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REPORT -‘FOR~ 1898

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Professor W. A: Herpman, D:Sc., F.R.S:,

Hon. Director of the Scientific Work ;

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“1899.

| UNIVERSITY COLLEGE, LIVERPOOL,

_ SEA-FISH HATCHERY, AT PIEL.

LANCASHIRE SEA-FISHERIES LABORATORY

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Report on the INVESTIGATIONS carried on in 1898 in
connection with the LANCASHIRE SEA-FISHERIES
LABoRATORY at University College, Liverpool, and
the Sza-FisH Hatcuery at Piel, near Barrow.

Drawn up by Professor W. A. Herpman, F.R.S., Honorary

With Compliments from

Proresson W. A. HERDMAN, F.R.S.,
UNIVERSITY COLLEGE,

LIVERPOOL.

who will be glad to recewe your publications in

exchange.

: ott’s work at
Piel Hatchery and of Mr. Johnstone’s work at the
Liverpool Laboratory, and a glance merely at the above
table of contents will show the extent and variety of the
investigations that have been undertaken.

Mr. Scott’s work has been in the main economic—the
hatching of eggs of marketable fishes and the improve-
ment of apparatus and fittings so as to carry on such
work more efficiently in the future. He hasalso, however,
examined many tow-net gatherings and other samples of
the organisms in the waters and on the shores of our
district, and has carried out a further series of experi-

tee Rag h AN Wae aes tee man Frnt

m

Report on the INVESTIGATIONS carried on in 1898 in
connection with the LANCASHIRE SEA-FISHERIES
LaporaTory at University College, Liverpool, and
the SEA-FisH HatcHeEry at Piel, near Barrow.

Drawn up by Professor W. A. Herpman, F.R.S., Honorary
Director of the Scientific Work; assisted by Mr. ANDREW
Scort, Resident Fisheries Assistant at Piel, and Mr.
JAMES JOHNSTONE, Fisheries Assistant at Liverpool.

CONTENTS.
Introduction - : “ é 2 . bse act
Fish Hatching Work at Piel - - - - : : 12
Observations on Leptocephalus - - : : 7
Observations on Habits and Food of Young Fishes . - 22
The Plankton Work - : = 3 > “OF
Experiments with Weighted Drift Bottles - - - - 30
The Spawning of the Mussel - - - - : = a6
On Sea-Fish Hatching - - = : : - - 54
Oysters and Disease - - - : = : 2 - 62
Iron and Copper in Oysters - - - - - = E 67
Mussel Beds and Mud Banks - 79
Report from Messrs. Keeble and Gamble o on Work done at Piel 81
Appendix :—Laboratory Regulations at Piel - - - 86
INTRODUCTION.

Tuis is the first complete year of Mr. Scott’s work at the
Piel Hatchery and of Mr. Johnstone’s work at the
Liverpool Laboratory, and a glance merely at the above
table of contents will show the extent and variety of the
investigations that have been undertaken.

Mr. Scott’s work has been in the main economic—the
hatching of eggs of marketable fishes and the improve-
ment of apparatus and fittings so as to carry on such
work more efficiently in the future. He has also, however,
examined many tow-net gatherings and other samples of
the organisms in the waters and on the shores of our
district, and has carried out a further series of experi-

2

ments with large ‘‘ drift” bottles. These, and also his
observations upon young stages of the Hel, are given)
below in separate sections. In addition to Mr. Scott's
own work at Piel we have a first report from Messrs.
Gamble and Keeble, Demonstrators of Biology at the
Owens College, Manchester, upon the interesting work
that they were conducting at Piel during a considerable
portion of last summer.

In one of his letters to me at the beginning (June) of
the research Mr. Gamble says: ‘‘ We hope by the end
of summer to have some sound experimental evidence of
the nature of colour change in Virbiws and possibly in:
Mysis as well. . . . Our apparatus consists partly of|
an arrangement for maintaining a constant stream of
water through a series of observation vessels and partly’
of an arrangement by which air is sucked through a.
second set of vessels. Thus we can determine whether
change of air or change of water is the most conducive tc
health. Then in addition to a dark box we have a series
of ‘light-filters’ by means of which we can obtain the
influence of monochromatic light on Virbius both in the
above-mentioned vessels and under the microscope.

For exact physiological work, the sea-wate:
and gas laid on in the Laboratory at Piel are an immense |
advantage—to say nothing of the excellent accommoda-
tion, and from what we managed to do a few weeks ago
both Keeble and I hope that before the end of September}
we may have settled some important questions in |
connection with the colour-reactions of Crustacea to

}

authors’ report given below (p 81).
This work has, at present, no obvious connection with}

3

application of science to industries, how soon the results
of what now seems an investigation in pure science may
turn out to have some important practical bearing. For
my part I am of opinion that all knowledge of animal life
in our seas is of importance, and will help us to
understand the life and ways of fishes.

That a detailed knowledge of the sea and its contents
(however minute) must be the basis of fishery practice
and regulation is recognised in the following extract from
the Memorial in favour of International Oceanographic
Exploration sent last April by the Swedish Government to
our Foreign Office :—‘‘ All fishing in the North Atlantic,
and especially the presence of the migratory fishes,
depends upon the great currents in the upper layers of the
sea, and the variation of the presence in these layers of
the food required by the fishes, viz., ‘ Plankton’ or organ-
isms of animal or vegetable origin floating in the water.
A knowledge of these currents and of the quality and
quantity of food they contain is necessary in order to deter-
mine the legislation required for the creation of a rational
organisation of the fisheries.” Then, again, the migrations
of the Cod towards the Lofoten banks and fjords, and of the
winter Herring into the Skagerack, seem, according to
Otto Pettersson, to be regulated by the impact of cold
Arctic and west Atlantic water in winter driving the fishes
to those parts of the sea where the conditions are less
unfavourable.

It is considerations such as these that lead naturalists
to urge that fishery observations and investigations must
not be restricted by any territorial or administrative
boundaries, but should be extended to off-shore waters,
aud even the high seas, so as to follow up and unravel the
factors that contribute to the distribution of our coast
fisheries.

4

Mr. Ascroft has also stayed some time at the Piel
Hatchery, and we include in this Report a short account
from him of his observations on the separation of mud
from sea-water by shell-fish and on the growth of mud
banks upon beds of shell-fish, especially Mussels.

It may be well to note here that the well-equipped
biological Laboratory with tank-house at Piel is now
open, upon certain conditions, to duly qualified investiga-
tors. In addition to the Laboratory accommodation, the
building provides dining-room, writing-room or library,
and about eight bed-rooms for workers. No charge is
made for residence, and meals are provided at a fixed and
reasonable rate. The regulations for workers, as approved
by the Committee, are appended to this Report.

During the course of his work in hatching Cod, Plaice,
and other fish at Piel last spring, Mr. Scott made a number
of coloured drawings of the various embryonic and larval
stages of our common fishes. We hope that these may be
published on a future occasion, when the series is more
complete.

Having succeeded so far, and shown that the work can
be conducted with the sea-water pumped up at Piel, Mr.
Scott is naturally anxious to be supphed with a pond in
which to keep spawning fish, and with a proper outfit of
hatching boxes, so as to be able to carry on operations on
a much larger scale. As Capt. Dannevig in Norway and
the Scottish Fishery Board (lately at Dunbar, and for
the future at Aberdeen) have adopted a special form of
hatching apparatus, in which the little cubical boxes con-
taining the developing eggs are rocked up and down
constantly in the water of a larger tank, with, so far as
we can ascertain, very good results, it certainly seems
desirable that we should try some of these ‘‘ Dannevig
rocking boxes”’ at Piel, for comparison with the simple

5

tanks with constant flow of water, which we used last
year. Five sets of rocking boxes have, therefore, been
ordered from Norway, where they are made under the
direction of Capt. Dannevig, and are expected to arrive at
Piel in a few days. ‘They wiil be set up along the east
wall of the tank-house, and the plain tanks, which will
also be in use this coming season, are now being moved into
the adjoining portion of the verandah, which is being
enclosed for the purpose so as to form an extension of the
tank-house.*

The provision of a satisfactory spawning pond, in which
the parent fish can be kept in considerable numbers until
they produce their eggs, 1s a more difficult matter. The
Scientific Sub-Committee have had the matter under
consideration at several meetings, and I have gone care-
fully into the question of alternative sites, on the ground,
with the Chairman, the Superintendent, Mr. Scott, and
the Engineer to the Railway Co. (our landlords at Piel).
The difficulty is to get a site which is sufficiently near to
the hatchery, sufficiently protected from heavy seas,
which can be excavated to a sufficient depth, and which
will enable the pond to be constructed at a reasonable
cost. A tidal pond, such as that now being constructed
at Bay of Nigg, Aberdeen, by the Fishery Board for
Scotland, has certain obvious advantages, the chief of
which is that no pumping is required, but it is open to
the objection that it must of necessity (at Piel) be on the
shore, and, therefore, exposed to the seas.

We are trusting for one year more to such supplies of
spawn as can be obtained by the steamer or from the
trawlers, but if these supplies are as poor as they were
last year, we shall require in early summer, at the latest,

* Since the above was written the hatching boxes have arrived, and the
necessary changes in the accommodation have been carried out.

6

to decide upon the position and nature of the spawning
pond, in order that it may be completed in time for the
following season.

Mr. Johnstone’s work at Liverpool has been partly
the investigation in the Laboratory of any specimens
that were sent to us, partly assisting me in the
work, and partly (with Mr. Tom Mercer) looking after
the Fisheries Museum, and the Circulating Fisheries
Exhibition now at Preston. A good deal of Mr.
Johnstone’s time in the Laboratory has been taken
up with the examination of Mussels and other shell-fish,
at all times of the year, and from various parts of the
district. The evidence as to the spawning habits of the
Mussel obtained from the microscopic characters of the
reproductive organs is rather puzzling, but it now seems
most probable that the Mussel commences to produce
mature reproductive elements in the middle of winter,*
and continues to emit eggs and spermis in small quantities
for the first six months of the year (probably in increasing
amount after April), during which time large eggs are
always to be found in the ovary; and then, in the middle
of summer, produces rapidly a much greater number of ova,
so as to clear out the contents of the ovary, which suddenly
(about end of July) undergoes a great change, easily
recognisable under the microscope as the ‘“‘ spent” con-
dition. It then, after a brief interval, proceeds to develop
fresh ovarian tubules, and load up rapidly with young ova,
which develop during the autumn and early winter in
time to be mature at the end of the year. The full details
of these changes in condition will be found in Mr. John-

* We have obtained Mussels with completely formed active spermatozoa
in the middle of December. Mr. Ascroft has found the free-swimming larva
at Lytham in April and May, and the first ‘‘strikes” of young Mussels
are frequently found here upon Alge in June.

v

stone’s section of the Report at p. 36, and the various
stages are illustrated by two plates. I have also started
Mr. Johnstone on an investigation of the structure of our
edible Cockle, and hope in next year’s Report to publish
his full detailed account of that animal.

Our travelling ‘‘ Fisheries Exhibition”’ is working its
way through the more important towns of the county.
At the beginning of March, 1898, after a very successful
period at Liverpool, when it was repeatedly visited by
many interested in the subject, the exhibition was trans-
ferred to the Royal Museum, Salford, where it remained
till the end of October. In the meantime, a circular was
issued from the County Offices, Preston, stating that this
Fisheries Exhibition might be obtained on loan, on certain
terms to meet the expenses of packing, unpacking, re-
arranging, and carriage. Applications were received from
the Museums of Preston, Warrington, Bolton, and St.
Helens; and early in November the exhibition was trans-
ferred to the Harris Free Museum at Preston, where
it will remain for some months. The transference of the
cases and collections (which have to be very carefully
packed and unpacked) from one institution to another
occupies Mr. Johnstone, with the assistance of T. Mercer
and a joiner, for about a fortnight, and it occasionally
happens that there are specimens which become accident-
ally broken or damaged, or for some other reason require
to be replaced from the Laboratory, and re-labelling is
sometimes necessary. All this, and the correspondence
connected therewith, has taken up a not inconsiderable
part of our Liverpool Assistants’ time during the past
year; but I think we are all agreed that it is well worth
doing. The collection, it will be remembered, was
originally formed for the Fisheries Exhibition at the
Imperial Institute in 1897, and as it mainly illustrates

8

our local fisheries and local investigations it is important
that it should be shown locally, and to the people who are
interested in these fisheries and who contribute to the
expense of regulating them. The educational value of
the exhibition must also be considerable, and may perhaps
be gauged by the keen interest shown by visitors.

I can speak to that from my own experience when the
collections were at Liverpool; and I may also quote a
few sentences from letters sent to me by Mr. B. H.
Mullen, M.A., the Curator of the Museum at Salford
when the Exhibition was in that town, as follows :—

“‘The Fisheries Exhibition is a very great attraction
here, and must be doing a lot of good. During the past
three days we had almost 1,000 more visitors than during
the same period in 1897. I place the greater part of this
to your most interesting exhibition.”

“You will notice that in those four nae (June,
July, August, Repiensber) last year over 95,000 persons
visited our museum.’

“T estimate the number of persons who visited the
Museum while your exhibit was here to be 119,852—say,
120,000.”

Mr. Mullen prepared, partly from the catalogue given
as an appendix in our last Report, a ‘“‘ Popular Guide,”
which was largely sold to visitors to the Salford Museum
at the price of one halfpenny. All this can scarcely fail to
do much good in interesting the public in the importance
of Fishery questions, and in disseminating correct and
useful information as to the work of the Lancashire Sea-
Fisheries Committee.

It is proposed that the Exhibition should be sent in April,
1899, to Warrington, and after that to Bolton, and then
St, Helens, and any others of our neighbouring towns that
can provide suitable accommodation, in the order of their

‘

formal application.* The permanent home of the Exhi-
bition, when not on loan, is in the Fisheries Museum at
University College, Liverpool.

It may be mentioned, in this connection, that last May
Professor Boyce and I exhibited at the Royal Society the
practical results of our investigations on Oysters and
Disease which are discussed further on in this Report.

The educational aspect of such matters naturally leads
me to a question of Technical Instruction, which has
arisen almost simultaneously on the Scientific Sub-
Committee and at University College, Liverpool, viz. :—
The formation of a ‘‘ School of Fisheries Science,” or a
curriculum of instruction in the sciences which underlie
Fisheries knowledge and investigations. In November
the Scientific Sub-Committee drew up the following
report :—‘‘ Having regard to the increasing development
of knowledge on Fishery questions, the Sub-Committee
has considered a scheme for the establishment of a School
of Fishery Science, prepared by Professor Herdman, and
is now in communication with the Technical Instruction
Committee of the County Council, with the view to this,
or some suitable scheme for enabling students to obtain
advanced instruction in Fishery Science, being adopted.
It has also been considered desirable, if arrangements can
be made, to allow the Sea-Fishery Bailiffs to avail them-
selves of opportunities for instruction in more advanced
knowledge than they possess of sea-fish, their habits and
food, in order that they may be able to instruct the fisher-
men in matters of which, at present, there is probably
considerable ignorance, and upon which accurate know-
ledge would be advantageous.” This report was approved
by the General Committee at the meeting in November.

* Applications should be sent to Prof. Herdman, University College,
Liverpool.

10

The matter has also been fully considered by a com-
mittee at University College, which has drawn up a
detailed curriculum of instruction, and the scheme now
only awaits a conference between the University and the
County authorities before becoming a working department
in a most important branch of technical knowledge.
With our extensive scientific Laboratories and the
Fisheries department and Museum at University College,
with our sea-fish hatchery and experimental tanks at Piel,
and with the steamer and system of bailiffs under Mr.
Dawson, we possess already organised and co-ordinated in
Lancashire such a mechanism for instruction in Fishery
knowledge from the scientific, from the industrial, and
from the administrative sides, as probably does not yet
exist elsewhere in the country.

If the County Technical Instruction Committee will
help in meeting the necessary expenses of selected
students passing through a two or three years’ curriculum,
and the Laboratory expenses of showing to the bailiffs and
a limited number of fishermen the methods of investigation
and the microscopic, chemical, and other facts which they
hear about in lectures and reports, it can scarcely be
doubted that much more will be done thereby in the
dissemination of real and accurate knowledge than can
possibly be effected by imperfect and sporadic courses of
lectures to the fishermen.

