass, detach the muscle bands as before, and turn the whole
forwards so as to expose the ventral side of the buccal mass.
This method, however, involves cutting the visceral nerve
cords. |

The following nerves arise from the buccal ganglia :—

1. From the commissure is given off a median radular
nerve (rad. ».), which runs forward, plunges into the muscles
of the buccal mass and enters the radular sac on its ventral
side.

2. A small nerve (buc. n. 2) which supplies the basal
muscles of the buccal mass.

3. A large nerve (buc. n. 3) which soon bifurcates to
supply the lateral muscles of the buccal mass. [n some
specimens there appear to be two distinct nerves as the branch-
ing occurs at the root. On the posterior side of this nerve

238 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

a small artery supplies the smus in the connective tissue
surrounding the nerve. This may at first be mistaken for a
branch of the nerve.

4. A large nerve to the salivary gland and oesophagus.
This nerve runs inwards. On the right side the nerves to
salivary gland (r. sal. n.) and alimentary canal (r. oes. n.)
arise separately as two distinct nerves. The nerve to the gut
runs parallel to the oesophagus and branches mto two. One
branch runs forward again to the pharyngeal crest of the buccal
mass, internal to the salivary gland; the other branch runs
backwards along the oesophagus, giving off twigs to it. With
its fellow nerve it forms an anastomosing network, which, -
according to Mazzarelli, accompanies the gut to the anus.
Nerve rings occur at the level of the gizzard. On the left.
side the nerve (J. sal. oes. n.) branches into three. One branch
goes to the salivary gland, another forwards to the pharyngeal
crest, and the third backwards along the oesophagus.

SENSE ORGANS.

The sense organs in Aplysia consist of paired eyes, paired

“* ctocysts,”

and a single osphradium. In addition there are
scattered sensory cells in the epithelium of various parts of the
body, particularly on the two pairs of tentacles. The sense
of touch is present over the whole outer surface, but is
especially acute in the tentacles. Taste is located in the
epithelium lning the entrance to the buccal cavity. . The
rhinophores are the seat of the olfactory sense, but the osphra-
dium, which tests the water passing over the ctenidium, must
also be said to have some appreciation of odours. The
“ otocysts”’ function as organs of orientation and the eyes are

the organs of sight.

Tur EPITHELIAL SENSE CELLS.

On the inner sensory surface of both pairs of tentacles
and on the floor of the mantle cavity, roof of the mantle

APLYSIA. 239

cavity, and lower part of the inner side of the right parapodium
(i.e., on the walls of the pallial cavity) occur, amongst the
ordinary epithelial cells, cells which give rise to brush-like
bunches of stiff but slender processes resembling cilia in
appearance. (Fig. 21, pz.) These are the “ Pinselzellen ” of
Flemming. The nerves supplying the Pinselzellen penetrate
the epithelium and end on the surface in fine fibrils.

EYES.

There are two eyes, one being situated at the hase of each
rhinophore on its anterior side. During life the eye often
appears to be situated on a small elevation, but in a contracted
condition may be completely sunk in the skin. Tach eye is a
bluish black spot and is surrounded by a clear circular patch
of unpigmented skin.

The eye consists of a closed vesicle lying just beneath
the surface skin, the epithelium covering it forming a trans-
parent cornea. Between the wall of the vesicle and the
epithelium lies a small amount of connective tissue, and the
vesicle is surrounded internally by tissue of a similar nature,
but more closely packed together.

The optic vesicle is an ovoid sac whose walls are formed
by a single layer of cells. These cells are not, however, of equal
depth. Those in proximity to the cornea, i.e., on the outer
side of the organ, are thin and flattened, and form the false
cornea. Laterally and internally the cells are of much greater
vertical diameter, increasing in height from the false cornea
to the internal wall of the vesicle, where they form the retina.
There is abundant pigment on the wall abutting on the interior
of the vesicle, but not in the cells forming the false cornea.
The pigment zone thus forms a rather broad horseshoe, whose
open ends reach to the false cornea. The retinal cells are of
two kinds, called by Pelseneer the retinulae and retinophora.
The former are pigment cells, the latter the sensory cells of the

organ of sight.

240 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

On the inner portion of the retina is poised a gelatinous
non-cellular Jens, whose outer margin, facing the cornea, is
smooth and evenly convex, but whose inner edge, abutting on
the retina, is ill-defined. Hair-lhke processes, known as
“ Stiftchen,” project from the retina to hold the lens in place.

Blood lacunae surround the eye, and blood is brought to
it by a branch of the cephalic artery. (Vig. 13, opt. a.) It
is innervated by a small optic nerve (Fig. 16, opt. 1.) which
arises from a comparatively large optic ganglion attached to
the cerebral ganglion.

THE STATOCYST.

The statocysts or otocysts (Fig. 23, of.) are situated on
the anterior face of the pedal ganglia. Hach otocyst is a
hemispherical sac whose flattened base is attached to the pedal
ganglion of its side. The wall of the sac consists of a thin
non-ciliated epithelium. The connective tissue which enwraps
the whole nervous system covers the otocyst too, and separates
it from the nervous tissue of the pedal ganglion. Within the
otocystis a granule of calcareous matter. The sac is innervated
from the cerebral ganglion, the auditory nerve lymg between
the cerebro-pedal and cerebro-pleural connectives. Theotocyst
forms the organ of orientation, and like the eye is epithelial
in origin.

THE OsPHRADIUM.
(Olfactory Organ, Organ of Spengel.)

The single osphradium is situated at the base of the
ctenidium on its anterior face. In the living condition it can
usually be recognised as a yellowish patch, due to the branchial
ganglion showing through the skin at this point and not to the
osphradium itself. The osphradium is the water-testing organ.
Should the water approaching the ctenidium become deficient
in oxygen, the nerve impulse generated by the osphradium
causes the animal to open its parapodia and thrust out the

APLYSIA. 241

ctenidium so as to obtain as much oxygen as possible. If
foul water enters, the parapodia are forcibly closed and the
ctenidium withdrawn.

The osphradium consists of a slightly elevated patch of
columnar epithelial cells. These are not ciliated, and the
organ shows no trace of the leaf-like arrangement of the
osphradium of certain Prosobranchs (e.g., Buccinum). The
osphradium is innervated from the branchial ganglion.

GENERATIVE SYSTEM.
(Figs. 18-20.)

Aplysia, like other Euthyneurous Gastropods, is herma-
phrodite. The genital organs consist of an unpaired ovotestis
or hermaphrodite gland, a common genital duct, female
accessory glands, reservoirs for the male elements, and a male
copulatory organ or penis.

The ovotestis (Fig. 20, herm. gl.) is a compact gland of
irregular shape, and is embedded in the visceral mass on its
right posterior border. In the freshly-killed animal it can be
easily separated from the liver, and its golden yellow colour
forms a marked contrast to the dull brown of the latter.
A common genital duct forms a mid-rib to the gland, and
receives ductules from both sides. The size of the gland
varies with the time of year and age of the specimen. On
leaving the ovotestis the little hermaphrodite duct (lit. herm. d.)
increases in width and becomes sinuous. It separates itself
from the visceral mass and passes forward to the right of the
latter beneath the floor of the pallial cavity. It is held in place
by enveloping connective tissue, which fastens it to the right
body wall. At the level of the anus an ovoid mass, consisting
of -the female accessory glands and a reservoir for sperms,
occurs on the left of the duct. These accessory glands are
small and poorly developed in young specimens, and only
become fully developed when the animal is sexually mature.

