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Full text of "Report of the British Association for the Advancement of Science"

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REPORT 



FOURTH MEETING 



BRITISH ASSOCIATION. 



REPORT 



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FOURTH MEETING 



BRITISH ASSOCIATION 



ADVANCEMENT OF SCIENCE; 



HELD AT EDINBURGH IN 1834. 



LONDON: 

JOHN MURRAY, ALBEMARLE STREET. 

1835. 



PEINTKD BY EICHAKD TAYLOK. 
RED LION COURT, FLEET STREET. 




CONTENTS. 



Proceedings op the Meeting . 



REPORTS ON THE STATE OF SCIENCE. 

Report on the Geology of North America. Part I. By Henry 
D. Rogers, F.G.S 1 

Report on the State of our Knowledge of the Laws of Contagion. 
By William Henry, M.D., F.R.S., &c., late Physician to the 
Manchester Royal Infirmary and Fever -Wards 67 

Report on Animal Physiology ; comprising a Review of the Pro- 
gress and Present State of Theory, and of our Information re- 
specting the Blood, and the Powers which circulate it. By 
William Clark, M.D., F.R.C., F.G.S., F.C.P.S., late Fellow 
of Trinity College, and Professor of Anatomy in the University 
of Cambridge 95 

Report on the Recent Progress and Present State of Zoology. By 
the Rev. Leonard Jenyns, M.A., F.L.S., F.Z.S., F.C.P.S. . . 143 

Report on the Theory of Capillary Attraction. By the Rev. James 
Challis, late Fellow of Trinity College, Cambridge 253 

Report on the Progress and Present State of Physical Optics. 
By the Rev. Humphrey Lloyd, A.M., M.R.I. A., Fellow of 
Trinity College, and Professor of Natural and Experimental 
Philosophy in the University of Dublin 295 

Report on the Progress and Present State of our Knowledge of 
Hydraulics as a Branch of Engineering. Part II. By George 
Rennie, Esq., F.R.S., Acad. Reg. Sc. Turin. Corresp., &c. &c. 415 

TRANSACTIONS OF THE SECTIONS. 

I. Mathematics and Physics. 

Professor Hamilton on the Application to Dynamics of a General 
Mathematical Method previously applied to Optics 513 

Professor Hamilton on Conjugate Functions, or Algebraic Couples, 
as tending to illustrate generally the Doctrine of Imaginary 
Quantities, and as confirming the Results of Mr. Graves re- 
specting the Existence of Two independent Integers in the com- 
plete expression of an Imaginary Logarithm 519 



vi " CONTENTS. 

Page. 

John Thomas Graves on the Theory of Exponential Functions. 52S 

JoHK S. Russell's Notice of the Reduction of an anomalous Fact 
in Hydrodynamics, and of a new Law of the Resistance of 
Fluids to the Motion of Floating Bodies 531 

Eaton Hodokinson on the Collision of imperfectly Elastic Bodies 534 

The Rev. James Challis's Theoretical Explanations of some Facts 
relating to the Composition of the Colours of the Spectrum . . 514. 

The Rev. Professor Powell on the Achromatism of the Eye ; in 
Continuation of a Paper in the last Volume of the British Asso- 
ciation Reports 548 

The Rev. Professor Powell on the Theory of the Dispersion of 
Light by the Hypothesis of Undulations 549 

The Rev. Professor Powell on the Repulsion excited between 
Surfaces at minute distances by the Action of Heat 549 

The Rev. William Whewell's Suggestions respecting Sir John 
Herschel's Remarks on the Theory of the Absorption of Light 
by coloured Media 550 

The Rev. T. R. Robinson on the Visibility of the Moon in Total 
Eclipses 552 

Professor Miller's Account of some Observations made for the 
purpose of determining the Positions of the Axes of Optical 
Elasticity in oblique prismatical Crystals 556 

R. Addams's Account of a new Phaenomenon of sonorous Inter- 
ference 557 

Professor Lloyd's Account of Magnetical Observations in Ireland, 
and of a new Method of observing the Dip and the Force with 
the same Instrument 557 

Sir Thomas M. Brisbane on an apparent Anomaly in the Measure 
of Rain 560 

Professor Phillips's Second Report of the Result of Twelve 
Months' Experiments on the Quantities of Rain falling at different 
Elevations above the Surface of the Ground at York, under- 
taken at the request of the Association by William Gray, Jun., 
and Professor Phillips, F.R.S. F.G.S., Secretaries of the York- 
shire Philosophical Society 560 

Luke Howard on the difference of the Quantity of Rain at different 
Heights above the Surface of the neighbouring Ground 563 

Professor Stevelly's Attempt to connect some of the best-known 
Phaenomena of Meteorology with established Physical Principles 564 

Professor Christie — Extract of a Letter to Professor Forbes . . 566 

Lieut.-Col. Sykes's Notes on mean Temperatures in India 567 

The Rev. J. Hailstone on a peculiar Oscillation of the Barometer 569 

H. H. Watson on the use of Leslie's Hygrometer with a new Scale 569 

Alexander J. Adie's Account of Experiments on the Expansion 
of Stone by the Application of Heat 569 



CONTENTS. Vn 

Page. 

il. Chemistry. — Mineralogy. 

Adam van deb Toorn's Table of the Proportions of anhydrous acid 
in acetic acid of every degree of concentration between pure 
water and the hydrated acetic acid, compared with the specific 
gravities, water at 59° Fahr. being taken as unity 571 

Robert W. Fox's Account of some Experiments on the Electricity 
of the Copper Vein in Huel Jewel Mine 572 

Sir David Brewster's Notice respecting a remarkable Specimen 
of Amber 574 

Sir David Brewster's Remarks on the value of Optical Characters 
in the discrimination of Mineral Species 575 

The Rev. William Vernon Harcourt's Experiments on the ef- 
fects of long-continued Heat on Mineral and Organic Substances 576 

Dr. Clark's Explanation of the Successful Application of the Hot 
Blast to the Production of Cast Iron 578 

Professor Graham on hydrated Salts and metallic Peroxides ; 
with Observations on the doctrine of Isomerism 579 

George Lowe on some new Chemical products obtained in the 
Gas-works of the Metropolis 582 

Henry Hough Watson on the quantity of Carbonic Acid in the 
Atmosphere • • • ^^^ 

J. F. W. Johnston on the Chemical Composition of crystallized 
Oxichloride of Antimony 587 

Charles J. B. Williams on the phaenomena and products of a 
low form of Combustion 588 

Dr. Wm. Gregory's Abstract of the Discoveries made by Dr. 
Reichenbach, in his examination of the products of destructive 
Distillation 591 

III. MAtHEMATlCAt INSTRUMENTS AND MECHANICAL ArTS. 

Professor Forbes on a new Sympiesometer 593 

David Dick on the construction of Achromatic Object-Glasses . . 59S 
John Dunn on a new Klinometer and portable Surveying Instru- 
ment 594 

E. J. Dent on a Chronometer with a Glass Balance-spring .... 595 

Mr. Gordon on the Polyzonal Lens 595 

Mr. Rennie on an Instrument for taking up Water at great depths 595 
Professor Stevelly on the application of a Vernier to a Scale, not 
of equal but of variable parts, and particularly to WoUaston's 
Scale of Chemical Equivalents 596 

IV. Natural History, Anatomy, and Physiology. 

Botany. 
Robert Brown on the plurality and development of Embryos in 
the Seeds of Coniferce 596 



vm CONTENTS. 

Page. 

Dr. Arnott on tlie Cocculus Indicus of Commerce 597 

Dr. Daubeny on Excretions from the Roots of Vegetables 598 

W. C. Trevelyan on the Distribution of the Phsenogamous Plants 
of the Faroe Islands 598 

Zoology. 

John Graham Dalyell on the Propagation of certain Scottish 
Zoophytes 598 

J. O. Westwood on the Transformations of the Crustacea 608 

P. J. Selby's Observations on the Orbital Glands in certain tribes 
of Birds 609 

P. J. Selby's Notice of Birds observed in Sutherlandshire, June, 
1834 610 

Sir W. Jardine's Observations on the Salmonidce which were met 
with during an Excursion to the North-west of Sutherlandshire 
in June 1834 , 613 

James Wilson's Notice regarding the Coleopterous Insects col- 
lected during a Tour in Sutherland 615 

M. Agassiz on the different Species of the Genus Salmo which 
frequent the various Rivers and Lakes of Europe 617 

Dr. Allen Thomson's remarks on some specimens of Reptiles. . 623 

Dr. Traill on the Laryngeal Sac of the Reindeer 623 

J. B. Pentland on the Ancient Inhabitants of the Andes 623 

Geology. 

David Milne on the Geology of Berwickshire 624 

Major-General Lord Greenock on the Coal-fields of Scotland . . 639 
Dr. HiBBERT on the Ossiferous Beds contained in the Basins of 

the Forth, the Clyde, and the Tay 642 

Dr. Traill on the Geological Structure of the Orkney Islands. . 644 
Professor Jameson's remarks on the Fossil Fish Cep/ialaspis . . . . 646 

M. AoAssiz on the Fossil Fishes of Scotland 646 

Mr. Maclaren on the Pentland Hills 649 

W. Macgillivray's account of the central Portion of the great 
Mountain Range of the South of Scotland, in which- arise the 

Sources of the l\veed 650 

C. G. S. Menteath's notice of the Limestone of Closeburn, in re- 
ply to a Query of the Geological Committee 651 

Dr. Knight's notice of the Flints of Aberdeenshire 651 

R. I. MuRCHisoN on the Old Red Sandstone and other Forma- 
tions on the Welsh Border 652 

C. Lyell on the Change of Level of the Land and Sea in Scandi- 
navia 652 

W. GiLBERTsoN on Marine Shells of recent Species found at consi- 
derable elevations, near Preston 654 

Professor Phillips's Notices in reply to a Question proposed by 



CONTENTS. IX 

Page, 
the Geological Committee at Cambridge, as to the Relations of 
Mineral Veins and the Non-metalliferous Joints in Rocks .... 654 
James Bryce on some Caverns containing bones, near the Giant's 

Causeway • 658 

Thomas Andrews on some Caves in the Island of Rathlin and the 

adjoining Coast of the County of Antrim 660 

W. NicoL on the Anatomical Structure of recent and fossil Woods 660 

V. Anatomy and Physiology. 

Sir C. Bell's Observations on the proper method of studying the 
Nervous System • • 667 

Dr. Abercrombie on the importance to the Medical Profession 
of the study of Mental Philosophy 670 

Dr. J. Reid's notice of some Experiments on the connexion between 
the Nervous System and the Irritability of Muscles in Living 
Animals. With Observations by Dr. Alison 671 

Dr. Alison's Notice of some Observations on the vital properties 
of Arteries leading to inflamed parts 674 

Dr. Marshall Hall and Mr. Broughton's Report of Progress 
made in an Experimental Inquiry regarding the Sensibilities of 
the Cerebral Nerves, recommended at the last Meeting of the 
Association 67G 

Dr. HoDGKiN and Dr. Ruppell on the Effects of Poisons on the 
Animal CEconomy 681 

Dr. T. J. Aitkin's Inquiries into the Varieties of Mechanism by 
which the Blood may be accelerated or retarded in the Arterial 
and Venous Systems of Mammalia 681 

Dr. Sharpey's Observations on the Anatomy of the Blood-vessels 
of the Porpoise 682 

Mr. Dick on the Use of the Omentum 683 

Dr. W.Thomson on the Infiltration of the Lungs with black Matter, 
and on black Expectoration 683 

Professor Syme on Excision of diseased Joints 684 

Dr. Joseph Clarke's account of a Registry kept in the Lying-in 
Hospital of Great Britain-street, Dublin, from the year 1758 to 
the end of 1833 685 

VI. Statistics. 

Dr. Cleland's Statistics of Glasgow 685 

Mr. Heywood — Statistics of Manchester 690 

Mr. Gordon's notice of the new Statistical Account of Scotland . . 692 
Earl Fitzwilliam's remarks on the Statistical Reports regarding 

Agriculture 693 



OBJECTS AND RULES OF THE ASSOCIATION. 



OBJECTS. 

The Association contemplates no interference with the ground occu- 
pied by other Institutions. Its objects are, — To give a stronger im- 
pulse and a more systematic direction to scientific inquiry, — to promote 
the intercourse of those who cultivate Science in different parts of the 
British Empire, with one another, and with foreign philosophers, — to 
obtain a more general attention to the objects of Science, and a removal 
of any disadvantages of a public kind, which impede its progress. 



RULES. 

MEMBERS. 

All Persons who have attended the first Meeting shall be entitled to 
become Members of the Association, upon subscribing an obligation to 
conform to its Rules. 

The Fellows and Members of Chartered Literary and Philosophical 
Societies publishing Transactions, in the British Empire, shall be en- 
titled, in like manner, to become Members of the Association. 

The Office- Bearers and Members of the Councils, or managing Com- 
mittees, of Philosophical Institutions shall be entitled, in like manner, 
to become Members of the Association. 

All Members of a Philosophical Institution recommended by its 
Council or Managing Committee, shall be entitled, in like manner, to 
become Members of the Association. 

Persons not belonging to such Institutions shall be elected by the 
General Committee or Council, to become Members of the Association, 
subject to the approval of a General Meeting. 

SUBSCRIPTIONS. 

The amount of the Annual Subscription shall be One Pound, to be 
paid in advance upon admission ; and the amount of the composition 
in lieu thereof, Five Pounds. 

Subscriptions shall be received by the Treasurer or Secretaries. 

If the annual subscription of any member shall have been in arrear 
for two years, and shall not be paid on proper notice, he shall cease 
to be a member ; but it shall be in the power of the Committee or 
Council to reinstate him, on payment of arrears, within one year. 



RULES OF THE ASSOCIATION, 



MEETINGS. 



The Association shall meet annually, for one week, or longer. The 
place of each Meeting shall be appointed by the General Committee at 
the previous Meeting ; and the Arrangements for it sliall be entrusted 
to the Officers of the Association. 



GENERAL COMMITTEE. 

The General Committee shall sit during the time of the Meeting, or 
longer, to transact the Business of the Association. It shall consist of 
all Members present, who have communicated any scientific Paper to a 
Philosophical Society, which Paper has been printed in its Transactions, 
or with its concurrence. 

Members of Philosophical Institutions, being Members of this Asso- 
ciation, who may be sent as Deputies to any Meeting of the Association, 
shall be Members of the Committee for that Meeting, the number 
being limited to two from each Institution. 

COMMITTEES OF SCIENCE. 

The General Committee shall appoint, at each Meeting, Committees, 
consisting severally of the Members most conversant with the several 
branches of Science, to advise together for the advancement thereof. 

The Committees shall report what subjects of investigation they 
would particularly recommend to be prosecuted during the ensuing 
year, and brought under consideration at the next Meeting. They 
shall engage their own Members, or others, to undertake such inves- 
tigations ; and where the object admits of being assisted by the exer- 
tions of scientific bodies, they shall state the particulars in which it 
might be desirable for the General Committee to solicit the co-opera- 
tion of such bodies. 

The Committees shall procure Reports on the state and progress of 
particular Sciences, to be drawn up from time to time by competent 
persons, for the information of the Annual Meetings. 

LOCAL COMMITTEES. 

Local Committees shall be appointed, where necessary, by the General 
Committee, or by the Officers of the Association, to assist in promoting 
its objects. 

Committees shall have the power of adding to their numbers those 
Members of the Association whose assistance they may desire. 

OFFICERS. 

A President, two Vice-Presidents, two or more Secretaries, and a 
Treasurer, shall be annually appointed by the General Committee. 



RULES OF THE ASSOCIATION. 



COUNCIL. 



In the intervals of the Meetings the affairs of the Association shall 
be managed by a Council, appointed by the General Committee. 



PAPERS AND COMMUNICATIONS. 



The General Committee shall appoint at each Meeting a Sub-Com- 
miitee, to examine the papers which have been read, and the register of 
communications ; to report what ought to be published, and to recom- 
mend the manner of publication. The Author of any paper or commu- 
nication shall be at liberty to reserve his right of property therein. 



ACCOUNTS. 



The Accounts of the Association shall be audited annually, by Audi- 
tors appointed by the Meeting. 



TREASURER. 

John Taylor, Esq., 14, Chatham Place, London. 
LOCAL TREASURERS. 



Dr. Daubeny, Oxford. 
Charles FoRBES,Esq. Edinburgh. 
Jonathan Gray, Esq., York. 
Prof, Henslow, Cambridge. 
William Hutton, Esq., Newcas- 

tle-on-Tyne. 
Dr. Orpen, Dublin. 



Dr. Prichard, Bristol. 
George Parsons, Esq., Birming- 
ham. 
Rev. John J. Tayler, Manchester. 
Samuel Turner, Esq., Liverpool. 
H, WooLCOMBE, Esq., Plymouth. 



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FOURTH REPORT. 



PROCEEDINGS OF THE MEETING. 



1834. 

X HE British Association resumed its sittings on Monday the 
8th of September, 1834, in the city of Edinburgh. The Meet- 
ing was attended by a greater number of members than had as- 
sembled on any former occasion* j but by means of the arrange- 
ments adopted by the Secretaries and local Committee, its pro- 
ceedings were conducted with order and facility. All the 
public accommodations which this magnificent capital possesses 
were opened to the Association : the members received their 
tickets in the gallery of the Royal Institution j the gerieral Com-^ 
mittee sat in the meeting- room of the Royal Society 3 the Sec- 
tions were distributed through the class-rooms of the Univer^ 
sity ; the meetings of the entire body were held in the public 
Assembly Rooms and in the hall of the College Library. 

GENERAL MEETINGS. 

On Monday evening, at eight o'clock, the first General 
Meeting was held in the great Assembly Room. The President 
of the preceding year (the Rev. Professor Sedgwick) addressed 
some remarks to the meeting on the progress of the Associa- 
tion ; he congratulated them on the increased strength in which 
they had assembled, in a place endeared to the feelings of every 
lover of science, by so many delightful and elevating recollec- 
tions, especially by the recollection of the great men whom it 
had fostered or to whom it had given birth. Among the per- 
sons congregating together from different countries to this great 
philosophical union it had been his good fortune to encounter 
on his road thither M. Arago the Perpetual Secretary of the 

* The number of tickets issued was 1298. 
1834. b 



X FOURTH REPORT — 1834. 

French Institute, a name which the meeting well knew was not 
inferior in scientific reputation to any in Europe. To meet with 
such men, to breathe the same atmosphere with them, to partake 
the same sentiments, to enjoy their conversation, and to gain, 
he hoped, their friendship, these were among the highest privi- 
leges which such unions bestowed. 

If he were to be asked what the power is which this Associa- 
tion peculiarly applies to the advancement of science, he would 
answer, — the power of combination : how feeble is man for any 
purpose when he stands alone, how strong when united with his 
fellow-men ! It might be true, perhaps, that the greatest philo- 
sophical works have been achieved in privacy ; but it is no less 
true that those works would never have been accomplished if 
their authors had not mingled with men of similar pursuits, and 
availed tliemselves of their assistance. To such a commerce of 
ideas they haA^e often been indebted for the germs of their ap- 
parently insulated discoveries, and without such mutual aid they 
would seldom have been able to carry their investigations to any 
valuable conclusion. Even in the highest departments of philo- 
sophical reasoning, when a question of fact arises, when a point 
of experiment is reached, the greatest masters of analysis are 
obliged to call in the cooperation of other labourers, and to wait 
for the observations of experimental men. 

The manner in which the power of combination is brought 
into action by these meetings might, in some measure, be col- 
lected from the results which had sprung out of the proceedings 
of the last meeting. A discussion, for instance, had then taken 
place on the subject of the aurora borealis, and measures were 
adopted for promoting the investigation of the circumstances 
connected with that remarkable phaenomenon. Soon afterwards 
a beautiful arch appeared across the heavens ; it was simulta- 
neously observed by diflferent members of the Association at 
distant points ; and thus elements were furnished for a compu- 
tation of its height. Again, observations of great value had 
long since been made at the Royal Observatory of Greenwich 
by Bradley and Maskelyne : these had lain till now unreduced, 
like unwrought ore, or raw materials for a valuable manufacture 
not worked up ; and they might still have continued useless and 
lost to science but for the application to Government resolved 
upon at the last meeting of the Association, the success of which 
had been announced in the volume of Reports which had since 
been printed. The Professor next referred to the progress which 
by the same agency is making in the observing of the tides and 
the discussion of tide observations, and to the experiments on 
the effects of long-continued heat, which are going on in the 



PROCEEDINGS OF THE MEETING. Xi 

iron-furnaces of Yorkshire. He concluded by recommending to 
the meeting a strict adherence to the principle of excluding 
from their discussions every subject of a nature not strictly 
scientific, and expressed the satisfaction with which he resigned 
his office into the hands of one who had ali'eady been placed at 
the head of science in Scotland, and who had added to laurels 
gained in fighting the battles of his country the glory of having 
kindled up the light of philosophj^ even at the antipodes. 

The President (Sir Thomas Brisbane) assured the meeting of 
the strong desire which animated individuals of every rank in 
the city of Edinburgh and its neighbourhood to give the warm- 
est welcome to the Association, and to uphold, by its reception, 
the national character for hospitality. He announced that the 
Principal and Professors of the University had given the 
free use of their class-rooms and of other apartments in the 
College, which would be found admirably adapted for the Sec- 
tional meetings of the Association ; and he added that other 
public bodies had not been backward in making similar oflfers, 
and in contributing whatever lay in their power towards its ac- 
commodation. 

The senior Secretary (Mr. Robison) stated the course of pro- 
ceeding which it was intended to adopt in conducting the busi- 
ness of the present meeting. The principal variation to be 
made fi-om the course pursued in former yeai-s consisted in de- 
voting the entire moi'ning to the meetings of the Sections and 
their Committees ; and transacting the detail of scientific business 
solely at the morning meetings. In tlie evening the Chair would 
be taken at eight o'clock ; the officers of each Committee would 
give a short summary of the proceedings which had taken place 
in their respective Sections, and these statements would be fol- 
lowed by any communications of a more popular character that 
might be selected for the evening meetings. In addition to 
what had been already said of the liberal conduct of public 
bodies in Edinburgh, he was bound to mention the peculiar ob- 
ligation under which the Association lay to the proprietors of 
the building in which they were then assembled, who had not 
only granted the gratuitous use of their apartments, but had ex- 
pended a large sum of money in preparing and decorating them 
for the meeting. 