Turning now to such special work as I have been able
to do myself for this Report :—

(1.) I have considered it useful in the present state of
affairs to discuss somewhat fully Mr. Fryer’s criticism
of Sea-Fish Hatching in America, which appeared in the
last Report of the Inspectors for England and Wales
(1898). Ihave had some correspondence on the matter
with the United States Fish Commission, and I may

11

quote here the following sentences from a letter recently
received from the Commissioner :—‘‘ For about ten years
the Cod work has been attended with marked success,
and in Massachusetts has resulted, not only in establish-
ing the in-shore Cod fishery on grounds long exhausted,
but, through favourable distribution of the fry, in extend-
ing the fishery to other waters not originally frequented
by the Cod.” . . . ‘‘Some investigations made a few
years ago by the Commission indicated that the value of
the Cod now annually taken on new grounds is at least
several times greater than the entire yearly expenditures
of the Commission for fish-cultural work, and is increasing
each season.”’

(2.) The investigation into the condition of Oysters from
various localities’ and under various circumstances, and
their relation to infective diseases in man, which I have
been carrying on during the last three years in conjunction
with Professor Boyce and Dr. Kohn is now concluded,
and our full memoir on the subject with illustrations of
‘the detailed evidence will soon be published. I have
therefore considered it right to lay before you in a special
section of this report the final conclusions at which we
have arrived on ‘The Oyster Question;”’ and I have
appended to it a reprint (from our paper at the Bristol
meeting of the British Association in September) of Dr.
Kohn’s account of the presence of iron and copper in
certain Oysters. I think it is clear that what the public
wants at present is an assurance that the Oysters they
buy and eat come from grounds that are above suspicion.
There is a great opportunity for an independent autho-
rity—either ‘‘ Health” or ‘‘ Fisheries,” ‘‘ Central” or
“ Local ’’—to take up the matter, and after due investi-
gation to license or certify certain grounds or certain
Oysters upon the lines I have indicated in the conclusions

on p. 66. W. A. HERDMAN.

JANUARY, 1899.

12

FisH HatcHinc WorK AT PIEL.
(ANDREW SCOTT.)

At the beginning of December, 1897, I entered upon my
duties at Piel, and at once proceeded to place everything
in working order for the approaching spawning season.
Various little defects in the machinery and tanks were
discovered and put right. By far the most serious defect
was found in the large overhead store cisterns in the tank
room, where considerable leakage was taking place, making
the room uncomfortable to work in. However, with some
difficulty and expenditure of time, they were made fairly
water-tight, and at the end of twelve months are now
practically free from leaks.

The wooden hatching tanks used in the previous season
were cleaned out, fresh sand put in the filtering compart-
ments, and a constant circulation of sea-water established.
All the apparatus was in satisfactory working order by the
end of January.

On January 27th the steamer visited the spawning
grounds in the central part of the Irish Sea, between the
Isle of Man and Lancashire, where a few hauls with the fish
trawl and surface nets were taken. No mature fish were —
obtained, but in the tow-net collections made at the “ Top
end of the Hole’’ and ‘‘On the Shoals” a few fish eggs
were observed. The grounds were again visited during
February, and although no spawning fish were found, a
marked increase in the number of floating eggs was
noticed. A quantity of living tow-net material brought
into the Laboratory was found to contain three forms
of fish eggs, in various stages of development—in some
the larvee were quite lively. ‘These eggs were carefully
picked out and placed in glass aquaria, with a constant
circulation of sea-water. In the course of the same even-

13

ing a few of the larve hatched out, and two forms were
identified, from the arrangement of the colouring matter,
as being the larve of Cod and Flounder. The third, a
colourless larva, was not identified, and only lived a few
days. The Cod and Flounder larve lived for twelve days.
By this time the yolk sac had been completely absorbed,
but the larve made no attempt to feed, although kept
supplied with plankton taken in the tow-net.

On March 9th the steamer again visited the spawning
grounds, and this time secured a number of mature Cod,
Haddock, and Plaice, from which a quantity of eggs were
obtained and fertilized. These, however, were probably
not quite mature, and at the end of the following day
they had all died and sunk to the bottom of the tanks,
no development having taken place. The tow-nettings
contained an increased number of developing eggs of Cod,
Flounder, Plaice, &c.

Amongst some living fish brought in by the steamer
from this expedition was a mature female Flounder.
These fish were placed in the tanks, and on the following
day the Flounder was observed to be shedding its eggs.
The fish was therefore taken out, and the eggs pressed
out into a jar, and successfully fertilized with the milt of
a male Flounder that had been captured, amongst other
fishes, in the Barrow Channel by Mr. Wright, a few days
previously. Development proceeded rapidly, and eight
days later all the larvee hatched out, there having been
practically no mortality amongst the eggs. The larve
lived without loss for fourteen days. The contents of the
yolk sac had been absorbed several days previously. At
this stage a marked mortality set in, and during the next
few days the larve died off rapidly. Notwithstanding the
various experiments tried to persuade them to feed, at the
end of eighteen days all had died,

14

On March 16th the steamer arrived with a further
supply of eggs from Plaice and Flounder. None of the
Flounder eggs, and very few of the Plaice eggs, had been
fertilized. On the 18th March a supply of Cod eggs was
brought in by the steamer. Many of these were fertilized,
and the development proceeded rapidly.

The spawning grounds were again visited on March
22nd, and a number of sailing trawlers were boarded
when hauling in their nets. Many mature fish had been
captured, and a supply of Cod, Haddock, Plaice, Flounder,
and Dab eggs were obtained. The eggs of the Haddock,
Plaice, and Dab did not fertilize, nor did many of the
Cod and Flounder.

The surviving eggs of the Plaice fertilized on the 16th,
of the Cod on the 18th, and of the Flounder and Cod on
the 22nd, and 23rd March developed satisfactorily, hatch-
ing out at the end of eighteen, sixteen, eleven, and thirteen
days respectively. Throughout these periods a consider-
able daily mortality was observed, which was, no doubt,
due largely to the condition of the eggs when fertilized.
In several cases the larve were clearly visible through the
membrane of the eggs when death occurred.

Through the kind permission of the Fishery Board for
Scotland, the steamer was allowed to visit the Clyde and
trawl there for spawning fish. Three visits were made,
but on only one of these, the first, were mature fish
obtained, and the eggs successfully fertilized. The eggs
were from Plaice, and the quantity on arrival at Piel
measured 150 cubic centimeters. This was by far the
ereatest individual quantity of eggs received during the
season. On the first visit the eggs of the Witch, Dab,
Grey Gurnard, and Haddock were also obtained; but the
Gurnard and Haddock eggs did not fertilize, The Dab

15

and Witch eggs were fertilized, and underwent partial
development, but died after three days.

Development in the Plaice eggs proceeded through its
usual course with scarcely any mortality, and at the end of
twelve days, the hatching of the larvee commenced, and was
completed on the following day. Shortly after hatching
was completed the larve were carefully transferred to
glass aquaria, through which a constant circulation of
water was maintained, and when they were a week old
various experiments were tried to persuade the larve to
feed. ‘To one jar material collected in the filter was
added; to a second, Diatoms; to a third, Copepoda; toa
fourth, plankton from the tow-nets, and to a fifth, ‘‘ Mussel
broth ” obtained by squeezing up the living shell-fish and
passing the semi-fluid mass through a fine sieve. All
these experiments were of no avail, and the larve began
to die off when they reached the age of fourteen days.
During the following fourteen days there was a consider-
able daily mortality, and at the end of twenty-nine days
all the larvee were dead, they, apparently, having made no
attempt to feed, as no trace of food could be seen in the
stomach when examined under the microscope.

Other expeditions were made to our own spawning
grounds in search of nature fish, but no more fish eggs
could be obtained.

The method of collecting fertilized eggs by the steamer
is one of some difficulty and uncertainty, owing to the
stormy weather sometimes experienced during the spring
of the year. It may happen that just at the very time
spawning fish are on the ground it is unsafe for the
steamer to venture out. ‘The collecting of eggs from fish
caught in the net of an ordinary trawler is also unsatis-
factory, owing to the circumstance that when the eggs are
ready for shedding the least pressure on the sides of the

16

fish forces the eggs out. Fish caught in a trawl-net are
generally mixed up with a large quantity of debris,
especially after a four or five hours’ drag, and the weight
of this ‘‘rubbish”’ pressing against the ripe fish forces the
eggs out before the net is emptied on deck. The majority
of the eggs that are brought in to our hatchery from
these expeditions, therefore, are not perfectly mature,
consequently the eggs may not be fertilized at all, or if
fertilized, die off before hatching out. It is from this
cause that the high mortality arises.

An instance of this was demonstrated during the past
season. A large female Plaice, fully distended with eggs,
was brought in by the steamer from one of the expeditions,
and was kept alive in one of the tanks. In the course of
a few days however, it turned sickly, and to all appear-
ances was In a dying condition. The eggs were therefore
pressed out into a bucket containing a small quantity of
sea-water, and mixed with the milt of a male Plaice that
had been brought in along with the female. None of the
eggs floated, although examination showed a number of
them to have been fertilized, and to be undergoing develop-
ment. The living ones were carefully picked out and
placed in a jar by themselves. Notwithstanding a con-
siderable daily mortality, development proceeded rapidly,
and in a few days the little fishes were showing very
clearly through the egg membranes, but only two hatched
out. A number of the embryos reached the hatching-
out point and then died. The two that did hatch out were
feeble in their movements, and lay on their backs at the
bottom of the jar. They were very different from the
larvee of the Clyde Plaice, and only lived a few hours.

It is clearly evident then, that fish eggs for hatcheries
must be under the most natural condition obtainable.
The only way to secure this is to collect the fish towards

2 nee

tg

the end of the previous year, or very early in the spawning
season, and keep them alive in a suitable pond, allowing
them to shed the eggs by their own efforts.

That the water is satisfactory for the purpose is proved by
the result of the past year’s hatching work. After passing
through the filter it was perfectly pure and transparent,
the specific gravity varying from 1:0025 to 1:0026, and the
temperature from 4° C. to 4°8° C.

The mortality of the larve kept after hatching is very
serious. Further experiments will be tried, as it may be
that we have merely not yet hit upon the proper food.
It may, however, be found best to set the young fish free
before they reach the critical stage in their development.

OBSERVATIONS ON THE OCCURRENCE AND HABITS OF
LEPTOCEPHALUS.

(ANDREW SCOTT.)

In recent years much light has been thrown upon this
peculiar group of fishes (the Leptocephalidze), which were
at one time considered to be fully developed animals and
classed by naturalists as such, under the generic name of
Leptocephalus. Thanks to the observations made at
Roscoff, in France, in 1886, the form then known only as
Leptocephalus morrisit, was actually observed to change
into the Conger eel (Conger vulgaris), and later, in 1891-95,
two Italian investigators, Grassi and Calandruccio, carried
on careful experiments on the Leptocephalus brevirostris
taken in the Straits of Messina. They found that this
so-called species went through a transformation, changing
into the common Eel, Anguilla vulgaris.* So that there
can no longer be any doubt now that the Leptocephali of
the older naturalists are only the larval stages of Eels.

* Proceedings Royal Society, London, vol. LX., No. 363. Dec., 1896.

18

That there is still a considerable amount of definite
information wanted regarding the movements and true
habitat of these larvee in our own seas, may be gathered
from the fact that the records of their capture along the
British coasts are few and far between.

In our surface tow-net gatherings, taken along the
Lancashire coast during the past year or two, we have
occasionally found a little flat, transparent fish, which has
been entered on our lists as ‘‘ Leptocephalus sp.” In
January, 1896, three were taken in the estuary of the
Wyre, by tow-net worked from the steamer. In April of
the same year, one was taken by tow-net worked off
Lytham Pier. These were forwarded to us by Mr.
Ascroft. In January, 1897, one was taken in the Mersey,
off New Brighton, and in the year finished (1898), a
number of individuals have passed through my hands, as
follows :—

On April 26th, Mr. J. Wright, Chief Fishery Officer at
Piel brought into the Laboratory a tow-net collection he
had made in the vicinity of the north end of Roa Island,
and amongst the material was a living Leptocephalus.
This specimen was kept alive for a few days, but eventually
died. Shortly afterwards, May 18th, while I was collect-
ing young flat-fishes in the shore pools and gutters at low
water in the same neighbourhood, three Leptocephali were
captured. From that date onwards, to the end of June,
when the weather and tide permitted, careful examination
of the shores was made, with the result that eighteen
specimens of this hitherto rare fish were obtained ; others
were seen but not captured.

The method adopted for the capture of these and other
young fish, and which proved very successful, was the
following one :—Advantage was taken of the fact that,
during the ebb of the tide here, there is a rapid fall of

19

water, which has scooped out regular well-defined gullies
in the more level stretches of the shore, and although the
adjoining parts of the shore may be almost dry, there is
still a considerable current sweeping down these gullies.
By closing up the smaller gullies, and digging gutters
between them and the larger ones, we were able to divert
almost the whole of the retiring water on certain parts
of the shore into one or two main gullies, which we after-
wards partially closed up with stones, leaving only sufficient
space in the centre to hold a tow-net. On going to these
places during particular states of the ebb, which later on
we were able to locate with considerable accuracy, and
fixing our nets so that the water passed through them, we
were able to secure practically all the material swept off
a considerable area of the shore by the force of the
receding tide. On favourable days, when there was no
wind and the water free from suspended mud, we could
actually see the various kinds of young fishes, Crustacea,
&c., being carried into the net with the current. The
nets were lifted up from time to time, and their contents
emptied into collecting bottles. After the water had
ceased running, we removed the nets and returned to the
Laboratory with our captures, where they were sorted
out, the fish being placed in tanks and glass aquaria.
The Crustacea captured were chiefly used for feeding fish
already in the tanks.

It was amongst the fish taken in this way that we
obtained the majority of our Leptocephalit. Occasionally
others were captured by forcing the tow-net over the
surface mud at the roots of Zostera, which is fairly
common in some parts of our district. With everything
in our favour, we could almost depend with certainty on
having at least one Leptocephalus each time we tried for
them. Sometimes we would get two, and once we cap-

20

tured four. At the end of June, when we ceased finding
them, we had as many as fourteen Leptocephali living in
the glass aquaria. ‘They were then measured one by one
and placed in two aquaria, which had a layer of sand on
the bottom. The sizes ranged from 2; to 275 inches in
extreme length, ,3, of an inch in vertical depth, from fin to
fin, and about 54; of an inch thick. They were flat, colour-
‘less, and perfectly transparent, the viscera, and the heart
-and its movements, being easily seen through the skin.
On being placed in the aquaria, the Leptocephala swam
swiftly round the sides, with an undulating movement,
like that of the sand-eel. They soon settled down to
their new surroundings, and quickly buried themselves in
the sand. The movements gone through in burrowing
are exactly similar to those made by the sand-eel. The
chead is first directed into the sand, then by a rapid back-
ward and forward movement of the posterior part of the
body, the anterior part is forced into the sand, and finally,
by a gliding motion, the posterior part disappears. During
the day-time the Leptocephali remained hidden away in
-the sand. On the slightest disturbance of the water, such
as would be caused by the throwing in of food, their heads
-would be thrust out and a rapid survey taken to ascertain
-the nature and position of this disturbing element. If it
were food that happened to fall close to them, they would
seize it without coming entirely out of the sand, and
would then glide backwards into the burrow. If the food
did not fall within reach, they would not venture to pur-
sue it in daylight. On going into the tank-room at night,
when all was in darkness, and suddenly flashing a light on
the aquaria, it would usually be seen that the Leptocephah
were swimming about actively, but soon retired into the
sand if the light were continued.
~The Leptocephali were kept under observation for a

21

week or two, when all, with the exception of two, were
unfortunately lost through the overflowing of the aquaria
in the night, no doubt having jumped out when the jars
were full. The survivors remain alive, and at the end of
November measured 375 inches in length, one having
grown three-fourths of an inch in four months and the
other slightly less. The transformation of these larve
from the Leptocephalus stage was not actually observed,
but on June 30th they were flat, transparent, colourless
Leptocephali ; and on August 3rd had passed into young
eels, having a smoky-tinted back, silvery-grey sides, and
being no longer transparent.
_ During the earlier parts of August numbers of young
eels were found under the stones on various parts of the
shore, which exactly corresponded with the appearance of
the transformed Leptocephal.