242 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

The accessory genital mass comprises an albumen gland
and a mucous or nidamental gland in connection with the
female elements, and a spermatocyst (spct.) for storing the
sperms introduced during copulation. The various parts are
closely bound together, and owing to their brittle nature are
difficult to separate in a preserved specimen. The little
hermaphrodite duct passes forward to the right antero-ventral
side of the mass and disappears from view. On turning up the
glands, however, it is seen to become suddenly constricted (Ip.),
and the slender duct loops round a pear-shaped caecum, the
spermatocyst. The duct then enters the mass, and its course
can no longer be traced in surface view. The spermatocyst—
is a blind pouch which occupies the concavity of the hemi-
spherical loop formed by the little hermaphrodite duct. It is
usually densely packed with pure sperms. Its stalk or duct
is bent ina figure S. It communicates with the central portion
of the large hermaphrodite duct as described below.

Forming the anterior portion of the accessory genital
mass is a much convoluted portion of the mucous gland (wind.
gl.), called by Guiart the twisted or winding portion (glande
contournée) and by Mazzarelli the “ portion coiled like a ball
of thread” (porzione a gomitolo). This is the first part of
the voluminous mucous or nidamental gland which forms the
outline of the accessory genital mass. If the folds of the
winding portion be traced it can be seen that the narrow
sinuous portion suddenly enlarges, opening into the smaller
loop of the mucous gland (muc. gl'.). . After this small loop
the mucous gland makes a larger loop, and discharges into the
base of the large hermaphrodite duct on its sacculated right side.
The surface of the mucous gland appears transversely striped
owing to the presence of internal septa, arranged in a parallel
fashion at right angles to the walls of the gland. The centre
of the mass is occupied by an albumen gland (alb. gl.), which
is greenish or yellowish in colour and forms a contrast to the

APLYSIA. 243

whiteness of the mucous gland. Like the latter it shows
transverse stripings due to internal septa, but these are less
regular than those of the mucous gland.

The large hermaphrodite duct (la. herm. d.) arises from
the right anterior portion of the genital mass, close to the
point of entrance of the little hermaphrodite duct. It connects
the accessory genital mass with the common genital aperture,
conveys the egg ribbon and the sperms to the exterior, and
receives the foreign sperm. All three products pass through
the same aperture, which is undivided and is therefore described
as monaulic, in contrast to the diaulic condition in Tritonia,
where male and female ducts separate, and to the triaulic
condition in Doris, where the male, female, and copulatory
portions of the duct are distinct. The large hermaphrodite
duct is divided into a posterior and anterior portion, the two
being abruptly marked off both internally and externally.
The posterior part lies between the accessory genital mass
and the swelling called the bursa seminalis (b. sem.), the
anterior part between the bursa and the external aperture.
The former portion lies in the connective tissue beneath the
sub-pallium, the latter is embedded in the muscles of the
sub-pallium.

The posterior portion of the large hermaphrodite duct is
divided longitudinally imto two parallel divisions separated
internally by folds, but readily discernible externally owing to
a difference in appearance. The portion on the left, which is
the vaginal portion of the duct (vag.), into which the penis is
thrust during copulation, is straight, that on the right is thicker
walled and sacculated (od.), and conveys the egg cordon to the
exterior. The part along which the sperms pass on their way
outwards is not visible externally.

At the anterior end of this portion of the duct a slight
constriction occurs. On the left or vaginal side a glandular
pouch, the bursa seminalis (b. sem.),is present ; on the right side

244 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

the sacculations of the female portion disappear. Immediately
anterior to the bursa enters the slender duct of a spherical
vesicle, the spermatheca (receptaculum seminis, Swammerdam’s
vesicle, copulatory pouch of Guiart). The spermatheca (spth.)
lies ventral to the pericardium, to the floor of which it is
attached by connective tissue. Its wall is thin and the matted
contents are of a purple or pinkish colour. The duct is so
slender that unless care be taken it will be cut through in
dissection and the vesicle left attached to the floor of the
pericardium.

Anterior to the bursa seminalis there is no distinction
externally between male and female portions of the duct, which-
narrows and becomes more muscular as it nears the external
opening. Muscle bands encircle it, and also connect it with
the sub-pallium, in which it becomes embedded.

The common genital aperture (c. gen. ap.) is situated on
the right side of the body at the junction of the sub-pallium
and the neck, at the level of the anterior insertion of the
parapodium. There is here an abrupt change from unpig-
mented to pigmented skin. .

Through the genital aperture pass (a) the sperms of the
animal that produces them (this animal will be referred to as A),
(b) the egg cordon of A, and (c) sperms from another individual
B, for the fertilisation of the eges produced by A.

From the genital orifice a shallow ciliated groove (sem. gr.)
runs forward somewhat diagonally to the penis, situated at the
base of the right anterior tentacle. This groove, the seminal
or spermatic groove, 1s unpigmented. Its lateral walls are
formed by projections of the body wall, the left fold being
rounded in section, the right sharper and frilled. By approxi-
mation of the two folds, a tube is formed along which the
sperms pass from the common genital aperture to the penis.

The penis (Fig. 19, pn.) is completely retractile within its
sheath, but is not invaginable. It is a pedal] structure. The

APLYSIA. 245

sheath (pn. s.) is a muscular cul-de-sac whose blind end, to
which the penis is attached, is posterior. The walls of the
sheath are attached by numerous muscles to the body wall
in this region, and there is a large retractor muscle situated
posteriorly. On slitting up the sheath the penis itself is seen
attached to the blind end by its base, with its free end directed
forwards. In shape it is spatulate or like a leaf with the
edges curled upwards. The surface is chitinised, but does not
bear nodosities as in Aplysia depilans and A. limacina. A deep
eroove runs along its dorsal side. On the ventral side is a linear
longitudinal groove of uniform diameter throughout. This is
the seminal groove, which terminates close to the tip of the
penis and can be traced backwards to its base, then forwards
along the right ventral side of the penis sheath and over the
edge of the penial aperture, where it is continuous with the
lateral seminal groove on the exterior of the body. “When the
penis is everted by afflux of blood and relaxation of the muscles
attached to its base, it is thrust from its sheath, the latter
becoming evaginated. The seminal groove is thus straightened
out. When the penis is withdrawn the groove becomes §
shaped. There is no prostatic gland in Aplysia punctata.

It is now necessary to describe the internal structure of
the parts of the reproductive system. The hermaphrodite
eland is a racemose gland consisting of mmmumerable acini,
each of. which produces eggs and sperms, which, when ripe,
are discharged into the cavity of the acmus. The various
acini are connected with the little hermaphrodite duct. Young
individuals are protandric and produce only sperms, but
later both eggs and sperms are found in the same acinus,
though the latter are always the more numerous. The ova
are discharged in an unripe condition, so that their fertilisation
by the sperms of the same individual is impossible at this
stage. The ovum is a large cell with distinct nucleus and
nucleolus, and is crowded with yolk granules. The sperms

246 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

are produced in groups or bunches, fastened together by their
heads. They are of the usual elongated type common amongst
the Mollusca. The head of the mature active sperm is narrow
and sinuous, its tail very long and slender. In the younger
stages the head may bear a clear disc of protoplasm, or this
may be distributed in the form of droplets along the course
of the tail.

The cavity of the gonad, together with the renal and
pericardial cavities, constitutes all that remains of the true
coelom of Aplysia. The eggs and sperms are thus discharged
into the coelom before making their way to the exterior.

The little hermaphrodite duct is thm-walled and is lmed.
by a non-ciliated epithelium. According to the age of the
animal and the condition at the time of death, the duct contains
either pure sperm or mixed eggs and sperms. On reaching
the level of the accessory genital mass it has already been
noticed that a constriction occurs, and that the duct loops
round the spermatocyst. At this point the epithelial lining
of the duct becomes ciliated and a fold appears internally.
(Fig. 20d, lp.) This fold later becomes the sperm fold, which
is continuous from this pomt to the penis. As the duct
plunges into the accessory genital mass it becomes extremely
slender, and is difficult to trace in a hardened specimen.
Very shortly after entering the mass the duct suddenly enlarges
to form a large thin-walled chamber, whose inner walls are
strongly ciliated. This is the fertilisation chamber (/fert. ch.).
Part of the albumen gland and of the winding portion of the
mucous gland must be dissected away to expose it. By
careful dissection it is seen that the sperm fold of the loop
passes along the right side of the fertilisation chamber and so
travels forward to the large hermaphrodite duct. Its course
will be traced later.