The junior Secretary (Professor Forbes) then delivered the 
following address : 

" It having been suggested that the general view of the pro- 
gress of the affairs of the Association, so ably executed last year 
by Mr. Whewell, should annually be continued by the Secretary 
for the time being, I have undertaken this portion of the duties 

b2 



Xii FOURTH REPORT — 1834, 

which devolve upon the Secretaries for Edinburgh, at the desire 
of my learned colleague Mr. Robison, who, on the other hand, 
has engaged briefly to state the nature and motives of the prac- 
tical arrangements for the present meeting, of which he has had 
the kindness to superintend by far the most laborious part. 

I felt anxious that such a periodical report as I have men- 
tioned should be continued, because of the necessarily fluctua- 
ting state of our Body, and the small number of persons who, 
by circumstances, have been enabled to attend all the meetings, 
and to become acquainted with the actual operation of a some- 
what complicated machine ; and I was ready to undertake that 
duty, because I hoped that I might be able, by an appeal to 
facts, in the first place, to put in a clear point of view, what 
has not perhaps been enough insisted on, and has therefore 
been very generally misunderstood, — the pei'fectly tinique cha- 
racter of this Association, and the high aims to which its efforts 
are directed ; and, in the second place, to demonstrate that these 
aims and objects are in the due course of attainment ; that the 
members, and especially the projectors of this institution, are 
fulfilling the pledges, of no common character, which they gave 
to the public, and this more especially in relation to the pro- 
ceedings of the past year. 

*' The character of the Association, I have said, may be con- 
sidered as unique. It is not to be confounded with those nu- 
merous and flourishing institutions which have sprung up, es- 
pecially of late years, for the simple diffusion of scientific truths. 
Such diffusion does not even, properly speaking, include any 
attempt at extension or accumulation : if in many cases it does 
promote such extension, it is indirectly, and beyond a doubt 
has sometimes had the opposite tendency. The intellectual 
wealth of mankind is no more increased by this operation, than 
is the weight of the precious metals under the hand of the gold- 
beater. A greater display may indeed be attained, and a more 
commodious application to the useful and the elegant purposes 
of life ; but for actual increase of the stock which may hereafter 
be fashioned with ease and expedition by the hands of a thou- 
sand artificers, we must recur to the miner toiling in his solitary 
nook, and to the labourer who painfully extracts some precious 
grains from the bed of the torrent. It is the furtherance of this 
species of productive energy that the British Association claims 
for its capital object. The diffusion of a taste for science amongst 
its numerous members is no doubt also one of the most neces- 
sary and most desirable consequences of the principles upon 
which it is founded ; but it is not the basis of these principles. 
To teach those who have never pursued natural knowledge but 



PROCEEDINGS OF THE MEETING. XIU 

as an occasional amusement, — to feel that for tliem a field lies 
open which tomorrow they may call their own, — to lend them 
such aid as may promote the success of their exertions, by re- 
moving the preliminary difficulties, and pointing out the exist- 
ing boundary betwixt the known and the unknown, — to stimu- 
late these exertions and those of others who have already be- 
come, to a certain degree, familiarized with the labours and with 
the results of intellectual toil, by enabling them to mix with the 
veterans in each department who have gained, and who still con- 
tinue to gain, the highest rewards which the investigation of na- 
ture confers, — who will point out the methods which they pur- 
sued, the disappointments which they met, and the difficulties 
which they surmounted, thus affording at once the gratification 
which every generous mind feels in personal communication 
with those who have signalized themselves by intellectual achieve- 
ment, and the instruction and encouragement for the pursuit of 
a similar course which words, and words alone, can impart, — 
these we hold out as amongst the first and the most valuable 
objects proposed to be attained by the institution of this Asso- 
ciation. 

" No doubt societies for the promotion of natural knowledge 
have been in existence for near two centuries, and these have 
done much to the due advancement of science itself, as well as 
the promotion of a more general taste for its cultivation. They 
were admirably adapted to the period of their institution, when 
the difficulties of ordinary communication, and the want of sci- 
entific journals, made the Royal Society of London the great 
centre of philosophical information, — when new experiments 
were there first repeated, — when new theories were there first 
discussed, — and when its Transactions, and those of the other 
academies of Europe — fraught with the literary treasures which 
Hooke and Wren, and Boyle and Leibnitz, and the Bernouillis, 
loved to display, and which Newton alone loved to conceal — 
were the couriers which published to Europe the intelligence of 
the successive intellectual victories of that mighty age. Rarely 
even then, however, and latterly still less, did these societies at- 
tempt to guide in any specific direction the investigations of their 
members, or to form any school of science for the initiation of 
fresh inquirers. The formation of such schools of disciples wlio 
voluntarily combined under some philosopher of emuience, partly 
did away with the necessity of this on the Continent ; whilst the 
total want of anything similar in our own country, and the less 
specific objects of those honorary rewards which from time to 
time have been given by learned societies in all countries, and 
which have occasionally drawn forth all the powers of some mas- 



xiv FOURTH REPORT 1834. 

ter mind to the solution of a specific difficulty proposed as a 
pri/e question, necessarily produced a greater want of systema- 
tic cooperation amongst scientific men in Britain than is to be 
found in several countries not her political superiors. 

" The migratory scientific associations of Germany and Swit- 
zerland — to which we gratefully acknowledge that our British 
one owes its rise, — embrace only one class of the objects to 
which we have above alluded as characterizing this Body. Their 
aim was simply to promote the intercourse of scientific men, 
and to diffuse a taste for the prosecution of science. Their ex- 
istence is not permanent, — they execute no functions but for the 
moments during which their members are once a-year assembled, 
— they regard not the past, and have no cares for the future, — 
they merely receive and consider the communications which the 
zeal of individual members places in their way. Such was at 
first proposed to be the character of the Body this day assem- 
bled, in imitation of the foreign meetings ; but a more extensive 
design was subsequently adopted, and it was determined to 
establish a permanent society, of which these annual reunions 
should simply be the meetings, but which, by methods and by 
influence peculiarly its own, should continue to operate during 
the intervals of these public assemblies, and should aspire to 
give an impulse to every part of the scientific system, to mature 
scientific enterprise, and to direct the labours requisite for dis- 
covery*. 

" If we now turn from the aims to the acts of the Associa- 
tion, we shall find gratifying proof that these designs were not 
chimerical, and that the primary machinery devised for effecting 
them was wanting neither in efficiency nor in permanence. The 
first and most signal proof which we can cite, is the produc- 
tion of those Reports on the Progress of Science, which ap- 
peared to be one of the most important objects of such an in- 
stitution, and one which, beyond all dispute, no existing society 
could have attempted. To call upon persons whose time was 
in all cases more or less valuable, for such a devotion of it 
as was required for a systematic and precise detail of the re- 
cent progress of the sciences which they respectively culti- 
vated, was to make a demand, the boldness of which cannot 
perhaps well be appreciated but by those who have had expe- 
rience in the labour of bringing together the substance of de- 
tached, though often profound, papers in the extensive range of 
scientific periodicals and academical collections. Yet so obvious 

• The author here described the share which some of the founders of the As- 
sociation liad respectively talien in planning and conducting the institution. 



PROCEKDINGS OF THK MJSBTING. XV 

was the utility of the proposed undertaking, that, in the very- 
infancy of the Association, there were found several distinguished 
individuals, and chiefly from the University of Cambridge, who 
had not even been present at the first meeting, but who volun- 
teered to undertake some of the most valuable of those reports 
which appeared in the first volume of the Proceedings of the As- 
sociation. As Mr. Whewell enumerated these in his last year's 
address, I will not further allude to them. It ought, however, 
specially to be observed, that these reports diifer entirely from 
the short systematic treatises on scientific subjects with which 
the press teems. They are not primarily intended for the gene- 
ral reader — they are not meant for the purpose of popularizing 
technical subjects ; their main object is so to classify existing 
discoveries as to lead the individual who is prepared to grapple 
with its difficulties, to start with the most complete and accurate 
knowledge of what has already been done in any particular sci- 
ence, — not intended itself to contain that knowledge, but merely 
to serve the purpose of a catalogue raisonnee, by means of a 
lucid analysis and arrangement, at the same time (and here is 
the great necessity of securing the cooperation of persons di- 
stinguished in the several departments,) that the report should 
point out the most important questions which remain for solu- 
tion, whether by direct experiment or by mathematical investi- 
gation. 

" The second volume of Reports has amply justified the ex- 
pectations with which it was hailed ; and whilst the first was 
chiefly occupied with reports upon great and leading divisions 
of science, we have here several happy specimens of a still 
greater division of labour, by the discussion within moderate 
limits of some particular provinces. Thus, Mr. Taylor has 
treated of one particular and most interesting question in Geo- 
logy, the formation of Mineral Veins, — one of the most impor- 
tant, in a theoretical point of view, which could have been stated, 
and which, from its intimate connexion with commercial specu- 
lation, might have been expected in a country like ours to have 
been more specifically treated of than it has been. It strictly 
belongs to the dynamics of the science, to which, since the time 
of Hutton, but little attention has been paid until very recently. 
By the exertions, however, of Mr. Carne, of Dr. Boase, and Mr. 
Henwood of Cornwall, whose researches are to form one point 
of discussion in the Geological Section at the present meeting, 
the question of the origin of mineral veins, though probably by 
no means decided, has been brought prominently forward. 

" That electric agency was concerned in the disposition of 
metalliferous veins can scarcely be doubted ; and the connexion 



Xvi FOURTH REPORT — 1834. 

between electricity aild magnetism, now so fully established,^-^ 
the connexion between metalliferous veins and lines of elevation, 
and between the latter and the isodynamical lines of terrestrial 
magnetic intensity, as suggested by Professor Necker of Geneva, 
— point out a bond of union between this subject and that of ter- 
restrial magnetism, on which we have a report by Mr. Christie, 
where the very interesting direct observations of Mr. Fox of Fal- 
mouth, on the electro-magnetic action of mineral veins, are par- 
ticularly noticed. Mr. Christie's theory of the diurnal variation 
of the needle, which he is desirous should be submitted to the 
test of a laboratory experiment, is likewise intimately connected 
with the actual constitution of our globe*. The whole subject 
of Terrestrial Magnetism is one of the most interesting and 
progressive of the experimental sciences. The determination of 
the direction of the magnetic energy by means of two spheri- 
cal coordinates, termed the variation and the dip, and the mea- 
sure of the intensity of that force, are the great objects of imme- 
diate research, as forming a basis of theory. The existence of 
four points on the earth's surface, to which the needle tends, has 
long been known ; and the position of two of these (in Northern 
Asia and America,) has recently been elucidated by the perse- 
vering efforts of Professor Hansteen and Commander Ross. The 
precise numerical determination of the elements just alluded to 
acquires a deep and peculiar interest from the multiplied varia- 
tions which they undergo. Not only are these elements subject 
to abrupt and capricious changes, which Baron Humboldt has 
termed magnetic storms ; but gradual and progressive variations 
are undergone at different hours of the day, at different seasons 
of the year, and throughout longer periods, which may even per- 
haps bear a comparison with the sublime cycles of Astronomy. 
*' Natural History forms a more prominent subject in this 
volume than in the last, though the reports of Professor Lindley 
* on the principal questions at present debated in the Philosophy 
of Botany'; and of Dr. Charles Henry ' on the Philosophy of 
the Nervous System', refer only to particular departments of 
widely extended subjects, which are again to be resumed in more 
general reports, undertaken for the present meeting,^that by 
Mr. Bentham, on Systematic Botany, and by Dr. Clarke of 
Cambridge, on Physiology in general. We cannot but remark 
with pleasure, that one of the points for inquiry particularly in- 
sisted on by Professor Lindley, that of the influence of the che- 
mical nature of soils, and of the excretions of plants, was taken 
up at an early period of the existence of the Association, by one 

» Report, p. 122-3. 



PROCEEDINGS OF THE MEETING. XVU 

of its most zealous supporters, Dr. Daubeny ; and that, in re- 
ference to the review by Dr. Henry of the labours of European 
physiologists, we may quote, as a national honour, the disco- 
veries of our distinguished associate Sir Charles Bell. 

" On the general connexion and occasional apparent opposi- 
tion of theory and practice, I would refer to some very pertinent 
remarks in the address of Mr. Whewell at the last meeting. The 
importance of carrying on both simultaneously and independ- 
ently, and of looking to our increased knowledge of both as the 
only sure means of ultimately reconciling discrepancies, has been 
manifested by the desire of the Council of the Association to 
procure two distinct reports on the Theory and Practice of Hy- 
draulics, which have been drawn up with remarkable perspicuity, 
aud within a small compass, by Mr. Challis and Mr. Rennie. 
Both of these gentlemen have shown their zeal in the objects of 
the Association by promising to continue their valuable labours. 
Mr. Rennie, on that part of his subject which relates to the mo- 
tion of fluids in open channels, and Mr. Challis on some of those 
exceedingly interesting branches of theory altogether modern, 
which physically, as well as in their mathematical methods, have 
the closest analogy to that case of the motion of fluids treated of 
in the present volume, namely, the theory of Sound, and the in- 
timate constitution of Liquids. When, in addition to these re- 
ports, we shall have received that undertaken by Mr. Whewell 
upon the mathematical theory of Magnetism, Electricity, and 
Heat, we shall undoubtedly possess the most complete outline 
extant of a department of knowledge entirely of recent date. 

" In the science of Hydraulics, indeed, some progress in theory 
has accompanied the increase of practical information, at least 
since the time of Newton ; but in the other strictly practical 
report of the present volume, that of Mr. Barlow on the very 
interesting subject of the strength of materials, little or nothing 
has been done of much theoretical importance since the days of 
Galileo. Circumstances, which it would be easy to point out, 
prevent our setting out, except in rare cases, from unimpeach- 
able data; but several very interesting conclusions of general 
application are derivable from well-conducted experiments, and 
the Association may claim some credit for having brought into 
general notice the ingenious investigations of Mr. Hodgkinson 
of Manchester, more particularly alluded to in this paper. 

" One report, and that the longest which has been printed 
by the Association, remains to be mentioned. It is by Mr. 
Peacock on the present state of Mathematics. When we con- 
sider the vast extent of the subject, and the extremely limited 
number of persons, even in the whole of Europe, capable of 



xviii FOURTH REPORT 1834. 

undertaking it, we must consider the production of a work of 
so much labour as the present, which, as yet, is incomplete, but 
which the author has promised to resume, as the best trophy 
to which we can refer in proof of the entire efficiency of the As- 
sociation according to its original plan, — as a proof of the 
ability and the indefatigable industry which it has enlisted in 
its service, — as a proof that its aim is not the dissemination of 
superficial literature, stamped with the effigy of science, and 
lowered for the demand of the indolent and the careless, — but 
that it is intended to refine the precious metal until it reaches 
a state of chemical purity, not to alloy and coin it for the pur- 
poses of a promiscuous and debased currency. Mr. Peacock 
undertook his report in the early days of the Association, when 
its friends were yet few and its success dubious ; its execution 
has been delayed by the extent of the subject and labour of the 
task. The report on the Dilferential and Integral Calculus, which 
v.as intended to form the basis of it, is delayed, and the present 
one is devoted to a discussion chiefly of algebraic methods, and 
a close examination of the metaphysical principles upon which 
this interpretation of analysis is founded. The author has thus 
been led to extend the views which, in his recent systematic 
treatise, he had developed in regard to the signs of affection of 
algebraic quantities, including those of imaginary quantities, of 
discontinuous functions, and the interpretations of zero and infi- 
nity. The author has then treated of Series, as regards their 
fitness for giving directly conclusive results, particularly when 
such series are divergent, leaving to the other part of the report 
a detail of the progress in the application of series, which is 
more practical than metaphysical. The author then treats hi- 
storically of the elementary works in use on Algebra and Trigo- 
nometry ; and devotes the last part of the report, consisting of 
above fifty pages, to the Theory of Equations, in which he has 
minutely analysed some of the most remarkable papers on this 
abstruse subject. Altogether this report (especially when com- 
pleted,) cannot fail to fulfill, in a striking manner, the two great 
objects of such works : first, to supply those engaged in colla- 
teral branches of science with the means of referring to and ob- 
taining the information they may require upon methods which 
perhaps are of daily utility in physico-mathematical inquiries, 
but with which, from the vast extent of the science of pure ma- 
thematics, the shortness of human life prevents the possibility 
of a complete and systematic acquaintance, unless it be made 
the special object of study ; and, in the second place, to point 
out, where chasms of reasoning occur, what mathematical me- 
thods are impregnable, and what rest upon a still dubious basis, 



PROCEEDINGS OP THE MEETING. XIX 

in a metaphysical point of view, several of which are very spe- 
cifically treated of in Mr. Peacock's report. It is much to be 
desired that nothing may longer postpone the conclusion of a 
work which cannot fail to reflect honour upon the Association. 

" Were those annual Reports the only fruits of the labours of 
this Society, there would be no reason to complain. But yet more 
specific results of its impulsive action on science may be quoted. 
The questions suggested by the reporters and others, and recom- 
mended for investigation, have met with ready attention from se- 
veral individuals capable of satisfactorily treating them. Pro- 
fessor Airy has himself investigated, from direct observation, the 
mass of Jupiter, suggested as a desideratum in his report on As- 
tronomy ; and since the last meeting of the Association, has con- 
firmed his first results by new observations, which give almost 
the same mass by the obsei'ved elongations of the satellites, as 
had been deduced from the perturbations of the small planets 
by Jupiter. Hourly observations of the Thermometer in the 
South of England have, in two instances, been commenced ; 
and we are assured that the same desirable object is about to 
be attained by the zeal of the Committee in India, where the 
Association has established a flourishing colony. A series of 
the best observations for ascertaining the law which regulates 
the fall of rain at different heights, conducted at the sugges- 
tion of the Physical Section, by Messrs. Phillips and Gray of 
York, have been ably discussed by the former gentleman, in 
last year's report, and have since been continued. A regu- 
lar system of Auroral observation, extending from the Shet- 
land Isles to the Land's End, has been established under the 
superintendence of a special committee, and specimens of the 
results have been published. Observations on the supposed in- 
fluence of the Aurora on the Magnetic Needle have likewise 
been pursued in consequence of this proceeding. The condi- 
tions of Terrestrial Magnetism in Ireland have been experimen- 
tally investigated by Professor Lloyd. An important inquiry 
into the law of Isomorphism has been undertaken by a special 
committee, which has likewise reported progress ; and an ela- 
borate synopsis of the whole Fossil Organic Remains found in 
Britain is in progress, under the hands of Professor Phillips, 
Many specific inquiries are besides going forward, under parti- 
cular individuals, to whom they were confided ; whilst it is not 
to be doubted that numberless persons, many of them perhaps 
new to the world of science, are at this moment pursuing inves- 
tigations recommended in general terms, in one or other of the 
publications of the Society. 

" To others the Association has not scrupled to commit a por- 
tion of the funds at their disposal, for the purpose of pursuing 



XX FOURTH REPORT — 1834. 

objects which required an outlay not to be expected from in- 
dividuals. Among the most important of these is the collec- 
tion of the Numerical Constants of Nature and Art, which are 
of perpetual recurrence in physical inquiries, and which has 
been confided to the superintendence of Mr. Babbage. When 
objects of still more peculiar national importance presented 
themselves, the Association has fulfilled its pledge of stimu- 
lating Government to the aid of science. Five hundred pounds 
have been advanced by the Lords of the Treasury towards the 
reductions of the Greenwich Obsei*vations, at the instance of the 
Association ; and more recently the observations recommended 
by the Committee on Tides have been undertaken, by order of 
the Lords of the Admiralty, at above 500 stations on the coast 
of Britain. 

'* Individuals, as we have said, have been stimulated by the in- 
fluence of the Association ; but so may nations and great bodies 
of men. Its published proceedings have found their way into 
every quarter, and are tending to produce corresponding efforts 
in distant lands. Our reports on science have produced some 
very interesting counterparts in the literary town of Geneva. 
America has taken the lead in several departments of experiment 
recommended by the Association ; and the instructions for con- 
ducting uniform systems of observation have been reprinted and 
circulated in the New World. We must likewise consider it as 
an especial proof of the influence and importance of the Associa- 
tion, that a Report on the Progress of American Geology has 
been undertaken and executed by Professor Rogers of Philadel- 
phia*. Similar contributions from some other foreign countries 
have been promised, which will extend the utility of the Asso- 
ciation, by making us acquainted with the more characteristic 
state of science in the various parts of Europe. Nor can we fail, 
on the present occasion, to consider as a most auspicious pro- 
mise of the future success of the Association, that the distin- 
guished Secretary of the Institute of France has not only ho- 
noured this meeting by his presence, but has promised to interest 
that powerful body on behalf of the important objects contem- 
plated by the Association, which its cooperation might effec- 
tually secure. The formation of a Statistical Section at Cam- 

• Some strictures having been made in America on the extracts from this re- 
port which appeared in the Edinburgh New Philosophical Journal, it may be 
proper to remark that, in requesting from Professor Rogers a general outline 
of what is known of the geology of the United States, the Association could not 
expect that all parts of such a sketch should be verified by the personal obser- 
vation of the author ; it is also due to him to state that his report is published 
inider the unavoidable disadvantage of not having been revised by the author 
in passing through the press. — Editor. 



PROCEEDINGS OF THE MEETING. XXI 

bridge was the prelude to the establishment of a flourishing 
society, which acknowledges itself the offspring of this Institu- 
tion, and which promises, by a procedure similar to that intro- 
duced by the Association, to advance materially the greatly neg- 
lected subject of British statistics. 