From these observations it would thus appear that
the Leptocephali are inhabitants of the mud, and their
occasional presence in surface tow-net collections is due
to their having been swept out of their burrows by the
strong currents, and that they are never taken in the
dredge is owing to their activity. Attempts to capture
them with a tow-net when they are swimming against the
current usually ends in failure.

In passing, it may be noted that all the Leptocephali I
have obtained from tow-nettings on the Lancashire coast
are identical with the hemi-larval stage described by
Grassi, and many of the observations agree with those
made by him, and published in his paper in the Proceed-
ings of the Royal Society already referred to.

OBSERVATIONS ON THE HABITS AND Foop oF YOUNG

FISHES.
(ANDREW ScoTT.)

Early in May the young flat fishes hatched out under
natural conditions in the sea began to appear on all the
sandy shores. By allowing the water draining down the
gullies, when the tide was ebbing, to pass through a tow-
net, considerable numbers were captured. Many of these
were kept alive in our tanks and aquaria; some were pre-
served for future study, and others were examined at once
to ascertain the nature of the stomach contents.

These little fish, chiefly Plaice and Flounders ranging
from two-fifths to three-fifths of an inch in length, were
quite colourless and transparent, the stomach and alimen-
tary canal showing clearly through the skin. Although
they had assumed the flattened character of their parents
and the eye had begun to move over the head, they still
swam about in a vertical manner. In the course of a day
or two they were observed to have considerable difficulty
in maintaining the upright position, and ere long, after a
few more feeble attempts to swim vertically, they settled
down to a semi-sedentary life in the sand. During the
day-time they remained buried, except the mouth and eyes,
and could only be detected with difficulty. In the dark-
ness they came out and swam freely on the surface of the
sand. After a few weeks, when the little flat fishes had
become accustomed to their surroundings, they ceased
burying themselves, and simply lay on the surface. Some-
times they clung to the sides of the jars with great
tenacity.

The food of these young fishes was found to consist
almost entirely of Copepoda. Collections made later on,

23

when the fish had grown to an inch and upwards in
length, showed them to be feeding on Mysis alone.

From their peculiar structure, one would naturally
expect that the flat fishes would be rather sluggish in
their movements, and not at all particular as to the nature
of their food. Far from this being the case, however,
they pursue their food with much vigour and select a
special diet, as is clearly shown when one examines the
contents of their stomachs. The stomachs of the smaller
ones, from one inch up to four inches in length, captured
on the shores of our neighbourhood, are usually almost
entirely filled with Mysis, a group of Crustacea that depend
chiefly on the power to escape capture by making sudden
leaps when approached by any moving object. The flat
fish appear to be aware of this peculiarity, as they care-
fully stalk the Mysts, and when they get close up make a
sudden spring, seldom failing to capture their prey. That
the young flat fish prefer living to dead food can easily be
seen by throwing a mixture of dead and living Mysis
amongst them. The fish are always on the look out for
food, and at once proceed to investigate any object that
makes its appearance in their vicinity. If the Mysis
swims or leaps away, then it is pursued and captured, but
if it makes no attempt to escape, the fish will abandon it
for a more lively prey. Of course, when the fish are
hard pressed for food they may not be so particular in
waiting until the object shows considerable signs of life
before they capture it.

The older flat fishes, from four inches and upwards,
captured on the Roosebeck Scars, usually feed on young
shelifish, such as*Mussels, &c., worms (Arenicola), and
Crabs (Carcinus).

Shortly after the advent of the flat fishes, the young of
the various round fishes, such as the codling, bluffin, sand-

24

eel, herring, goby, lumpsucker, stickleback, and lesser
grey mullet, began to make their appearance in regular
order; each having their own manner of capturing their
prey, and all, with the exception of the young mullet,
feeding on Mysis. Even the ungainly-looking and
awkwardly-swimming young lumpsuckers are able to
capture Mysis. They swim after their prey at, for them,
a rapid rate, making sudden dashes as they pass, and
usually trying to seize the Mysis by the middle. This
is probably done to prevent too much attention being
bestowed upon them by their less fortunate companions,
which they would otherwise be sure to receive if the prey
were captured by the head or tail. It occasionally happens
that the young lumpsuckers do capture the Mysis by one
end, and before they can swallow it another lumpsucker,
usually a smaller one, has seized the free extremity. It
is rather an interesting sight to see the stronger one try-
ing to shake off the weaker, but so tenaciously do they
cling to their victim, that the smaller fish is frequently in
danger of disappearing after the Mysis. Only at the last
moment does it reluctantly relinquish its hold.

The last of the young fishes to appear on the shores in
the vicinity of Piel, so far as has yet been observed, are
the lesser grey mullet. Numbers of these fish were
captured in a well-defined gully on the east side of the
breakwater joining Foulney Island to the land. ‘They
were first noticed about the middle of September, and
were then fully an inch in length. The stomachs, on
examination, were found to be filled with vegetable food,
chiefly Diatoms, Navicula being the prevailing species.
Later on, when they had reached the length of one and a
half inches, the food was found to consist of a mixture of
Diatoms and Copepoda (Tachidius).

There appears to be little or no difference in the food

25

of the young fishes frequenting the shore, and no matter
whether they were captured at mid-day or mid-night, the
the food was always the same. On several occasions we
trawled the gullies at mid-day and mid-night with a small
otter shrimp net. This was found to be very successful
in capturing young fish, &c.

A number of experiments were made to ascertain how
far the colours of certain Crustacea protected them from
falling a prey to the fishes. It was found that when semi-
transparent and dark-coloured Mysis were put in the jars,
the colourless ones were eaten before the dark. Similarly,
when a large number of variously coloured Hippolyte (Vir-
bius) varians, ranging from transparent to almost black
were used, the transparent ones were the first to disappear.
Gradually the others were captured; last of all, but very
seldom, were the dark ones pursued. Are the pigmented
forms less noticeable under the circumstances, or is the
pigment itself distasteful ?

THE PLANKTON WORK.
(ANDREW SCOTT.)

The examination of the floating plankton collected in
the vicinity of the Lancashire coast has been continued
throughout the greater part of the year. A satisfactory
investigation of the material, and the accurate identifi-
cation of the organisms contained therein, is a matter of
considerable difficulty, owing to the ee quantity of
debris that is nearly always present.

Areas of the sea into which the contents of large rivers
flow are usually contaminated with the spoil carried off
the land. This finds its way into the river either by
accident or intention, and the period during which the

26

lighter particles remain afloat depends largely upon the
strength of the current that carries the material along.

Practically the whole of the Lancashire coast-line is
influenced more or less by the outpouring of large rivers,
such as the Dee, Mersey, and Ribble in the southern and
central part, and by all the rivers flowing into Morecambe
Bay in the north. Therefore, unless we can go to a con-
siderable distance from land, our tow-net collections
are almost wholly composed of vegetable debris, the
land origin of which is clearly demonstrated by the
presence of sporangia of ferns, seed capsules and leaves
of mosses, protecting scales of leaf-buds, twigs and leaves
of trees, etc.

The quantity of debris present in these local tow-
nettings is, of course, subject to weather and tidal
influences. After a spell of calm, during neap tides, we
occasionally get a gathering nearly free from rubbish.
One or two gatherings from the vicinity of the Bar Light-
ship in the Mersey consisted almost entirely of the
Copepod Eurytemora. In the summer of 1895, gatherings
were taken in the Rock Channel, which contained nothing
but large quantities of Noctiluca. This was unusually
abundant throughout the southern part of our district for
a few weeks, occasionally giving the water a distinct
brown appearance. None of the gatherings taken in the
Barrow Channel, outside of Walney Island Lighthouse,
have been free from debris, and the same is true of those
taken in the Ribble, off Lytham Pier, and in the neigh-
bourhood of Nelson Buoy. Mr. Ascroft’s system of
placing his tow-nettings in white dishes with clean sea
water, and allowing the organisms to separate out and
come to the sides of the vessels, where they are secured
and preserved, is a very useful one, but, unfortunately,
not always practicable by our fishery officers, as their
police work takes up most of their time.

27

After the experience gained last year, we arranged that
the gatherings should be taken in more seaward positions
during 1898. This has been done, but the results are
very much the same as before. The weather is frequently
quite unsuitable for our sailing boats to venture far from
land, and on calm days rowing out to the stations is
tedious and dangerous, owing to the tides.

To gain an accurate idea of the floating plankton of the
Irish Sea other means will require to be adopted. The
method that suggests itself as being the most convenient
from all points of view, is to make use of the lightships
that are anchored off various parts of our coast. There
is probably sufficient current set up by the rise and fall of
the tide to keep a tow-net extended. By supplying the
keepers with bottles containing preservatives, tow-nets,
and necessary instructions for working the nets, pre-
serving the material collected, and the times (night or
day, or both) when the collections should be taken, a
more satisfactory knowledge of the plankton would be
obtained. One of the men when off duty might be taken
out in our steamer and shown the methods. Then the
steamer could visit the lightships when convenient, say
once a month, leave a fresh supply of bottles, replace
worn out tow-nets, and bring back the collections taken
during the interval.

The success of this method, of course, depends entirely
upon (after the necessary permission has been obtained)
the zeal and care of the men themselves, and the en-
couragement we give them.

The collecting stations which might be tried this
ensuing year are the North-West, the Morecambe Bay,
the Selker, and the Bahama Lightships, and if the results
prove satisfactory, which no doubt they will, the system
can easily be extended.

28

The material examined during the past year has given
us results which vary very little from those already given
in former Reports. The following are a few of the more
noteworthy organisms observed :—

Mysis occurred in many of the gatherings throughout
the year, but only a few individuals were present in each
tow-netting. They were very common during the
whole year in the shore pools in our neighbourhood. On
September 14th, immense number of young Mysis were
observed in the channels near Baicliff. This is un-
doubtedly one of the most valuable sources of food supply
for young fishes.

Crangon, Pseudocuma, Gammarus, and Eurydice were
occasionally noticed, but only one or two individuals at a
time. Ona warm day, when the sea is calm, numbers of
Eurydice may be seen disporting themselves on the
surface. In their movements they are not unlike the
“Whirligig” beetle of the fresh-water ponds.

Copepoda—Eurytemora, Acartia, Paracalanus, Temora,
Calanus, Pseudocalanus, and Oithona, were present more
or less throughout the year, but never, as a rule, in any
quantity. In a few of the gatherings from the vicinity of
the Bar Lightship, Eurytemora was, on one or two
occasions, verycommon. The striking difference between
local and off-shore collections was clearly demonstrated
by the comparative scarcity of Copepoda in-shore. As
early as January 10th one-fifth part of the tow-nettings,
taken by the ‘‘ John Fell,” five miles north of the Selker
Lightship, consisted of Calanus, Paracalanus, and Acar-
tia. At the same time, only a few individuals were taken
in local gatherings.

At a very early stage in the life history of most fishes,
Copepoda play an important part as a food supply. The
majority of the young flat fishes—Plaice, Flounder, Dab,

—

29

&c.—when they first appear on the sandy shores, feed
almost entirely on these minute crustaceans. The species
usually found in the stomachs of the young fishes, between
half-an-inch and an inch, are chiefly littoral, such as
Eurytemora, Ectinosoma, Tachidius, and Jonesiella. Al-
though the Copepods at particular stages form a food
supply for the fishes, 1t is just possible that the fishes
themselves, when they are newly hatched, may be eaten
by the Copepods. Instances of this were demonstrated
during our feeding experiments, and a species of Copepod
(Centropages) was seen to capture one week old Flounders
and eat them.

~ Other invertebrates, such as Sagitta, Meduse, Cteno-
phora, and Oikoplewra occurred very sparingly in the
local gatherings.

The eggs and larvee of fish were very plentiful in tow-
nettings taken in the open sea, but very few eggs and no
larvee occurred in the local collections. The first collec-
tion in which fish eges were observed were those taken
by the steamer on January 27th, at the “Top end of
the Hole.’ None were found in local gatherings until
February 4th.

Amongst the surface material collected by tow-net when
the steamer was in the Clyde on April 21st, were three
large fish eggs, measuring fully three millimeters in
diameter. he larvee were well developed, and hatched
out a few days later, but did not survive. There was one
large and one small amber-coloured oil globule present,
but no space between the embryo and the egg membrane.
The species of fish to which these eggs belonged is still
uncertain. The only eggs corresponding to them in size
are those of the Halibut; but the eggs of this fish have
apparently not yet been taken in surface nets. The
newly hatched larve had a large yolk sac and very short tail,

30

Larve of various groups of the invertebrata, including
Mollusca, Crustacea, Polyzoa, Vermes, and Coelenterata,
were occasionally observed in the local collections. The
floating eggs of Alcyoniwm were very common in Barrow
Channel, off Roa Island, in the beginning of April, and
also in the tow-nettings taken in the Clyde.

Noctiluca was very common in the collections taken in
the vicinity of the Bar Lightship, Mersey, on June 24th
and onwards; but was not observed in the northern part
of the district until the end of August.

Ceratium tripos, C. furca, and C. fusus, occurred in
many collections throughout the year.

Diatoms (Biddulphia, Coscinodiscus, &c.) were very
seldom found in the local collections, but were abundant
in the gatherings made by the steamer further out, in the
spring months.

EXPERIMENTS WITH WEIGHTED DRIFT BoTTLEs.
(ANDREW SCOTT.)

In a former Report,* under the title, “‘ The Drift
Bottles and Surface Currents,’ in which the result of the
distribution of drift bottles over the Irish Sea, and the
conclusion drawn therefrom, is given, reference is made
to an experiment of Mr. Ascroft’s, where, instead of using
small bottles containing only the post card, larger bottles
were employed, but, in addition to the post card, were
so weighted with sand that they floated almost entirely
submerged, and of which nearly 30% were returned. It
is also incidentally remarked that some of them sunk out
of sight when set free, one being subsequently brought up
in a steamer’s trawl while fishing in the vicinity of the
Bahama Lightship on the north-east coast of the Isle of

Report for 1895, Sect, II., p. 12,

3l

Man. This is now accounted for by the following explana-
tion. During transit some of the bottles were broken,
but in order that the post cards should not be wasted,
other whole bottles were obtained, the card and the same
sand put in, then the whole sealed up, over-looking the
fact that all bottles may not be of the same weight, each
requiring careful ballasting, consequently when these
bottles were thrown overboard the majority of them
sank.

The result of this experiment of Mr. Ascroft’s showed
that weighted bottles tended to go south, thus differing
from the light ones, which largely went to the north. In
order to throw further light on this apparent southerly
drift of weighted bottles, it was decided to give the
weighted bottles a further trial, and in addition, by set-
ting them free on the spawning grounds when the steamer
was trawling for spawning fish, perhaps gain some definite
information regarding the direction of the drift of the
surface waters in which the embryos and larval fish
usually are.

Accordingly we had a number of ordinary post cards
having the same notice previously used, printed on the
back, and we purchased a supply of bottles, known as ‘‘ cocoa
wine bottles,’ of about one pint capacity. These bottles
were placed one by one floating in a bucket of sea-water
of 1:0026 specific gravity, and then carefully ballasted with
dry sand, so that when the rolled up and numbered post

?

card was placed inside, the cork inserted, and the whole
sealed up with paraffin wax, only about an inch of the
neck of the bottle was above the surface of the water.
They were then sent on board the fisheries steamer in
batches, each batch being accompanied by forms having
the numbers of the bottles, and spaces for the insertion of
the position of the steamer when the bottle was set free,

32

the date, time, state of the tide, direction of the wind,
and approximate quantity of floating eggs taken in the
tow-nets. The forms were filled up by Captain Wignall,
and returned to me, after the bottles had been set free.