The fertilisation chamber receives the discharge of the
albumen gland, whose walls are very thick, with parallel septa

APLYSIA. QA7

arising from the internal walls in order to increase the secretory
surface. The cells stain deeply. Leaving the chamber on its
left side is a short thin-walled duct leading to the winding
portion of the mucous gland. The winding portion, as has
been already seen, is contimuous with the small and large
loops of the mucous gland. Both the winding and the loop-like
portions stain feebly in contrast to the albumen gland.
Parallel septa occur in the looped portion. |

The large hermaphrodite duct leaves the mass on its right
side. If the duct be split up longitudinally along its ventral
side the connection between the various parts can be traced.
The oviducal portion can be followed from the accessory
genital mass to the external aperture, but the sperm duct
and vaginal duct are best traced backwards from the external
aperture. The anterior portion of the large hermaphrodite
duct (i.e., the part between the bursa seminalis and the external
genital aperture) consists of two chambers (Fig. 20a and 20b),
a large one (vag.) into which the penis of the copulating
individual is thrust and out of which passes the egg string,
and a small portion (int. sem. gr.) partly cut off from the
former by paired folds which are continuous with those of the
spermatic groove. These are the vaginal or copulatory duct
and the spermatic duct respectively. The spermatic groove
leaves the genital aperture on its right side, but within the duct
it passes dorsalwards and to the left, reaching the latter
position posterior to the entrance of the duct of the sperma-
theca. The groove becomes less distinct as it is traced back-
wards, though its identity is clear in sections owing to the fact
that the cells are of greater height and more strongly ciliated
than are those of the rest of the duct. The groove is continuous
with the channel along one side of the fertilisation chamber
(Fig. 20d), and so with the fold that arises in the loop of the
little hermaphrodite duct.

Q

248 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

The vaginal portion of the large hermaphrodite duct lies
on the left of the duct near the opening, the penis entering it
from the left during copulation. In its anterior portion the
walls are only slightly folded. It is connected with the lateral
pocket or bursa seminalis. The walls of the bursa are composed
of tubular glands (Fig. 20b, 6. sem. gl.) which discharge into
the cavity of the bursa. The duct of the spermatheca (spth. d.)
enters the bursa anteriorly. The spermatheca (Qwammerdam’s
vesicle) is thin walled, and both vesicle and duct are ciliated
internally. The vesicle is rarely empty, but usually contains
a mass of waste matter agglutinated together by the secretion
from the glands of the bursa. The contents consist of effete
eggs, granules of yolk and albumen, and a few sperms.

Just as the spermatic portion of the duct crosses from right
to left of the large hermaphrodite duct, so the vaginal or
copulatory portion crosses from the left to the ventral side.
It is difficult to trace the vaginal duct with accuracy by the
ordinary methods of dissection. The investigation was
carried out in the followimg way. The penis of an individual
acting as male was cut as close to its base as possible durmg
copulation. The “female” was then killed, and the repro-
ductive apparatus removed and sectioned with the penis still ©
within the vagina. It was found that the penis penetrated
much further into the large hermaphrodite duct than is usually
stated. Mazzarelli describes it as reaching to the level of
the bursa, and discharging its sperms in an impure condition
into the duct leading to the spermatheca. It was found,
however, that the tip of the penis was thrust into the vaginal
pocket (vag. p.) leading to the spermatocyst, i.e., almost to
the base of the large hermaphrodite duct. It was held in
place, not only by the folds separating the copulatory duct
from the sperm duct and oviduct, but by a double fold,
within the trough of which it lay, arising from the wall of the
copulatory duct. From the pocket a double fold runs into

APLYSIA, 249

the tortuous stalk of the spermatocyst. The stalk also com-
municates, along the opposite side of the fold, with the base
of the large hermaphrodite duct and so with the fertilisation
chamber. Sections show that in this region the oviduct
and sperm duct are together separated by a complete
partition from the copulatory duct, which leads to the sperma-
tocyst. The latter, therefore, receives foreign sperm, and is not
a vesicula seminalis in the true sense of the word. The same
conclusion follows from an injection of the vaginal duct through
the external aperture by means of a glass pipette drawn out to
a very fine point. The injection (Prussian blue) ran into the
bursa, overflowed into the duct of the spermatheca, reached
the stalk of the spermatocyst, and finally entered the fertilisa-
tion chamber, whence it arrived at the albumen and mucous
elands. By dissecting out the apparatus in a freshly-killed
animal before injecting, the order in which the injection mass
reached the various portions was ascertained.

There remains only the oviduct (od.). This, on leaving
the mucous gland, passes up along the right side of the
large hermaphrodite duct. Its walls are thick, glandular
and sacculated, especially during the breeding season. Inter-
nally numerous folds project imwards and so increase the
glandular surface. The glands probably secrete a fluid which
lubricates the passage and so aids in the extrusion of the
ego cordon. It has already been noted that the sacculations
disappear at the level of the bursa seminalis, and that the
anterior portion contains only a vaginal and a spermatic duct.

The spermatic groove is strongly ciliated. The surface of
the penis is covered with a ciliated epithelium, the cilia being
longest within the sperm groove. Numerous unicellular
glands open on the surface and secrete a lubricating fluid.
In some places a depression occurs, and a number of glands
open into the crypt so formed. The interior of the penis
consists of loose tissue with large blood spaces. By the rapid

250 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

fillmg of these spaces with blood, aided by muscular action,
the penis becomes tense and is thrust out of its sheath, appear-
ing large and swollen. Interlacing muscle fibres occur, but the
main muscle is a stout hollow band which occupies the centre
of the penis and is continuous with the retractor muscle at
the base of the sheath.

COPULATION AND OVIPOSITION.

It is often the case in hermaphrodite animals (e.g., Earth-
worm, many Gastropods) that the passage of sperms from one
individual] A to another individual B is effected simultaneously
with the passage of sperms from Bto A. The possibility of this
depends to a large extent upon the relative positions of the male
and female apertures, which must be so arranged that lateral
coupling can take place. In Aplysia the mutual interchange
of reproductive elements between two individuals does not
occur, and if only two individuals come together one acts as
male and the other as female. After an interval the réles may
be reversed. Usually, however, a far more remarkable thing
takes place. A number of individuals, varying from three
to as many as ten, form acham. (Fig. 5.) A member of the
chain fixes itself above and behind the preceding member of —
the chain. The lowermost individual of the series acts as
female only, the topmost as male only, and all the intermediate
ones function as male for the preceding (1.e., lower) and female
for the succeeding (1.e., higher) individual of the chain.*

Copulation may be observed in Aplysia punctata in spring
or in late summer. The first individual of the chain (A) fixes
itself by its foot to weed or rock. Individual B crawls over
the visceral hump of A and takes up a position with the
aperture of the penis on a level with the common genital
aperture of A. B then attaches the anterior portion of its foot
to the mantle of A and grasps it with considerable tenacity.
The posterior part of the foot of B, however, remains free and

* Coupling in chains occurs also in other Gastropods, e.g., Crepidula.

APLYSIA. 251

curls round the “tail” of A. The parapodial lobes of A open
widely and embrace the body of B, but the anal spout protrudes.
The penis of B is then thrust from its sheath and curves
downwards and backwards in the form of an inverted U, to be
inserted into the common genital aperture (vaginal portion)
of A. The whole of the penis is thrust into the vagina and
reaches to the base of the vaginal pocket close to the spermato-
cyst, as already described. Sperms pass along the spermatic
eroove of B, along the penis groove, and into the vaginal
cavity of A. Individual C, in the same way, inserts the
penis into the vagina of B, fixing itself above and behind B.
Owing to the curvature of the body of each of the individuals
forming the chain, a large chain rolls itself almost into a ball.
The coupling lasts for several hours or even days. Judging
by the emptiness of the spermatic groove in many individuals
that were examined during the long coupling period it is
probable that the actual passage of the sperms takes place
in a few minutes. .