" Gentlemen, I shall be satisfied if, in the preceding hasty re- 
view, I shall have given you some direct and tangible proof of 
the working of a system, the excellence of which may best be 
appreciated by such statements. Did it come within the scope 
of these observations, (which it does not,) I could quote exam- 
ples, equally specific, of the powerful moral influence of the 
Association. Yet, in conclusion, I will call upon you to remark, 
because I believe that it comes home to the breast of every one 
who has habitually attended these our annual reunions, what a 
spirit is infused into otherwise isolated and perhaps ineffective 
exertions, when many minds, conversant with one class of ob- 
jects, and aiming at one great end, unite in friendly and intel- 
lectual converse. There is an impulse there which no system of 
cold calculation can estimate. There is a bond in the sense of 
community of purpose, which is the cement of society. There 
has been, we fear, a general but most erroneous impression 
abroad, that philosophers are incapable of enjoying, and stoically 
superior to, the ordinary sociabilities of life, — that scientific ar- 
dour dwells only in the mind of the solitary, and gives place to 
narrow-minded jealousy, when another attempts to share the 
prize. If, in a few cases, such allegations have not been with- 
out a colouring of truth, it is to meetings like these that we 
should look for a cure which no mere reasoning can effect. The 
most striking feature of these meetings has ever been, the per- 
vading sense which has thrown a peculiar character over them, 
of the one great and exalted object which united so many di- 
stinct and unconnected individuals, — which not less has dravni 
into this great assembly, the single and unaided labourer in the 
cause of science, from the solitudes of the country, or the still 
greater intellectual solitude of some noisy and commercial city, 
and the phalanx of scholars who have shared the advantages, and 
sustained the reputation, of the great academical foundations of 
the country. 

" True it is that, looking merely to the moral influence of the 
Association, some there are whose zeal for the promotion of 
science places them above the necessity of such an external sti- 
mulant. But we must not legislate for individual and such rare 
cases. Those who have once trod the higher walks of science, 
need perhaps no inducements to revisit these sublime elevations. 
The footway may be sharp and narrow, surrounded with preci- 



XXii FOURTH REPORT — 1834. 

pices and occasionally enveloped in mists, — but they have there 
breathed that pure and elastic air which descends not to lower 
regions, — and through the cloudy openings they have caught 
rich and extensive views, showing at once the configuration and 
the bearing of the country, which less daring spirits must pain- 
fully and partially explore. Such men are independent of any 
reward but that which the exertion itself bestows ; yet, let it 
not be called an ignoble motive, if the traveller, embarked on 
the discovery of a new, and hitherto untrodden, path, wliich 
leads to the point to which he aspires, feels fresh vigour infused 
into his frame, by the consciousness that, in the valley beneath, 
a thousand eyes are watching his progi'ess, and that a shout of 
applause, unheard except perhaps in imagination by him, will 
announce the arrival of the adventurer at the summit of the al- 
pine chain. 

" We look forward without anxiety to the future fate of the 
Association. So long as it continues to be guided by the same 
principles as heretofore, it cannot fail to confer a substantial be- 
nefit upon the science of Britain. We have enough of energy 
in action to communicate to the many the knowledge of the few, 
but it is to prevent the stagnation of the stream at the fountain- 
head, which should be our especial object. True it is that but a 
few are able or disposed to devote themselves unreservedly to 
those great enterprises which require the whole man ; yet, 
though it is morally impossible that any others should under- 
take the highest generalizations to which we have just alluded, 
a division of labour is as practicable in intellectual as in mecha- 
nical science. If one designing mind direct the whole, distinct 
labourers may be engaged, unknowing each other's tasks, yet 
happy in the consciousness of being more usefully and more 
honourably employed than in imperfectly attempting the execu- 
tion of works which they might individually complete. The ex- 
quisite piece of mechanism which, in the form of a watch, issues 
from the manufactories at Paris or Geneva, has its various ele- 
ments of its wheels and pinions, its balance and fusee, collected 
from the detached cottages of the peasantry of the Jura. 

" To combine individual effort, to render parts capable of com- 
bination into a whole, to economize time, and thus virtually to 
lengthen the lives of those whose exertions are valuable in the 
cause of science, may be considered as humble, yet surely most 
important, contributions to its advancement. We shall have 
little reason to regret the want of a National Institute, whose 
existence is the just subject of pride to our continental neigh- 
bours, so long as individual exertion can supply the stimulus 
which even the sunshine of wealth and patronage has sometimes 
failed to excite." 



PROCEEDINGS OF THE MEETING. XXIU 

The Members reassembled at the same time and place on the 
evenings of Tuesday, Wednesday, Thursday, and Friday. At 
these meetings lectures on various subjects of science were de- 
livered by Dr. Robinson, Dr. Lardner, Dr. Buckland, Professor 
Sedgwick, and Mr. WhewelL On each evening the Chairmen or 
Secretaries of the Sectional Committees reported the proceed- 
ings which had taken place during the morning in their respec- 
tive sections. In concluding the last report of the transactions 
of the Medical section. Dr. Abercrombie said, " The whole 
business of the section, Sir, has been conducted in the most 
satisfactory manner, and a great variety of important communi- 
cations has been laid before it; but considering these as not 
adapted in general for a mixed audience, I have alluded to them 
in very few words ; having, therefore, intruded but little upon 
your time, I trust you will indulge me with your attention while 
I express in the name of the medical profession of Edinburgh 
the high satisfaction we have received from the meeting which 
is now drawing to a close, especially by having been brought 
into personal intercourse, and, I trust, personal friendship with 
so many distinguished individuals whose names have been long 
familiar to us as holding the highest rank in science. From 
their combined exertions we expect the most valuable results to 
every department of human knowledge. I am none of those 
who anticipate from the researches of physical science anything 
adverse to the highest interests of man as a moral being. On 
the contrary, I am convinced that those who have made the 
greatest advances in true science will be the first to acknowledge 
their own insignificance when viewed in relation to that incom- 
prehensible One who guides the planet in its course, and main- 
tains the complicated movements of ten thousand suns and ten 
thousand systems in undeviating harmony. Infidelity and irre- 
ligion, I am satisfied, are the offspring of ignorance united to 
presumption ; and the boldest researches of physical science, if 
conducted in the spirit of true philosophy, must lead us but to 
new discoveries of the power, and wisdom, and harmony, and 
beauty which pervade all the works of Him, who is eternal." 

The last General Meeting was held on Saturday the 13th of 
September, at 3 p.m., in the hall of the College Libi'ary. The 
General Secretary reported the Proceedings of the General Com- 
mittee, the time and place appointed for the next meeting, the 
names of the Officers and Council who had been elected, the 
objects and extent of the votes of money for promoting experi- 
ments and investigations, the number and nature of the reports 
solicited from men eminent in science, and the recommendations 
of special subjects for research. 



Xxiv FOURTH REPORT — 1834. 

The thanks of the Association were then voted to the follow- 
ing bodies and individuals : — 

"On the motion of the Rev. Dr. Buckland, seconded by the 
Rev. Dr. Lloyd, — To the University of Edinburgh, its Patrons 
and Officers, for the ample accommodation afforded to the meet- 
ing in the College; 

On the motion of Lord Greenock, seconded by Prof. Forbes,— 
To the Royal College of Physicians and the public bodies who 
have given or offered the use of their premises to the Association : 

On the motion of the Rev. Baden Powell, seconded by G. B. 
Greenough, Esq., — To the proprietors of the Assembly-rooms, 
who have given the gratuitous use of their spacious premises, 
and fitted them up in a splendid manner for the reception of the 
Association ; 

On the motion of R. L Murchison, Esq., seconded by the 
Rev. Prof. Sedgwick, — To the Highland and Agricultural Society 
of Scotland. 

Mr. Murchison stated that this Society was eminently en- 
titled to the thanks of the Association for their liberal and zea- 
lous endeavours to promote the geology of their country. Inti- 
mately persuaded that the agricultural and mineral resources of 
Scotland would be improved by an increased knowledge of its 
subsoil and rocks, the Highland Society had advanced premiums 
for the completion of a geological map of Scotland, and had 
exerted themselves to obtain possession, through His Majesty's 
Government, of the valuable unpublished documents of Dr. Mac- 
Culloch, which, without these spirited efforts, might long have 
lain dormant. 

On the motion of the Rev. Wm. Whewell, seconded by Prof. 
Hamilton, thanks were voted — To the President (Sir Thomas 
Brisbane,) and the Vice-Presidents (Sir David Brewster, K. H., 
and the Rev. Dr. Robinson) ; 

On the motion of the Rev. W. V. Harcourt, seconded by Prof. 
Phillips, — To John Robison, Esq., and Prof. Forbes, Secretaries 
for the Edinburgh meeting ; 

On the motion of John Taylor, Esq., seconded by John 
Robison, Esq., — To the T purer and the Committee of Re- 
ception, I 

Mr. Charles Forb J Treasurer, 
Dr. Christison, "" f 
Dr. Borthewick, 

Mr. Cay, )> Committee of Receptiofif 

Mr. Craigie, 
Mr. Burt, J 

and other gentlemen who gave their Valuable aid in making ar- 
rangements for the meeting ; 



PROeEKDINGS OF THE MEETING. XXV 

On the motion of Prof. Sedgwick, seconded by Lord Brougham, 
— To M. Arago and other distinguished foreigners wlio have ho- 
noured the meeting with their presence on this occasion j 

The Lord Chancellor said, " I rise to second the motion con- 
veying thanks to these most illustrious men. The high honour 
of being called upon to perform this duty I owe, not, certainly, 
to any service I have done to this Association, because this your 
last day of meeting is (owing to an accident of a domestic na- 
ture, which retarded my journey,) the first of my appearing 
here. I owe it to the circumstance of having the honour, the 
very undeserved honour (but yet one of the proudest of my life), 
to be a member of the National Institute of France, and the 
friend of the distinguished philosopher whose name is mentioned 
in this motion. Gentlemen, allow me to say that I look upon 
this as one of the most important and unquestionable of all the 
benefits this Association is calculated to bestow — that it brings 
together men of science from every quarter of the world. The 
benefits of this are great to science ; but they are great, also, to 
society ; for in propoi'tion as men know one another, they are 
the more disposed to cultivate habits of friendly intercourse, 
especially if their intimacy subsists on grounds so mutual as 
science : for they who devote themselves to science are of no 
country ; over them the angry blast and tempest of war rages 
innocuous ; the pursuits in which they unite are naturally favour- 
able to that greatest of all objects which human rulers ought to 
have in mind, I mean the maintenance of peace and goodwill 
among men. It has sometimes been remarked, that war is a 
game at which, if the people were wise, governments would not 
often play ; and it has also been said of men, that the longer they 
live the more clearly tkey see that life is too short to be spent in 
personal quarrels ; it is the same with nations : the world is grow- 
ing too wise and experienced to bear war. As there is no duty 
more sacred and imperative on the part of governments than to 
promote, by every means, that peace which ought to bind the 
great family of mankind together in all its departments and in- 
stitutions, so I hold, that whatever brings men into contact on 
such mutual ground as science tends to facilitate the task of 
rulers, and makes it easy to keep at peace with neighbouring 
states. I beg leave, therefore, both on scientific principles and 
also on the principles of universal philanthropy, most heartily 
to second the motion." 

On the motion of the Rev. Dr. Robinson, seconded by Sir 
Charles Lemon, thanks were voted to the Rev. William Vernon 
Harcourt for his continued and unremitting exertions as General 
Secretary. - 

1834. c 



XXvi FOURTH REPORT — 1834. 

The President, in closing the meeting, said, that it had been 
his good fortune to attend all the former meetings of the Asso- 
ciation at York, Oxford, and Cambridge, and he was rejoiced to 
think that Scotland had not fallen short in the reception which 
it had given them on the present occasion ; he had himself shared 
in the benefit of those hospitable feelings with which the Associ- 
ation had been welcomed, having had the honour that day of 
receiving with several distinguished individuals the freedom of 
the City of Edinburgh*. "The eminent foreigners," he added, 
" who have attended the meeting have all expressed their desire 
to assist in promoting the objects of the Association, and I have 
been requested by my illustrious friend M. Arago, whom I have 
had the happiness of knowing for nineteen years, to assure them 
of his own willingness and that of the Institute of France to co- 
operate with them in every thing in which mutual assistance 
might be serviceable to the advancement of science." -He then 
adjourned the meeting to the 10th of August, 1835, at Dublin. 



GENERAL COMMITTEE. 

The General Committee met in the apartments of the Royal 
Society on Monday the Sth of September, and came to the fol- 
lowing Resolutions : 

Hides. — That in Rule 2, respecting privileges of admission, 
for the words ' Fellows and Members of Royal and Chartered 
Societies', be substituted the words ' Fellows and Members of 
Chartered Literary and Philosophical Societies publishing Trans- 
actions'. 

That grants of pecuniary aid for scientific purposes from the 
fimds of the Association shall expire at the meeting following 
that at which they were granted, unless they shall have been 
acted upon, or a continuation of them ordered by the General 
Committee. 

Committee of Recommendatio7is. — That Mr. W, Baily, Sir 
D. Brewster, Dr. Brown, Rev. Dr. Buckland, Rev. G. Peacock, 
Professor Forbes, Professor Hamilton, Professor Roget, Dr. 
Turner, Rev. W, Whewell, Dr. Richardson, and the Rev. W. 
V. Harcourt be a Committee to report in what manner the funds 
of the Society may be best appropriated to the promotion of sci- 

• At an extraordinary meeting of the Town Council, held on Saturday, the 
13th of September, diplomas of the freedom of the City of Edinburgh were pre- 
sented by the Lord Provost to the following Members of the Association : Sir 
Thomas Brisbane, M, Arago, Professor Moll, Dr. Dalton, and Dr. Brown. 



PROCEEDINGS OF THE MEETING. XXVll.' 

ence, and what reports on the state and progress of science it 
is desirable to obtain, directing their attention especiallj^ to the 
recommendations of the Committees of Science. 

That this Committee have power to add to their number the 
names of any Members of the Association whose assistance they, 
may desire. 

That this Committee be directed to communicate with M. 
Arago, and to report whether there are any scientific objects 
which may be advanced by the cooperation of the Association 
with the Institute of France. 

That the Committees for Science be requested to communicate 
to the Committee of Recommendations any suggestions they 
may think useful respecting particular scientific objects which 
might be advanced by the appropriation of the funds of the 
Association, and particular departments of science on the state 
and progress of which reports are wanted. 

Committees of Science. — -That the Members of the Committees 
of Science established at Cambridge be considered as the Sec- 
tional Committees of this meeting, with power to add to their 
number from the Members of the General Committee. 

Two Secretaries were appointed to each Committee. 

Corresponding Members. — That MM. Arago, Quetelet, CEr- 
sted, and De la Rive be elected Corresponding Members of the 
Association. 

That the Council be empowered to add to the list of corre- 
sponding members the names of foreigners eminent in science, 
and desirous to cooperate in the objects of the Association*. 

The Committee met from day to day for the election of Mem- 
bers. 

On Saturday, the Committee of Recommendations having 
made their report, after receiving from the Treasurer an account 
of the state of the funds, the General Committee adopted the 
recommendations and allowed the grants of money therein con- 
tained. 

Letters of invitation to the Association having been received 
from the Bristol Institution, the Literary and Philosophical So- 
ciety of Liverpool, the Royal Dublin Society, the Royal Irish Aca- 
demy, the Geological Society of Ireland, the University of Dublin, 
— Itwas resolved, That the next meeting of the Association beheld 
in Dublin, and that the thanks of the Association be returned to the 
scientific institutions from which invitations have been received. 

* In consequence of this resolution Baron Humboldt, Professor Berzelius, 
Professor Schumacher, Professor Agassiz, and Professor Moll were elected Cor« 
responding Members of the British Association. 

C 2 



XXviii FOURTH REPORT 1834. 

That the Council be instructed to make such arrangements 
that the Sections may be enabled to meet for scientific business 
on the morning of the second Monday in August. 

That the salary of the Assistant General Secretary be increased 
to the sum of 200/. per annum, to enable him to attend at the 
places of meeting for the purpose of making arrangements pre- 
vious to the assembly of the Association, and to bear such ex- 
penses as the Council may think proper to indicate. 



Officers and Council elected. 

President elect. ^^ev. Dr. Lloyd, Prov. of Trin. Coll. Dublin. 

Fice-Presidents elect. — Lord Oxmantown. Rev. W. Whe- 
well. 

Secretaries for Dublin. — Professor Hamilton. Professor 
Lloyd. 

Treasurer. — John Taylor. 

General Secretary. — Rev. W. V. Harcourt. 

Assistant General Secretary. — Professor Phillips. 

Council. — Professor Airy. Rev. Dr. Buckland. Dr. Brown. 
G. Bentham. William Clift. Professor Christie. J. E. Drink- 
water. Geo. B. Greenough. Dr. Hodgkin. John W. Lubbock. 
G. Rennie. Rev. G. Peacock. Dr. Roget. William Yarrell. 
Ex officio, — ^The Trustees (Professor Babbage, R. I. Murchison, 
John Taylor,) and the Officers of the Association. 

Secretaries. — Dr. E. Turner. Rev. J. Yates. 



Members of Committees of Sciences elected. 

I. Mathematics and General Physics. 

Chairman. — Rev. W. Whewell. 

Deputy Chairmen. — Rev. Dr. Lloyd. Rev. Dr. Robinson. 
Secretaries. — Professor Forbes. Professor Lloyd. 
. Committee. — M. Arago. F. Baily. Sir David Brewster. Sir 
Thomas Brisbane. Rev. J. Bowstead. E. J. Cooper. Lieute- 
nant Drummond. Rev. R. Greswell. Professor Hamilton. Tho- 
mas Henderson. William Hopkins. Dr. Jackson. Dr. Knight. 
Rev. Dr. Lardner. Professor Moll. Rev. R. Murphy. Lieute- 
nant Murphy. Rev. G. Peacock. Rev. Dr. Pearson. Profes- 
sor Powell. John Ramage. G. Rennie. Rev. Dr. Robinson. 
John Robison. Professor Stevelly. Professor Thomson. Pro- 
fessor Wallace. W. L. Wharton. Charles Wheatstone. 



PROCEEDINGS OF THE MEETING, XXIX 

11. Chemistry and Mineralogy. 

Chairman. — Dr. Hope. 

Deputy-Chairmen. — Dr. Dalton. Dr. Thomas Thomson. 

Secretaries. — Mr. Johnston. Dr. Christison. 

Committee. — Dr. Daubeny. Dr. Turner. Dr. Lloyd. Rev. 
W. V. Harcom-t. Thos. J. Pearsall. William Hatfeild. Pro- 
fessor Traill. Dr. William Gregory. Dr. Thomas Clark. Pro- 
fessor Graham. Arthur Connell. Luke Howard. Charles Ten- 
nant. Charles Mackintosh. William West. Richard Phillips. 

in. Geology and Geography. 

Chairman. — Professor Jameson. 

Deputy- Chairtnen.— Lord Greenock. G. B. Greenough. 

Secretaries.— Professor Phillips. T. Jameson Torrie. Rev. 
J. Yates. 

Committee.— Viev. Dr. Buckland. Dr. Boase. J. Bryce. 
Major Clerke. Rev. Professor Sedgwick. Colonel Silvertop. 
H.T.Witham. William Smith. John Taylor. W. C. Trevelyan. 
R. I. Murchison. William Hutton. Charles Lyell. L. Horner. 
J. B. Pentland. R.J.Griffith. William Copland. Dr. Hibbert. 
R. Stevenson. Lieut. Murphy. William Clift. Sir Thomas 
Dick Lauder. Sir George Mackenzie. Rev. Dr. Fleming. 
Dr. Traill. Captain Maconochie. Henry Woolcombe. S.P.Pratt. 
M. Agassiz. William Nicol. Rev. W. Turner. 

IV. Natural History. 

Chairman. — Professor Graham. 

Deputy -Chairman. — Sir William Jardine, Bart. 

Secretaries. — William Yarrell. Professor Burnett. 

Committee. — G. A. Walker Arnott. M. Agassiz. Rev. Dr. 
Adam. C. Babington. Dr. Robert Brown. W. Christy. 
Dr. Coldstream. Allan Cunningham. John Curtis. David Don. 
P.B.Duncan. Dr. R.Dickson. Dr.Daubeny. Rev.L.W.P.Gar- 
nons. Dr. Greville. B. D. Greene, Boston, U.S. Professor 
Henslow. Professor Hooker. Rev. Dr. Hincks. Professor 

Jameson. Rev. L. Jenyns. Mackay. Dr. Richardson. 

Commander Ross. J. F. Royle. P. J. Selby. Colonel Sykes. 
W. Spence. Richard Taylor. Professor Treviranus. William 
Thompson. Dr. Wasse. James Wilson. 



XXX KOUUTU REPORT— 1834. 

V. Anatomy and Medicine. 

Chairman . — Dr. Abercrombie. 

Dejnity-Chairmeii. — Sir Charles Bell. Professor Clark. 

Secretaries.— Dv. Roget. Dr. William Thomson. 

Committee. — Dr. Alison. Dr. Arnott. Sir G. Ballingall, 
S. D. Broughton. Dr. J. Campbell. Professor Clark. William 
Clift. Dr. Davidson. Dr. Hodgkin. Dr. Holme. Dr. Home. 
Dr. Maclagan. Dr. Roget. James Russell. Dr. Thomson. 
Dj*. a. T. Thomson. Dr. Wm. Thomson. Professor Trevi- 
ranus. Dr. Turner. Dr. Yelloly. 

VI. Statistics. 

Chairman. — Sir Charles Lemon, Bart. 

Deputy-Chairmen. — Colonel Sykes. Benjamin Hey wood. 

Secretaries. — Dr. Cleland. C, Hope Maclean. 

Committee. — Howard Elphinstone. Rev. E. Stanley. J. E. 
Drinkvvater. Rev. W. Whewell. The Earl Fitzwilliam. Sir 
John Sinclair, Bart. Sir Thomas Acland, Bart. John Kennedy. 
Captain Churchill. R. I. Murchison. John Whishaw. Dr. 
Chalmers. L.Horner. John Marshall. Neil Malcolm. Fran- 
cis Clark. Major Shadvvell Clerke. George William Wood. 
Right Hon. Lord Jeffrey. John Gordon. Sir Henry Jardine. 
Right Hon. Holt Mackenzie. Rev. Dr. Henry Duncan. Dr. 
Brunton. Rev. Peter Chalmers. 



COMMITTEE OF RECOMMENDATIONS. 