Altogether 102 bottles were made up, but one of these
was broken in transit, so that during the time the steamer
was trawling for spawning fish, from February to the
middle of May, 101 bottles were set free, of which we
have exact particulars regarding their distribution. Of
this number 41 or 40°5% have been returned to Piel from
various parts of the coast-line of Cheshire, Lancashire,
Cumberland, and the South of Scotland.

The following table gives the position of the steamer
when the bottles were let off, the place where they were
subsequently picked up, and the number of days that
elapsed between their despatch and recovery (see p. 34) :—

From this table it will be seen that nearly 22% of the
bottles have drifted in an easterly or southerly direction
after being set off, and nearly 18% have taken a northerly
direction. Only one bottle, No. 60, appears to have
crossed the head of the tide. Of the 40 set free in the
vicinity of the Bahama ship, 12 have been returned, and
of these eight have gone north to the south coast of
Scotland, and four have taken a south-easterly direction,
landing on the Cumberland coast. Bottles 51 and 53, set
free within fifty-five minutes of each other, yielded rather
peculiar results, the first going to Holyhead in seven
days, and the second to Duddon in 47 days, distances of
fifty-five miles and twenty miles respectively in a straight
line from the point of despatch, but in exactly opposite
directions.

Of the various days on which the bottles were found,
only three were Sundays, and seven were Mondays. The
conclusion naturally drawn from this evidence is, that the

33

bottles were probably found almost immediately after
being stranded. The shores are so regularly patrolled by
the people living in the immediate neighbourhood, that
there is little chance of any unusual object being long
over-looked. One or two of the finders stated that the
bottles came ashore during the previous tide, and one
was picked up at sea, five miles from Blackpool, by a
fisherman, after it had been 23 days in the water.

In all probability the bottles would float slightly higher
in the water of the open sea than they did in the bucket
at Piel, as the specific gravity of the water at the various
stations ranged from 1:00268 to 1:0027, so that there would
be little chance of their going towards the bottom of the
sea till they entered the estuaries of rivers.

The table shows that out of the 101 bottles set free,
fully 30°6% have been stranded on the Cheshire, Lanca-
shire, and Cumberland coasts, and therefore the result of
this experiment, even with weighted bottles in place of
light ones, confirms, in a striking manner, the conclusion
arrived at by Professor Herdman* when summing up the
results of the first series of experiments, 7.e., ‘‘ That the
embryos of fish spawning in the deep water on the eastern
side of the Isle of Man would go to supply the nurseries
in the shallow Lancashire and Cheshire Bays.”

Fish eggs and larve were found in all the tow-nettings
made during the experiment.

(Table over page.

* Rep, Lane. Sea-Fish. Lab., 1895, pp. 20—21,

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36

THE SPAWNING OF THE MussEL (Mytilus edulis).
(J. JOHNSTONE.)

During the last year an investigation of the reproductive
organs of the common Mussel has been made in relation
to the period during which spawning takes place on the
beds along the Lancashire sea coast, and to the histo-
logical changes accompanying the ripening and extrusion
of the reproductive products. The methods employed
were :—(1) The microscopic examination of the gonads of
specimens taken by Mr. A. Scott from the Roosebeck scars
and the beds in the Barrow Channel, and of specimens sent
by the bailiffs from the Wallasey, New Brighton, and
Morecambe beds; (2) the search for free-swimming and
fixed larve on the beds themselves, and (3) the examina-
tion of the in-shore tow-nettings taken by Mr. Wright in
Morecambe Bay, and by Mr. Eccles outside the estuary of
the Mersey. The records of a continuous weekly series of
tow-nettings, taken in the year 1895 by Mr. R. L. Ascroft,
at Lytham Pier, have also afforded valuable evidence.

As a result of this year’s observations, it has been found
possible to fix approximately the date of a maximum in
the spawning of the Mussel, during which a rapid.and com-
plete extrusion of the genital products, accompanied by
other histological changes in the mantle and visceral mass
of the animal, takes place. In the year 1898 this was
found to begin about the beginning of July and last till
about the beginning of August; but it is probable that the
limits of this period are variable to some extent. There
is, however, considerable doubt as to whether this is the
only time in the year during which spawning takes place,
and various observations render it at least possible that
there is a secondary spawning period early in the year,
and that there is a continual but slow emission of ova and

37

spermatozoa from the time when these have accumulated
in considerable quantity in the gonads, that is to say, from
the beginning of April on to the beginning of the summer
spawning period. And it seems certain, considering the
variability observed in the ripening of the gonads, that
isolated individuals may undergo complete spawning @
considerable time in advance of, or later than, the date of
occurrence of the maximum. However that may be, there
can be no doubt that the number of larve resulting from
spawning in the early part of the year bears a very small
proportion to those produced during the maximum spawn-
ing period in the summer months.

There is still some uncertainty regarding the rate of
growth of the young Mussel, and this is due probably to
variations contingent on the conditions under which the
adult animal spawns, and the larva undergoes its early
development. Most probably in the early stages during
which the young Mussel has a free-swimming existence,
the development and rate of growth are fairly constant,
but with the acquisition of the byssus and the fixation of
the larva, the subsequent growth is dependent, to a large
extent, on the situation it finds itself in, the supply of food,
the extent to which the larve are crowded together, and
on the time of year in which spawning of the parent
occurred. From the observations made by Wilson,* who
succeeded in artificially fertilizing eggs of the Mussel, and
tracing out the early development, it appears that the
larva, about 0°15 mm. in length, provided with semicircular
valves, showing the first rudiment of the anterior adductor
muscle, and still using the velum as a locomotive organ, is
at most 12 days old. An older stage than this, with the

* J. Wilson.—‘‘On the Development of the Common Mussel.” Annua

Report of the Fishery Board for Scotland for the year 1885, pp. 218—222, and
Report for 1886, pp. 247—256, Plates XII.—XIV.

38

valves assuming an oval form, the foot developing, the
posterior adductor muscle present, rudiments of four gill
filaments appearing, and the velum still functional is, at
the outside, a month old. Subsequently to this (0°28 mm,
long) blue pigment is deposited round the margin of the
shell, the foot becomes the organ of locomotion, and the
larva prepares for fixation by the development of byssus
gland and byssus.

Free-swimming larve, somewhat younger than the stage
last referred to, that is, about 0°25 mm. in diameter, and
provided with circular valves showing no trace of pigment,
were taken by Mr. Scott in a tow-net gathering at
Piel, on September 9th, last year. These Mussels were
certainly less than one month old, and their appearance at
this time is in accordance with anatomical observations
made on specimens taken in the neighbourhood, which led
us to fix July and early August as the months during
which spawning took place. But the evidence given by
other observations of this kind is very perplexing. ‘Thus
young Mussels with circular or oval valves ranging in size
from 0°27 to 0°45 mm., and with the rudiments of four or
more gill filaments present, were taken in June, 1892,
fixed to various zoophytes, and assuming the age of these
not to exceed a month, the time of spawning is thrown
back to May or early June. An examination of the
in-shore tow-nettings shewed that young Mussels of

approximately this size (0°3 to 0°6 mmm.) were taken in the ~

estuary of the Ribble on January 27th, 1898, and others,
varying in size from 0°2 to 0°7 mm., were found in Ulver-
ston Channel on February 4th. Some of these had
probably been already fixed and were loosened by the
force of the tide, but others had all the characters of the
free-swimining stages described above, and their presence
at this time is only explicable on the assumption that

39

there had been considerable retardation in the rate of
growth, or that they had resulted from spawning early in
the year. The early maturity of the spermatozoa is in-
teresting in this connection. In some specimens taken
in December by Mr. Scott, ripe spermatozoa, which
remained alive for about 12 hours, were expressed from
the mantle lobes. An attempt was made to bring about
artificial fertilization, but although the eggs were found to
be covered with motile spermatozoa, and in some cases the
formation of the first polar body took place, the segmen-
tation of the ovum was not observed.

The assumption that some Mussels at least may spawn
early in the year is necessary to explain the presence of
larve in January and February, if it should be found
impossible to account for the presence of such by con-
siderable variation in the early development and rate of
growth; and that there is a gradual emission of spawn
during April, May, and June seems probable also in view
of the fact that free-swimming larve are to be found in
May and June. But from the anatomical standpoint,
such secondary spawning periods are accidental, and do
not effect the statement that there is a yearly cycle of
changes in the reproductive organs of the Mussel, which
begins with the termination of the act of spawning some-
time in the summer months, includes the gradual and
continuous ripening of the gonads, and ends with a com-
paratively rapid extrusion of the reproductive products,
leaving the animal in a “spent’’ condition, after which
a short period of rest occurs, and the cycle of changes is
repeated. The duration of the maximum spawning period
we have not precisely made out, and its date is probably
variable and dependent on changing meteorological con-
ditions, but that it occurs during May, June, July, and
August seems perfectly certain. This cycle of changes
will now be considered.

40

It will be remembered that in the common Mussel the
sexes are separate. Hermaphrodites, if they exist, must
be extremely uncommon as, in the examination of many
hundreds of specimens, none have been observed. There
is a slight preponderance of males over females, the ratio
in 218 specimens examined being 118: 100; but it is
probable this is too low, as it is hard to avoid selection in
choosing the specimens for examination.* Except for a
slight difference in the colour of the mantle lobes there
are no external sexual characters.

The gonad (Pl. L., fig. 2) is situated in the visceral
mass and mantle lobes; the organ is paired and bilaterally
symmetrical, and consists of a branching tubular gland,
the efferent duct of which is situated on the summit of a
small papilla (Pl. I., fig. 1, pp. gen.), about 1 mm. in
height, which lies posterior to the foot and immediately
beneath the gills (67. #.), and can be easily seen by
reflecting the latter and the mantle (Mn. R.). This duct
is richly ciliated for some distance internally, when the
ciliated wall is partially replaced by germinal epithelium.
Strips of columnar ciliated epithelium (Pl. IL., fig. 7, ep.
cil.) are present along the greater length of the tubules,
but the terminal portions are entirely lined by germinal
epithelium. Passing inwards these tubules branch

* Since the above was written the tabulated results of the examination of
the specimens sent to the Laboratory by the Bailiffs have been referred to.
The portion of these records dealt with relates to the examination of a large
number of Mussels taken at random from most of the Mussel beds in the
district, and sent to the Laboratory in lots of a dozen each, and extends over
the years 1892-96. In order to eliminate as many sources of error as may be
possible, all those sheets in which the sex of one or more of the specimens is
regarded as doubtful, and also those dealing with Mussels taken about the
time of the ‘‘spent” period, have been rejected. This leaves a total of 821
specimens of which the sex was probably accurately determined. Of these

449 were male and 372 female, giving a ratio of males to females equal to
6: 5 (very nearly).

41

repeatedly and in quite an irregular manner. Anastomoses
between the various branches have been figured by Wilson,
but we have not seen these. All along the course of the
main branches small twigs are sent out, some no longer than
their own diameter, and these grow and invade whatever
portions of the body they can find room in. The gonad
thus occupies no particular part of the body of the animal
except that the position of the external opening is con-
stant, but it may be conveniently said to be situated
posteriorly to the digestive gland, and as ripening proceeds,
to invade every part of the body, where only connective
or parenchymatous tissue is found (Pl. L., fig. 2, twd. ov.).
Simultaneously with the encroachment of the genital
tubules, this tissue undergoes absorption or degeneration.
The keel-like mass, the ‘“‘abdomen,” (PI. L., fig. 1., abd.)
situated medially and posteriorly, is thus completely filled
up by the organ, and as maturation goes on, the whole
space in the mantle lobes (Pl. I., fig. 2, Mn. L.; Mn. £.),
between the internal and external epidermal surfaces is
filled up by the branching tubules of the gonad and
except for the merest trace of connective tissue contains
nothing else. Long before spawning occurs these tubules
have invaded almost every part of the body (Pl. L., fig. 2),
even the delicate membrane forming the external wall of
the pericardial cavity being overspread by them and
becoming opaque. With the act of spawning the whole
appearance of the animal may be changed, owing to the
emptying of these tubules of their contents, and the
mantle lobes may lose their thick and opaque appearance,
and become thin and transparent. This is the case in
the Mussels in some of the beds in the district, but more
usually the mantle lobes remain thick and opaque. After
spawning it is only by microscopic examination that the
condition of the animal can be determined.

492

As indicated above, the cycle of changes in the gonads
is a yearly one, or approximately a yearly one, variations
due to the nature of the season doubtless taking place.
This cycle of changes may be represented by four stages.
In giving the dates, we refer more particularly to what was
found during the year 1898

SracE I.—The end of July and the beginning of August.
The Mussel is ‘“‘ spent,” that is, the reproductive products
have been entirely extruded, and in the mantle lobes and
visceral mass the genital tubules are, to a large extent,
collapsed or degenerated. The state of the animal in
respect of its reproductive function is one of rest.

Srace II.—September. The gonads have begun to
invade the mantle lobes and other parts of the body.
Proliferation of ova and spermatozoa from the germinal
epithelium is in progress, and goes on slowly and continu-
ously from now till early in the following year, when it
becomes very active, and the mass of the gonads becomes
much greater.

SracE III.—April. The mantle lobes have attained
their maximum of thickness, and are completely filled up
by the gonads. The tubules composing the latter have
increased greatly in sectional area, and are completely
filled up by ova or spermatozoa in female and male respec-
tively. Proliferation from the germinal epithelium is not
now so active as in the earlier part of the year, and
maturation of the genital products probably goes on.
Where the ova or spermatazoa are in contact with the
ciliated portions of the tubules, they are probably being
swept away and removed out of the body.

Srace I[V.—July and early August. Spawning in the
sense of a complete removal of the genital products is
now in progress. There is a rapid decrease in the mass
of the gonads, both in visceral mass and mantle lobes,

43

and a corresponding increase in mass of the parenchy-
matous tissue lying between the tubules. Many of the
branches of the tubular gonad disappear entirely, but
many others, and particularly the ciliated, non-glandular
portions, persist 7m situ. At the end of this period, when
the animal again enters on Stage I., the parts of the body
formerly occupied by the swollen genital tubules are now
the seat either of a massive syncytial tissue, or of a delicate
reticulum, the difference depending probably on the con-
dition of nutrition obtaiming on the bed from which the
specimen was taken.

We inay now consider the characters presented by the
animal in the various stages referred to more particularly.

SracE I. (Pl. IL., figs. 3, 4, 6).—Eixternally there may
be nothing to indicate that the specimen under examina-
tion has spawned, although in a section, or in a cleared
preparation, the difference between this stage and the
preceding one is striking. The sex of the animal is
determinable only with some difficulty, by the presence of
stray masses of ova or spermatozoa, which have failed to be
extruded. Where the germinal epithelium can be recog-
nized, it is not very different in male and female. The
area in a section of the mantle now occupied by the
tubules of the gonads is so greatly reduced that, on a
superficial examination, it might be thought that the
latter had completely disappeared. But more careful
scrutiny reveals the presence of many tubules in a col-
lapsed condition (Pl. I1., figs. 8, 4, twb. ov.), the walls
pressed against each other by the pressure of the reticular
tissue. It is, however, only the larger tubules which so
persist ; the finer branches have been absorbed or broken
down in some way.

The space occupied in the ripe Mussel by the gonads is
now filled up by a large celled parenchymatous tissue

44

(Pl. II., fig. 3, ret.) of peculiar characters. This tissue
which, in the ripe Mussel, was represented by a few
delicate fibres, lying wedged in between the tubules, has
now increased greatly in mass, and occupies almost the
whole thickness of the mantle lobes. It does not, like the
corresponding tissue in the Oyster, consist of cubical or
polygonal cells, with clear bodies arranged to form a
coarse network, the bars of which are composed of distinct
cells, but is rather a syncytium, in which cell outlines
cannot be readily distinguished. The surfaces of attach-
ment of the parts to each other are large, but occasionally
delicate fibrous connecting strands may be found. The
cells are multinucleated, an isolated patch may be seen to
possess several nuclei, but no trace of cell walls. The cell
substance stains deeply with eosin. In moderately thick
sections it appears to be dotted over with small, light,
circular areas, but in thinner parts these are seen to be
vacuoles, possibly filled with a substance which does not
readily stain.