There is always a certain amount of debris introduced
with the sperms, and this, agelutmated by the secretion of
the glands lining the wall of the bursa seminalis, is drawn
up into the spermatheca, where it is either absorbed or dis-
charged through the external aperture. No satisfactory
evidence, however, has been obtained on this point. The
sperms travel down the vagina to be stored in the spermatocyst
at its base. It is not known where the separation of detritus
from pure sperm takes place. Mazzarelli states that the
spermatheca receives all the spermatic fluid, but the description
given above shows that this is not the case. Further, the
spermatheca never contains many sperms either during the
quiescent period or immediately after copulation. Whenever,
however, the spermatheca is full of detritus the spermatocyst
is full of pure sperm. It seems probable, therefore, that the
separation of the detritus from the pure sperm takes place on
their entry into the vagina, and not after an interval. This

252 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

would be effected by the motility of the sperms, enabling
them to wriggle free from the waste matter and make their
way down to the spermatocyst, either along the penial groove
or down the vagina itself.

During the coupling it is not unusual for the female to
extrude the egg cordon, or the eggs may be laid some hours
after the individuals have separated. Fertilisation takes place
within the fertilisation chamber by sperms from the spermato-
cyst meeting the eggs which have just entered by the little
hermaphrodite duct. The albumen gland provides the eggs
with a coating of albumen, but as eggs are not found within
this gland, it is inferred that the albumen gland discharges
its secretion into the fertilisation chamber. The eggs then
leave the fertilisation chamber and enter the winding portion
of the mucous gland, pass through the smaller of the loops of
the mucous gland, and finally through the large loop of the
same gland. Here a group of from six to ten eggs is provided
with a clear gelatinous capsule, the shells are coated with
mucus and the balls so formed are strung together to make
the cylindrical egg strmg. It is not known, however, what
portion of the mucous gland makes the shell, though the
natural inference is that the wimding portion does so. The
cordon passes out by the oviduct, whose glandular walls secrete
a lubricating fluid. On leaving the common genital aperture
the cordon often makes use of the spermatic groove as a guide,
so that the eggs may even appear to come from the penial
aperture. More frequently, however, the string becomes free
about an inch in front of the genital orifice, distorting the
spermatic groove at the point where it does so. It is thus
possible to infer, from the presence of the crinkle in the other-
wise smooth groove, that oviposition has recently taken place.

The egg string is not extruded continuously, but in little
spurts of about an inch at a time “like paying out lengths
of cable.” As it frees itself it curls backwards and forwards,

APLYSIA. 253

forming an orange or pink tangled mass on or around the weed.
Deposition usually takes place at night in the aquarium. The
number of eggs in a single cordon is always very large. Fischer
measured an ege string eighteen metres in length, and estimated
that it contained about 108,000 eggs. Relatively few of these,
however, will reach maturity. In addition to the hazards of a
pelagic larval period and of the metamorphosis, the spawn is
often eaten by Crustacea, and it is said that Aplysia itself
will consume its own mutilated ege strings.

The account given above of the function of the spermato-
cyst and spermatheca agrees in the main with that described
by Ehot for Doris, where the genital apparatus is triaulic and
therefore less complicated. It differs from the description
given by Mazzarelli and by Guiart of the reproductive apparatus
of Aplysia. Mazzarelli* did not find the connection between
the external seminal groove and the little hermaphrodite
duct, but states that the sperms pass out by the oviduct.
He describes the penis as being directed by a fold so that the
sperms enter the spermatheca, whose function is to purify
the sperms from extraneous matter. The sperms, he says,
then pass in the pure condition to the spermatocyst. The
above description shows, however, that the sperms pass out
by a continuous groove from the little hermaphrodite duct
to the external seminal groove, and examination of large
numbers of individuals immediately after copulation revealed
only a negligible quantity of sperm in the spermatheca, and
pure sperm, in an active condition, in the spermatocyst.

Guiart,t on the other hand, homologises the spermatocyst
of Aplysia with that of other Opisthobranchs, and says that it
is a true vesicula seminalis and does not open into the vagina.

* Mazzarelli, G. ‘*‘ Monografia delle Aplysiidae del Golfo di Napoli.”
Mem. Soc. Ital. Scienze, 3, IX, 1893, p. 120.

+ Guiart, J. ‘‘ Contributions 4 l’étude des Gastéropodes Opistho-
branches et en particulier des Cephalaspides.” Mem. Soc. Zool., France,
1901.

254 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. —

It should be noted that a spermatheca and spermatocyst
occur on the vaginal portion of the reproductive apparatus
of certain Prosobranchs, as described by Bourne* in the
Neritacea. Here the spermatheca (sperm sac) receives sperma-
tophores, whose sperms when liberated pass into the spermato-
cyst (receptaculum seminis). A duct of unknown function,
called by Bourne the ductus enigmaticus, is thought by him
to serve for conveying the debris to the exterior.

* Bourne, G. C. ‘Contributions to the Morphology of the Group
Neritacea of Aspidobranch Gastropods.”’ Proc. Zool. Soc., 1908, p. 810-887.

bo
ee)
CH

APLYSIA.

LITERATURE.

Only the most important works are included here. A full
account of the early literature will be found in Mazzarelli’s
Monograph on the Aplysiudae.

GENERAL. (External anatomy, habits, etc.) J
1. Purny. Historia naturalis, Lib. IX; Lib. XXXII. c. 60 a.p.

2. AELIAN, C. De Natura Animalium, Lib. II, ec. XLV; Lib. XVI,
ce. XIX. ec. 150 a.p.

_3. ApuLErus. Apologia, sive de Magia, c. XXXX; p. 287 of Geo. Bell’s
English translation. c. 180 a.p.

4, Berton, P. De Aquatilibus, Book II, Chap. 12. 1553.

5. RoNDELETIUS. De Piscibus Marinis, pp. 520-527. 1554.

6. GESNER, C. Historiae animalium, Lib. IV, p. 475. c. 1551.

7. PENNANT. British Zoology, Ed. 4, Vol. IV, p. 42. 1777.

8. Linnazus, C. Systema naturae, Ed. 10, 12, and 13. 1758, 1767,

9. Barsut. Genera Vermium, p. 31. London, 1783.
10. Sowersy. British Miscellany, p. 111. 1806.

ll. pe Lamarck, J. B. Extrait du cours de Zoologie du Museum
@histoire naturelle sur les animaux sans Vertébres, p. 114. Paris, 1812.

12. Fuemine. British Animals, p. 290. 1828.
13. Owen, R. Anatomy of Invertebrates, Vol. II. 1843.
14. Darwin, C. Voyage of the Beagle, Chap. 3, p. 6. 1845.

15. THompson, WiLL. Additions to the Fauna of Ireland. Ann. Nat
Hist., Vol. XV, p. 313. 1845.

16. Jounston. Marine Conchology. 1850.
ive Trans. Berwick Nat. Club, Vol. II, p. 29. c. 1850.

18. JEFFREYS, Gwyn. Report on Dredging among the Channel Islands.
Report British Association, Vol. 35. Birmingham, 1865.

19. FiscHer, P. Observations sur les Aplysiens. Ann. Sc. Nat. (5),
T. XIII, p. 724. 1870.

20. Hunt, A. On some large Aplysiae taken in Torbay. Trans. Devon.
Assoc., Vol. IX, pp. 400-403. 1877. Also Vol. X, pp. 611-617. 1878.

21. LanKkestrer, R. Encyclopaedia Britannica. Art. Mollusca. 1883.

22. BiocuMann. Die im Golfe von Neapel vorkommenden Aplysien.
Mitth. aus der Zool. Stat. zu Neapel, V, p. 32. 1884.

23. Bourne, A. G. On the supposed communication of the Vascular
System with the exterior in Pleurobranchus. Q.J.M.S., Vol. 25, n.s. 1885.