Meetings of this Committee were held on Thursday, Friday, 
and Saturday, for the purpose of conferring with M. Arago, 
and considering and revising the recommendations to be sub- 
mitted to the General Committee. 

M. Arago, having been requested to state his views as to 
any points on which it appeared to him that it might be use- 
ful for the British Association to cooperate with the Institute 
of France, noticed in particular the great advantage which 
rnight be expected to accrue to magnetical science from the 
establishment of observatories furnished with adequate instru- 
ments, and under the superintendence of a competent observer, 
throughout the extensive possessions of the British empire, and 
dwelt upon the necessity of arranging magnetical observations 
upon a uniform and well-approved plan. He also spoke of the 
value of more extensive and systematic observations on the tem- 



PROCEEDINGS OF THE MEETING. XXXI 

perature of the earth and springs at small and great depths from 
the surface, and mentioned some of the sources of error in such 
researches, and the means of obviating them*. 

The Committee came to the following Resolutions : 

That it be represented to the Government of this country that 
the British Association conceive it would be of great service to 
science, if magnetical and meteorological observatories were esta- 
blished in several parts of the earth, furnished with proper in- 
struments well constructed on uniform principles, and if provi- 
sion were made for careful and continued observations at those 
places ; — that in Great Britain and its colonies there are points 
favourable for such observations ; and that it is the more desirable 
that the British nation should take a part in carrying them on, 
since a system of similar observations, as the Association is 
informed, has begun to be established in France and its de- 
pendencies. 

That Mr. Baily, Mr. D. Gilbert, Mr. Lubbock, and the Rev. 
G. Peacock be a Committee to make the required representation 
to the Government, and to solicit the cooperation of the French 
Institute. 

That the East India Company be requested to further the 
same objects, especially at their establishment at Madras. 

That notice be given that any persons who may be able to 
obtain the temperature of the air, w^ater, and rock, in mines 
and borings of known depth, or the indications of thermo- 
meters sunk to different depths, in different kinds of soil and 
in different parts of the earth, are requested to make known 
their names and the places where they have this opportunity, in 
order that they may receive instructions for making such ob- 
servations, and communicating the results to the Association. 

That Mr. Taylor, Prof. Forbes, Prof. Powell, Mr. R. Fox, 
Mr. Lubbock, Dr. Dalton, Rev. Dr. Robinson, Prof. Christie, 
Prof. Lloyd, and Prof. Phillips be a Committee, with power to 
give instructions and to make arrangements on the subject of 
the thermometrical observations recommended in the above reso- 
lution, and that 100^. be placed at their disposal for these ob- 
jects f. 

That M. Arago be respectfully requested, with the least pos- 
sible delay, to publish, and to have reduced, his valuable and ex- 
tensive collection of magnetical observations made at the obser- 
vatory at Paris. 

• On the subject of Artesian wells, see the Anmiaire for 1835. 

f The Committee has taken steps to have instruments constructed suitable 
for the experiments in mines, wells, &c., and to have sufficient instructions con- 
veyed to persons who wUl undertake the researches required at selected points 
in various parts of the country. 



XXXll FOURTH REPORT — 1834. 

M. Arago expressed his readiness to comply with the request 
of the Committee as soon as it should become practicable j 
and stated that the immense collection referred to (amounting to 
more than 100,000 careful observations, and relating to nearly 
all parts of magnetical science,) had been some time since des- 
tined for publication, but that the printing of them had been post- 
poned in consequence of an application which had come from 
England for the cooperation of France in furnishing data for the 
improvement of the theory of the tides. When Mr. Lubbock ap- 
plied to the Bureau des Longitudes, through M. Poisson, for tlie 
loan of the manuscript observations on the tides at Brest, it was 
decided, at the earnest recommendation of M. Arago, that an 
object in which other nations were thus taking interest should 
have the preference given to it; that the observations on the 
tides at Brest should be printed at the expense of the French 
Government, and that copies shovUd be furnished to those per- 
sons in foreign countries who were ready to use them. 

The Committee then proceeded to receive and revise the re- 
commendations laid before them by the Committees of Science. 



COMMITTEES OF SCIENCE. 

The several Committees met daily at 10 a.m., to arrange the 
business of the Sections and to determine on the recommenda- 
tions which were to be presented to the Committee appointed 
to receive them. 

Committee for Mathematical and Physical Science. 

The Committee reported on the part of the Sub-Committee for 
discussing observations on the tides (see vol. ii. p. 471-), that 
the discussion of the tide observations, and the formation of 
tide tables, was in considerable progress, and woidd be conti- 
nued with all practicable expedition. That the sum of 50/. only, 
out of the 200/. appropriated by the British Association for this 
purpose, had at present been paid by the Treasurer ; but that it 
was probable that the whole of the sum so appropriated might 
be eventually required. 

The gentlemen of the AtheniBum of Liverpool, on being ap- 
plied to on the part of the British Association, with great libe- 
rality and kindness sent the original manuscript of Mr. Hutch- 
inson's observations to Mr. Dessiou of the Admiralty, who was 
engaged by the Sub-Committee to discuss them. These observa- 
tions are now undergoing the requsite calculations. 



PROCEEDINGS OF THE MEETING. XXXIU 

The Corporation of Liverpool also, at tlie suggestion of the Sub- 
Committee, have established two sets of apparatus for the pur- 
pose of making tide observations at Liverpool, the one at the 
Clarence Docks, the other at the Black Rock. Mr. Yates of 
West Dingle, and Lieut. Drummond, R.N., the director of the 
Ordnance Survey of the coast in that neighbourhood, have given 
much valuable aid to the objects of the Sub-Committee. 

The Committee reported on the part of the Sub-Committee 
for superintending the reiduction of the Observations of Bradley, 
Maskelyne, and Pond, on the Sun, Moon, and Planets, made at 
Greenwich, (see vol. ii. p. 469.), that the reduction of these ob- 
servations was in progress ; that the Royal Society had con- 
tributed a copy of Maskelyne's Observations for that purpose; — 
That the Syndicate of the University Press at Cambridge had 
given the paper and press-work for the printed forms requisite for 
the calculations ; — That one calculator had been employed since 
the beginning of March, in which interval the transits have been 
taken out of Bradley and Maskelyne; the means of the wires have 
also been deduced, some advances made towards completing the 
imperfect transits, and considerable progress in preparing the 
apparent right ascensions of the fundamental stars; — that a 
temporary stop was put to a portion of the work, in conse- 
quence of a very severe illness with which Professor Airy was at- 
tacked during the last summer, but that the work was again 
proceeding with as much expedition as possible. 

The Committee reported the following Recommendations : 

1 . That it is desirable that the Constant of Lunar Nutation 
should be deduced from observations made with the mural circle 
at Greenwich. 

2. That it is expedient that the sum of 100/. be appropriated to 
the purpose above mentioned by the British Association ; and 
that Sir Thomas Brisbane, Rev. Dr. Robinson, and Mr. Baily be 
requested to superintend the deductions. 

3. That it is desirable that the Standard Scale made some 
years ago by Mr. Troughton for the town of Aberdeen should 
be compared with the Standard Scale recently made for the 
Royal Astronomical Society; and that application should be 
made by the British Association to the magistrates of that town 
for the loan of the same for the purpose above mentioned. 

4. That Mr. Baily be requested to make the requisite com- 
parisons, provided the loan of the Scale can be obtained*. 

5. That the Difference of Meridians between the Observatories 
of Greenwich, Cambridge, Oxford, Edinburgh, Dublin, and Ar- 

* The scale has been received, and is under examination by Mr. Baily. 



XXXiv FOURTH REPORT — 1834. 

magh should \>e determined by means of chronometers, or by 
signals, or by both methods, and that application be made to 
•Government for their assistance in accomplishing this object. 
That the Astronomer Royal, Dr. Robinson, Prof. Airy, Prof. 
Rigaud, Prof. Henderson, Prof. Hamilton, Sir Thomas Brisbane 
and Lieut. Drummond be requested to carry this recommenda- 
tion into effect. 

6. That Mr. W. Gray, jun., and Prof. Phillips be requested 
to continue their experiments on the Quantities of Rain falling 
on the top of York Minster and other adjacent stations. 

7. That Mr. Peacock be requested to continue his Report on 
certain branches of Analysis for the next meeting. 

8. That Mr. Whewell be requested to execute for the next 
meeting the Reports on the Mathematical Theories of Heat, 
Electricity, and Magnetism. 

9. That Mr. Challis be requested to proceed with his Report 
on the Mathematical Theory of the Motion of Fluids. 

10. That Mr. Rennie be requested to proceed with his Report 
on Practical Hydraulics. 

11. That Mr. Willis be requested to prepare his Report upon 
Acoustics for the next meeting. 

Committee for Chemical and Mineralogical Science. 

The Committee reported that they had received statements 
of the progress of the experiments on the specific gravity of cer- 
tain gases, and on the effects of long-continued heat on mineral 
and organic substances, for which sums of money had been ap- 
propriated at a former meeting, and recommended the conti- 
nuance of those appropriations. 

They reported also the following Recommendations : 

1. That Mr. Graham be requested to submit to further investi- 
gation the amount of security to be derived from the Safety Lamp. 

2. That Mr. Graham and Dr.Williams be requested to investi- 
gate further the phaenomena of Low Combustion. 

3. That a sum of 10/. be placed at the disposal of Mr. Johnston 
to defray the expense of preparing a specimen of Chemical Con- 
stants, in conformity with the suggestions of Mr. Babbage. 

4. ThatDr.Dalton, Dr.Hope, Dr. T.Thompson, Mr. Whewell, 
Dr. Turner, Prof. Miller, Dr. Gregory, Dr. Christison, Mr. R. 
Phillips, Mr. Graham, Prof. Johnston, Dr. Faraday, Prof. Da- 
niell. Dr. Clark, Prof. Cumming, and Dr. Prout be appointed a 
Committee, to report to the next Meeting their opinion on the 
adoption of an uniform set of Chemical Symbols ; with power to 
add to their number. Dr. Turner to be Secretary. 

5. That Dr. Roget be requested to report on the progress of 



PROCEEDINGS OF THE MEETING. XXXV 

Electro-chemistry and Electro-maguetism, so far as regards the 
experimental part of the subject. 

6. The Committee recommended the researches commenced 
by Sir David Brewster into the Optical properties of Minerals to 
the attention of chemists. 

Committee for Geology and Geography, 

The Committee reported the foUovring Recommendations : 

1. That Mr. Stevenson be requested to complete the Report 
of the relative level of land and sea, and on the waste and exten- 
sion of the land, which he has presented to this Meeting. 

2. That with a view to perfect our knowledge of the Fossil 
Ichthyology of the British islands, a sum not exceeding 105 Z. be 
paid by the Treasurer to Dr. Buckland, Prof. Sedgwick, and 
Mr. Murchison, to be applied for the purpose of assisting 
M. Agassiz in carrying on his Ichthyological work. 

3. That the recommendations relating to the veins and sections 
of Flintshire, the heaves of Cornwall, the quantity of mud and 
silt, the experiments of Mr. G. Watt, and the desiderata noticed 
by Mr. John Taylor and Mr. Conybeare, and the sixth and tenth 
queries, be repeated. 

4. That a sum not exceeding 20/. be placed at the disposal of 
Mr. J. Yates and Mr. G. Rennie, for the purpose of the experi- 
ments on the quantity of mud and silt in rivers. 

5. That evidence should be collected as to the direction and 
probable sources from which drifted blocks and pebbles, referri- 
ble to rocks not existing in the neighbourhood where they now 
occur, whether in insulated masses, or in beds of superficial gra- 
vel, may have been derived*. 

6. That evidence should be collected as to the form and direc- 
tion of hills or ridges of superficial gravel, and the sources whence 
the materials of such gravel hills may have been transported to 
their present place. 

7. That observations should be made on the direction and depth 
of grooves and hollows, such as are often found on the faces of 
hard rocks and beneath superficial deposits of drifted clay and 
gravel not referrible to the action of any existing currents. 

8. The Committee further reported that it appeared to them 
that the advancement of various branches of science is greatly 
retarded by the want of an accurate map of the whole of the 
British Islands : — that it be recommended to the Council to con- 
sider of the propriety of representing this opinion to His Ma- 

• The Assistant-Secretary has forwarded to persons known to possess infor- 
mation on these subjects a circular, of which copies may be had on application 
to him. 



XXXVi FOURTH REPORT. — 1834. 

jesty's Government, with a view of expediting the completion of 
the still unfinished or unpublished parts of the Ordnance Survey* . 

• In consequence of this recommendation the following Memorial, upon the 
state and progress of the Ordnance Survey of Great Britain, was presented to 
the Chancellor of the Exchequer on the part of the Association, by a deputation 
from the Council : 

Memorial. 

"The Trigonometrical Survey of Great Britain, conducted by men of high Sci- 
entific attainments, commenced its operations in 1798, with a view to the con- 
struction of a general map, and in 1805 the first sheets of that work were pub- 
lished. Of one hundred and eight sheets required to form the whole map of 
England sixty-five only have yet been published, at which rate of progress 
thirty years would elapse before the survey could reach the banks of the Tweed. 
Now, although from the exertions recently made in this department, the rate of 
publication has been accelerated, yet, on reference to the highest authorities on 
this subject, no prospect is held out, even upon the present improved system, 
that the desired result can be attained in less than ten years, after which the 
entire map of Scotland will remain to be constructed. 

" Your memorialists conceive that this simple statement of the condition 
and future prospects of the Survey might in itself be a sufficient reason to in- 
duce Parliament to increase the grant allotted to this branch of public service. 
But to place the evil complained of in a clear light, they venture to submit to 
you the following considerations. 

" Urgent calls for the acceleration of this Map are made by many proprietors of 
land and mines both in the North of England and in Scotland, who contend that 
in the construction of rail-roads, canals, or other public works, that portion 
of the kingdom is subjected to great expenses and difficulties from the want of 
it. In forming the Western rail-road from London to Bristol an outlay of several 
thousand pounds in surveying has been saved by the possession of those por- 
tions of the Map which are published, whilst the correctness of the physical 
features laid down upon them has enabled the engineer at once to select his line 
of operations, and thus to gain at least a year of time in the commencement of 
the work. Similar results have been obtained in Ireland, in forming the Ulster 
canal, in consequence of the publication of the Ordnance Map of that country. 
Another important benefit will be conferred upon the public by the completion 
of this Map, in the correction of the coast surveys, determining the precise posi- 
tion of headlands and form of bays ; a point of considerable moment in the 
northern parts of this maritime countr}', where the outline of the coast is broken 
and dangerous. In illustration of this it maj' be mentioned, that in the progress 
of the yet unpublished parts of this Survey, errors of position in the most ac- 
credited charts of this coast have been detected to an extent in one instance of 
eleven miles ! 

" Your memorialists particularly invite attention to the fact, that although 
a very large portion of the expense relating to the Scottish survey has been in- 
curred, not only in establishing the great triangulation, but also in minutely and 
accurately surveying a large portion of the South-west of Scotland, the mate- 
rials so collected are now, they believe, laid by in the archives of the Map-office, 
without the prospect of their being made available for many years; whilst it 
must be observed that the knowledge thus locked up relates to one of those 
tracts of the empire where its diffusion would prove of singular advantage. 
Upon this head, indeed, it can be shown that the delay is not only a negative but 
a positive evil, in as much as, but for the conviction that many years could 
not elapse between the execution of this Survey and its publication, the inhabi- 
tants themselves would have endeavoured to improve the maps. 

'• In this backward state of a national geographical survey, Great Britain 



PROCEiEDINGS OF THE MEETrNG. XXXVU 

.; Committee for Natural History. 

The Committee reported the following Recommendations : 
// was resolved, 

1 . That Mr. James Wilson be requested to report on the pre- 
sent state of our knowledge of the geographical distribution of 
Insects, particularly Coleoptera. 

2. That Dr. Richardson be requested to prepare a Report on 
the state of our knowledge of the Zoology of North America. 

stands almost alone among the civilized nations of Europe, whilst it is obvious 
that in no country can the perfection of its maps be more imperiouslj' called 
for. The trigonometrical survey of Austria is completed as respects the Tyrol, 
the Eastern Alps, Bohemia, and Austria Proper. 

" Prussia has nearly completed her survey. 

" France, though possessing the elaborate maps of Cassini, has still deemed it 
essential to institute a new survey of her whole dominions, which is now going 
on in so vigorous a manner, that though only commenced in the year 1828, 
there is every reason to suppose that the whole will be finished long before 
the British survey (at its present rate of progress) will have been completed. 

" Bavaria holds forth an example highly worthy of imitation. Her survey, 
commencing in 1819, has made such rapid progress that out of one hundred 
sheets to illustrate her territories sixty-three have been already published, and 
the whole work will be terminated in six years, and this too upon a scale of 
three inches to a mile. 

" Now in none of these countries is there the hope that such expenditure of 
public money can be repaid, whilst in England and Scotland there are many 
districts where the sale of the Trigonometrical Survey tvill go far towards re- 
paying the cost of production. 

" Though deeply sensible of the advantages which must accrue to physical 
science from the diffusion of these maps, seeing that the published portions of 
them have already enabled the geologist to develope with precision the mineral 
structure of large tracts of England, your memorialists solely avoid dwelling 
upon this important point because the subject requires more explanation than 
can be well condensed into a short memorial. 

" Anxious for the progress of science, and its application to national uses 
in evei-y portion of the United Kingdom, your memorialists have had their at- 
tention the more powerfully attracted to the languid condition of the Ordnance 
Survey of Great Britain, by the contrast which it presents to the active manner 
in which the survey of Ireland is now conducted ; for whilst they rejoice that 
this important object is there so munificently supported as to admit of the rapid 
publication of a map constructed upon a scale of six inches to a mile, they must 
at the same time deplore, in regard to some of the most valuable tracts of 
'England and Scotland, that a survey upon a scale of only one inch to a mile 
is making such feeble progress. 

" Your memorialists therefore trust that His Majesty's Government will 
suggest to Parliament the propriety of an adequate gi-antfor the acceleration of 
a work in which so many public interests are involved, and they feel confi- 
dent that enlightened men of all political parties will unite in the support of 
such a truly useful and national measure. 

" By order of the Council of the British Association 
for the Advancement of Science, 
. "May 28, 1835. (Signed) " ROD. I. MURCHISON, 

" Chairman," 



XXXVlll FOURTH REPORT 1834. 

3. That Dr. Greene and Dr. Hooker be requested to prepare a 
Report on the state of our knowledge of the Botany of North 
America. 

4. That the Zoological Queries introduced in last year's Re- 
commendations be continued, except the 6th and 7th. 

5. That the Botanical Inquiries be continued. 

6. As a full and arranged Catalogue of the works on Natural 
History (including Memoirs, &c., in Journals and Transactions,) 
would greatly facilitate the study of that branch of science, it is 
recommended that at the next meeting of the Association a 
Committee be appointed for devising the means of forming and 
publishing such a catalogue ; and that in the mean time, to aid 
the labours of that Committee, gentlemen who have devoted 
themselves to the study of particular departments of natural 
history be earnestly requested to send in to the Assistant-Secre- 
tary lists of the works, memoirs, &c., relating to such depart- 
ments. 

Medical Committee. 

The Medical Committee reported that the sum of 25/. was 
placed at the disposal of Dr. Marshall Hall and Mr. Broughton 
for the investigation of the subject of the Sensibilities of the 
Nerves of the Brain ; that these gentlemen have presented a 
report, which has been read and highly approved ; that their 
experiments are not yet complete, but they do not ask for any 
further grant for the prosecution of them. {Report received.) 

They further reported that a sum of 25/. was placed at the 
disposal of Dr. Roupell and Dr. Hodgkin for prosecuting an in- 
quiry into the effects of poisons on the animal oeconomy ; that 
an interim report has been read from these gentlemen who are 
prosecuting the inquiry, and that they do not at present ask for 
any further grant. 

The Committee recommended, as an important object of in- 
quiry, the anatomical relations of the absorbent and venous sy- 
stems in the different classes of animals, to be illustrated by in- 
jected preparations and gr.iphic representations. 

The Committee, considering the contradictory results ob- 
tained by the distinguished anatomists who have prosecuted this 
subject of investigation, recommended that two Sub-Committees 
be appointed for prosecuting the inquiry, the one to sit at Edin- 
burgh and the other in London. 

The Edinburgh Sub-Committee to consist of Dr. Allen Thomp- 
son, Dr. Alison, Dr. Fletcher, Dr. Sharpus, Dr. Hardyside, Dr. 
Reid, Mr. Mackenzie and Mr. Dick ; and the London Sub-Com- 
mittee to consist of Dr. Hodgkin, Dr. Roget, Dr. Clark of Cam- 
bridge, Mr. Bracey Clark, Mr. Clift and Mr. Broughton, with 



PROCEEDINGS OF THE MEETIXQ. XXXIX. 

power to add to their numbers. They further recommended 
that a sum not exceeding 25 Z. should be placed at the disposal 
of each Sub-Committee for assisting the prosecution of such re- 
searches. 

The Committee recommended the prosecution of inquiries on 
the pathology of the Nervous System ; on the successive motions 
of the different parts of the heart, and the sounds which accom- 
pany them. Three Committees were named for the prosecution 
of these researches in London, Edinburgh, and Dublin. 

The Committee recommended the appointment of Medical 
Sub-Committees, to communicate with the Statistical Com- 
mittee of the Association, or with the Statistical Society in Lon- 
don, relative to a registration of deaths, comprising particulars 
of a medical nature, with the view that if any legislative measure 
should hereafter be adopted as to registration, such suggestions 
may be offered by the Association as may seem best fitted to at- 
tain the requisite information for this desirable object. Two 
Committees were named, one in London and the other in Edin- 
burgh. London : Drs. Yelloly, Bright, Roget, Bisset Hawkins, 
and Clark, 6, George Street, Hanover Square. Edinburgh: 
Drs. Abercrombie, Traill, Christison, W.Thomson, and Alison*. 
The Committee recommended that Dr. Christison be re- 
quested to draw up a Report on the circumstances in vegetation 
which influence the medicinal efficacy of plants. 

Statistical Committee. 