The epidermis (Pl. I1., fig. 8, ep. ext.) of the mantle is
formed of a single layer of cells, with large nuclei and
rather indistinct cell walls. On the internal face of the
mantle this epidermis is ciliated. Beneath it there may
be a layer of longitudinal fibrous tissue, but this is not
constantly present. The reticular tissue of the interior
of the mantle is connected with the epidermal layer by
delicate strands, but occasionally large rounded masses
may be seen lying beneath the former. The epidermis
contains eosinophilous cells forming projections internally
and externally. Blood vessels are abundant along the
external face of the mantle (Pl. IIL., fig. 4, bl. sp.). The
larger of these have a fine endothelial lining the structure
of which is difficult to make out. ‘These, as well as the
interspaces of the reticulum beneath the epidermis, may
be crowded with blood corpuscles.

45

The characteristic of this stage is the enormous develop-
ment of this reticulum, which has all the characters of a
tissue produced by the rapid multiplication of nuclei,
without a corresponding differentiation of cell bodies and
walls. In some sections the space occupied by it is so great,
that the appearance is almost that of a homogeneous
nucleated matrix, perforated in many places.

The description given of this stage applies to the
Mussels obtained from the Wallasey and Morecambe
beds, the Roosebeck outer scar, and from those in the
Barrow Channel. Mussels obtained from the Roosebeck
inner scar have different characters in respect of the
condition of the gonads at this stage, and these are
probably correlated with the different conditions of nutri-
tion obtaining on this bed, which have been commented
on in a former Report.* Spawning in these Mussels
leaves the mantle lobes delicate and transparent. The
reticular tissue has the form of an attenuated network of
large mesh, and, in consequence of this, the remains of
the genital tubules are more easily seen, and a resting
stage is not so conspicuous.

Stace II. (Pl. I1., fig. 7; Pl. L., fig. 2).—The period
of rest which follows immediately after spawning, and
which is represented by Stage I., is of short duration, and
as early as the beginning of September the developing
gonads may be seen in the mantle. There can be no
doubt that, after spawning, many of the tubules break
down and disappear, but it seems quite clear that the
more important branches persist in the mantle through
the period represented by Stage I. Towards the end of
September ripening has commenced, and_proliferatiom
from the germinal epithelium is in progress. At any

* A. Scott. ‘‘ Mussels and Mussel Beds.” Lance, Sea-Fish. Laby, Report
for 1895, pp. 21—32,

46

stage this process is further advanced in the male than in
the female. During September the tubules are of small
diameter, no greater than that of an interspace in the
reticulum. The structure of the cells composing the
germinal epithelium of this stage is nearly similar in both
sexes. An irregular layer of cells is supported on a base-
ment membrane. The female germinal epithelium (Pl. IT.,
fig. 7, ep. ger.) can be distinguished by the large nuclei of
the cells. At this stage it consists of few cells, and the
first few ova separated off fill the lumen of the tubule.
Proliferation is a more rapid process in the male, and in
a short time the tubules are filled with cells, resulting
from the divisions in the germinal epithelium. Most of
these cells become spermatoblasts, and divide subsequently
to form the spermatozoa, but many of those separated off
at this stage become modified to form the system of sup-
porting filaments so conspicuous at later stages (Pl. IL.,
fig. 5, sup. fil.) The cell migrates towards the centre of
the tubule, becomes slightly elongated in a radial direc-
tion, and its outer end becomes frayed out into one or
more delicate filaments, which seem to retain some con-
nection with the wall of the tubule. The nucleus and
cell body then break down and disappear, and a group of
filaments is left arranged radially in the lumen of the
tubule, on which the spermatozoa formed at this time,
and subsequently are arranged in rows. In the smaller
and terminal portions of the tubules the whole epithelium
takes part in the formation of spermatozoa or ova, accord-
ing to the sex, but in the larger branches, and this is the
more common appearance in the sections, the tubule
possesses a longitudival strip of columnar epithelium,
cells with clear cell bodies, and with long cilia projecting
into the lumen. ‘This strip of ciliated epithelium extends
round the tubule for about one-fourth or less of the cir-

ea

47

cumference. It is more common in the male gonad, but
is present also in the female.

The parenchymatous tissue between the tubules has
much the same characters as in Stage I., but it is now
arranged in a more even system of bars and is not so
massive. Certain appearances, such as the difficulty of
distinguishing the limits of the growing tubules in relation
to the surrounding reticulum, seem to indicate that the
gonads grow at the expense of this tissue, or at least
absorb it during the process of growth. It was, however,
impossible to demonstrate this with certainty in the pre-
parations studied.

Ripening of the gonads proceeds slowly from now on to
the end of January, and consists of a gradual increase in
the width of the already-existing tubules and of the for-
mation of side twigs. The contents of the tubules slowly
increases, and it must be understood that from November
onwards there is an increasing number of free and
apparently mature ova and spermatozoa in the gonads.
The fact that moving spermatozoa may be obtained from
the mantle at the end of the year has been already referred
to. Whether the genital products present in the gonads
at the end of the year are fully mature and are capable of
development is uncertain, but if so, the presence of free-
swimming larve in the sea about this time may be easily
explained, since ova and spermatozoa may be swept out of
the lower partially ciliated tubules, and fertilization may
result. But a certain time may also be required for the
complete maturation of the genital products after their
proliferation from the germinal epithelium.

Srace III. (Pl. IL., figs. 1, 2)—About this time the
mantle lobes have attained the maximum of thickness, and
the gonads have invaded every part of the body un-
occupied by the other organs, even the outer wall of the

48

pericardial sac being overspread by them. The whole
space between the internal and external faces of the
mantle is now filled up by the gonads, and the tubules of
the latter are filled, in female and male, with a dense mass
of ova and spermatozoa respectively. The spermatozoa
are arranged in rows on the radial-supporting filaments
already mentioned, and the mutual pressure of the ova
against each other in slightly later stages than this gives
them a polyhedral form. The germinal epithelium is still
undergoing proliferation, but this is not so active now.
Where, in the male, the walls of the tubules are closely
compressed together, the basement membrane can be seen
as a thin, homogeneous line, on either side of which is an
irregular row of large, rounded cells, with clear cell bodies
and conspicuous nuclei, and internal to this the tubule is
filled with a mass of radially-arranged rows of spermatozoa.
The conspicuous reticular tissue present in earlier stages
is reduced to the merest trace, and is present mostly at
the angles formed at the junction of several tubules. It
stains less intensely with eosin, but the peculiar vacuo-
lated appearance already referred to still exists. Here
and there it is present as rounded masses possessing single
nuclei, but it is mostly fibrous.

As in the male, the germinal epithelium still exists in
the female, and ova are still being separated off. Most of
the eggs lie freely in the cavity of the tubule in contact
with each other, but some are still attached to the wall by
a short stalk. In some parts the wall of the tubule seems
to consist of the basement membrane only.

Stace IV. (Pl. I., fig. 5).—From April onwards there
is apparently little change in the appearance of the gonads.
The maximum development, as indicated by the increase
in mass of the tubules, the numbers of ova and sperma-
tozoa liberated from the germinal epithelium, and the

49

reduction of the other tissues in the mantle, was obtained
in the specimens taken during April. Some taken later
were, indeed, less advanced, but generally this seems to be
the time at which proliferation from the walls of the
tubules mainly ceases. In July, Mussels were taken in
which spawning was in progress. In these the females
had almost completely spawned, and in the males the
gonads had undergone a great reduction in mass. A few
stray eggs lay scattered over the section situated in tubules
of greatly reduced diameter, one egg being present, as a
rule, in the cross section of the tubule, and generally
nearly filling it. Many tubules were completely empty.
The germinal epithelium persisted in some of these tubules
as one or more layers of small, rounded cells, but more
often its structure was difficult to make out.

The reticulum so apparent in Stage I. is already formed,
but in structure is more spongy than in the stage following
the complete extrusion of the ova, and the spaces between
the bars are about equal to those occupied by the tissue
itself. These interspaces have, Im many cases, a Cir-
cular outline, and probably represent the former situation
of ovarian tubules. The general histological characters of
the tissue are similar to those described in Stage I., except
that the vacuolated appearance is not so apparent.

The most striking changes have occurred in the male.
In some of the specimens taken at this time extrusion of
the spermatozoa has been almost completely effected, but
in others the animal had been taken in the act (Pl. IL.,
fig. 5). Here the sperm tubules have been greatly con-
tracted in cross area, and the mass of spermatozoa (PI. IL.,
fig. 5) within the tubule has become correspondingly
denser. The reticulum has increased enormously, and as
it seems difficult to derive this tissue from the exceedingly
fine fibrous network present in the last stage, it is possible

50

that it has spread into the spaces surrounding the tubules
of the gonad from other parts of the body. Round each
tubule this reticulum forms a dense mass, with few or no
interspaces, and its syncytial character is here strongly
suggested. The nuclei are not so evident as at a later
stage. Within the tubule itself the linear arrangement of
the spermatozoa is very striking, but instead of being
directed towards the centre these rows point towards that
part of the wall lined with the strip of ciliated epithelium
already described (Pl. II., fig. 5, ep. cal.). Often a blood
space (b/. sp.) is situated beneath this epithelium; over
the cilia and within the tubule is a space free from sper-
matozoa. The wall of the tubule has become indistinct
from the mass of spermatozoa which seem to abut directly
on the tissue of the reticulum (et.) surrounding the tubule.
The whole arrangement strikingly suggests the exercise of
pressure on the tubule by the rapidly developing reticulum
and the removal of the genital products brought into close
contact with the ciliated strips of the tubules. The lower
conducting portions of the gonads are entirely lined with
ciliated epithelium, and once here the genital products
must be speedily removed.

Briefly summarised then, the history of the yearly change
in the reproductive organs of the Mussel is as follows:—
(1) There is a short period of rest following spawning, and
occupying some part of August and September, during
which the space in the body of the animal formerly
occupied by the gonads is largely filled up by a large-celled
reticulum. ‘This is followed by (2) the reformation of the
germinal epithelium and a slow proliferation of ova and
spermatozoa, lasting for the rest of the year. During this
period the gonads increase greatly in mass, and invade the
mantle and other parts of the body, displacing the reticu-
lum formed during spawning. Succeeding this is a period

51

(3) of active formation of the genital products, ending late
in the spring, after which ova and spermatozoa are formed
less rapidly. A slow emission of these now goes on until
in the summer, about June or July, the maximum spawn-
ing period of the Mussel occurs.

It is unlikely that any great proportion of the larve
found during the course of the year are spawned otherwise
than at the maximum spawning period in the summer
months. We have seen that it is probable that a certain
proportion are spawned during the first half of the year,
but that these probably result from the spawning of
isolated individuals or from the slow emission of ova and
spermatozoa prior to the act of spawning proper, and the
fact that this occurs does not materially affect the general
statement that the Mussel spawns in the summer. For
the year 1898 we have fixed this spawning period as
having occurred during July, but it is probable that it
is variable, and as the Committee’s bye-law fixes the
months of May, June, July, and August as those during
which it is illegal to take Mussels from the beds in the
district, it is very probable that, notwithstanding some
considerable variation in the occurrence of this period, it
will always fall within that close time. Probably spawning
is very generally over before August begins, but of this
further evidence is wanted.

EXPLANATION OF THE PLATES.
PuateE I.

Fig. 1. Dissection of an adult Mussel to show the external
opening of the gonad. ‘The right valve has been
removed, and the right gill and mantle lobe cut
away close to the junction with the visceral mass
and reflected upwards. Full size. o—f indicates
the plane of the section shown in fig. 2.

Fig. 2.

Hig, I,

Fig. 2.

Fig. 3.

Fig. 4.

y

5

Complete transverse section through the body of
an adult female Mussel passing through the peri-
cardial cavity just posterior to the heart. Note the
presence of ovarian tubules in every part of the
section, the stage of development being the same
both in mantle lobes and in visceral mass. The
specimen was taken about the end of September,
and proliferation of ova from the germinal
epithelium is beginning, but the diameter of the
tubules is still very small. > 5 diameters.

Prare UL.

Transverse section of mantle of nearly ripe female
Mussel from Roosebeck outer scar, taken during
March. The mantle is nearly filled with the
tubules of the gonad containing many free ova.
The germinal epithelium is still undergoing
proliferation. x 40 diameters.

Transverse section of mantle of nearly ripe male
Mussel from Roosebeck outer scar. (March).
The mantle is filled with sperm tubules. x 40
diam.

Transverse section of mantle of female spent
Mussel from New Brighton beds, taken during
August. The tubules of the gonads have in many
cases broken down. T'wo are shown in the section,
one containing an egg which has not been
extruded during spawning. Note the great
development of the reticulum. %X 200 diam.
Transverse section of mantle of spent female
Mussel from the beds in the Barrow Channel
(August). A blood space lying immediately
beneath the epidermis is shown, beneath which
are two collapsed ovarian tubules. Note that

53

each is lined partly by ciliated and partly by
germinal epithelium. X 200 diam.

Fig. 5. Transverse section of mantle of spawning male
Mussel (New Brighton beds, July). A sperm
tubule is shown, partly lined with ciliated
epithelium. Note the great development of the
reticular tissue. XX 230 diam.

Fig. 6. Transverse section of mantle of completely spent
female Mussel (Barrow Channel, August). x 35
diam.

Fig. 7. Portion of transverse section of mantle of female
Mussel (Barrow Channel, September 30). A
developing ovarian tubule is shown. Actual
size=0°568 mm. Note the proliferating germinal
epithelium, and the ciliated strip of wall. x 660
diam.

REFERENCE LETTERS.

abd., abdomen; add. a., anterior adductor muscle of
the shell; add. p., posterior adductor muscle of the shell ;
br. R., right gill; br. L., left gill; 61. sp., blood space; cr.
st., crystalline style; ep. ger., germinal epithelium; ep.
cul., ciliated epithelium; ep. ext., external epidermis
of mantle; znt., intestine; Mn. L., left mantle lobe; Mn.
R., right mantle lobe; per., pericardial cavity; per. gld.,
pericardial gland and auricle; pp. gen., right genital
papilla; pa. d., right dorsal labial palp; pa. v., right ventral
labial palp; ren., renal organ; ret., reticulum of mantle;
ret. bys., retractor muscles of the byssus; ret. bys. n.,
insertion of retractor of the byssus into the shell; rect.,
rectum; sup. fil., supporting filaments in sperm tubule ;
st., tubular portion of the stomach; sp., rows of mature
spermatozoa; tub. ov., ovarian tubule; visc. nv., visceral
nerve cord.

54

On SzA-FisH HATCHING.
(W. A. HERDMAN.)

In the Twelfth Annual Report of the Sea-Fisheries
Inspectors for England and Wales (1898), under the mar-
ginal heading ‘‘ Sea-Fish Hatcheries”’ (p. 29), Mr. C. H.
Fryer enters upon such a severe and detailed criticism
of the results attained that it cannot be regarded as
other than an attack upon the practice of artificial
hatching of sea-fish eggs as developed in America. It is
fair to say that it is the results of the hatcheries in America
that are attacked, as, although Scotland and Norway are
mentioned, these countries are treated very briefly, and no
conclusions are drawn from the few statistics quoted. The
greater part of the discussion deals, then, with Canada,
Newfoundland, and especially the United States. I gather
that Mr. Fryer has not himself visited the hatcheries he
discusses, and that his information is entirely derived from
the published annual reports—an unexceptional source, so
far as 1t goes, but one which may usefully be supplemented
by personal impressions and conversation with those
engaged in the work.