24. VAYSSIERE. Recherches zool. et anat. sur les Mollusques Opistho-
branches du Golfe de Marseille.- Ann. Mus. D’Hist. Nat. de Marseille, T. IT,
p. 91. 1885:

25. PELSENEER, P. Sur l’epipodium des Mollusques. Bull. Sci., p. 182.
1888.

256 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

26. Branco, 8. Lo. Sui periode di maturita sessuale degli animali del
Golfo di Napoli. Mitth. Zool. Stat. Neap., Bd. VIII. 1889.

27. Ropert, E. De Thermaphrodisme de J Aplysie. C.R. Par.,
T. CVIIT. 1889. Also T. CTX. 1889.

28. Garstanc, W. List of Opisthobranch Mollusca of Plymouth.
Journ. Mar. Biol. Assoc., Vol. I, n.s., p. 401. 1890.

29. PELSENEER, P. La classification gencrale des Mollusques. Bull.
Scient. de France et Belg., XXIV, p. 347. 1892.

30. Apropos de l’asymétrie des Mollusques univalves. Journ.
de Conchol. (3), XXXII, p. 229. 1892.

dl. Recherches sur divers Opisthobranches. Mem. Cour. Acad.
Belg., LITT. 1894.

3la. GintcHrRist, J. D. Beitrage zur Kenutniss der Anordnung,
Correlation und Funktion der Mantelorgane der Tectibranchiata. Jena,
1894.

32. Hunt, A. Thirty-five years’ Natural History Notes. Report Trans.
Devon. Ass. Ady. Science, Vol. 36, p. 445-486. 1904.

ANATOMY.

33. Repi, Fr. Opere. Tom. IJ. Osservazioni intorno agli animali
viventi che si trovano negli animali viventi. 1684.

34. Bouapscu. De Animalium Marinis, p. 49 f. Dresden, 1761.

30. CuviEeR, G. Mémoires pour servir a l’histoire et 4 Panatomie des
Mollusques. Paris, 1817. Contains Mem. sur le genre Laplysia. Pub. 1803.

36. DE BLAINVILLE, H. Liévre marin. Dict. Sc. Nat., XXVI. 1823.
Also Monographe du genre Aplysie. Journ. d. Phys., Bd. 96, p. 277.

37. DELLE CutaJE. Descrizione e Notomia delle Aplysie. Atti. Istit.
Incoragg. Napoli, T. IV.. 1823. _

38. — Memorie sulle storia e notomia degli animali senza vertebre
del Regno di Napoli, Vol. IV i, p. 71: Vol. II, p. 64. 1823.

39. SanpER Rane (ed. Férussac). Histoire naturelle des Aplysiens de
Vordre des Tectibranches. Paris, 1827.

40. -—--— Monograph of the Aplysiae. 1829.

41. Mitne Epwarps. Zoological Researches in Sicily, Tom. VIII.
1847. (Circulation.)

42. Observations et expérimentes sur la circulation chez les

Mollusques. Mem. de I’Acad. des Sci. de I’Instit. de France, XX. 1849.
Also earlier paper pub. in Ann. d. Sei. Nat. Zool., Sér. 3, T. VIII. 1847.

43. Koxti~mann. Der Kreislauf des Blutes bei den Lamellibranchiern,
Aplysien und Cephalopoden. Zeits. Wiss. Zool., Bd. XXVI. 1875.

44, Spencer, J. W. Die Geruchsorgane und das Nervensystem der
Mollusken. Zeits. f. w. Zool., T. XXXV. 1881.

45. CUNNINGHAM, J. T. Notes on the structure and relations of the
kidney in Aplysia. Mitth. Zool. Stat. Neap., IV, pp. 420-8. 1883.

46. Lacaze Dututers. Dusystéme nerveux des Gastéropodes pulmonés
aquatiques et d’un nouvel organ d’innervation. (Osphradium.) Arch. de
Zool. Expér., T. I, pp. 437-500. 1887.

47. VayssIERE, A. Atlas d’Anat. comparée des Invertebrés. 1888.

48. PrLSENEER, P. Sur la classification des Gastéropodes d’apreés le
systeme nerveux. Bull. Soc. R. Malac. de Belg., T. XXIII. 1888.

APLYSIA. 257

49. Sartnt Love. Observations anatomiques sur les Aplysiens. C.R.
Ac. Se., Paris, T. CVII. 1888. Also two other papers published in the
same journal in 1889 and 1890.

50. Mazzarevui,G. Richerche sulla morfologia e fisiologia dell’ apparato
riproduttore nelle Aplysiae del Golfo di Napoli. Zool. Anz., XII, p. 330.
1889. Also papers in Italian journals in 1891.

51. Prtsenrer, P. L’innervation de Vosphradium des Mollusques.
C.R. Ac. Sc., Paris, CTX, p. 534. 1889.

52. Bouvier, E. L. Recherches anatomiques sur les Gastéropodes
provenant des campagnes du Yacht “ Hirondelle.” Bull. Soc. Zool. de
France, XVI, p. 56. 1891

53. MazzarEeLuI, G. Note anatomiche sulle Aplysiidae. II Cieco
epatico. Boll. Soc. Nat. in Napoli, Vol. V. 1891.

54. — Monografia delle Aplysiidae del Golfo di Napoli. Mem.
Soc. Ital. Scienze, 3, IX. 1893.

55. AmaAupDRuT, A. La partie antérieure du tube digestive et la torsion
chez les Mollusques Gastéropodes. Ann. d. Sc. Nat. Zool., T. VII, pp. 1-291.
1898.

56. Lacaze Dutuiers. Les ganglions dits palléaux et le stomato-
gastrique de quelques Gastéropodes. Arch. Zool. Exp. et Gén. (3), T. VI,
No. 3. 1898.

57. Mazzarevui, G. Intorno al tubo digerente et al centro stomato-
gastrico delle Aplysie. Zool. Anz., 22 Bd., No. 587, pp. 201-6. 1899.

58. Gutart, J. Les centres nerveux viscéraux de lAplysie. C. R. Soc.
Biol., Paris, T. 52, No. 16, pp. 426-7. 1900.

59. Contribution & l’étude des Gastéropodes Opisthobranches
et en particulier des Cephalaspides. Mem. Soc. Zool., France, T. XIV.
1901.

60. Buatrn and Vuéts. Systéme artérielle de Aplysie. Arch. zool.
exper. (4), T. V, pp. 90-102. 1906. .

HISTOLOGY AND PHYSIOLOGY.

61. Goopsir,Jonn. Secreting structures. Trans. Roy. Soc., Edinburgh.
1842. (Purple gland and liver.)

62. pE Nrcri, A.and G. Della porpora degli Antichi. Atti. R. Accad.
dei Lincei. (2), Vol. IIT. Rome, 1876.

63. Mosretey, H. N. On the Colouring Matter of various Invertebrate
Animals. Q.J.M.S. 1877.

64. Buiocumann. Die Driisen in Mantelrand der Aplysien und verwandte
Formen. Zeits. wiss. Zool., Bd. XX XVIII, p. 411. 1883.

65. Rospert, E. Sur la spermatogénése chez les Aplysiens. C.R.,
Parise /OVIn 1888. ;.T. CLIX, p..916.° 1889.

66. Mazzareuui, G. Intorno alle secrezioni della glandola opalina e
della glandola dell’ opercolo branchiale nelle Aplisie del Golfo di Napoli.
Zool. Anz. 1889.

67. Brrnarp, F. Recherches sur les organes palléaux des Gastéropodes
Prosobranches. Ann. Sc. Nat. Zool. (7), T. IX, p. 250. 1890. (Includes
osphradium of Opisthobranchs.)