The Committee recommended that a Sub-Committee should 
be formed, who should associate with themselves certain jrentle- 
men connected with the conduct and pubUcation of the new 
Statistical Account of Scotland, to be named by that body for 
the purpose of drawing up a set of queries by which more mi- 
nute information on statistical subjects than that hitherto re- 
ceived may be obtained, and that the Committee be autho- 
rized to defray the expense which may attend the printing of the 
queries. 

That Mr. Taylor be requested to draw up a series of ques- 
tions upon the condition and habits of the mining population 
of Cornwall and Wales, with a view to obtain a complete ac- 
count of the statistics of that class. 

The Committee reported that in pursuance of a recommenda- 
tion of the Association, Professor Jones had applied for leave of 
access to the archives of the East India Company, and that 
that body, with its accustomed liberality, had afforded him every 
facility in prosecuting his researches. 

• These Committees have been for some time in operation. 



xl FOURTH REPOKT — 1834. 

APPROPRIATION OF FUNDS, 
At the instance of the Committee of Recommendations : ^ 

For the prosecution of Thermometrical Observations 
at various depths from the surface, under the direc- 
tion of a Committee named for that purpose . . .100 

On the recommendation of the Committee for Mathematical 
and Physical Science : 

For determining the Constant of Lunar Nutation from 

the Greenwich Observations 100 

For discussing Observations of the Tides in order to 
improve the Tide Tables (vote of last year continued 

and enlarged) 250 

For the construction of a telescopic lens of rock salt, 
{vote of last year enlarged) 80 

On the recommendation of the Committee for Chemical 
and Mineralogical Science : 

For the execution of a specimen of chemical constants 

on the plan of Professor Babbage 10 

, For experiments on the effects of long-continued heat 
on mineral and organic bodies, {vote of last year 

continued) 50 

For determining the specific gravity of hydrogen and 
other gases {vote of last year continued) .... 50 

On the recommendation of the Geological and Geographi- 
cal Committee : 

For advancing our knowledge of British fossil Ichthy- 
ology 103 

For experiments on the quantity of mud transported 
by rivers 20 

On the recommendation of the Committee of Anatomy and 
Physiology : 

For experimental investigations on the effects of poi- 
sons on the animal economy, {vote of last year con- 
tinued) 25 

For investigating the relations of the absorbent and ve- 
nous systems 50 

. For defraying certain expenses incurred in the execution 
of thermometrical observations at Plymouth by the 
late Mr. G. Harvey 20 

£860 



PKOCEEDINGS OF THE MEETING. xli 



SECTIONAL MEETINGS. 

The Sections assembled daily at eleven a.m., in the Class 
Rooms of the College, to hear the communications in different 
departments of science prepared to be laid before them by the 
secretaries of their respective committees. 

The following is a list of the communications which were 
made to the meeting, divided into four classes : 1st, Reports 
on the state and progress of science, drawn up at the request of 
the Association ; 2nd, Accounts of researches undertaken at the 
request of the Association ; 3rd, Notices in answer to queries and 
recommendations proceeding from the Association ; 4th, Miscel- 
laneous communications. 

I. Reports on the State and Progress of Science, drawn up 

at the request of the. Association. 

On the Geology of North America, Part I. By Professor 
Rogers. 

On the State of our Knowledge of the Laws of Contagion. 
By Dr. Henry. 

On Animal Physiology. By Dr. Clark, Professor of Ana- 
tomy, Cambridge. 

On the recent Progress and present State of Zoology. By 
the Rev. L. Jenyns. 

On the Theory of Capillary Attraction. By the Rev. James 
Challis. 

On the Progress and present State of the Science of Physical 
Optics. By the Rev. H. Lloyd, Professor of Nat. Phil. Dublin. 

On the Progress of Hydraulics considered as a Branch of En- 
gineering: Part II. By George Rennie. 

II . Accounts of Researches undertaken at the request of the 

Association. 

Remarks on the relative Level of Land and Sea, &c. By 
Robert Stevenson, Engineer. 

Results of a Second Series of twelve months' observations 
on the Quantities of Rain falling at different elevations above 
the ground. By William Gray, jun., and Professor Phillips. 

Account of the institution of Experiments on the effects of 
long-continued Heat. By the Rev. W. V. Harcourt. 

Account of researches in Crystallography. By Professor 
Miller. 

1834. d 



xlii FOURTH REPORT — 1834. 

Account of the progress of experiments on the nature of the 
Secretions from the Roots of Vegetables. By Dr. Daubeny, Pro- 
fessor of Chemistry and Botany, Oxford. 

Notice of the progress made in the comparative analysis of 
Iron in the different stages of its manufacture. By Professor 
Johnston. 

Notice of the progress made in determining the specific gravi- 
ties of Oxygen, Hydrogen, and Carbonic Acid. By Dr. Dalton. 

Account of researches on the effects of Poison on the animal 
ceconomy. By Dr. Roupell and Dr. Hodgkin. 

Account of researches on the Sensibilities of the Nerves of 
the Brain. By Dr. Marshall Hall and S. D. Broughton. 

Account of the performance of a Chronometer with a Glass 
Balance-spring. By E. J. Dent. 

Notice of the performance of an Instrument for ascertaining 
the quantities of mud transported by Rivers. By George Ren- 



III. Notices in reply to Queries and Recommetidations of 
the Association. 

On the electrical condition of Metalliferous Veins. By R. W. 
Fox. 

On the peculiar circumstances attending certain Coal Di- 
stricts in the midland counties of England. By R. I. Murchison. 

On the direction &c. of Non-metalliferous Fissures. By Pro- 
fessor Phillips. 

On the Limestone of Closeburn. By C. G. S. Menteath. 

On the Beds inclosing the Haematite of Dalton. By Professor 
Sedgwick. 

On the supposed Metamorphosis of Crustacea. By J. O. West- 
wood. 

On the progress made in inquiries relative to the Secretions 
from the Roots of Vegetables. By Dr. Dunbar. 

On the nature and quantity of the Gases given off from Ther- 
mal Springs. By Dr. Daubeny. 

On the purity and specific gravity of Mercury, Dr. Thompson 
remarked that he considered the mercury as imported into this 
country to be pure, and the specific gravity assigned to it by 
Cavendish to be correct, as it agrees with recent determinations 
by Mr. Crichton, from experiments continued through a whole 
winter. 

On products collected in Chimneys of Furnaces. By Mr. 
Lowe. 



PROCEEDINGS OF THE MEETING. xllii 

IV. Miscellaneous Communications. 

Abercrombie, Dr. On the study of Mental Philosophy as a 
part of Medical Literature. 

Adam, Rev. W. On a Sextant furnished with a Spirit Level, 
to be used at sea or land when the horizon is invisible. 

Addams, R. On a phfenomenon of Sound. 

Adie, J. On the Expansion of Stone. 

Agassiz. On the Fossil Fishes of Scotland. 

On the recent genus Salmo. 

Aitken, Dr. On the Motions of Blood in Mammalia. 

Alison, Dr. On the Vital Powers of Arteries leading to in- 
flamed parts. 

Andrews, T. On certain Caves in Rathlin, &c. 

Arago. Remarks on the methods of conducting experimental 
researches in Magnetism, especially for the detection of 
minute variations of Intensity and Direction. 

■' Proposal of submitting M. Poisson's conclusions regarding 
the Change of Density near the Surface of Fluids to an 
experimental test, by the observation of the angle of the 
complete polarization of light at these surfaces. 

On the hypothesis of Transversal Vibrations in Physical 

Optics, and the claims of Dr. Thomas Young as the first 
to propose it. 

Arnott, G. W. On Cocculus Indicus. 

Auldjo, J. Notice of a work of M. Rotindo on the Statistics 
of Naples. 

Badnall. On Friction on Railways. 

Bell, Sir Charles. Discourse on the Nervous System. 

Blackadder. Notice of a Fossil Fish from Glammis. 

Boase, Dr. Statement of his views on the question of the Stra- 
tification of certain primary Rocks. 

On Fissures and Veins. 

Boujou, Dr. Sur les rapports reciproques de la Medecine et la 
Philosophic. 

Breen, Hugh. On a property of Numbers. 

Brewster, Sir David. On Colours in the spaces of the Rainbow. 

Experiments on the effects of Reflexion from the surfaces 

of Crystals when those surfaces have been altered by so^ 
lution. 

On a large specimen of Amber from Ava. 

On the Optical Characters of Minerals. 

On the Structure of Feathers. 

Brisbane, Sir Thomas. Notice of a fact observed in registering 
the Fall of Rain. 

d2 



xliv FOURTH REPORT — 1834. 

Brisbane, Sir Thomas. Notice of Sand from New South Wales 
for the manufacture of Glass. 

Notice of an Ephemeris of Halley's Comet by Mr. Rumker. 

Brown, Dr. On the Plurality of Embryos in Coniferce. 

Brown, Capt. On Pecten asperstis. 

Brunei. On the Construction of Arches without centering. 

Bryce, W. J. On certain Caves in the North of Ireland. 

Buckland, Rev. Dr. A Lecture on several remarkable Fossil 
Fishes and Reptiles, delivered at an Evening Meeting 
of the Association. 

Notice of a fossil Marine Plant from the Red Sandstone 

near Liverpool. 

Bushnan, Dr. On the detection of Worms in the Human 
Veins. 

Challis, Rev. James. Theoretical explanations of some facts 
relating to the composition of the Colours of the Spec- 
trum. 

Christie, Professor. Description of a Meteorological Phfenome- 
non. 

Christison, Professor. Action of Water on Lead. 

Clark, Dr. On the use of the Hot Air Blast in Iron-furnaces. 

Clarke, Dr. (deceased.) On the Ventilation of Hospitals. 

Cleland, Dr. On the Statistics of Glasgow. 

Dalyell, J. G. On the Propagation of Scottish Zoophytes. 

Dick, David. On the cementing the internal surfaces of Object- 
glasses. 

On a new Suspension Railway. 

Dick, William. On the use of the Omentum. 

On the Elastic Tissue of animals. 

Observations on the Tongue of the Chamaeleon. 

Drake. On the Change of Colour in the Elder. 

Drinkwater, J. E. On the Origin of the Statistical Society of 
London. 

Dunn, John. Description of a new Clinometer. 

Fitzwilliam, Earl. On the details desirable in Statistical Re- 
ports relating to Agriculture. 

Forbes, Professor. On a new Sympiesometer. 

Graham, Professor. On Hydrated Salts. 

Grant. On Tables of Insurance. 

Graves, J. T. On Exponential Functions. 

Gilbertson, William. On Marine Shells of existing species at 
various elevations near Preston. 

Gordon, Alex. On the construction and uses of Polyzonal 
Lenses. 

Greenock, Lord. On certain Coal Tracts in Scotland. 



PROCEEDINGS OF THE MEETING. xlv 

Greenock, Lord. Notice of the section of Trap and Sandstone 
in the Castle Hill, Edinburgh. 

Greenough, G. B. On the Stratification of certain primary 
Rocks. 

Gregory, Dr. W. Notice of various Organic Products. 

Abstract of Reichenbach's discoveries. 

Hailstone, Rev. J. On minute Oscillations of the Barometer. 

Hall, Colonel. Account of excursions in Quito. 

Hall, Elias. Exhibition of a model of the Geology of Derby- 
shire. 

Hamilton, Professor. On Conjugate Functions. 

On a General Method in Dynamics. 

Harlan, Dr. Notice of some Organic Remains of the United 
States. 

Hibbert, Dr. On the ossiferous beds in the Basins of the Forth, 
Clyde, and Tay. 

Hodgkinson, E. Experimental Researches on Collision. 

Howard, Luke. On the Quantities of Rain at different eleva- 
tions. 

Jameson, Professor. Notice concerning the Fossil Fishes of 
Scotland, and the geological age of the formations in 
which they occur. 

Jardine, Sir William. Account of Fishes collected in Suther- 
landshire. 

Johnston, Professor. On Oxichloride of Antimony. 

Jordan, T. B. On a construction of the Magnetic Needle. 

Kemp, K. T. On the Liquefaction of the Gases. 

Knight, Dr. On the Organic Remains in the Flints of Peters- 
head, &c. 

On a method of rendering visible the Vibrations of heated 

Metals. 

Lardner, Rev. Dr. A Lecture on Professor Babbage's Calcu- 
lating Machine, delivered at an Evening Meeting of the 
Association. 

Lloyd, Prof. On a method of observing the Magnetic Needle. 

Lovee, George. Exhibition of certain products obtained in Gas 
Works, &c. 

Lyell, Charles. On the relative Level of the Land and Sea on 
the shores of Scandinavia. 

On the Characters of Stratification in the discussion on 

Primary Rocks. 

MacConnochie, Captain. Notice of a work by M. Guerry, Sur 
laS tatistique morale de la France. 

MacDonnell, Dr. On the Pulse, and the variation of its quick- 
ness from various causes. 



Xlvi FOURTH REPORT 1834. 

MacGilliviay, W. On the Natural History of the Transition 
Ranges of Scotland. 

Exhibition of drawings of the Vertebrate Animals of Great 

Britain and Ireland. 

Maclaren, Charles. On the Geology of the Pentlands. 

Milne, David. On the Geology of Berwickshire. 

Murchison, R. I. On the Transition Formations of the Welsh 
Border. 

Murphy, Rev. R. Notice of some recent electrical Experi- 
ments, by Mr. Snow Harris, on the retention of Elec- 
tricity on the surfaces of bodies in vacuo. 

Murphy, Lieut. Notice of the progress made in the Ordnance 
Survey of Ireland. 

Murray. On Rates of Mortality. 

Murray, J. On the cultivation of Phormium tenax in Scotland. 

On the Chamseleon. 

On the Ascent of the Sap. 

Nicol, W. On the structure of Fossil Wood. 

Pentland, J. B. On a peculiar configui'ation of the Skull in a 
race of men formerly existing in Peru. 

Phillips, Professor. On a method of causing the centre of 
gravity of a Dipping-needle to coincide with its axis 
of motion. 

On the Stratification of Primary Rocks, (in discussion on 

that subject.) 

Powell, Professor. On the Repulsion produced by Heat. 

On the Achromatism of the Eye. 

On the Dispersion of Light. 

Quetelet. In a letter to Mr. Whewell, M. Quetelet states his 
belief that he has succeeded in reducing the examination 
of the Law of Population to the discussion of ma- 
thematical formulae, and requests that his views may be 
tested by a comparison of the calculated results with those 
furnished by obsei-vations in England, the United States, 
and elsewhere. 

Ramage, John. On the construction of large reflecting Tele- 
scopes. 

Reid, Dr. On the Connexion of Muscles with Nerves. 

Rennie, G. Notice of the successful performance of an In- 
strument to measure the quantity of Mud in the water 
of Rivers. 

Robinson, Rev. Dr. A Discourse on Halley's Comet, delivered 
at an Evening Meeting of the Association. 

On the Visibility of the Moon in total eclipses. 

On the Situation of the Edinburgh Observatory. 



PROCEEDINGS OF THE MEETING. xlvii 

Royle, J. F. On the Character of the Vegetation of the Hi- 
malaya Mountains. 
Russell, J. On the Resistance to Floating Bodies. 
Sang, Edward. On the Geometry of Lines of the third order. 

On Vibrating Wires. 

On a property of successive Integer Numbers. 

Saull, W. D. Drawing of the Incisors and Canine Teeth of the 

Hippopotamus, from a gravel-pit near Huntingdon. 
Saumarez, Richard. On Light and Colours. 
Saxton, Joseph. On an Instrument for measuring minute Va- 
riations of Temperature in Metal Rods, &c. 
Secretary to the Society of the Sons of the Clergy in Scotland. 

Notices relating to a Statistical Survey of Scotland. 
Sedgwick, Rev. Professor. On the Stratification of certain Pri- 
mary Rocks, (in reply to Dr. Boase's views.) 
— — A Review of the Geological Proceedings of the Meeting at 
Edinburgh, delivered at an Evening Meeting of the As- 
sociation. 
Selby, P. J. Notice of Birds collected in Sutherland. 

On the Postorbital Glands in Natatorial Birds. 

Sharpey, Dr. On the Vascular System of the Porpoise. 
Smith, William. Observations on the Waste and Extension of 

Land on the East Coast of England. 
Stanley, Rev. E. Notice regarding Statistical Returns for 

Parishes. 
Statistical Society of Manchester, by Mr. Heywood. Statisti- 
cal Returns relating to Manchester. 
Stevelly, Professor. On some branches of Meteorological Sci- 
ence. 

On a Vernier to be adapted to a scale of unequal parts. 

Sykes, Lieut.- Col. On Mean Temperatures in India. 

Syme, Professor. On removing portions of Joints. 

Taylor, John. On the Directions of Mineral Veins in different 

countries. 
Thomson, Dr. Allen. On the Structure of the Human Foetus 
and that of Mammalia at early periods of development. 
■ On the external Gills of the Young of the Skate, and on the 
Gills of some Reptilia. 

On the Change of Colour observable in the Cuttle-fish. 

Thomson, Dr. A. T. On Iodides. 

Thomson, Dr. T. Notice of a Fossil Plant (probably marine) 

from the Glasgow Coalfield. 
Thomson, Dr. W. On black Discoloration of the Lungs. 
Toorn, M. Vander. On the Water in Sulphate of Zinc. 



xlviii FOURTH REPORT 1834. 

Tough, Rev. Mr. On a Glass Celestial Sphere. 

Traill, Professor. On the Laryngeal Sac of the Reindeer. 

■ On the Geology of the Orkneys. 

On the Fossil Fishes of the Orkneys. 

Trevelyan, A. On the application of Vapour of Alcohol to the 
purpose of a chemical Lamp Furnace. (See Phil. Mag, 
1834.) 

Trevelyan, W. C. On Fossil Wood from Faroe. 

On the Geographical distribution of Plants in Faroe. 

Turner, Dr. E. On Atomic Weights ; that they are not repre- 
sentable by whole numbers. 

West, William. On the presence of Sulphur in Bar Iron. 

Whevvell, Rev. W. A Lecture on certain Phfenomena of the 
Tides, delivered at an Evening Meeting of the Associa- 
tion. 

Suggestions regarding Sir J. Herschel's explanation of Di- 
spersion according to the Undulatory Theory. 

Williams, Dr. C On the State of Knowledge regarding Sound. 

On the Phaenomena of Low Combustion. 

Wilson, J. On the Coleopterous Insects of Sutherland. 

Yates, Rev. J. On some facts regarding the Stratification of 
Primary Rocks. 



REPORTS 



ON 



THE STATE OF SCIENCE. 



Report on the Geology of North America, Part I., hy Henry 
i). ROGKRS, F.G.S. 

In obedience to the request of the British Association, ex- 
pressed to me at the last Annual Meeting, I beg leave to oiFer 
the following Report on the present state of our knowledge of 
the geology of North America. 

The magnitude of the region, our remoteness from the foun- 
tains of science in Europe, and likewise some peculiarities in 
the geological structure of the country, have operated hitherto to 
make our efforts in exploring its formations tardy and uncertain. 
But the friendly interest expressed by the British geologists in 
our labours is calculated to cheer and quicken our progress. 

It will be seen to be among not the least important of the 
good results of this Association, that it can invigorate by its 
ample spirit the youthful science of a distant but kindred con- 
tinent. 

The plan and object of this Report make it necessary to offer 
an introductory section on the general physical geography of 
the country. In no section of the globe will a more obvious 
and marked connexion be seen between the geographical features 
of the surface and the geology. Such a description is indispen- 
sable indeed, for certain geographical boundaries will be found 
the best, in fact almost the only, guide we possess at present for 
judging of the probable range and extent of certain formations 
oveir many extensive districts not yet explored. 

Physical Geography . — Omitting the minor irregularities, and 
confining our survey to the great masses which compose the 
continent of North America, its structure will be seen to exhibit 
great simplicity and regularity. From 1;he Atlantic to the Pa- 
cific Ocean, and from the Arctic Sea to the Gulf of Mexico, 
the whole area seems naturally divided into two great plains, 

1834. B 



2 rOLRTH REPORT — 1834. 

bounded by two broad ranges, or rather belts, of mountains. 
One plain, the least considerable by far, occupies the space 
between the Atlantic and the Appalachian or Alleghany Moun- 
tains, and extends from Long Island, or more properly from the 
eastern coast of Massachusetts, to the Gulf of Mexico, losing 
itself at its south-western termination in the plain of the Mis- 
sissippi : this last is a portion of the second great plain, which 
we may style the central basin of the continent, and occupies 
much the largest portion of the whole surface of North America. 
In breadth it spreads from the Alleghanies to the Rocky Moun- 
tains, and expands from the Gulf of Mexico, widening as it 
extends northward, until it reaches the Arctic Sea and Hudson's 
Bay. Over the whole of this great area occur no mountain 
chains, nor any elevations beyond a few long ranges of hills. It 
is made up of a few very wide and regular slopes, one from the 
Appalachians, westward to the Mississippi ; another, more ex- 
tensive and very uniform, from the Rocky Mountains eastward 
to the same ; and a third from the sources of the Mississippi and 
the great lakes northward to the Arctic Sea. The most striking 
feature of this region is the amazing imiformity of the whole 
surface, rising by a perfectly regular and very gentle ascent from 
the Gulf of Mexico to the head waters of the Mississippi, and 
the lakes reaching in that space an elevation of not more than 
700 or 800 feet, and rising again in a similar manner from the 
banks of the Mississippi westward to the very foot of the Rocky 
Mountains. From the Alleghanies to the Mississippi the sur- 
face is more broken into hills, and embraces the most fertile 
territory of the United States. Three or four hundred miles 
west of the Mississippi a barren desert commences, extending 
to the Rocky Mountains, covering a breadth of between four 
and five hundred miles, from the Missouri in lat. 46°, the whole 
way into Mexico. The territory from the sources of the Missis- 
sippi, north, is little known except to fur traders and the Indians, 
but is always described as low, level, and abounding in lakes. 