_ I regard Mr. Fryer’s paragraphs as a most useful state-
ment, drawing attention to the present position of the
hatching question from the critic’s point of view, counter-
acting any exaggerated opinions that may have been
expressed, and impressions that may have been enter-
tained, in regard to the immediate and enormous results
to be obtained from artificial operations, but requiring
some criticism, some modification, and some additions
before it can be accepted as a wholly satisfactory state-
ment of the matter. For although Mr. Fryer seems rather
carefully to avoid drawing any formal conclusions, he

55

certainly, consciously or unconsciously, by his manipula-
tion of the statistics, conveys to the reader an impression
entirely adverse to sea-fish hatching. And this impression
is, I believe, derived mainly from statements in regard to
the difficulty and not in regard to the efficacy of the
operations.

Mr. Fryer’s remarks are largely directed towards
removing impressions that may prevail as to the sim-
plicity of artificial hatching; and here we, in common
with all who have taken any part in such work, readily
concur in the general conclusion that the work 1s suffi-
ciently difficult and troublesome, if pains be taken to
attain success. I do not think that amongst those in this
country who have had to obtain in mid-winter or early
spring the spawning fish or the fertilized spawn, who have
had to filter the sea-water and watch day and night
its purity, salinity and temperature, who have jealously
guarded the embryos from danger and have tried to obtain
suitable foods for the larve, there can ever have been any
fond delusions as to the simplicity of the business. The
work is hard, there are many difficulties, the operation is
a delicate one, requiring constant and intelligent attention ;
but all that need not deter. Given suitable conditions and
the right men, and the work can be successfully carried out.

While agreeing with Mr. Fryer that ‘ simplicity”
delusion, I must demur against an impression which his
pages are liable to convey. It must be remembered that
the harrowing descriptions on pp. 36 and 37 of fish perish-
ing in the nets owing to the heavy storms, and freezing in
the boats and on the cars, and of embryos killed by the
million in the hatching boxes on account of the intense
cold, refer to conditions on the coast of North America,
and do not apply to our seas. These exceptional difficulties

Is a

either do not exist or are only present in quite a minor

56

degree for very short periods in our warmer and more pro-
tected coastal waters.

Turning now to the question of efficacy, we meet with this
difficulty—Mr. Fryer apparently does not accept the turning
out of millions of healthy young fry into the sea as a proof
of successful hatching operations. He seems to demand
a demonstration that the number of adult fish in the neigh-
bourhood has increased, without taking into account the
fishing operations that may be going on. In asking for
immediate proof that the fry live to become adult fish the
opponents of fish hatching are taking up what may seem
a very secure, but is, I consider, a very unreasonable position.
So many factors enter into the case that it is almost impos-
sible to devise a crucial experiment, or give immediate
scientific proof of a result. The demand may possibly be
satisfied in any locality next year, or the answer may be
delayed for 10 years or for longer; and yet the fisheries may
all the time be largely benefitted by—may owe their con-
tinued existence to—the artificially hatched fry added to
the population of the sea. And this may be the case even
if not a single individual out of the millions of fry set free
ever lives to become adult.

I do not think it at all probable that such unfavour-
able conditions ever exist, but I wish to point out that
even in such an extreme case the expenditure on land
and the sacrifice of life of the fry in the sea will not
have been in vain. If we try to realise the struggle
for existence in the sea, the toll that is taken at every
period of life from the egg to the adult, but which is excep-
tionally heavy in young stages, a moment’s reflection will
show that the addition in any natural hatching area of
some millions of young fish must distribute the danger of
being caught by an enemy over a much larger number
of individuals and so give to each a greater chance of

57

escape. And if—as may be the case, we do not know—
the naturally hatched fry are hardier or more active, then
they will be the more likely to survive the perils, and will
owe their continued existence and their appearance in due
course somewhere as marketable fish to the presence for a
time in the sea of their brethren from the hatchery.

I shall come now from these general considerations—
to which Mr. Fryer does not seem to give enough atten-
tion—to some of the detailed statements in his report as
to the results of hatching, and upon some aspects of
which, such as the mortality in captivity, in my opinion
he lays far too much stress. I cannot now go into every
point upon which we may differ more or less, but shall
take up his treatment of the United States statistics, as
they are, perhaps, the most important, and the ones
discussed at greatest length.

After quoting (p. 39) the statistics of the Cod operations
at the Wood’s Holl Hatchery, he admits that the figures
show “successful results.”” He then attempts to upset
this conclusion by arguing that in computing the number
of eggs and fry derived from a parent fish we should take
into account not merely the actual parents, the fish that
spawned, but also all the others that were penned up in
the spawning pond. This is surely a most unjustifiable
procedure. What reason is there to think that these
non-spawning fish would have spawned if left in the sea ?
In fact, if the object is to make a comparison between
natural and artificial conditions, surely from what we
know of life in the sea it is highly probable that some of
the fish that spawned in captivity would, if left at large,
have been destroyed by man, or their natural enemies,
before they became parents. Consequently, I consider
that the Superintendent of the Hatchery was perfectly
right in considering as parent fish only those from which

58

spawn was obtained, and I should remove from Mr.
Fryer’s table, at the foot of p. 39, the three columns
headed ‘‘ penned up,” as giving no additional useful
information.

It is also unfair to compare an average obtained by
including all the fish penned up, many of which did not
breed, with the total number of ova calculated as being
present in one selected large breeder. The comparison
can only be fairly made with the eggs in a similar number
of Cod, of the same size as those in captivity, chosen at
random from the sea. Even in that case the comparison
would only indicate whether there was a diminution in
the amount of spawn produced per captive fish. There
probably is such a diminution; but, on the other hand, it
is certain that a large number of possible spawners in the
sea are killed by man and other enemies before or during
the spawning season.

Then, again, in making a further comparison between
artificial hatching and the “processes of nature,” it is not
right to substitute (p. 41) the number of eggs calculated
to be present in the body of a parent for the actual
number of eggs treated in the hatchery. This method of
‘counting the chickens”’ not only before they are hatched
but even before the eggs are laid, is an ingenious method
of making the proportion of fry produced in the hatchery
seem very small; but I think the Superintendent’s figure,
54°6 per cent. of fry to ova, will commend itself to most
people as the correct calculation on the common-sense
basis of so many ova supplied and so many fry produced.
What would have happened to, say, 100 of the hatchery
spawners if they had been left in the sea, no one can say.
How many of them would live to spawn and how much
spawn they would produce we do not know. The per-
centage of fry to parent fish in the hatchery may, under

&

59

some circumstances, be small, but it may be smaller still in
a state of nature.

It is curious how My. Fryer entirely ignores that side
of the question—the destruction in nature. He makes
a great point of the mortality in artificial operations,
and virtually assumes that in the sea every egg in
every fish will be spawned and will then hatch out.
This is entirely contrary to the experience of naturalists.
In addition to the destruction of the parents in the sea,
and the risks of non-fertilisation, and of being cast ashore,
we find at the spawning season nearly everything that has
a mouth (such as Meduse, Sagitta, Copepoda, and many
fishes) feeding upon fish eggs. One of the strongest
arguments in favour of the hatchery is that it protects the
embryos from their natural enemies. Judging from the
apparently stationary condition of the fish population in
the sea, from the enormous numbers of eggs produced, and
from our observations on the contents of fishes’ stomachs,
it is obvious that there must be a very great destruction of
eggs, and embryos and larve under natural conditions—
probably much greater than anything known in artificial
operations.

Moreover, in talking (as many do) of the small scale of
man’s hatching work compared with what takes place in
the sea, we do not sufficiently realise the meaning of what
is called ‘‘the balance of nature.’ Millions of millions
of young are produced and these same millions of millions
are destroyed by natural causes, with the result that the
species remains fairly constant. If now man disturbs the
balance by catching some thousands of the adult fish in
a district, he is only equalizing matters and endeavouring
to minimise his destructive effect when he adds to that
sea-area some millions of artificially hatched fry. And
(theoretically at least—probably practically also, for correct

60

theory and perfect practice must be in accord) he is the
better equalizer of the disturbed balance when he uses for
the hatchery the eggs of fish which would not have
spawned in a state of nature—that he can do by obtaining
ripe spawn from the fish trawled for market at the spawn-
ing season. This plan has been adopted in some hatcheries;
and in our own experiments at Port Erin and at the Piel
hatchery. It is the least expensive method of getting
spawn, but it is open to several difficulties and objections.
The other method 1s to collect the parent fish beforehand
and keep them in ponds until they spawn. It is the
method adopted in Norway and to a large extent in the
United States, and which Mr. Fryer has tried to show
results in a comparatively small number of fry per fish
used.

I shall not pursue the matter further. There is no need
for me to defend or expound the methods and statistics of
the United States Fish Commission. Their own officials
are very well able to answer for themselves, and very
probably they will do so—if they think it worth while.*

I have merely gone into some of the questions raised in
Mr. Fryer’s article because it seemed to me that he was
modifying the statistics in an unjustifiable manner, and
drawing conclusions with which I could not agree, and
which might have some bearing upon our procedure in this

* It may be well before leaving this part of the subject to point out that in
the appendix (a Manual of Fish-Culture, based on the methods of the United
States Commission of Fish and Fisheries, Washington, 1898) to their last
published report, which appeared only a few months ago, the United States
authorities remark in regard to their artificial propagation of the Cod:—‘‘The
unmistakable economic results which have attended these efforts warrant all
the time and money devoted to them and justify the greatest possible
expansion of the work.”” I have also more recent letters from the Com-

missioner and the Naturalists on his Staff making detailed statements to the
same effect.

61

country. We are not, however, in our work here so much
concerned with the actual details and difficulties of the
American work which Mr. Fryer criticises, as with those
general biological principles which I have emphasised
above—such as the destruction of young under natural
conditions in the sea, and the duty of man if he disturbs
the balance of nature in a locality to do what he can to
equalize matters by helping in the production and protec-
tion of the young.

With Mr. Fryer’s remark (foot of p. 41) as to breeding
from the larger and more vigorous parents I am in cordial
agreement. If aquiculture has been long delayed as a
scientific industry, it has as a consequence this advantage,
that it can adopt at once principles and practices evolved
eradually in the long history of agriculture and stock-
raising. It labours, however, under the obvious disadvan-
tage that so much of the result of our labour passes at
once beyond our ken. We cannot control the fish through-
out their life-history, we cannot yet take stock of the
population of our seas. This introduces such an element
of uncertainty into the problem, that, although I think we
have good reason to be encouraged and to continue the
work vigorously in a hopeful spirit and with an open
mind, still I for one would not go so far as to say (as some
have done) that marine fish-hatching had passed beyond
the experimental stage; and I may refer in this connection
to the somewhat fuller statement on the subject I made in
last year’s report,* and to my discussion there of the con-
ditions of a crucial experiment for the purpose of testing
the results of adding artificially hatched fry to the popula-
tion of a circumscribed sea-area. We await with interest
the result of the Fishery Board for Scotland’s work in

Loch Fyne.
* Report for 1897, pp, 24 and 25,

62

I cannot do better than conclude this section by quoting
a couple of sentences from a letter received during the
year from Professor M‘Intosh, whom we regard as the
pioneer of scientific fisheries work in this country. In
speaking of marine hatcheries, he says:—‘‘ Of course such
institutions are strictly experimental, and it may be some
time before a decisive result is evident. Meanwhile, work
them thoroughly and support them liberally.” I desire to
endorse that opinion.

OYSTERS AND DISEASE.
(W. A. HERDMAN.)

In collaboration with my colleagues, Professor Boyce
(Bacteriologist) and Dr. C. Kohn (Chemist), 1 have been
working at this subject in our laboratories at University
College, Liverpool, for the last three years, and interim
reports upon the progress of the work have appeared in
our three last Fisheries Laboratory Reports. A detailed
paper, giving the full results of the investigation, has
lately been laid before the Royal Society of London, and
the main conclusions of that paper are as follows* :—

“1, Although our primary object was to study the
Oyster under unhealthy conditions, in order to elucidate
its supposed connection with infective disease, we found
it necessary to study in minute detail the histology of
certain parts of the body, especially the yills and mantle
lobes, the alimentary canal and liver. We give figures
and descriptions of these structures in both normal and
abnormal conditions.

“9. We have also worked out the distribution and
probable function of a minute muscle, which we believe

* Quoted from Nature for January 26th, 1899, p. 305.

ee

63

to be the modified representative of the protractor pedis
muscle of some other molluscs.

“3. A diseased condition we found in certain American
Oysters very soon brought us into contact with the vexed
question of the
results we arrived at was that there are several distinct
kinds of greenness in Oysters. Some of them, such as

‘

greening’ of Oysters, and one of the first

the green Marennes Oysters, and those of some rivers on
the Essex coast, are healthy; while others, such as some
Falmouth Oysters, containing copper, and some American
Oysters re-bedded on our coast, and which have the pale
green ‘leucocytosis’ described in our former paper to the
Royal Society, are not in a healthy state.

“4. Some forms of greenness (e.g., the leucocytosis)
are certainly associated with the presence of a greatly
increased amount of copper in the Oyster, while other
forms of greenness (e.g., that of the Marennes Oysters)
have no connection with copper, but depend upon the
presence of a special pigment, ‘ marennin.’

“We are able, in the main, to support Prof. Lankester
in his observations on Marennes Oysters; but we regard
the wandering amoeboid granular cells on the surface of
the gills as leucocytes which have escaped from the blood
spaces, and have probably assumed a phagocytic function.

“5. We see no reason to think that any iron which
may be associated with the marennin in the gills, &c., is
taken in through the surface epithelium of the gill and
palps, but regard it, like the rest of the iron in the body,
as a product of ordinary digestion and absorption in the
alimentary canal and liver.

“6. We do not find that there is any excessive amount
of iron in the green Marennes Oyster compared with the
colourless Oyster, nor do the green parts (gills, palp, &c.)
of the Marennes Oyster contain either absolutely or

64

relatively to the colourless parts (mantle, &c.) more iron
than colourless Oysters. We therefore conclude that
there is no connection between the green colour of the
‘Huitres de Marennes’ and the iron they may contain.

“7, On the other hand, we do find by quantitative
analysis that there is more copper in the green American
Oyster than in the colourless one; and more pro-
portionately in the greener parts than in those that are
less green. We therefore conclude that their green colour
is due to copper. We also find a greater quantity of iron
in those green American Oysters than in the colourless;
but this excess is, proportionately, considerably less than
that of the copper.

‘8. In the Falmouth Oysters, containing an excessive
amount of copper, we find that much of the copper is
certainly mechanically attached to the surface of the body,
and is in a form insoluble in water, probably as a basic
carbonate. In addition to this, however, the Falmouth
Oyster may contain a much larger amount of copper in
its tissues than does the normal colourless Oyster. In
these Falmouth Oysters the cause of the green colour may
be the same as in the green American Oyster.

“9. By treating sections of diseased American Oysters
under the microscope with potassium ferrocyanide and
various other reagents, we find that the copper reactions
correspond in distribution with the green coloration; and
we find, moreover, from these micro-chemical observations
that the copper is situated in the blood-cells or leucocytes,
which are greatly increased in number. ‘This condition
may be described as a green leucocytosis, in which copper
in notable amount is stored up in the leucocytes.

“10. We find that an aqueous solution of pure hema-
toxylin is an extremely delicate test for copper, Just as
Macallum found it to be for iron,

65

“11. Experiments in feeding Oysters with weak solu-
tions of various copper and iron salts gave no definite
results, certainly no clear evidence of any absorption of
the metals accompanied by ‘ greening.’

“12. Although we did not find the Bacillus typhosus
in any Oysters obtained from the sea or from the markets,
yet in our experimental Oysters inoculated with typhoid
we were able to recover the organism from the body of
the Oyster up to the tenth day. We show that the typhoid

bacillus does not increase in the body or in the tissues of

the Oyster, and our figures indicate that the bacilli perish
in the intestine.

“13. Our experiments showed that sea-water was
inimical to the growth of the typhoid bacilh. Although
their presence was demonstrated in one case on the
twenty-first day after addition to the water, still there
appeared to be no initial or subsequent multiplication of
the bacilli.

“14. In our experiments in washing infected Oysters
in a stream of clean sea-water the results were definite
and uniform; there was a great diminution or total dis-
appearance of the typhoid bacilli in from one to seven
days.