68. Cuinor, L. Le sang et la glande lymphatique des Aplysies. C.R.,
Paris: ; CX, p. 774. 1890.

258 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

69. Mazzarevui,G. Sul valore fisiologico della vesicola di Swammerdam
delle Aplysiae. Zool. Anz., XIII, p. 391. 1890.

70. Richerche sulla morfologia e fisiologia della glandola del
Bohadsch nelle Aplysiidae e diagnosi di una nuova specie di Aplysia. Reale
Accad. delle Sci., Napoli. 1891.

71. PELSENEER, P. Sur la function de l’osphradium des Mollusques.
Proc. Verb. Soc. R. Malac. Belg., XII, p. 66. 1893.

72. Hermaphroditism in Mollusca. Q.J.M.S., Vol. 37. 1895.

73. GILcHRIST, J. On the minute structure of the Nervous System of
the Mollusca. Journ. Linn. Soc., Vol. 26. 1897.

74. Borazzi, F. Ricerche fisiologiche sul sistema nervoso viscerale dell’
Aplisie e di aleuni Cefalopodi. Riv. di Sc. Biol., An. 1, Nos. 11/12, pp. 837-
924, 1899.

75. MacMunyn, C. The Pigments of Aplysia punctata. Journ. of Phys.,
Vol. 24, pp. 1-10. 1899.

76. RouMANN. Einige Betrachtungen iiber die Verdauung der Kohlen-
hydrate bei Aplysia. Centralbl. f. Phys., Bd. 13, No. 18, p. 455. 1900.

77. CaraAzzi, D. Studi sui Molluschi. Intern. Monatschr. Anat. Phys.,
Bd. 18, pp. 1-18. 1901. (Histology.)

78. JorDAN, H. Die Physiologie der Locomotion bei Aplysia limacina.
Zeits. f. Biol., 41 Bd., 2 Heft, pp. 169-238. 1901.

79. Briot, A. Sur le sécrétion rouge des Aplysies. C. R. Soc. Biol.,
Paris, T. LVI, pp. 899-901. 1904.

80. GAUTIER, C., and Vi~~aRD, J. Recherches sur le pigment vert
jaune du tégument des Aplysies. C. R. Soc. Biol., Paris, T. LVI, pp. 1037-
1039. 1904.

81. SrepHAN, P. Remarques sur le tissu conjonctif d’ Aplysia punciata.
C. R. Soe. Biol., Paris, T. LVI, pp. 1097-1099. 1904.

82. Srravus, W. Beitrige zur physiologischen Methodik mariner
Thiere. I Aplysia. Mitth. Zool. Stat. Neapel., Bd. XVI, pp. 458-468. 1904.

83. Fortgesetzte Studien am Aplysienherzen nebst Bemerkungen
zur vergleichenden Muskelphysiologie. Arch. ges. Physiol., Bd. CII,
pp. 429-449. 1904.

84. Brtcxe, E. Zur Physiologie der Kropfmuskulatur von Aplysia
dzpilans. Arch. ges. Physiol., Bd. CVIII, pp. 192-215. 1905.

85. Enriquses, P. Studi sui leucociti ed il connettivo dei Gastropodi.
Arch. ital. Anat. Embriol., Vol. IV, pp. 153-160. 1905.

86. Laprausz, L., and Mme. Laprieue. Sur la forme de la loi d’ excita-
tion electrique exprimée par la quantité. C. R. Soc. Biol., Paris, T. LVIII,
pp. 668-670. 1905. (Muscles of Aplysia.)

87. ArtoLta, V. Richerche sulla digestione delle Aplisie. Atti. Soc.
Ligust. Sc. Nat., Genova, Ann. 17, pp. 110-120. 1906.

88. VurEs, F. Sur les ondes pédieuses des Mollusques reptanteurs.
Compt. Rend. Acad. Sci., Paris, T. CXLV, pp. 276-278. 1907.

89. Pataprino, R. Uber das spektroskopische und chemische Verhalten
des Pigmentsekretes von Aplysia punctata. Beitr. Chem. Phys. Path., Bd. XI,
pp. 65-70. 1908.

90. FréuHLIcH, F. W. Experimentelle Studien am Nervensystem der
Mollusken. Zeits. allg. Physiol., Bd. XI, pp. 121-144 and 351-370. 1910.

APLYSTA. 259

91. Hormann, F. B. Gibt es in der Muskulatur der Mollusken periphere,
kontinuierlich leitende Nervennetze bei Abwesenheit von Ganglienzellen.
Arch. ges. Physiol., Bd. 132, pp. 43-81. 1910.

92. Horrmann, P. Uber das Elektrokardiogram von Aplysia. Zentralbl.
Physiol., Bd. XXIV, pp. 699-702. 1910.

93. Brrue, A. Die Dauerverkiirzung der Muskeln. Arch. ges. Physiol.,
Bd. CXLII, pp. 291-336. 191].

94. Parker, G. H. The Mechanism of Locomotion in Gastropods.
Journal of Morphology, U.S.A., Vol. XXII, No. 1, pp. 155-170. 1911.

-95. Poxtimanti, O. Contributi alla fisiologia del movimento e del
sistema nervoso degli animali inferiori. Arch. Nat. Jahrg., LX XVIII,
Heft V, pp. 190-231. 1912.

96. STARKENSTEIN, E.,and Henze, M. Uber den Nachweis von Glykogen
bei Meeresmollusken. Zeits. Physiol. Chem., Bd. LX XXII, pp. 417-424.
1912.

EMBRYOLOGY.

97. VAN BENEDEN, P. J. Recherches sur le development des Aplysies.
Ani..d.Se. Nat., T. XV. -1841.

98. LANKESTER, E. R. Summary of Zoological Observations made at
Naples in the winter of 1871-2. Ann. and Mag. Nat. Hist., Vol. XI, 4th
Series. 1873. (Embryology of Aplysia.) Also Mag. of Nat. Hist., 1875,
and Phil. Trans., 1874.

99. Manrrepi. Le prime fasi dello sviluppo dell’ Aplysia. Atti R.
Accad. Sc., Vol. IX. Naples, 1882.

100. BriocumMann, F. Beitrige zur Kenntniss der Entwicklung der
Gastropoden. (Aplysia limacina.) Zeits. f. wiss. Zool., XX XVIII, p. 392.
1883.

101. Mazzareui, G. Intorno al preteso occhio anale delle larve degli
Opisthobranchi. Rend, R. Accad. Lincei., 5, Vol. 1, Fasc. iii. 1892.

102. Bemerkungen tiber die Analniere der freilebender Larven
der Opisthobranchien. Biol. Centralblatt., Vol. XVIII. 1898.

103. BocHENEK, A. La maturation et la fécondation de l’oeuf de l Aplysia
depilans. Rozpr. Akad. Krakow, pp. 265-274. 1899. And T. XXXIX,
pp. 69-91. 1902.

104. Carazzi, D. Sull’embriologia dell’ Aplysia limacina. Monit. zool.
ital., Vol. XI, pp. 124-127. 1900. Also Zool. Centralbl., p. 297. 1900.

105. GrorGeEvitcH, P. Zur Entwicklungsgeschichte von Aplysia depilans.
Anat. Anz., XVIIT Bd., Nr. 6/7, pp. 145-174. 1900.

106. Mazzareuui,G. A proposito dell’ Embriologia dell’ Aplysia limacina.
Zool. Anz., X XIII Bd., Nr. 612, pp. 185-186. 1900. Also Monit. zool. ital.,
Vol. XI, pp. 224-230. 1900.

107. Carazzi, D. L’embriologia dell’ Aplysie e i problemi fondamentali
dell’ embriologia comparata. Arch. ital. Anat. Embriol., Vol. IV, pp. 231-305
and 439-504. 1905.

108. Buerta, G. Sullo seambio gassozo delle uova di Aplysia limacina
nei vari periodi dello sviluppo. Arch. Fisiol. Firenze., Vol. V, pp. 455-469.
1908.