Of the two chief mountain belts which range through the con- 
tinent, both nearly parallel to the adjacent coasts, the Alleghany, 
or Appalachian, is by far the least considerable. This system of 
mountains separates the central plain or basin of the Mississippi 
from the plain next the Atlantic, though its ridges do not in 
strictness divide the rivers which severally water the two slopes. 
The northern and southern terminations of these mountains are 
n.)t well defined; they commence, however, in Maine, traverse 
New Ei^gland nearly from north to south, deviate from the sea 
and enter New York, cross Pennsylvania in a broad belt, in- 
flecting first to the west and then again to the south, and from 



REPORT ON THE GEOLOGY OF NORTH AMERICA. J 

thence assume a more decidedly south-western course, penetra- 
ting deeper into the continent as they traverse Virginia, the two 
CaroHnas, and Georgia, into Alabama. Throughout this range, 
especially in the middle and southern portions, they are marked 
by great uniformity of structure, an obvious feature being the 
great length and parallelism of the chains, and the uniform level 
outline of their summits. Their total length is about 1200 
miles, and the zone they cover about 100 miles broad, two 
thirds of which is computed to be occupied by the included 
valleys. They are not lofty, rarely exceeding 3000 feet, and in 
magnitude and grandeur yield immeasurably to the Rocky or 
Chippewayan Mountains which traverse the opposite side of the 
continent. 

This last system of mountains, the Andes of North America, 
skirts the continent on the side of the Pacific in a broad belt from 
the Isthmus of Panama almost to the Arctic Sea, its extreme 
northern limit, as defined by Captain Franklin, being far north 
on the Mackenzie's River. The chains within this zone are 
many of them very lofty, their average direction, until they en- 
ter Mexico, being nearly north and south. Within the United 
States territory they rise abruptly from the sandy plain before 
described, in longitude about 32^° west from Washington ; and 
from that meridian nearly the whole way to the ocean the region 
is mountainous, with elevated sandy plains, and volcanic tracts 
resembling those of Mexico. The summits of many of the 
Chippewayan chains are far above the limit of perpetual snow, 
the highest points being about 12,000 feet above the sea. 

When we regard the grandeur of the dimensions exhibited in 
these several divisions of North America, the extreme regularity 
prevailing over great distances both in the plains and systems 
of mountains, and the straightness and parallelism of these to 
its long coasts, we are prepared to look for a proportionately 
wide range and uniformity in its geological features. To com- 
prehend the relations of our formations to each other, and the 
true extent of the portion of our geology at present partially 
developed, the exhibition of which is in fact the main end and 
object of this Report, a further description, rather more in detail, 
of our geography is here requisite. 

Let us first contemplate that long and comparatively narrow 
plain defined above, which lies between the Atlantic Ocean and 
the chains of the Alleghany mountains. This tract, which in the 
New England States is very narrow, comprising the mere coast 
and islands, expands in its course southward, the mountains in 
Carohna being more than 200 miles from the sea, It is divided 
longitudinally nearly through its whole length by a well marked 

B 2 



4 FOURTH REPORT — 1834. 

geographical and geological boundary, commencing on the coast 
of Massachusetts and running to Alabama. The boundary meant 
is the eastern edge of a well exposed range of primary rocks, 
which, from New Jersey as far south as North Carolina, forms a 
nearly definite limit to the flowing up of the tide in the Atlantic 
rivers. Between it and the ocean the country is throughout 
low, flat, and sandy, while westward the rest of the plain rises 
in gradually swelling undulations to the base of the blue ridge 
or eastern chain of the Alleghanies. The rivers descend from 
the mountains over this western portion of the tract, precipitate 
themselves over the rocky boundary mentioned, either in falls 
or long rapids, and emerge into the tide level to assume at once 
a totally new character. South of North Carolina this line of 
primary rocks leaves the tide and retires much nearer to the 
mountains, though it still preserves its general featui-es, sepa- 
rating the rolling and pictm-esque region of the older rocks from 
the tertiarjr plains next the ocean ; and though the tide does not 
any longer lave its base, as in Virginia, Maryland and Pennsyl- 
vania, it still produces rapids and cataracts in the southern 
rivers which cross it. Ranging for so very great a distance 
with a remarkable uniformity of outline and height, on an 
average between 200 and 300 feet above the tide, it consti- 
tutes as admirable a geographical limit as it does a commercial 
one. Nearly all the chief cities of the Atlantic States have 
arisen upon this boundary, from the obvious motive of seek- 
ing the head of navigation ; a striking example of the influence 
of geological causes in distributing population and deciding the 
political relations of an extensive country. Below this boundary 
the aspect of the region is low and monotonous, the general 
average elevation of the plain probably not exceeding 100 feet. 
Its general width through the Middle and Southern States is 
from 100 to 150 miles. As the tide enters this tract so exten- 
sively, flowing, except in the more southern States, entirely 
across it, a series of very abundant alluvial deposits occurs, dis- 
tributed throughout. The surface is everywhere scooped down 
from the general level to that of the tide by a multiplicity of 
valleys and ravines, the larger of which receive innumerable 
inlets and creeks, while the smaller contain marshes and allu- 
vial meadows. The whole aspect of the barrier of primary rocks 
forming the western limits of this plain forcibly suggests the 
idea that at a rather lower level they once formed the Atlantic 
shore, and that they exposed a long line of cliff's and hills of 
gneiss to the fury of the ocean : a survey of the plain just de- 
scribed as strongly suggests the idea that all of it has been lifted 
from beneath the waves by a submarine force, and its surface 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 5 

cut into the valleys and troughs which it presents by the retreat 
of the upheaved waters. The submarine origin of all this tract 
will be made apparent in treating of its geology ; but in refer- 
ence to its valleys, it may be well to remark that it has no doubt 
been torn by more than one denuding wave, in as much as the 
great current which has evidently rushed over other portions of 
the continent has also passed across this tract, and strewed it as 
we see with diluvium. How many such denudations of the 
strata have operated to form the present broad valleys of its 
enormous rivers, or how much of the excavation has been due 
to the continued action of the rivers themselves, we have, so far 
at least, no sufficient data to form a decision. 

The level region here spoken of I propose calling, for conve- 
nience, the Atlantic Plain of the United States, while the ter- 
ritory between it and the mountains may be fitly entitled the 
Atlantic Slope. 

The extensive denudation of the surface of this plain will be 
found highly favourable to the accurate development of its geo- 
logy. It is from this and the accessible nature of its rivers that 
we already know more of its strata, and especially of its organic 
remains, than we do of any other district of the country. Its 
horizontal strata are in many places admirably exposed in the 
vertical banks of the rivers, often through many miles' extent; 
and the mass of appropriate fossils thus procured, as will be 
seen from this Report, is already far from insignificant. This 
plain, widening in its range to the south-west, bends round the 
southern termination of the Alleghanies in Alabama, and expands 
itself into the great central plain or valley of the Mississippi. 
The tract in question embraces the greater portion of the newer 
secondary and tertiary formations hitherto investigated upon 
this continent, though, notwithstanding the great area it covers 
from Long Island to Florida, it may yet be found to constitute 
but a small section of the whole range of those deposits, when 
we shall, on some future day, have explored in detail the vast 
plains beyond the Mississippi. 

The ledge of primary rocks, bounding the tertiary and cre- 
taceous secondary deposits of the Atlantic coast, may be de- 
lineated by commencing at the city of New York, and tracing a 
line marked out by the falls in nearly all the rivers from thai 
point to the Mississippi. It is thus marked in the falls of the 
Passaic at Patterson, in the Raritan near New Brunswick, in 
the Millstone near Princeton, in the Delaware at Trenton, the 
Schuylkill near Philadelphia, the Brandywine near Wilmington, 
the Patapsco near Baltimore, the Potomac at Georgetown, the 
Rappahanock near Fredericksburg, James River at Richmond, 



6 FOURTH REPORT 1834. 

Munford Falls on the Roanoke, the Neuse at Smithfield, Cape 
Fear River at Aveiysboro, the Pedee near Rockingham, the 
Wateree near Cambden, the Congaree at Columbia, the Falls at 
the junction of the Saluda and Broad Rivers, the Savanna at Au- 
gusta, the Oconee at Milledgeville, the Ockmulgee at Macon, 
Flint River at Fort Lawrence, the Chattahooche at Fort Mit- 
chell, &c., deviating thence north-west through the state of 
Mississippi. Towards the southern termination of this rocky- 
ledge, in Alabama for instance, it does not consist, as it generally 
does elsewhere, of gneiss, but is formed of the ancient sandstone 
and limestone of the Alleghanies. It every^vhere, however, ap- 
pears as a natural line of division, of great length and vinifor- 
mity, separating two tracts of very dissimilar geological age and 
features. The upper tract, which I have called the Atlantic slope, 
possesses a very variable width; it is narrow in New York and the 
New England States, where the mountains approach the coast, 
and narrow also in Alabama, where they approach the plains oc- 
cupied by the cretaceous rocks of the south, but is much expanded 
in Virginia and the Carolinas. Here it has a breadth of about 
200 miles, ascending from the tide in an undulating hilly sur- 
face, to a mean elevation of perhaps 500 or GOO feet near the 
mountains. As it approaches these, its hills swell into bolder 
dimensions until we gain the foot of the blue ridge or first chain 
of the Alleghanies. It consists almost exclusively of the older 
sedimentary and stratified primaiy rocks. This fine hill tract 
exhibits a marked uniformity in the direction of its ridges and 
valleys, running very generally north-west and south-east, or 
parallel with the mountains. The ridges, though not high, are 
long, and the fertile intervening valleys very extensive. It em- 
braces a variety of fine soils, and an immense water power in its 
rivers and running streams. 

Geology of the United States. — I propose to treat of our 
formations in the order of the latest first, commencing the 
survey of each group in the districts where it is best known. I 
shall therefore, in this first part of my Report, describe whatever 
is known of our recent, tertiary, and cretaceous formations, and 
shall reserve an account of the rest of the secondary and all the 
primary rocks for the next annual meeting of the Association. 
By the delay I hope to be able to add materially to the accu- 
racy of the geological map, and it will enable me to present 
some of the results of the geological survej-s now set on foot by 
the States of Maryland and Tenessee, together with whatever 
else may in the mean while be brought to light. 

The tertiary and cretaceous groups yet known to us in North 
America are confined almost exclusively to the Atlantic plain 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 7 

of the United States, and to the southern part of the great cen- 
tral valley, or basin of the Mississippi. The lines along which 
these formations have been traced in the valley of the west are 
few and far apart, so that our present survey is chiefly confined 
to the tide-water plain along the Atlantic. 

The same line, which was before sketched as forming the 
boundary of the Atlantic plain, will be observed, in tracing it 
through the states of New Jersey, Pennsylvania, Delawai-e, 
Maryland, Virginia, and North and South Carolina, to coincide 
almost exactly with the western limit of the tertiary and se- 
condary formations here to be discussed. From Long Island, 
south, this barrier of primary rocks presents everywhere a re- 
markably abrupt and well defined line of separation between 
these newer deposits and the rocks of older origin. North of 
Long Island, on the main land of Connecticut, Rhode Island, 
and Massachusetts, the precise position of this line is not so 
readily traceable. Along the coast of the two first states little 
or nothing of the newer formations is seen; and, if we except 
the small portions stated by Hitchcock as occurring in the valley 
of the Connecticut river, and on the eastern peninsula of Mas- 
sachusetts near Cape Cod, they have not been noticed on the 
continent east of New York. The islands of Nantucket, Mar- 
tha's Vineyard, and Long Island are all, however, embraced 
within the area of the upper strata about to be described. 

The acknowledged difficulty of defining the exact sera to 
which the newest deposits belong, is sensibly felt in treating 
of those of the United States. The amount of strata within 
this area which have had their origin in the class of geological 
causes at present in action, is, no doubt, very considerable. 
Indeed, geologists are accustomed to allude to the changes 
wrought by the Mississippi and Niagara as among the most 
striking within the recent period anywhere to be met with. 
Nevertheless, it seems very possible that a large portion of the 
alluvial matter which borders the mouths of the rivers and 
coast, may have been formed before the earth, or this conti- 
nent at least, was tenanted by man. The evidence upon this 
point will be given present'y. The first class of phaenomena to 
be examined are those which are unquestionably recent. 

Of volcanic action we have no traces east of the Mississippi. 
The earthquakes which convulse the equatorial and southern 
sections of the continent rarely reach the United States ; and 
when felt, they come with such greatly diminished force as to 
be hardly sensible. The forces now in action are, therefore, 
exclusively aqueous. These, however, prevail over very exten- 
sive areas, as will be seen on adverting to the size and num- 



8 FOURTH REPORT 1834. 

ber of the rivers, the magnitude of the coast, and the enormous 
lakes where freshwater deposits are probably accumulating on 
a scale of great extent. 

Alluvial Deposits. — From the mouth of St. Croix River to 
Florida Point, the length of the Atlantic coast is about 1800 
miles ; and along the Gulf of Mexico, from Florida Point to 
Sabine Ri\er, the boundary of the United States coast, the di- 
stance is 1100 miles more. The first section receives the rivers 
which descend the Atlantic slope. The several basins drained 
by these rivers, according to the view given by Darby, are 
forty-two in number, and the total area drained is 252,900 
square miles. 

The smaller river bashis in the vicinity of the delta of the 
Mississippi, from Sabine River to the western slope of Florida 
inclusive, are, excluding the great basin of the Mississippi, six- 
teen, with an area of 144,240 square miles. The area drained by 
the Mississippi and all its tributaries is computed at 1,099,000 
square miles. I do not extend the survey to the many large 
rivers which enter the gulf west of the Sabine. The quantity 
of sediment conveyed to the ocean from so wide an area must 
be ven,' enormous ; and, as a proof, we behold either an alluvial 
'delta or a bar at the mouth of almost every river. The entire 
line of sea-coast, from the Sabine to the mouth of the Pearl, 
presents an uninterrupted marsh 400 miles long, and from 30 
to 50, or even 70 miles wide, the production solely of the Mis- 
sissippi and the rivers adjacent. From the mouth of the Pearl 
eastward, the sandy pine tract reaches the gulf, and extends, 
with little interruption, along the whole sea-coast of the Missis- 
sippi, Alabama, and great part of Florida. Along this part of 
the gulf, and along the Atlantic from the point of Florida to 
New Jersey, though many extensive marshes occur upon the 
coast, the shore is more generally sandy. At the mouths, how- 
ever, of nearly all the rivers, low, marshy, alluvial tracts are to 
be seen. Low down, towards their mouths, these rivers run 
through extensive flats or meadows, most of which are at pre- 
sent elevated above the highest spring-tides, though it is pos- 
sible that many of them, during unusually heavy storms or 
great freshets, may be liable to be partially submerged. These 
meadows are often several miles in width, and bordered on each 
side by abrupt banks, consisting of the solid strata of the coun- 
try, so that they have all the aspect of having been, at a former 
period, permanently beneath the tides, which, on this suppo- 
sition, penetrated their valleys in the shape of extensive bays 
;ind estuaries. 

The river meadows are never covered bv the coating of 



REPORT ON THE GEOLOGY OF NORTH AMERICA. V 

diluvial sand and gravel which conceals all the other forma- 
tions of the country; a circumstance which will enable us to 
distinguish between them and another group of more ancient 
alluvial deposits to be described further on. 

Recent Changes in the Mississippi. — I am informed by Mr. 
Tanner, the geographer, that a striking example of the manner 
in which this river ordinarily varies its channels was witnessed 
about two years ago, at the mouth of the Red River. A re- 
markable bend at that place, known as one of the longest and 
most circuitous loops in the Mississippi, was cut off by the 
simple expedient of digging a very short trench across the 
narrow neck which the stream was daily scooping away. In 
24 hours steam-boats passed through the new channel, and it 
immediately became the outlet of the Red River, which before 
entered the Mississippi by the lower side of the bend, but now 
discharges itself along the upper. By this change the river has 
been shortened 20 miles. 

When it is recollected that in freshets the current of the Mis- 
sissippi descends at the rate of five and even six miles an hour, 
and at low water at the rate of two miles, it will at once be seen 
how great a load of sedimentary matter it can annually sweep 
down into its delta, and how rapidly this must augment both in 
height and superficial area. As an example of the rate at which 
it is growing, the Old Balize, a post erected by the French about 
the year 1724, at the very mouth of the river, is now two miles 
above it. There was not at that time the smallest appearance 
of the island, on which, 42 years after, UUoa caused barracks 
to be erected for the pilots, and which is now known as the 
New Balize. 

The distance from the mouth of the river, at which the chief 
deposit of sediment usually takes place, is about two miles. 
When these shoals accumulate sufficiently, they form small 
islands, which soon unite and reach the continent; and thus 
the delta increases. So enormous has been the growth of such 
deposits, not only opposite the mouths of the Mississippi, but 
around the whole northern shore of the gulf, that nearly the 
entire coast of Louisiana is inaccessible, from the shallowness 
of the water, except immediately through the channels of the 
rivers. 

An almost universal feature in the entrances of the rivers of 
the Atlantic is the bar obstructing their mouths. That of the 
principal entrance of the Mississippi had, in 1722, about 25 feet 
of water upon it; Ulloa, in 1767, found 20 feet at the highest 
flood; and in 1826 the depth was only 16 feet. 

Above these obstructions the rivers are generally much 



10 FOURTH REPORT — 1834. 

deeper; the Mississippi, at New Orleans, being above 100 feet 
deep, which depth it preserves to the mouth of the Missouri. 
Mobile Bay is crossed by a bar, having only 10 feet of water, 
and the bar of the Altamaba of Georgia has 14 feet, which is, 
perhaps, about the average depth to be found at the entrance 
of most of the southern rivers of the Atlantic coast. 

Alluvial Terraces. — Besides the alluvial flats which border 
so many of the rivers at an elevation of only a fe^v feet above 
the tide, and which may have been formed during the present 
relative level of the land and sea, there are plains of another 
class, which often occupy the sides of the valleys in terraces 
more remote from the rivers. This common feature on many 
of the rivers of the United States, I mention not only from my 
own observation, but on the authority of various works, as 
Stoddard's Sketches, Drake's Picture of Cincinnati, Dar- 
by's Louisiana, and Professor Hitchcock's Report on the 
Geology of 3Iassachusetts ; some of them mentioning two, 
three, or even more of these river terraces. The latter author 
thus describes them on the Connecticut river in Massachusetts: 
" If we start from the edge of the stream at low water, and 
ascend a bank of 10 or 15 feet high, we shall come upon an 
alluvial meadow, which is frequently overflowed, and is conse- 
quently receiving yearly deposits : this may be regarded as 
the lowest terrace. Crossing this, we ascend the escarpment of 
a second terrace, .30 or 40 feet in height, which may be seen at 
intervals on the same level on all sides of the meadow. This 
second terrace is rarely very wide in any place, and seems to be 
only the remnant of a meadow, once much more extensive, 
which has been worn away. Ascending from this 40 or 50 
feet up another escarpment, we reach the plain that forms the 
bottom of the great valley of the continent : this constitutes the 
upper terrace." He adds, that terraces, more or less distinct, 
exist on almost every stream of considerable size in the State, 
wherever the banks are low enough to admit of alluvial flats. 
Professor Hitchcock imputes these terraced valleys to the sud- 
den bursting of the barriers of a lake or pond through which 
the stream flowed, or the sudden removal of an obstruction in 
the river, by which it cut a new channel into the soft soil above 
the obstruction. I -would beg leave to suggest, however, whe- 
ther, in the case of so many successive terraces, such an ex- 
planation is not rendered improbable, from the difficulty of 
imagining so many debacles taking place in succession upon 
the same river. The circumstance that nearly all our river 
valleys which have the structure described, occur in districts 
where the rivers could ne^er have been crossed by ridges of 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 11 

rock — no relics of such barriers being seen, for example, among 
the horizontal formations of the Atlantic plain — is, I think, 
conclusive evidence that we must seek for some other cause. 

That the cause which has given the delta of the Mississippi 
its present elevation was the uplifting agency of forces from 
within the earth, we shall see additional evidence for admitting, 
when I treat presently of some of the newest of our fossilifer- 
ous deposits. In the present infancy of geological research in 
the United States, we are not prepared to venture any views 
upon the age to which the terraces in question belong. It is 
very possible that they may be finally referred to several distinct 
periods. Many of them are covered by the general capping of 
diluvium, which I'enders it very likely that the date of some 
of them is earUer than the recent period. In the absence of 
organic remains, it is wisest to leave the discussion of the age 
of these formations open until a larger stock of information has 
been gathered concerning them. 

Of the Coast Islands, and their probable Origin. — Having, 
in the previous section, given some account of a few of the 
causes now in action on this continent, as a specimen of the 
kind of phsenomena which in this country present themselves on 
a scale of peculiar magnitude, I sliall proceed to a feature in 
our geology closely connected vidth the foregoing class of opera- 
tions, implying the agency of almost the very same powers, 
and, if I mistake not, taking us into a period very little, if at 
all, earlier than that of the river deltas and alluvium just de- 
scribed. There is to be seen lying a little off from the main 
shore, along the chief extent of the Atlantic coast, an interesting 
range of shoals and islands, all running parallel with the shore, 
and distinguished by the same uniform features. These long, 
narrow, and low islands of sand range from Long Island to 
Florida, and around nearly the whole northern sweep of the 
Gulf of Mexico. They are rarely more than a mile or two 
wide, sometimes 20 or 30 miles long, and, on an average, 
about 12 feet high. The geology of Anastasia Island, on the 
coast of Florida, is a representation of many others, though it 
must be confessed we know extremely little respecting them. 