“15. The colon group of bacilli is frequently found in
shell-fish as sold in towns, and especially in the Oyster ;
but we have no evidence that it occurs in mollusca living
in pure sea-water. The natural inference that the presence
of the colon bacillus invariably indicates sewage con-
tamination must, however, not be considered established
without further investigation.

“16. The colon group may be separated into two
divisions: (1) those giving the typical reactions of the
colon bacillus, and (2) those giving corresponding negative
reactions, and so approaching the typhoid type; but in

66

no case was an organism giving all the reactions of the
B. typhosus isolated. It ought to be remembered, how-
ever, that our samples of Oysters, although of various
kinds and from different sources, were in no case, so far
as we are aware, derived from a bed known to be con-
taminated or suspected of typhoid.

‘““17. We have shown also the frequent occurrence, in
various shell-fish from the shops, of anaérobic spore-
bearing bacilli giving the characteristics of the B.
enteritidis sporogenes recently described by Klein.

“18. Consequently, as the result of our investigations,
and the consideration of much evidence, both from the
Oyster-growers’ and the public health officers’ point of
view, we beg to recommend—

‘““(a) That the necessary steps should be taken to
induce the Oyster trade to remove any possible
suspicion of sewage contamination from the beds and
layings from which Oysters are supplied to the
market. This could obviously be effected in one of
two ways, either (1) by restrictive legislation and the
licensing of beds only after due inspection by the
officials of a Government Department, or (2) by the
formation of an association amongst the Oyster-
erowers and dealers themselves, which should provide
for the due periodic examination of the grounds,

stores, and stock by independent properly qualified —

inspectors. Scientific assistance and advice given
by such independent inspectors would go far to
improve the condition of the Oyster beds and layings,
to re-assure the public, and to elevate the Oyster
industry to the important position which it should
occupy.

““(6) Oysters imported from abroad (Holland,

France, or America) should be consigned to a member

67

of the ‘Oyster Association,’ who should be compelled by
the regulations to have his foreign Oysters as carefully
inspected and certified as those from his home layings.
A large proportion of the imported Oysters are,
however, deposited in our waters for such a period
before going to market that the fact of their having
originally come from abroad may be ignored. If this
period of quarantine were imposed upon all foreign
Oysters a great part of the difficulty as to inspection
and certification would be removed.

“(c) The grounds from which Mussels, Cockles,
Periwinkles are gathered should be _ periodically
examined by scientific inspectors in the same manner
as the Oyster beds. The duty of providing for this
inspection might well, we suggest, be assumed by the
various Sea-Fisheries Committees around the coast.”’

NoTE ON OCCURRENCE OF IRON AND COPPER IN OYSTERS.*
By Cuaruzs A. Koun, B.Sc., Ph.D.

‘The investigations of Professors Herdman and Boyce
on the life conditions of Oysters, which have been in
progress since 1895, have pointed to the desirability of
ascertaining the quantities of iron and of copper they may
contain under either normal or abnormal conditions.

‘Two points of interest have arisen in this connection.
In the first place the relation of iron to the greenness of
the healthy French Oyster (Huitre de Marennes); and
secondly, the extent to which copper is responsible for the
pale green colour of American and other Oysters, a
diseased condition accompanied by a leucocytosis dis-
covered and especially studied by Herdman and Boyce.
The presence of minute quantities of copper and of iron

* Quoted from Report of Oyster Committee to Brit. Assoc., 1898.

68

as normal constituents of all Oysters has been shown by
the analytical data obtained.

‘The results recorded have been made at Professor
Herdman’s request, and have proceeded side by side
with his investigations. Now that these are completed,
a summary of the work from a more purely chemical
standpoint may be of interest, especially since the occur-
rence of these metals—copper and iron—either from the
point of view of the origin of colouration or the cause of
poisoning has from time to time been the subject of
discussion.

‘The Analytical Method Employed.—Electrolytic
methods of analysis were adopted both for the determin-
ation of iron and copper: these methods, I have already
shown,* possess marked advantages for the estimation of
minute quantities of metal, especially if derived from
organic matter, for they are quite free from any prejudicial
influences traces of organic matter may exert, such
as arise when volumetric or colorimetric methods are
employed. In each determination the bodies or gills only
of six or more Oysters were carefully washed, dried
between filter paper to remove as much adherent moisture
as possible, and then carefully dried in porcelain dishes in
the air bath at 100°C. When this drying was as com-
plete as possible, the Oysters were heated in the air bath
until thoroughly carbonised, the carbon carefully burnt off
over the free flame, and the residue finally ignited in a
porcelain crucible. Special care was taken to exclude
dust during both the drying and the ignition. The ash
was then thoroughly extracted with a mixture of 25 c.c.
hydrochloric acid and 25 c.c. sulphuric acid (1:2) on the
water bath, and the resulting solution filtered and

‘Brit. Assoc. Rep., 1893, p. 726,

69

concentrated. The residue was free from both copper
and iron. The acid solution obtained was electrolysed
for copper with the usual precautions, a spiral of fine
platinum wire weighing about 5 grme. being employed as
the cathode. The iron was determined in the residual
’ solution, after neutralisation with ammonium hydrate, &c.,
acidifying with a few drops of oxalic acid solution, and
boiling with ammonium oxalate: 4 grme. of the oxalate
were added in each case, the precipitated calcium oxalate
(which is quite free from iron) filtered off and thoroughly
washed and the resulting solution electrolysed, the metallic
iron being also deposited on a spiral of platinum wire. A
blank experiment with all the reagents employed was
made, and the amount of metal found (0°002 grme. iron)
deducted in each case. Also the deposited metal, both
iron and copper, was dissolved off the electrode by acid,
the solution obtained tested by the ordinary reagents and
the spiral re-weighed, as a check upon the determinations,
since the quantities found were extremely small.

‘The Green Colour of French Oysters, ‘‘ Huitres de
Marennes,” and the Presence of Iron in Oysters.—The early
observations of Dumas (1841) and of Berthelot (1855)
showed that the green colour of ‘‘ Huitres de Marennes”’ is
not due to chlorophyll, and that although every Oyster
contains a certain very small amount of copper in its
blood in the form of ‘‘ hemocyanin,”
Fredericq, the green colour of the French cultivated
Oyster is not due to this metal. Ray Lankester* in 1886
confirmed the latter statement, and states in his investi-
gation on the histological condition of the colour that

as determined by

there is neither copper nor iron in the refractory blue
pigment ‘‘marennin’’ of the coloured portions of the

* Quart. Journ. Micros. Sci., 1886, 26, 71.

70

Oyster. Berthelot, however, suggested that the green
colour was due to iron, and more recently Chatin and
Muntzt have extended and corroborated this statement.

‘From their analytical results these observers conclude
that both the green and the brown colourations of various
types of French Oysters are due to the presence of |
iron, and that the depth of colour bears a close pro-
portion to the quantity of iron contained. The coloura-
tions are chiefly apparent in the gills, but extend also to
the labial palps and parts of the alimentary canal. Chatin
and Muntz base their conclusions in the first place upon
the fact that they find considerably more iron in the gills
than the rest of the body of green Oysters; and secondly,
upon the occurrence of a larger quantity of iron in the
gills of green than of white Oysters.

‘Appended are some of their results, to which I have
added a column, showing the ratio of the iron in the body,
minus gills, to that contained in the gills.

Iron per 100 parts of
dried organic matter. ,
Oyster. Colour. Ban L .
I. Gills, | PE, Rest a
F * | of body.
Cancale... ...| White Ran ...| 0°0379 0°0241 1°57
Arcachon ... ae| baleereene.. | 0°0605 0:0357 1°69
Marennes ... ...| Very green... ...| 0°0702 0°0318 1°21
Cancale... ...| Brown green ...| 070804 00476 1°69
Sables d’Olonnes ...| Very dark brown | 0°0833 0°0436 1°91
green ah

‘The relative proportion of iron in the gills hardly bears
out the conclusions arrived at; it is the same in pale-
green and brown-green Oysters, and in both, but little
greater than in the white. On the other hand, the total

+ Compt. Rend., 1892, 118, 17 and 56.

71

iron, both in the gills and in the rest of the body,
shows a marked increase, apparently corresponding to the
depth of the colouration. The iron was determined in
these experiments by potassium permanganate, but the
absolute quantities of metal found are not stated. The
calculation of the results per 100 parts of dried organic
matter is apt to be misleading. In my own experiments
it was not found possible to get anything approaching
constant weights in this way, and the results are entirely
out of accord with those of Chatin and Muntz.

‘The following table gives the quantities of iron found in
French as compared with American Oysters, three pairs
of gills being analysed in each case.

‘These figures show conclusively that there is more and
not less iron in the gills of the white American Oysters

than in the French, and this irrespective of the basis on

which the result is calculated. The ash is undoubtedly
the most reliable factor to calculate on, provided the
Oysters are carefully washed before drying, which was
always done: the result per pair of gills (or Oyster) is
most in accord with this, and has the advantage of being
an easy and in many respects useful basis.

Huitres
—— | de American.
Marennes. |

Gross body weight, after drying between

filter paper ... .| 3°8 grins. | 6°5 ~ grms
Weight dried at 100° C. for six hours 0°52 Pr 150 20ers
Weight of ash ... ; ...| 0°0940 ,, 0°1140 ,,
Weight of Iron found . 0'0003_=C*#, 0:0008 ,,
Ratio of Iron found :—
(1) Calculated per pair of gills wee ss 1 to. 2-7
(2) e on gross body weight.. 1 to 1°56
(3) i at weight at 100° C. 1 to 1°36
(4) oy on ash ... : 1 to 22

72

‘The relative quantities of iron present in the gills as
compared with the rest of the body were next determined
in French, Dutch, and American Oysters. Six Oysters,
or the gills of six Oysters, were analysed in each case
with the following results :-—

Weight of Iron found in

} mgrme.
Six Oysters.

French. Dutch. |American.

Gills ... : fal 06 0°4 2°3
Bodies minus gills ... 1'2 1°5 1g
Weight of ash of gills... ee .. | 0°1880 0°0217 0°0294
5 », Of bodies minus gills _...}_ 0°5980 0°1125 0°1240
% Irononash. Gills... ah eo OBY 1°85 7°82
A . Bodies minus gills _...|_ 0°20 1°33 1:37
Ratio of Iron in gills to Iron in rest of
body.
Calculated per Oyster Sg al pelos thee Ce: 1:0°74
"a on ash ... wife = Rocle eae J Los 42d | Sysieee

‘From these figures it is evident that the gills of the
French Oysters do not contain an excessive quantity of
iron such as might account for their colour. Calculated
per Oyster the gills contain less iron than the rest of the
body, except in the American Oyster; calculated as a
percentage on the ash the reverse is the case. ‘The
proportionate quantity of iron in the gills as compared
with the rest of the body is somewhat greater in the

French Oysters than in the Dutch, but much less than in-

the American.

‘ Clearly, therefore, there is no connection between the
green colour and the quantity of iron present. This result
is quite in accord with Ray Lankester’s observation that
his ‘‘marennin”’ is free from iron as well as from copper.

‘Both the gills and bodies of Oysters contain a small

73

quantity of iron, which is evidently normally present, the
gills containing a somewhat larger amount in proportion
to the total quantity of mineral matter present.

‘Finally, the total iron in a variety of Oysters was
determined in order to ascertain the normal quantity
present. These data, which are tabulated below, show a
fairly constant proportion of iron per Oyster, from 0°15 to
0°36 mgrme., or from 0°18 to 0°65 per cent. on the ash.

Total Iron present in Oysters.

Mgrme. | Percent-

; | Number |Total Iron) Weightof; Tron age of
Variety of Oyster | Analysed.| grme. ASHE) per Iron on
| Oyster. Ash.
|
‘Iiuitres de Mar- |
rennes’ ... bea 6 0°0018 07860 | 0°30 0°23
Dutch Soe et 6 0:0009 0°13938 0°15 0°65
American Bae 5 0:0018 0°2791 0°36 0°64
Colne 10 0°0020 1°0938 0°20 0°18
Deep Sea 2 0:0064 15017 | 0°32 0°43
Falmouth 6 0°0016 0°4534 | 0:27 0°35

‘Tn considering the variations in quantity, the very small
amounts of metal present must be borne in mind.

‘It may be added that although Carazzi has attributed
the green colour of French Oysters to iron taken up from
the mud of the Oyster-park or “claire,” experiments on
feeding Oysters with very dilute solutions of iron salts
(0:02 to 0°01 per cent.) carried on in conjunction with
Prof. Herdman produced no green colouration whatever.
The only result was a certain amount of ‘“ browning”
throughout the Oyster, the gills being no more affected
than the rest of the body. More recently Carazzi has
shown that Oysters fed with similar dilute iron solutions
acquire a pale yellowish colour in certain parts (branchial
epithehum and the cesophageal mucous membrane), and

74

that in these parts microscopic tests show the presence of
granules of iron. The actual meaning of these results
can hardly be recognised without quantitative data.

‘The Presence of Copper in Oysters.—F redericq has shown
that a certain small amount of copper is present normally
in the hemocyanin of the blood of crustaceans and
molluscs. The quantity thus present in Oysters of
different origin is fairly constant as shown in the following
table: it varies from 0°25 to 0°66 mgrme. per Oyster, or
from 0°30 to 1:18 per cent. on the ash.

Mgrme. | Percent-
: Number | Total |Weight of} Copper age
Variety of Oyster. | Analysed.) Copper Ash. per | Copper on
oe Oyster. Ash.
‘Huitres de Mar-
rennes’ .... wii 6 00024 0°7860 0-40 0°30
Dutch 6 0:0015 0°1393 0°25 1°08
American ... 5 0-0033 0°2791 0:66 1:18
Colne 10 0°00386 1°0938 0°36 0°33
Deep Sea 2 0:0069 15017 0°34 0°46

‘('4 mgrme. per oyster may be taken as an average, a
quantity slightly greater than the average iron (0°26
merme.). The calculated percentages on the ash show
greater variations, due to the very considerable differences
in the total quantities of mineral salts present, and it is
probably to this last factor that the popularly recorded
differences in taste of the various kinds of oysters is really
due. Certainly the minute quantities of copper and iron
present cannot account for them.

‘The copper was also determined in the gills and in the
bodies minus gills of French, Dutch, and American
Oysters, with the following results :—

(i)

Determination of Copper.

Six Oysters. French Dutch. American.

‘Huitres de Marennes.’

Gills only ... we Trace 0°8 ey
Bodies minus gills... 14 mgrme. 1°4 3°3

‘These data show conclusively thatthe green colour of
the gills of French Oysters is also in no way connected
with the copper present.

‘Quantities of copper greater than those recorded point
to abnormal conditions. Such have been found to occur
with certain Falmouth Oysters, and in an especially
interesting manner with the green leucocytosis of American
and Falmouth Oysters—the diseased condition referred to
above.

‘Falmouth Oysters——The presence of relatively large
quantities of copper in Falmouth and other Cornish
Oysters has been repeatedly associated with their bluish-
green colour. Dr. T. EK. Thorpe* states that these
Oysters, the colour of which, both in character and dis-
tribution, is quite different from that of the Marennes
Oysters, contain on the average about 1°3 mgrme. of
copper per Oyster. This large proportion is, Dr. Thorpe
says, ‘“‘obviously caused by the mechanical retention of
cupriferous particles.” On relaying they lose their
colour, and the quantity of copper present becomes
normal, 0'4 mgrme. per Oyster.

‘Six Falmouth Oysters, the bodies of two of which were
of a distinct arsenic-green colour, were dried at 100° C.,
and then digested with water and subsequently with dilute
hydrochloric acid. The extract contained about half the
total copper present, showing that the metal is partially,

* ** Nature,” 1896, p. 107.