109. Rizzi, Marco. Sullo sviluppo della radula nel genere Aplysia.
Venezia Atti. Ist. Ven., LX VIII, pp. 261-274. 1908-9.

110. Saunpers, A. M. C., and Marcaret Poote. The Development of
Aplysia punctata. Q.J.M.S., N.S., Vol. LV, pp. 497-539. 1910.

2.60 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

EXPLANATION

REFERENCE

abd. ao. = Abdominal aorta.

aff. br. = Afferent branchial vessel.
alb. gl. = Albumen gland.

an. = Anus.

an. f. = Anal funnel.

an. in. = Anal incision in shell.

an. n. = Anal nerve (E2).

ant. ao. = Anterior aorta.

ant. giz. = Anterior portion of giz-
zard (first triturating stomach).

ant. giz. t. = Tooth of anterior
portion of gizzard.

ant. ped. a. = Anterior pedal artery.
ant. ped. gl. = Anterior pedal gland.
ant. tent. = Anterior tentacle.

ant. tent. a. = Anterior tentacular
artery.

ant. tent. n. = Anterior tentacular
nerve.

ap. pn. = External aperture of penis
sheath.

aud. n. = Auditory nerve (A6).
aur. = Auricle.
b. sem. = Bursa seminalis.

b. sem. gl. = Glands of bursa semi-
nalis.

b. w. a. = Artery to body wall.

bas. m. = Basal muscles of buccal
mass.

. br. g. = Branchial ganglion.

br. n. = Branchial nerve (D2).

br. n|. = Nerve to ctenidium.
buc. cav. = Cavity of buccal mass.
buc. f. = Buccal fold.

buc. g. = Buccal ganglion.

buc. m. = Buccal mass.

buc. n. 2 = Nerve to basal muscles
of buccal mass (F2).

buc. n. 3 = Nerve to lateral muscles
of buccal mass (F3).

OF PLATES.

LETTERS.

c. buc. conn. = Cerebro-buccal con-
nective.

c. comm. = Cerebral commissure.
c. g.. = Cerebral ganglion.

c. gen. ap. = Common genital aper-
ture.

c. pl. conn. = Cerebro-pleural con-
nective.

caec. = Caecum.

caec. a. = Caecal artery.
caec. v. = Caecal valve.
cart. = “‘ Cartilage ’’ of odontophore.
centr. t. = Central tooth of radula.
ceph. a. = Cephalic artery.

con. = Concavity of shell into which
liver projects.

conn. =Connective tissue.

Oi = (Cieoos

cr. ao. = Crista aortae.

ct. = Ctenidium.

d. hep. a. = Deep hepatic artery.
dors. a. = Dorsal artery.

dors. b. w. = Dorsal body wall.
é. = Eye.

eff. br. = Efferent branchial vessel.
eff. ren. = Efferent renal vessel.
f. = Foot.

fert. ch. = Fertilisation chamber.

g. oes. a. = Gastro-oesophageal
artery.

g. oes. n. = Gastro-oesophageal nerve
(E1).

gen. a, = Genital artery (from
anterior aorta).

gen. al. = Genital artery (from
abdominal aorta).

gen. g. = Genital ganglion.
gen. n. = Genital nerve (K3).

gt. = Gutter between mouth and
foot.

APLYSIA. 261

haem. = Haemocoele.

hep. int. a. = Hepato-intestinal
artery.

herm. gl. = Hermaphrodite gland.
int. = Intestine.

int. sem. gr. = Internal seminal
groove.

l. bd. = Left bile duct.

l. m. o. = Longitudinal muscles of —
odontophore.

. ped. m. = Longitudinal muscle

.
~~

band of foot.

. pl. visc. conn. = Left pleuro-
visceral connective.

~

~~

. sal. gl. = Left salivary gland.

~~

. sal, oes. n. = Nerve to left salivary
gland and oesophagus (F4).

l. stom. v. = Left valve of stomach.

la. herm. d. = Large hermaphrodite
duct.

lat. t=. 1 = First lateral tooth of —

radula.

lat. t. 2 = Second lateral tooth of
radula.

lit. herm. d. = Little hermaphrodite
duct.

liv. = Liver.

lp. = Loop of little hermaphrodite
duct.

m. = Mouth.
mand. = Mandible.
mant. = Mantle.

mant. {f. = Mantle fold enveloping
shell.

mant. n. = Mantle nerve (4).
mant. r. = Mantle roof.

mant. sin. = Sinus from mantle to
haemocoele.

muc. gl. = Mucous gland.

muc. gl!. = Small loop of mucous
gland.

ne. a. = Neural artery.
o. m. = Muscles of odontophore.

od. = Oviducal portion of large her-
maphrodite duct.

oes. = Oesophagus.
op. gl. = Opaline gland.

op. gl. a. = Artery to opaline gland.
opt. a. = Optic artery.

opt. n. = Optic Nerve (A4).

ot. = Otocyst.

p. giz. = Posterior portion of gizzard
(second triturating stomach).

p. gl. = Purple gland.

p. gl. n. = Nerve to purple gland.
pall, cav. = Pallial cavity.

par. g. = Parietal ganglion.

para. = Parapodium.

para. a. = Parapodial artery.

para. b, = Cut base of parapodium.
para. n. 1 = Large parapodial nerve

(C4)

para. n. 2 = Small parapodial nerve
(C6).

para. ped. comm. = Parapedal com-
missure.

para. sin. = Parapodial sinus.

pc. = Pericardium.

pe. n. = Pericardial nerve (D3).
ped. a. = Pedal artery.

ped. comm. = Pedal commissure.
ped. g. = Pedal ganglion.

ped. gl. = Pedal glands.

ped. lac. = Pedal lacunae.

ped. n. 2 = Middle pedal nerve (C7).
ped. n.3 = Posterior pedal nerve (C8).
peribuc. a. = Peribuccal artery.

ph. can. = Pharyngeal canal.

ph. can. n. = Nerve to pharyngeal
canal.

ph. cr. = Pharyngeal crest.
pl. g. = Pleural ganglion.

pl. ped. conn. = Pleuro-pedal connec-
tive.

pn. = Penis.

pn. a. = Penial artery.

pn. s. = Penis sheath.

post. ped. gl. = Posterior pedal gland.
pz. = Brush cell (Pinselzelle).

r. bd. = Right bile duct.

r. oes. n. = Right oesophageal nerve.

262 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

as)

. pl. visc. conn. = Right pleuro-
visceral connective.

=

. post. ped. a. = Right posterior
pedal artery.

r. sal. d. = Right salivary duct.

r. sal. n. = Nerve to right salivary
gland.

rad. = Radula.

rad. a, = Radular artery.
rad. n. = Radular nerve (F1).
rad. s. = Radular sac.

rect. = Rectum.

ren. n. = Renal nerve.

ren. mant. sin. = Sinus to kidney
from mantle.

ren. p. = Renal pore.

ren. peri. sin. =Sinus to kidney
from roof of pericardium.

ren. S. = kidney.
ren. sin. = Main renal sinus.

ret. mant. = Retractor muscle of vis-
ceral hump.

ret. pn. = Retractor penis muscle.
rh. = Rhinophore.

rh. a. = Artery to rhinophore.

rh. n. = Nerve to rhinophore (A3).
ros. = Rostrum of shell.

s. hep. a. = Superficial hepatic
artery.

sal. ap. = Aperture of salivary duct
(left).

sem. gr. = External seminal groove.

sem. gr. a. = Artery to seminal
groove.

sh. = Shell.
sh. ap. = Shell aperture in mantle.

shy if. = Shell forming region of
mantle.

sin. 1 =Sinus from left anterior
body wall.

sin. 2 =Sinus from left anterior
portion of haemocoele.

sin. 3 = Sinus from posterior portion
of haemocoele.

sin. 4 = Sinus from right body wall.

sin. 5 = Sinus from anterior portion
of haemocoele.

spct. = Spermatocyst.
spth. = Spermatheca.
spth. a. = Artery to spermatheca.

spth. d. = Duct of spermatheca.

spth. n. = Spermathecal nerve (D4).
stom. = Stomach. :
sup. ped. gl. = Supra-pedal gland.

t. m. o. = Transverse muscles of
odontophore.
teg. n. 1 = Anterior tegumentary

nerve (Al).
teg. n. 2 = Tegumentary nerve (A5).
teg. n. 3 = Tegumentary nerve (B1).

teg. n. 4 = Tegumentary nerve (B2),
left side only.

teg. n. 7 = Tegmentary nerve (C5).

vag. = Vaginal portion of large her-
maphrodite duct.

vag. p. = Vaginal pocket for tip of
penis.

ventr. = Ventricle.
visc. g. = Visceral ganglion.
vul. n. = Vulvar nerve (D1).

wind. gl. = Convoluted portion of
mucous gland.