Anastasia Island, opposite St. Augustine, upon the eastei-n 
coast of Florida, is, according to Mr. Dietz (Jour, of the Acad, 
of Nat. Sci. Philadelphia), about 10 or 12 miles long, l-^ broad, 
and has not more than 10 or 12 feet of elevation above the level 
of the ocean. It lies parallel to the shore, at a distance of from 
2 to 3 miles. The greater part of the northern portion, and 
perhaps the whole of the island, is composed of horizontal 
layers of a semi-indurated rock, consisting wholly of fragments 



12 FOURTH REPORT — 1834. 

of shells, belonging, as far as examined, almost, though not 
exclusively, to species inhabiting the adjoining coast. The 
mass is divided, by thin scams of some foreign matter, into 
layers from 1 to 18 inches thick, and is so soft before exposure 
to the air, that it is easily cut by a tool into slabs of any re- 
quired size, and in this form is extensively used for building. 
Near the surface the fragments of the shells, generally speak- 
ing, are the smallest; but they occur of various sizes, and 
frequently in the same layer the shells are entire. Much of 
this rock, especially the more comminuted kind, exhibits not 
unfrequently a confused crystallization ; this process having 
gone so far as to present the fragments in an almost obliter- 
ated state. The coarse varieties are composed of some frag- 
ments evidently thus altered, and of others which have not 
yet lost their colouring matter. The shells belong principally 
to the genus Area ; they are A. pexata, A. jwnderosa, A. in- 
congrua, A. transversa ; also Lutraria canaliculata, all of 
Say; besides a Mactra, a Donax, a Crepidula, a Lucina, and 
another species of Area, which is probably either extinct upon 
our coast, or extremely rare. Natica, Oliva, and N^assa tri- 
villata, of Say, are also mentioned. Mr. Dietz attributes the 
formation of this island to the agitation of the tides and winds, 
conceiving the shells to be driven first towards the shore, and 
deposited afterwards at their present distance from the beach 
by the retiring tide. But such an explanation seems not alto- 
gether satisfactory, for I cannot learn that this heaping-up of 
shells from beneath the water is anywhere noticed upon our sea- 
islands at present. The winds do indeed drive the sands from 
the beach, and the shoals which are laid bare at low water, upon 
them, but mingled with hardly any shells, while the rock of 
Anastasia Island is made tip of shells exclusively. Such agita- 
tion wovild seem incompatible with the accumulation of so ho- 
mogeneous a mass, which is found to contain neither pebbles, 
sand, nor other transported matter of any sort. My own pre- 
sent conviction regarding these coast-islands is. That they are 
all the portions of a range of shoals or bars formed along the 
line of junction of the turbid waters from our rivers, and the 
great in-setting currents connected with the gulf-stream; — that 
since the existence of the gulf-stream and the present drainage 
of the Atlantic plain, this growth of sediment opposite the coast 
has been going on ; — that in the more tranquil places upon these 
bars, vast colonies of shell-fish planted themselves ; — and that 
the whole line of shoals has been lifted, vvith part of the adjacent 
continent, by the force of an earthquake or earthquakes, to 
their present small elevation above tlie waves. Traces of more 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 1$ 

than one such up-heave of the continent during the tertiary- 
period, may possibly be found hereafter, when the various sy- 
stems of plains and terraces along the rivers and the coast shall 
have been more investigated. 

There can be no doubt that most of the islands opposite the 
coast of the Middle States, New Jersey for instance, are hourly 
on the increase. They consist, like the opposite main shore, 
of marsh as a substratum, which is seen to receive a covering 
of sand blown in from the sea side whenever the tides and gales 
are favourable. Thus, the side of these islands next the sea is 
sandy and on the increase, while that adjacent to the continent 
is marshy, and in many cases appears to be wearing down 
under the action of the rapid current which sweeps through the 
intervening sound or strait. As a proof of the daily growth of 
some of these islands, or beaches, as they are called. Cranberry 
Inlet is now closed up, though it still bears the name " Inlet," 
as may be seen upon any map of the Jersey coast. 

It is impossible, therefore, to refer them all to the period 
which produced Anastasia Island, and the islands and coast in 
its neighbourhood, though, regarding the manner of their for- 
mation, there can be no doubt that the same combination of 
causes, winds and currents, operated in producing them all. 
These causes, as I have already shown, are active, in the pre- 
sent day, in effecting similar deposits along the delta of the 
Mississippi ; nor do I perceive any good reason why we should 
not admit the agency of the same in remote tertiary periods. 
Our rivers, since the appearance of the carboniferous forma- 
tions, at least, must have been always very large, and have 
formed vast deposits of sediment in the sea ; and there is 
every reason to suppose that the gulf-stream, which has evi- 
dently much to do in shaping these deposits, has existed since 
an early period of our coast formations. The true age of that 
great ocean current can only be decided when we know more 
thoroughly the geology of the isthmus separating North from 
South America. In the mean time we may safely apply the 
actions which are daily witnessed upon our coast, to forma- 
tions so very little older, as that of Anastasia Island. 

Raised Estuary Formations ofHhe Gulf of Mexico. — A 
very extensive bed of shells, bordering on the Gulf of Mexico, 
seems to claim a position somewhere in the group of formations 
now before us. It appears to hold a place on the confines, as 
it were, of the tertiary and the recent formations. It is thus 
described by Mr. Conrad : " An interesting deposit borders the 
Gulf of Mexico, and is probably several hundred miles in ex- 
tent. It consists entirely of two species of shells, Cyrena Ca~ 



14 FOURTH REPORT — 1834. 

rolinensis, and Rangia cyrenoides of Des Moulins ( Clathrodon 

cuneatus, Gray) ; the former, however, is rare, the deposit con- 
sisting almost entirely of the latter shell. In the vicinity of 
Mobile, which is built on a sandy flat, very little elevated above 
the tide, the beds in question are superficial, although co- 
vered by a vegetable mould bearing a forest of gigantic pines. 
When one of the trees is prostrated by the wind, the decom- 
posing shells are seen adhering to the roots, but beneath they 
are entire, and nearly as hard, when dry, as the recent species. 
It is remarkable that they occur in beds with scarcely any ad- 
mixture of sand or earth, and they are consequently found 
extremely useful in repairing roads, and paving the streets of 
the city. Thejr are dug from the surface of the soil, both on 
the main shore and the islands of the bay. These deposits 
border the bays of the Gulf of Mexico between Mobile and 
New Orleans, and they occur in the vicinity of Franklin, 
Louisiana. The Chandeleur Isles, between Mobile Bay and 
the delta of the Mississippi, consist of deposits of these shells 
cov^ered by a fertile soil. The Rangia lives in vast numbers in 
the extensive flats below Mobile, burrowing three or four 
inches beneath the surface of the sand, in which numei'ous de- 
pressions indicate where they are to be found." According to 
Mr. Conrad, the Rangia was first seen in a sub-fossil state in 
the newer Pleiocene, at the mouth of the Potomac, where, how- 
ever, it is rare. Though it there occurs in a deposit of marine 
shells, the sea appears not to be the usual resort of the species; 
and it is only in the brackish water in the bays and estuaries 
that it is abundant. He is therefore inclined to regard the few 
found in marine deposits as coming from some neighbouring 
estuary. As it abounds in the recent state in the present shel- 
tered sounds which fringe the Gulf of Mexico, the presumption 
is very strong that the fossil beds above described are colonies 
which, previous to the change of level of the land, flourished in 
precisely similar situations. This would account satisfactorily 
for the narrow and very long belts in which they run, skirting 
round the bays and the coast above its present marshes, from 
Pensacola, in Florida, to near Franklin, in Louisiana. 

Diluvial Actio7i over North America. — Almost the whole 
surface of North America, as far as examined, may be said to 
be covered with an investment of earth, pebbles, and boulders, 
obviously of diluvial origin. The thickness of this deposit varies, 
though its average depth may be said to be from ten to twenty 
feet. All that low and level tract described as the Atlantic 
plain, and also the lower sections of the great valley of the Mis- 
sissippi, appear to be the districts where it conceals the under- 



REPORT ON THK GEOLOGY OF NORTH AMERICA. 15 

lying strata to the greatest depth. Over the whole of this ex- 
tensive territory it covers the horizontal strata of the tertiary 
and cretaceous deposits, and obscures them so effectually that, 
except in the cliffs, along the rivers, and in the sides of the ra- 
vines and valleys, these formations are rarely or never exposed. 
If we begin our examination of this great mass of detritus 
upon the Atlantic coast, we there find it to consist of fine sand 
and gravel, in which form it abounds over the peninsula of 
Jersey, Maryland, Virginia, and North Carolina, and all the 
states along the Atlantic to the Mississippi. This soil along 
the seaboard may very possibly, if we judge from its consisting 
so entirely of pure finely comminuted sand, have been reclaimed 
from the ocean since the general distribution of diluvial matter 
over the continent. But even upon this view, it is to be re- 
garded as the result of diluvial action. The pebbles are of a 
kind, in fact, which could only come from the interior, above 
the range of rocks bordering the tide. They do not belong to 
the tertiary and cretaceous strata of the Atlantic plain, but to 
the older rocks of the Atlantic slope and the mountains. As we 
advance inward from the coast, the mass of diluvial matter be- 
comes less sandy and coarser, the soil somewhat less barren, 
and the vegetation more diversified, though still consisting 
principally of pine. Over the upper portion of the Atlantic 
plain, or nearest its rocky boundary, the mass contains the 
gravel in a much coarser state, mingled with clay sufficiently 
pure for bricks. Rolled blocks and boulders of no inconsiderable 
size occur, especially in the valleys of the rivers, when within 
ten or twelve miles of the boundary mentioned. For many miles 
from the coast there is rarely anything but the diluvium. In 
the central districts of the tract the fossiliferous strata appear 
beneath it, though near the upper limits of this tract these 
often disappear again, and the region immediately eastward of 
the rocky boundary presents the diluvium covering another class 
of deposits very different from the tertiary and secondary beds 
which underlie it near the sea. 

The deposit along the east of the rocky boundary, or, in other 
words, at the head of tide hi the Middle States, is not diluvium, 
as from the absence of fossils many might at first imagine. At 
many places, as Bordentown on the Delaware, the deep cut of 
the Chesapeake and Delaware Canal, Baltimore, &c., the mingled 
mass of ordinary diluvium reposes upon very regularly stratified 
beds of dark blue clay, containing decayed trees, lignite, and 
amber ; the whole mass precisely such in appearance and con- 
tents as to lead to the conviction that it is more probably an al- 



16 KOUKTH REPORT — 1834. 

luvial mass deposited in front of the ancient rocky coast, than a 
portion of the detritus left by diluvial action. 

Proceeding now from the Atlantic plain towards the moun- 
tains, the diluvial matter is more irregularly distributed, in con- 
sequence of the undulations of the surface. It may be seen in 
greatest quantity in the valleys of the rivers, the boulders which 
cover their beds and sides being almost invariably traceable to 
formations which lie at some miles' distance to the north-west 
mid north. This distribution of the diluvium from the north 
and north-west is not confined to the rivers whose valleys run 
in those directions, but belongs, it is believed, to at least all the 
middle and northern latitudes of the continent. It is seen west 
of the Alleghanies, throughout the i-egion of the Ohio and Mis- 
sissippi, as well as extensively over the Atlantic slope and the 
tertiary Atlantic plain. Bigsby and the travellers to the north 
have already shown it to prevail in the latitudes north of the 
United States. 

The very extensive valley which crosses Pennsylvania, Mary- 
land and Virginia, lying immediately east of the blue ridge, though 
it consists principally of transition limestone and greywacke slate, 
is strewed also with innumerable blocks and boulders of the same 
sandstone which composes most of the blue ridge, and appears, 
so far as yet examined, to be newei', together with fragments 
from the hills between the valley and the Atlantic. Opposite to 
the passes or breaks in this first range of mountains, the quantity 
of such -transported matter on the south-east of them is particu- 
larly great ; and many of the first ridges of the chain are covered 
to an unknown depth upon their flanks and even their summits 
by the diluvial matter in a comminuted state. As an instance, the 
mountain which bounds this valley in Pennsylvania, running 
west from the Susquehannah through Cumberland county, and 
called there the North Mountain, is covered with a mass of little 
else than sand, such as could not be derived from the limestone 
tract to the south-east, but just such as would be formed from 
the disintegration of the sandstones of the Alleghanies. 

It is stated by Hayden, in his Geological Essays, that in 
Washington city itself, which is south of the first primary ridge, 
and about fifty miles south-east of the mountains, there is a 
small area covered with rolled masses of sandstone, some of 
which would weigh from 200 to 500 pounds, and containing 
perfect impressions of shells resembling Terebratula. Now, no 
fossiliferous formations occur until we pass beyond the blue 
ridge, and the blocks must have come from the north-east or 
north, at least sixty miles. I have myself seen fragments of 



REPORT ON THE GKOLOGY OF NORTH AMERICA. 17 

similar boulders in the neighbourhood of Columbia, on the Sus- 
quehanna, containing several species oiProducta and Terebra- 
tula, which could only have come from a like region within the 
mountains of Pennsylvania, a distance perhaps of fifty miles at 
least. Drake, in his Picture of Cincinnati, mentions large 
masses of granite in that part of Ohio, resting upon the ordinary 
finer diluvium. The nearest granite on the north is at least one 
hundred leagues distant ; while no primary rocks occur south or 
east within even a much greater limit. We are reminded here 
of the great detached blocks which strew the plains of northern 
Europe, and the explanation suggested that they have been car- 
ried there by floating upon ice. They occur, promiscuously dis- 
persed over a great extent of country in Ohio, Kentucky, and 
Indiana, and are in no way connected with the present river 
valleys. 

I may mention as an interesting fact, corroborating the opi- 
nion of the northerly origin of the current here advanced, that 
Mr. Conrad, who has explored the State of Alabama, was never 
once able to perceive a boulder upon its surface. 

Besides the fossiliferous deposits of very recent date, descx'ibed 
by Mr. Conrad, around the Gulf of Mexico, many of our rivers 
adjacent to the sea present extensive beds of shells, of another 
class, but probably referrible to the same origin and the same 
period of elevation. They consist of the common Ostrea virgi- 
nica, almost exclusively, with a very few of the recent univalves 
of the coast, all of these being shells peculiar to the bays and 
estuaries of the rivers, and the shallow sounds on the inner side 
of the Sea Islands and shoals along the coast. The position in 
which these beds of shells are invariably seen is upon the low 
level plains adjacent to the tide creeks of our rivers, where they 
appear to have dwelt in colonies in the sheltered bays at a time 
when these plains were at a small depth beneath the water, and 
to have been lifted with them by, perhaps, the last shock which 
has changed the level of the coast. These shells, in a sub-fossil 
state, occur in Cumberland County, New Jersey, on the bank of 
Stow Creek, at Egg Harbour, on the Severn, at Euston, in 
Maryland ; again, upon the York river in Virginia, and indeed 
upon many others of the southern rivers. They occur at the 
mouth of the Potomac, resting upon the beds of marine shells, 
which were originally described in the Journal of the Academy 
of Natural Sciences by Mr. Conrad, and considered by him as 
referrible to the newest of our fossiliferous formations. In the 
same locality these beds of fossil Ostrea virginica are seen to 
be covered by the diluvium, so that there can be no question of 
their origin having been during the latest §tage, as it were, of 

X834. C 



18 FOURTH REPORT — 1834. 

the tertiary period, and not connected, as imagined by the vulgar, 
with human agency. The usual position of these beds of Ostrea 
is near the rivers, at a small elevation from the tide. They seem 
to hold also nearly the same elevation along the coast of New 
Jersey and elsewhere. 

Ancient Alluvium. — The above subdivision of our strata is 
adopted for the sake of treating, under an independent head, a 
group of beds of no inconsiderable extent in the United States, 
and which, in their phsenomena, seem to cast important light 
upon the former revolutions of the Atlantic side of the Continent. 
They point to a period when this coast had a very different con- 
figuration, and denote in a striking manner one of the revolutions 
M'hich have impressed upon the tract included between the sea 
and the mountains the peculiar features which it now bears. 
The formation I allude to immediately underlies, wherever it 
occurs, the general investment of diluvium. 

It has produced, hitherto, very few organic remains of the 
description proper to enable us to judge of its relative place in 
the series ; but as the few shells occasionally found in it belong 
to species now inhabiting our Atlantic waters, and as, from aU 
its other characters, it has evidently been formed imder differ- 
ent circumstances from our other tertiary beds, and at a period 
apparently much more recent than any of the rest with which it 
can be compared, I am induced to place it thus apart, and to 
give it provisionally, from its obvious origin, the convenient and 
not too theoretical name of 'ancient alluvium.' 

This deposit is the same which has usually, in this country, 
gone under the name of plastic clay formation, — a title suf- 
ficiently inappropriate, even were it to express correctly its true 
place in the tertiary series, and now particularly ineligible, when, 
in place of being one of the lowest tertiary deposits, it will be 
seen, from the evidence I shall present, to be one of the verj"^ 
uppermost. The beds I am speaking of consist generally of 
numerous alternating deposits of gravel, sand, various coloured 
tenacious clays, often black and ferruginous conglomerates, 
iron ore, and lignite. They occur exposed in the deeper sec- 
tions of our canals and rail-roads, and in the banks of some of 
the rivers, where they usually reach from the water's edge to 
an elevation of sixty, seventy, or more feet. They extend along 
the upper edge of the Atlantic plain, ranging along the east- 
ern base of the rocky Atlantic slope, in a belt several miles 
wide, and appearing at intervals, where the rivers have cut 
through them, from the coast of Massachusetts as far at 
least, it is believed, as the Mississippi. Professor Hitchcock, 
speaking of these beds in the valley of the Connecticut river. 



I 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 19 

describes them under the name of the most recent tertiary, 
which I have stated to be my own view. But he makes a di- 
stinction between these and other similar beds in Martha's 
Vineyard and elsewhere, which he calls plastic clay. The first, 
he says, are horizontal layers of white siliceous sand and blue 
plastic clay, almost entirely destitute of any organic remains. 
These beds constitute most of the level and elevated terraces 
along the valley of this and most of the other rivers of New 
England; the height of the plains above the water is from 
fifty to one hundred feet. Along the Connecticut, in some 
places, the clay beds alone compose the clifi", and are from forty 
to more than seventy feet thick. They repose beneath fifteen 
or twenty feet of diluvial matter. Their position, and all their 
features, here and everywhere else, indicate a general uplift of 
the strata along the whole line of the primary boundary when 
that boundary formed the coast, and a consequent emergence of 
these beds from about the water level, where they seem to have 
grown as marshy deltas, accumulated along the ancient mouths 
.of the rivers. On this supposition, the mouths of the Atlantic 
rivers were at the points where they now form their falls, and 
break through the boundary of the older rocks ; and it is singular 
enough that all the conspicuous deposits of these clays, imbed- 
ding the trunks of trees and lignite, are just opposite, or near to, 
the same points. At Gay's Head, on the coast of Martha's Vine- 
yard, are alternating sands and clays, which I refer to this for- 
mation, rising in the cliff to a height of between 150 and 200 
feet. The clays contain a bed of lignite, which is, in some 
places, five feet thick. It alternates with the clays, especially 
-the blue, and is often intimately mixed with them, forming a 
comminuted dark mass, resembling peat. Woody fibre is often 
distinguishable in it, and the whole has the appearance of a 
deposit of peat, through which logs are interspersed. The prin- 
. cipal beds lie not far from the middle of the cliff, and have a dip 
of from 40° to 50° north. In this lignite bed are found impres- 
. sions of dicotyledonous leaves, apparently Ulmus, Salix, &c., 
trees at present growing in the country. Associated with these 
beds of clay, however, occur several variations of sand; and what 
at first seems startling enough, one bed described as a green sand, 
containing remains of Crabs, casts of shells, Alcyonites, &c., 
evidently referrible to the cretaceous formationof New Jersey, and 
also interstratified with the same osseous conglomerate, from 
which were procured the teeth of a Crocodile and several bones, 
some of them very large, being nine inches thick, and as much 
in length. The worn and mutilated state of these remains, and 
the mixture in which they are found, prove forcibly that the bed 

C 2 



20 FOURTH REPORT 1834. 

is derived from the violent disintegration of a much more ancient 
formation than that in which it occurs, namely, of a cretaceous 
deposit, like that of New Jersey, which may possibly underlie 
this island and Long Island also, they being exactly in its range. 
The dip and contortion of the strata at Gay's Head lend consi- 
derable probability to the foregoing explanation of the origin of 
this bed of detritus from the greensand. In other quarters, the 
ancient alluvial beds which I am discussing are usually nearly 
horizontal, or when they incline, it is with a gentle dip towards 
the ocean ; but in the strata at Martha's Vineyard the dip is 
abrupt and in the contrary direction, being to the north. These 
circumstances, taken in conjunction with the fact, that a pre- 
cisely similar deposit of detritus from the greensand formation 
covers the northern edge of that group of beds in many spots in 
New Jersey, where I have seen it not far east of the beds of 
so-called plastic clay and lignite, — as, for example, between New 
Egypt and Bordentown, — make me venture to put forward the 
suggestion that the cretaceous formations of our coast have 
probably extended further to the north-east than at present, oc- 
cupying what is now Long Island Soimd, and its prolongation 
eastward. Viewing the island of Martha's Vineyard and Long 
Island as remnants of a more extensive ancient tract in structure, 
like the peninsula of New Jersey, we can readily account, I 
think, for all the above phaenomena, together with some others 
which they present. 

According to Hitchcock, similar strata of the tertiary clays, 
which I have called ancient alluvium, underlie the diluvial 
covering in both Nantucket and Long Island. They are con- 
spicuously exposed in New Jersey, in the sections of the rail- 
road near Amboy, and again very strikinglj' on the Delaware, 
near Bordentown. Here they have all the features which they 
display at Martha's Vineyard, with the exception that they are 
nearly horizontal and less brightly variegated in colour. Lignite, 
containing pyrites, dicotyledonous M'ood, and amber, abound in 
the dark tenacious clay or ancient peat, which has here a thick- 
ness of many feet. The following description of this formation 
in New Jersey and the States south of it will serve to show its 
extensive range and important character. 