76

at any rate, mechanically retained on, or in the body of
the Oyster, probably as a basic carbonate.
‘The analytical results were as follows :—

Mgrme. | Mgrme. | Per cent. | Per

5 Cop- Wght.| Copper Iron Copper | cent.
Six Oysters. | per. | Ivon. |ofAsh.| per per on Ironon
Oyster. | Oyster. Ash. Ash.

|

Extract with

dilute acid ...| 0°0097| 0°0024/ 02272] 1°62 0°40 4°22 1:06
Oysters __....| 0°0114) 0°0016] 0°4534} 1:90 0°27 2°51 0°35
Total ...| 0°0211 0°0040/ 06806} 3°52 0°67 3°10 0°59

‘The total copper present is almost nine times the
normal quantity, and about half of this is easily removed
by dilute acid. It is quite likely that the remainder is
partially or wholly simply entangled in the food passages
of the Oyster, and that the green colour may be due to
some other cause than this mechanically retained copper,
as suggested by Herdman.* Mr. G. C. Bourne, indeed,
regards it as due, in some Falmouth Oysters, to a green
desmid upon which the Oysters feed in quantity.

‘The occurrence of copper under such conditions is due
to the locality, and may quite possibly attain injurious
proportions, for the Oysters were obtained from a creek
which is locally supposed to bring down copper, and the
mud of which was found by Thorpe to contain 0°148 per
cent. of copper. Normal sea-water contains such an
excessively small quantity of copper that it was not found
possible to detect its presence, even electrolytically, in a
litre of sea-water, after concentration.

‘The green leucocytosis already referred to was first
noticed by Herdman and Boyce in American Oysters

* “Nature,” 1897, p. 366.

7

which had been relaid near Fleetwood. The colour
manifests itself in patches and streaks of pale green on
the mantle, in engorgements of the blood vessels and in
masses of green coloured leucocytes in the heart. The
leucocytes are apparently all amoeboid wandering cells,
comparable to the colourless corpuscles of the blood of
higher animals, and the colouration coincides with their
distribution.

‘The six greenest and six whitest of 120 of these Oysters
were chosen for analysis ; also a quantity of the greenest
portions of the greenest Oysters was selected from another
batch, and compared with the corresponding portions of
the whitest Oysters. The iron was not determined in the
latter comparison, owing to contamination of metal in
cutting. ;
‘The following were the results obtained :—

| Mgrme. ; Mgrme. |} Per cent. | Per

Cop- Copper Iron Copper | cent.

Oysters. per. Iron. | Ash. per per on Ironon
Oyster. | Oyster. Ash. Ash.

Green ...| 0°0158/ 0:0091] 1°1450} 2°63 Lae 1°38 0:79
White ...| 0°0042] 0°0036} 1°0948 0°70 0°69 0°38 0°33
Greenest parts} 0°0033| — _ | 0°0780 — — | 4:23 —
Whitest parts} 0°0009) — | 0°0452 — | = 1 =

‘The excessive quantity of copper in the selected green
Oysters is 3°75 times that in the white calculated per
Oyster, and 3°63 times calculated on the ash. In the
selected parts the total copper present calculated on the
ash is high in both cases, and the green parts again show
a marked excess in the proportion of 2°1 to 1. The copper
and iron in the white specimens are about normal, but
the increased quantity of iron in the green is marked,
being 2°5 times that of the former. Still there is relatively

78

a large excess of copper as compared with iron in the
green Oyster, as 1s evident from the analyses, the ratio
being 1'1: 1 for the white and 18 : 1 for the green.

‘It is to be concluded, therefore, that the green colour
of these Oysters is coincident with the distribution of the
excessive quantity of copper present, and that the copper
is in consequence to be regarded as the cause of the
colour. The:histo-chemical investigations of Boyce and
Herdman have amply confirmed this conclusion.

‘Further, this leucocytosis is not accompanied by a mere
redistribution of copper, but by an absolute increase of
the amount present in the body.

‘The deposition of copper in this manner is regarded by
Boyce and Herdman ‘“‘ as a degenerative reaction, due to
a disturbed metabolism, whereby the normal copper of
the hemocyanin, which is probably passing through the
body in minute amounts, ceases to be removed, and
so becomes stored up in certain cells.” The change
is comparable in kind to the accumulation of iron in
pernicious anzemia.

‘The increased quantity of iron present may also be due
to abnormal conditions of life, but a more accurate
localisation of the normal iron of the Oyster is necessary
before this can be decided.

‘This green leucocytosis has been observed by Herdman
and Boyce in other Oysters, including those of Falmouth,
and it is likely to be the real cause of their colour; a
colour therefore due to copper as previously supposed,
but accompanied by a diseased condition. Whether the
presence of copper in the water facilitates in any way the
development of the disease has not been determined;
experiments made on keeping Oysters in very dilute saline
copper solutions give no affirmative results beyond a
certain amount of post-mortem green staining.

79

‘Manganese was found to be present in several of the
varieties of Oysters analysed. Its detection is readily
effected in the electrolytic method of analysis as it
separates at the anode as peroxide. Colne Oysters con-
tained 0:14 mgrme. per Oyster—a rather smaller quantity
than the iron found.’

MUSSEL-BEDS AND MUD-BANKS.
By R. L. Ascrorr.

On the Lancashire and Cheshire coasts it is often
noticed that Mussel-beds are situated on banks of mud.
Mussels require, in the earliest shelled stage, some
hard substance to attach themselves to, such as stone,
gravel, hardened sand (such as Sabellaria tubes, for
instance), shells, such as Cockles or Mussels, wooden
piles, and the bottoms of boats. As they grow up and
increase in size (when located where there is little wave
action), through their excreta and the mud settling
amongst them they are inconvenienced, and to escape
being buried a lengthening of their cables, or byssus, takes
place, and so they lft themselves. ‘This process, repeated
time after time, raises the Mussels a great height above
their original location, and the bed of mud increases
accordingly.

The greatest depth that I have heard of occurred in the
River Ribble, where a bed of gravel was bare in the
channel a little above Lytham, when a strike of Mussels
occurred on it, and in the course of three years the
Mussels accumulated a bank of mud ten feet in depth—
there being no wave action to affect it.

At St. Annes-on-the-Sea, below the pier, there is a bed
of gravel on which a strike of Mussels occurs every two
years. During the two years growth the mud gets to a

80

depth of two feet, and then the heavy seas reach the bed
and roll the Mussels off like a carpet, and I have seen
them strewn along the beach at high-water mark as far as
Lytham Pier, a distance of four miles, during the same
tide.

Under the refreshment rooms at Southport Pier is a
foundation composed of stone on which Mussels strike.
They then accumulate mud until their cables, or byssus,
reaching down to the stones, get too weak, and they
are then washed away. The same thing occurs in
the Rock Channel, and on the great scars at Heysham.

In the case of St. Annes, and doubtless in the other
cases also, if the seaward edge of the scar was protected
by piles or posts, and the Mussels so rendered less lable
to be broken into by the sea, they would then, in all
probability, be able to grow to a marketable size.

The researches of Mons. Viallanes at Arcachon, in the
South of France, have proved the power of Mussels in
comparison with Oysters to separate food and refuse (sand,
&c.) from the water. By his experiments he shows that
for one quart of water filtered by a French or native
Oyster 18 months old, a Portuguese Oyster of the same
age filtered 53 quarts, and a middie-sized Mussel 3 quarts.
The excreta respectively were 0:199 gramme, 1:075
grammes, and 1°768 grammes per 24 hours. So that in
proportion to the numbers covering the same area of
ground the Mussel will deposit three times as much
material as a Portuguese, and eighteen times as much as
a French or native Oyster.

There is no doubt but that the rate of growth is to a
great extent proportional to the food consumed, so that it
is clear that the Mussel has a much greater quickness of
growth than a native Oyster.

The accumulation of mud (other conditions being the

81

same) is much greater where brackish water flows at
times over the bed, and it is a well known fact that
Mussels in such a place thrive and grow much more
quickly than those in pure sea water, no doubt through
the large quantity of food brought down by the rivers.
So much is this the case that every year Mussels are
removed from the scars on the seaward side of the River
Wyre below Fleetwood and placed in the same river above
Fleetwood to have the benefit of the brackish water.

The number of young Mussels (eggs and embryos) given
off by their parents must be in quantity simply enormous.
At Southport during the autumn, if a rope’s end is
allowed to hang in the water for the space of a month
you find it at the end of that time coated with Mussels,
like a swarm of bees hanging on a bough.

Boats, buoys, and all wrecks or posts near low-water
mark are smothered with them. These objects form
natural bouchots from which the young Mussels might
well be removed for cultivation elsewhere.

REPORT ON THE PHYSIOLOGY OF COLOUR-CHANGE IN
HIPPOLYTE AND OTHER MARINE CRUSTACEA.

By F. W. Keene, M.A., and F. W. Gamsie, M.Sc.,
Owens College, Manchester.

By the recommendation of Prof. Herdman and the
permission of the Lancashire Sea-Fisheries Committee,
we were allowed to utilise the Piel Laboratory for the
purpose of investigating the colour-physiology of
Hippolyte varians. We paid two short visits (from May
27th to 30th, and July 1st to 5th) in order to ascertain
the resources of the Laboratory and to discover the
localities in which Hippolyte could be obtained. As these

82

visits were successful, it was decided to spend the long
vacation at Piel, and accordingly the work was started.
on July 15th and carried on without interruption till
Sept. 22nd., concluding with a visit Dec. 15-22. In the
present Report we merely give a short account of the
methods employed, since the results obtained by their
means are not yet ready for publication.

Hippolyte varians is one of the few Crustacea which
may be considered abundant in the neighbourhood of
Piel. It keeps, for the most part, to beds of weeds below
low-water mark, and hence its habits have largely to be
learnt from specimens in captivity. Compared with its
associates—Idothea, Mysis, and Crangon—Hippolyte is of
a delicate constitution, and needs constant aération or
constant change of sea-water to maintain it in good health.
The resources of the tank-room at Piel enabled us to
overcome this difficulty. Fresh weed or the dead bodies
of its fellows serve Hippolyte as food. With due
precautions specimens may be kept under observation for
ten days or a fortnight.

From the nature of the beds of sea-weed in the Barrow
Channel a haul with weighted canvas tow-nets usually
contains an assortment of Hippolyte of different sizes and
colours. Shades of brown and yellow are abundant,
whilst green and red are sometimes common, sometimes —
rare. With the large Halidrys siliquosa a dark brown |
variety is associated; among the fine Polyzoon
(Bowerbankia) which clothes the lower parts of the
Halidrys stems, a speckled variety of Hippolyte occurs:
in the tide-pools of Foulney Island the green variety, and
it alone, is found among the Zostera.

The methods employed for investigating whether there
is a power of colour-change, and if so, how this power may |
be tested, were for the most part quite simple. One

83

method consisted in testing the effect of light of differing
intensities upon a given variety. ‘T'o do this a number of
jars, some of clear glass, others enveloped with muslin,
others again with black cloth, were taken on board, and as
soon as the nets were hauled up, the Hippolyte were
recorded, and specimeus of each variety were placed
in each jar. The effects produced differed very markedly
according to the time of day at which the catch was made ;
the result of treating a haul in this way after dark or even
in waning light being very different from that obtained at
mid-day.

We also directed our attention to the influence of
variously coloured weeds, with the object of testing
whether a brown Hippolyte would become green when
placed with green weeds, and red when surrounded with
red ones. For this purpose we had devised an apparatus
which was described shortly before the British Association
at Bristol.

This instrument consists of a ‘‘ pressure-bottle,”’ hold-
ing a couple of gallons of sea-water, which is discharged at
a uniform rate through an escape-tube commencing with
a minute opening. The water is made to circulate
through a series of air-tight observation- dishes, in which
the Hippolyte are placed. The loss of water from the
pressure-bottle is made good by the entrance of air which
is first drawn through a second series of observation-
dishes, the water in which is changed once or twice a day
only. On the whole it was found that Hippolyte flourishes
best in the air-circulating dishes.

The influence of monochromatic light was investigated
by the aid of Landolt’s fluid “‘ colour-filters.”’ In order
that the light which reaches Hippolyte may be of fairly
high intensity and not merely equivalent to shade, we
employed a mirror to reflect sunlight or the light of an

84

incandescent lamp into the jars which were otherwise
quite opaque.

The effects of direct sunlight, reflected light and
scattered light upon the colour of Hippolyte were tested
by exposing carefully recorded specimens to these in-
fluences in the open grassy space outside the Laboratory.
To prevent a rise of temperature in the sea-water, we
employed a circulation of water derived from the supply
in the Laboratory to flow through our observation-dishes.
The methods we used for investigating the effects of
rise and fall of temperature, electrical stimulus and of
toxic agents do not call for remark here. At night and
often during the day the records (chiefly microscopical)
were made by the light of an incandescent lamp.

We have arrived at the conclusion that there are two
colour-phases in Hippolyte varians; one diurnal, the
other nocturnal. The recurrence of these phases is to
some extent independent of the conditions of illumination,
although the colour itself may be profoundly influenced
by varying the quality and intensity of the incident light,
and also by other stimuli, which do not act through the
eye.
The advantages which the Piel Laboratory affords for
work of this kind are very considerable, and while express-
ing our thanks to Professor Herdman and to the Curator
of the Laboratory (Mr. Andrew Scott), we wish to
acknowledge our marked indebtedness to the Lancashire
Sea-Fisheries Committee for the generous help which is
afforded by them for the prosecution of scientific work,
generosity which will surely become more widely
appreciated as it becomes more generally known.

85

ADDENDUM.

The species of Crustacea we worked with, have been
kindly identified by A. O. Walker, Esq. From the very
limited fauna of Piel shore, it may be of interest to give
the list, which, however, is not quite complete.

Hippolyte varians, Leach, common, just below the
level of ordinary spring tides.
Hippolyte fascigera, Gosse, a doubtful species.
Almost certainly a variety of H. varians.
Less common but oc-
curring with the
foregoing.

Hippolyte cranchw, Leach.
Hippolyte pusiola, Kroyer.

A species of Mysis which gave interesting results and
which occurs with Hippolyte has been determined as
Mysis neglecta, G. O. Sars.

A small collection of Pycnogonida, which have no con-
nection with the present research but which were taken
among the fine red weeds of the Barrow Channel, contains
the following forms :—

Ammothea echinata, Hodge.
Anoplodactylus petiolatus (Kroyer).
Pallene brevirostris, Johnst.
Nymphon gracile, Leach.

86

APPENDIX.

LANCASHIRE SEA-FISHERIES HATCHERY
AND LABORATORY AT PIEL.

REGULATIONS IN REGARD TO WORKERS.

1°. Biologists and Students desiring to work at the
Piel Hatchery should apply to the Hon. Director
(Professor Herdman) who, if there is room, will allot
them work places in the Laboratory in the order of
application.

2°. In the absence of the Director, the Resident
Assistant (Mr. Andrew Scott) will determine which
places in the Laboratory workers are to occupy, and to
what extent the instruments of the Laboratory (micro-
scopes, microtomes, &c.), and the boats and collecting
apparatus may be used by workers.

3°. The Aquaria in the tank house are intended for
experiments in Fish Hatching and Fish Rearing, and it
is ovly by express permission of the Director or the
Resident Assistant that they may be used for private
investigations.

4°. Laboratory accommodation and lodging in the
house are given free of charge to those duly qualified
workers or students whose applications have been
accepted, and who have been assigned places in the
Laboratory. Meals (breakfast, dinner, tea and supper)
are provided for those working in the Hatchery at a fixed
charge of 3s. per day or 15s. per week, payable to Mr.
Scott.

87

5°. The Resident Assistant will be ready to give
assistance to workers at the Hatchery, and to provide them
with material for their investigations so far as it does not
interfere with his routine duties and his “ fisheries”’
work.

6°. All dishes, jars, bottles, tubes and other vessels in
the Laboratory may be used freely, but must not be
taken away from the Laboratory. If any workers desire
tc make, preserve and take away collections of marine
animals and plants, they must provide their own bottles
and preservatives for the purpose.

7°. The fish and other specimens in the tank room
are the property of the Institution and must not be used
or disturbed by workers in the Laboratory.

8°. Each worker in the Laboratory is required to send
a short account of his work done at the Institution, and
of the results he has attained, to the Director before the
lst of December (at latest), in order that it may be
entered in the Annual Report to the Sea-Fisheries
Committee.

W. A. HrERDMAN,
Honorary Director of the Scientific Work
to the Lancashire Sea-Fisheries
Committee.

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