APLYSIA. 263

Piats I.

[All the figures are of Aplysia punctata. Unless stated
otherwise the drawings are of full-grown specimens. |

Fig. 1. Right lateral view of the living animal in the expanded
condition. X $.

Fig. 2. Left lateral view of the head of the living animal.
Expanded. x 4.

Vig. 3. Front view of the head of the living animal. x $.

Wig. 4. Side view of the living animal in the contracted
condition. x 4.

Hig. 5. Chain of three individuals. Drawn from life from a
chain of five mdividuals seen in the tanks at the
Laboratory, Plymouth. The lowermost individual
A is acting as female only. B is acting as male
for A, but as female for C, while C is acting as
male only. The parapodium of A has been turned
back to show the penis of B curved backwards to

enter the common genital aperture of A. x 4.

Fig. 6. Shell from ventral aspect. The dotted lines represent
lines of growth. x l.

The mantle and pallial complex from the dorsal
aspect. The parapodia have been cut close to the
base, and the edge of the mantle has been
reflected to expose the purple gland. x 1.

|
fie
Q

I

PLATE II.

Fig. 8. General dissection from the dorsal side to show the
alimentary canal and reproductive apparatus.
Part of the nervous system is shown. Only the
outline of the liver is seen; the remainder has
been dissected away to expose the coils of the
intestine. Stripings on the gut represent the
direction of the muscle fibres where these are
_ visible externally. x 2:5.

Puate III.

Fig. 9. Longitudinal optical section of the head to show the
interior of the buccal mass. The pharyngeal
crests, arising from the walls of the pharyngeal
canal, are not shown. (See Fig. 22.) x 2:5.

264

TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.

Fig. 10. Posterior view of five teeth of the radula. Drawn

Fig. 11.

Fig. 12.

Fig. 14.

Fig. 15.

io

under the Edinger Projection Apparatus. x 70.

Three teeth from the gizzard. a and 6b are from
the anterior and c from the posterior portion of
the gizzard. x 3.

Dissection of the stomach, caecum and the beginning
of the intestine, from the ventral side. The
portion from A to B, with the exception of the
intestine, is embedded in the visceral mass, which
has been dissected away to expose it. The
intestine comes to the surface and lies in a channel
on the surface of the visceral mass. The stomach,
intestine, caecum, and the left bile duct have been
cut open ‘longitudinally. ey

Dissection to show the afferent and efferent Beas
of the ctenidium. The kidney has been partly cut
away to expose the heart. The efferent renal
vessels lie on the ventral side of the kidney.
leis

Dissection to show the kidney and renal portal
system. From an injected specimen. The afferent
renal vessels lie on the dorsal surface of the kidney.
<r

Dissection of stomato-gastric system as seen from
the ventral side of the buccal mass. The cerebral
and pedal ganglia, pedal and parapedal commis-
sures are shown, but the cerebral ganglia have
been separated from one another and their com-
missures cut. X 3:5.

PuatTE LY.

Fig. 13. General dissection from the dorsal side to show

the heart and blood vascular system. Other organs
are shown only where necessary to demonstrate
the relations of the parts. The genital annexe
has been displaced backwards. The position of
the genital artery relative to the hermaphrodite
duct is variable. The cerebral ganglia are not
shown, and the pleural and pedal ganglia have
been laterally displaced. x 2:5.

APLYSIA. 265

PLATE V.

Fig. 16. General dissection of the nervous system from the
dorsal side. The stomato-gastric ganglia and
nerves are not shown. The branchial and genital
ganglia have been isolated from the organs they
innervate. Cerebral nerves 1, 3, 4, 6 are shown
on the left side, nerves 2,5, 6 on the right. The
distribution of the first three nerves from the pedal
ganglion, all of which run ventral to the buccal
mass, is not shown. The remaining pedal nerves
are shown on the right side only. x 2:5.

Puate VI.

Fig. 18. Ventral view of the accessory genital organs. The
hermaphrodite gland and external portions of the
male apparatus are not shown. X 2:5.

Fig. 19. Dissection of male copulatory organ from the dorsal
aspect. xX 3.

g. 20. Scheme of the reproductive apparatus as seen from
the ventral side. The various portions of the
accessory genita] mass have been separated to show
the course taken by the genital elements. The
external portions of the male apparatus are not
shown.

(a) Transverse section of the large hermaphrodite
duct with the penis in situ. The section is
taken along the line a on the schematic figure.
In this and succeeding sections the dorsal
side of the section is uppermost in each case.

(b) Transverse section of the large hermaphrodite
duct along the line J, viz. : through the bursa
seminalis and entrance of the spermathecal
duct.

(c) Transverse section of the large hermaphrodite
duct along the line ec.

(d) Transverse section of the accessory genital
mass along the line d.

In these sections note the travelling of the
seminal groove from ventral to dorsal sides of the
large hermaphrodite duct until in section c it no
longer lies in the wall of the duct, but passes over
into a fold from the wall. Jn section ¢ there are
therefore three tracts within the large duct, viz. :
the oviducal portion and the seminal groove, both

ce
Q

266 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY.
carrying the genital elements of individual A, and
the vaginal portion which receives the penis, and
with it the sperms, of individual B. There is not,
however, a complete partition between these three
portions. In section d the sperm groove and
oviducal portion are separated completely from
the portion receiving the sperm of individual B.
The entrance of the spermatocyst into the fertilisa-
tion chamber is not shown. All sections drawn
under the Edinger Projection Apparatus. x 20.

Puate VII.

Fig. 21. Transverse section of a young individual, 9 mm. in
length when preserved. (The specimen was much
contracted.) The section passes through the
visceral hump, above which he the mantle cavity,
the mantle, and the shell. Note that there are
differences between this and the adult stage, e.g.,
the upward projections of the mantle have not
yet enclosed the shell, the opaline gland is pro-
portionately much larger and the purple gland
smaller than in the adult. The connective tissue
surrounding the organs is not shown. The section
was drawn under the Edinger Projection Apparatus
and is slightly diagrammatic. x 10-5.

Fig. 22. Transverse section of the same individual as Fig. 21
passing through the buccal mass. The radula is .
impertectly developed. x 10-5.

Fig. 23. Semidiagrammatic transverse section to show the
relations of the ganglia formimg the circum-
oesophageal ring. The cerebro-pedal connectives
are not shown. The drawing has been made by
projecting structures occurring in five consecutive
sections each 10 yw thick into one plane. The
telescoping chiefly affects the buccal ganglia, which
are situated slightly anterior to the other parts.
Drawn under the Edinger Projection Apparatus
from the same individual as the two preceding
figures. x 10-5.

Fig. 24. Transverse section through the “ tail” region of an
adult specimen to show the posterior pedal gland.
The gland consists of paired invaginations of the
foot opening by separate ducts to the exterior.
The section is somewhat oblique so that the duct
of the right portion of the gland is shown, but not
that of the left. x 34.

_ L.M.B.C. Memoir XXIV | Prate I

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