In ascending the Raritan it is traced on the south-east shore 
to within three miles of Brunswick. Approaching Bordentown 
by the rail-road it is conspicuously exposed for several miles 
in nearly all the deep cuttings. At Bordentowii the banks of 
the Delaware consist of its various beds of brilliant sands and 
dark and white clays for more than two miles. At Philadelphia 
it occurs, but at a lower level, remains of trees having been 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 21 

found forty-five or fifty feet beneath the city. It is seen in the 
sections along the Delaware and Chesapeake Canal, where its 
black tenacious vegetable clay and its sands precisely resemble 
those above : also in the sections of the Newcastle and French- 
town rail-road. Around the harbour of Baltimore these de- 
posits occur on a large scale. In excavations made at Baltimore 
abundant remains of trees and their fruits, particularly the black 
walnut, have been found at the depth of forty-five or fifty feet. 
In Virginia, along the same line, as at Richmond for example, 
similar facts are well known. Near Baltimore, in sinking a well 
in the Star Fort at Fort M'Henry, two miles below the granite 
ridge, or supposed ancient coast, the workmen came upon a 
mass of carbonized wood in a boggy marsh fifty feet below the 
surface. In digging a well in the same Star Fort (perhaps the 
same well), a tooth of the Mastodon was found at the depth of 
nearly sixty feet. At a point on the Chesapeake Bay, about 
twenty miles below Baltimore, called Cape Sable, very extensive 
beds of these clays occur, abounding in lignite, pyrites, and 
amber. The uppermost stratum is sand, very ferruginous, often 
sixty or seventy feet thick, then a stratum of lignite three to 
four feet. Below this a bed of sand, intermixed with enormous 
quantities of pyrites, nests of this mineral occurring from a foot 
to a foot and half in thickness, and of fifteen or twenty square 
feet in surface. Next follows a bed' of earthy lignite, from five 
to twelve feet deep, containing an abundance of pyritous wood, 
with fragments of bituminous wood thirty feet long. In this 
stratum of lignite have been also found specimens of a curious 
comb or nest, the work of an insect. These are from one to 
three inches in length : each cell has several minute holes. The 
substance is a resinous matter, resembling amber in properties, 
and the whole nidus is generally attached around a stem or car- 
bonized twig. 

The next stratum is an argillaceous sandstone two to five feet 
thick, uneven on its surface, while the beds above are all nearly 
horizontal. Below is a bed of whitish grey clay four feet, and 
beneath all a bed of sand. The enormous accumulation of car- 
bonized trees in this place, now eighty miles in a direct line 
from the sea, and at least fifteen from the supposed ancient 
coast or boundary of primary rocks, points very clearly to the 
existence, at some ancient date, of an extensive delta here. 
Whether these beds at Cape Sable may hereafter be found con- 
tinuous with those around Baltimore in which the Mastodon's 
tooth was found, time will ascertain, but as yet we have no data 
precise enough from which to infer the probable place of these 
beds in the series. 



22 FOURTH REPORT — 1834. 

Their geographical position is between the supposed ancient 
openings of the Susquehanna and Potomac rivers. No one who 
is familiar with the annual floods of these rivers, and has seen 
the burden of wood and trees which the former tears up in its 
passage through the mountains, and discharges each spring into 
the Chesapeake Bay, can doubt that the very same rivers have 
probably been employed in olden time in forming these very 
tracts of sand, clay, and lignite. There are now in the upper 
part of the bay large flats, which consist solely of sand and 
drifted timber, the annual scourings of the Susquehanna ; and 
if we conceive these tracts to become converted into marshes 
and swamps, as might readily happen, we have all the circum- 
stances, and in the same district, which would be requisite to 
produce from these recent deposits beds perfectly similar to the 
more ancient ones just described. 

Whether those ancient alluvial deposits from Martha's Vine- 
yard to the Chesapeake are all of one date of formation, and 
what indeed their precise age is, are matters demanding much 
future research to detennine. I have called these beds alluvial, 
but by no means venture to suppose them all the results of ac- 
cumulation in deltas, strictly so called. Our rivers may have 
had basins or estuaries through the tracts in question, through- 
out which, as well as upon the coast, these beds may have col- 
lected. The details of this formation further south are not in a 
sufficiently authentic shape to be presented ; we know, however, 
that similar beds of clays, sands, and lignites occur largely upon 
most of the southern rivers, and upon the Mississippi, on a scale 
which is truly gigantic. 

I am inclined to consider as a portion of the same formation 
an extensive group of variegated clays and sands which spread 
themselves very widely over the States of Georgia and South 
Carolina. Like the others before treated of, these contain few 
fossils. They are seen to repose in some places upon the cre- 
taceous rocks, as those in New Jersey do ; in some places upon 
Eocene; and they are also found below the diluvium. 

These beds have been already referred by Vanuxem to ancient 
alluvial origin. He thus describes them ; 

"The ancient alluvial is chiefly composed of red earth. This 
earth is pretty uniform in its character, consisting of sand, with 
a minute portion of clay, coloured by red oxide of iron. Its in- 
ferior parts often contain pebbles, sometimes coarse nodules or 
geodes of iron, resting almost invariably on the white or varie- 
gated clays, or upon those masses which contain littoral shells. 
Though not often met with beyond North Carolina, it is ex- 
tremely abundant in all the States south of it. It appears to 



REPORT ON THB GBOI-OGY OF NORTH AMERICA. 23 

occupy the highest elevations above the secondary and tertiary 
classes, and consequently could not have been formed by our 
existing rivers. It is entirely unmixed with the tertiary, and 
destitute of the fossils vv^hich characterize the latter; it must 
therefore be considered as distinct from it, at the same time 
that it is unlike the modern alluvial, whose origin is clearly at- 
tributable to the overflow and inundation of our rivers." 

This red earth is precisely similar to the mixture of sand and 
clay which we may witness discharged from some of the turbid 
rivers of the Mississippi in the present day. It is seen covering 
tertiaries at Augusta in Georgia, Columbia in South Carolina, &c. 
The ancient alluvial beds, resembling in all respects tliose at 
Bordentown, are seen along the Santee canal in Georgia, whei'e 
they repose on secondary beds. In excavating this canal, not 
only the dark vegetable clay before described, but much lignite 
and the remains of a Mastodon were found, marking the agree- 
ment of the deposit in all respects with the corresponding beds 
at Baltimore and elsewhere. 

Fossil Mammalia of the United States. — ^The extinct species 
of the higher orders of animals found fossil in the United States 
are Mastodon giganteum, Elephas primigenius, another Ele- 
phant (a tooth only being known, differing considerably from 
the tooth of either the living or fossil species). Megatherium^ 
Megalonyx, Bos bombifrons, Bos Pallasii, Bos latifrons, 
Cervtis americanus, or fossil Elk of Wistar, and Walrus. 

Of living species also found fossil, we may enumerate the 
Horse, the Buffalo, and three or four species of Deer. The 
situations in which these have been found have been either very 
recent undisturbed alluvial bogs, or a slightly disturbed marshy 
deposit like Big Bone Lick, neither of them covered by the 
general diluvium; thirdly, boggy beds containing lignite re- 
ferrible to an ancient alluvium, covered by diluvial sand and 
gravel ; and lastly, the floors of caves, buried to a very small 
depth with earth not described. 

The largest collections of bone remains occur in boggy grounds 
called Licks, affording salt, in quest of which the herbivorous 
animals, wild and domestic, enter the marshy spot and are 
sometimes mired. The most noted of these deposits is Big 
Bone Lick in Kentucky, occupying the bottom of a boggy val- 
ley kept wet by a number of salt springs, which rise over a sur- 
face of several acres. The spot is thus described by Mr. Cooper : 
**The substratum of the country is a fossiliferous limestone. At 
the Lick the valley is filled up to the depth of not less than thirty 
feet with unconsolidated beds of earth of various kinds. The 
uppermost of these is a light yellow clay, M'hich apparently is 



24 FOURTH REPORT — 1834. 

no more than the soil brought down from the high grounds by 
rains and land floods. In this yellow earth are found, along 
the water courses at various depths, the bones of Buffalos (Bi- 
son) and other modern animals, many broken, but often quite 
entire. Beneath this is another thinner layer of a different soil, 
bearing the appearance of having been formerly the bottom of a 
marsh. It is more gravelly, darker coloured, softer, and con- 
tains remains of reedy plants, smaller than the cane so abundant 
in some parts of Kentucky, with shells of freshwater MoUusca. 
In this layer, and sometimes partially imbedded in a stratum of 
blue clay, very compact and tenacious, are deposited the bones 
of extinct species." Mr. Cooper has been at the pains to com- 
pute, from the teeth and other parts known to have been re- 
moved from Big Bone Lick, the number of individuals requisite 
to furnish the specimens already carried off: 

Mastodon maxiinus .... 100 individuals, 

Elephas primigenius ... 20 — 

Megalonyx Jeffersonii . . 1 — 

Jios bombifrons 2 — 

Bos Pallasii 1 — 

Cervus americaniis .... 2 — 
and it is probable that some still remain behind. 

It is possible that the Horse ought to be added to this list of 
animals once indigenous to America. During the early settle- 
ment of the country, the great bones were either lying on the 
surface of the ground, or so near it as to be obtained with very 
little labour. 

The next most important kind of locality in which such re- 
mains are often found, is simply a soft bog or meadow, where 
most of the finest specimens known in this country have been 
obtained. As an example of the common condition in which 
the Mastodon is found, I may describe the situation of one dis- 
interred in 1824 near the sea-coast of New Jersey, three miles 
from Longbranch. "The proprietor of the farm, walking over 
a reclaimed marsh, observed something projecting through the 
turf, which he struck with his foot, and found to be a grinder 
tooth. Two other teeth, some pieces of the skull, the spine, the 
humeral, and other bones were afterwards found. The soil 
around was a soft dark peat, full of vegetable fibres. Though 
the skull and many other bones had been removed before 
Messrs. Cooper, Dekay, and Van Ransaeller, examined the spot, 
they were able to behold the vertebral column with all the joints, 
the ribs articulated to them, resting in their natural position, 
about eight or ten inches below the surface. The scapulae both 
rested upon the heads of the humeri, and these^ as in life, in ? 



REPORT ON THE GEOLOGY OF NORTH AMERICA. £5 

vertical position upoatiie bones of the fore arm. The right fore 
arm inclined a little backwards, and the foot immediately below 
was a little in advance of the other, in the attitude of walking. 
Ten inches below the surface was the sacrum, with the pelvis 
united though decayed. The femora were close by, but lay xn 
a position nearly horizontal, the right less than the left, and 
both at right angles with the spine. Both tibiae, each with its 
fibula, stood nearly erect in their natural place beneath the fe- 
mora, and below them were the bones of the hinder feet in their 
places : no caudal vertebrae were seen. The marsh had been 
drained for three years, and the surface had in consequence 
been lowered about two feet, producing, it has been conjectured, 
the dislocated attitude of the thigh-bones. Beneath the peaty 
bed a sandy stratum was seen, and all the feet were noticed to 
be standing upon the top of this floor of the bog." 

I have already described the nature of the beds in which the 
antediluvian Mastodon tooth was found at Fort M' Henry near 
Baltimore; and concerning the bed in which the cane specimens, 
the Megalonyx, &c., have been buried, I have no uiformation 
sufficiently satisfactory to offer. 

Localities of Fossil Mammalia. —'Eleph as primigenius : 
Big Bone Lick, Kentucky, the teeth especially in great num- 
bers. Biggin Swamp, in South Carolina, teeth eight or nine 
feet below the surface. (Drayton.) Kentucky has furnished the 
greatest number of teeth, but South Carolina the largest col- 
lection of other parts of the skeleton. (Godman.) Monmouth 
County, New Jersey. (Mitchell.) Opelousas, west of the Missis- 
sippi, bones and teeth in recent alluvium. (See Durald in Ann. 
Phil. Trans, vol. vi. p. 55., also Darby in Mitchell's translation 
of Cuvier's Theory of the Earth.) Stone in Carolina, teeth. 
(Catesby.) Queen Anne's County, Maryland, a grinder, dif- 
fering considerably from the tooth either of the living or fossil 
species, in stiff blue clay by the side of a marsh. 

Mastodon maximus : Big Bone Lick, Kentucky, in a dark 
coloured marsh, the upper stratum somewhat gravelly, the 
substratum a blue tenacious clay, both imbedding bones ; over 
all a light yellow soil, brought apparentiy from the adjacent 
high grounds: all the larger bones broken as if by violent action 
(Cooper). 

The remains of Mastodon are found indeed in nearly all the 
Western States in bogs and soft meadows uncovered by any di- 
luvial stratum. White River, Indiana, upper jaw and teeth. 
(Mitchell.) The marshes and bogs near the Walkill, west of 
the Hudson, New York. Tliis vicinity yielded the first and 
finest skeleton yet procured, viz. the magnificent specunen in 
the Philadelphia Museum. (Peale.) Also on the North Holston^ 



26 FOURTH REPORT — 1834. 

a branch of the Tennessee river. Carolina, bones, &c., in a 
morass like the rest. (Jefferson's notes on Virginia.) 

Again, in Wythe Com«^?/, Virginia, at five feet below the sur^ 
face, near a salt-lick, a large number of bones, almost an entire 
skeleton, veas found, said to have been accompanied by a mass 
of triturated branches, leaves, &c., enveloped in a sac, supposed 
to be the stomach, not however correctly. (See Godman's Nat. 
History.) Chester, Orange County, New York, in a peat bog, 
four feet beneath the surface, many fine fragments. (Mitchell.) 
On the York River some fine members of a skeleton were found, 
in marsh mud, surrounded by roots of cypress trees. (Madison, 
Medical Repository,) On the coast of Neiv Jersey, near Long 
Branch, in a bog, almost an entire skeleton, in the natural erect 
posture, the head hardly below the surface. (Cooper's Annals 
of the Neiu York Lyceum.) In Kockland County, New York, 
grinders three feet deep in mud. (Mitchell.) Near Baltimore, at 
Fort M'Henry, in digging a well in the Star Fort, in a stratum 
of marsh mud, nearly sixty feet below the surface, under a layer 
of diluvium. (Hayden's Geol. Essays.) Remains of Mastodon 
abound at the Salines (Licks) of Great Osage River to as great 
an extent, it is said, as at Big Bone Lick, or ai'ound the Wal- 
kill. (Godman.) 

Megatherium. Fragments of at least two skeletons in re- 
cent marsh, Skidaway Island, Georgia. (Cooper.) 

Mecalonyx. a fragment of an arm or thigh-bone, a com- 
plete radius, an ulna, three phalangal claw-bones, and some 
bones of the feet, found about thirty feet below the surface of 
the floor of a cavern in Green Briar County, Virginia. (Godman.) 
Big Bone Lick has furnished a large humerus, a metacarpal 
bone, a right lower maxillary bone with four teeth, a detached 
molar tooth in good preservation, a clavicle, a tibia of the right 
side. (Cooper.) Megalonyx bones have also been found in TFhite 
Cave, Kentucky. 

Bos BOMBiFRONS : two hcads at Big Bone Lick. (Harlan's 
Fauna Americana; Wistar's Trans. American Phil. Society.) 
Bos Pallasii, Dekay : a head. Big Bone Lick, also New Ma- 
drid, on the Mississippi, — closely resembles Bos moschatus. 
Bos LATiFRONs (Harlau) : a portion of a skull, ten miles from 
Big Bone Lick : Cuvier allies it to the Bos Urus of Europe. 

Cervus americanus (Fossil Elk) : two imperfect skulls. 
Big Bone Lick {Cooper) . Horse: Big Bo7ie Lick (Cooper), 
Neiv Jersey (Mitchell). The existence of the Horse pervious to 
the occupancy of this country by the Europeans, is not well 
established by the occurrence of its remains, though the evi- 
dence is in favour of the opinion. Walrus : anterior portion 
of the cranium, fossil, from Accomac County, Virginia. Not 



REPORT ON THE GEOLOGY OF NORTH AMERICA, 27 

known whether it belongs to the living species. This animal 
has not been seen on the American coast south of lat. 47°. 
{Annals of the New York Lyceum, vol. ii. p. 271.) 

It was suggested, first, I believe, by Mr. Vanuxem, that all the 
bones of the Mammoth and other extinct quadrupeds of this 
country yet found, have been in either the ancient or modern 
alluvium. Some have been inclined to attribute them exclu- 
sively to the catastrophe which has strewed the surface of this 
continent with transported blocks and gravel, or have supposed, 
in other words, that the races perished by that diluvial action 
which I have before shown to have occurred, after the period of 
the ancient alluvium, and prior to the recent. Notwithstanding 
the extreme neglect which has been hitherto evinced in record- 
ing the geological situation of the interesting organic remains 
of the extinct Mammalia of this country, sufficient information 
has been collected to enable us to reason, I think with some 
certainty, concerning the date of their disappearance. 

It will be observed that we have authentic accounts of the 
remains of extinct Mammalia under two entirely dissimilar si- 
tuations. In one case, as in the Mastodon tooth discovered 
near Baltimore, the fossil occurs in an ancient bog, covered by 
a thick bed of sand and diluvium. This is one of the deposits 
which I have called ancient alluvium, and which seems to 
belong to some aera of the tertiary period, but what precise 
epoch is at present quite uncertain. Another set, apparently 
consisting of the very same species, occurs in the most recent 
class of bogs and marshes, buried to a very slight depth be- 
neath the surface. The latter is the situation in which by far 
the largest number of Mastodon, Elephant, and other bones have 
been found. These newer bogs or marshes are in no case seen 
to be covered by any diluvial matter, but appear, on the con- 
trary, from their low level and their wet state, being often tra- 
versed by streams, to have experienced little or no change since 
the fossil relics were originally entombed in them. In the re- 
gions beyond the AUeghanies, most of these remains occur in 
spots which are called Salt Licks, which are meadows and 
swampy grounds where the soil on the surface of the ground 
is impregnated with muriate of soda, from the springs which 
empty themselves from the muriatiferous sandstones which 
abound in the Western States. Big Bone Lick, in Kentucky, is 
an example of one of these. Here have been found not only vast 
numbers of the fossil bones of the extinct races, but quantities 
almost as great of the Buffalo, besides many of two or three 
species of Deer, now, like the Buffalo, indigenous to the country. 
This, therefore, would appear to have been resorted to not 
only in modern times by the living races, but more anciently by 



28 FOURTH REPORT — 1834. 

animals now extinct, for the salt, and it may be for the food and 
pleasant coolness produced by the marsh. Our travellers to the 
western regions, where the Buffalo or Bison now ranges, have 
daily opportunities of witnessing these animals entrapped and 
perishing in these licks and swamps ; and it seems evident that 
the Mastodon and Elephant of former times, from their huge 
size and unwieldy forms, must have been equally exposed to 
the same fate. Granting such to have been the chief cause 
which has buried these races, we see at once why such remains 
are found only in meadows or soft places, why they occur at 
such small depths, and why in so many cases the head has been 
seen resting nearly on the surface of the marsh ; the cranium 
universally decayed ; and the skeleton either in its natural erect 
position, or the ponderous bones below, and the ribs and verte- 
brae above. (See Annals of the Neiv York Lyceum, vol. i. 
p. 145., also Ossemens Fossiles, 2nd edit. tom. i. pp. 217, 222.) 

The state of perfect preservation in which so many of these 
bones are found, is another argvmient that the animals have 
perished by such a cause, and not by any violent catastrophe. 
There is at present in the Philadelphia Museum a pair of mag- 
nificent tusks of the Mastodon, so little acted on by time, that 
the beholder almost fancies he sees the marks and scratches on 
the enamel which it received in the living state. These beauti- 
ful remains were found by a countryman in Ohio when digging 
an ordinary ditch in his meadow, so that it is probable that the 
rest of the skeleton lies near, and at very little depth. From all 
the facts before me, I have little hesitation in giving my opinion 
that the extinct gigantic animals of this continent, the Mastodon, 
Elephant, Megalonyx, Megatherium, fossil Bos, and fossil Cervus 
lived down to a comparatively recent period, and that some of 
them were in existence as long ago as the sera anterior to that 
which covered the greatest part of this continent with diluvium. 

Two interesting conclusions seem here naturally to suggest 
themselves : first, that the diluvial catastrophe, whatsoever it 
may have been, could not have introduced any very material 
change of climate or condition upon the continent, or we should 
have beheld the races sooner extinguished ; and, secondly, that 
the physical features of the surface were the same or very nearly 
the same when the Mastodon lived as now ; so that his extinc- 
tion seems neither traceable to violent revolutions, so called, nor 
to any decided change of climate ; which, seeing that no appre- 
ciable change of physical geography has taken place since his 
day, ought to remain the same now as when he formerly stalked 
through the continent, and perished in the same morasses 
which at this day entrap and bury our less gigantic living races 
of animals. 



REPORT ON THE GEOLOGY OP NORTH AMERICA. 29 

It may seem at variance with what I have here advanced of 
the recent and tranquil extinction of these animals, that in the 
enormous accumulation of their relics at Big Bone Lick, the 
boggy matter should be found partially filled with gravel, and 
the larger bones universally fractured. However, the small 
amount of gravel described as mingling with the peaty mass, 
seems hardly to imply that this spot was visited at this time by 
any violent action, such as covered the adjoining hills with their 
boulders and gravel ; so that, on the whole, I am most inclined 
to explain the fractured condition of the jaws, femora, &c., by 
the constant treading and floundering of the huge animals over 
the skeletons of their ancestors. 

Tertiary Formations. — Many circumstances tend to give 
peculiar interest to the tertiary geology of America at the pre- 
sent time. The day appears to have come when some of the 
broad conclusions recently arrived at in Europe may be fitly 
tested by a comparison with the phaenomena of remoter regions, 
and America would seem to be so much dissociated from Eu- 
rope, both by its insulated position and different physical struc- 
ture, that the comparison between them will possess peculiar 
weight. The great range which characterizes all the deposits 
of America belongs, no less remarkably, to those of the tertiary 
age, and affords a very favourable opportunity for ascertaining 
to what extent formations so recent may be distributed 
without departing materially from an uniform type, or where 
they do depart, of determining the causes which influence the 
variation. The existing animal and vegetable races of this 
hemisphere differ so widely from those of the Old World, that 
we are induced to inquire when, or whether at any time, the 
species on the opposite sides of the Atlantic were more nearly 
identical. These inquiries, bearing intimately on some of the 
most important questions of the science, have been recently dis- 
cussed with great ability by Mr. Lyell. I do not consider that 
our researches have proceeded to a sufficient length to render 
them of much weight upon many points in tertiary geology; but 
I nevertheless venture to remark, that they will be found to af- 
ford a striking corroboration of the soundness of the new prin- 
ciple upon which the tertiary formations of Europe have been 
arranged in chronological order by Lyell. They will perhaps 
be seen at the same time to suggest some slight changes in the 
views hitherto entertained respecting the different circumstances 
under which tertiary and secondary groups are supposed to have 
been severally formed. 

The area within which the tertiary deposits of this country 
occur, so far as our information at present extends, is that por- 
tion of the United States which I have styled the Atlantic 



FOURTH REPORT — 1834. 



plain, together with an undefined portion of the part of the 
great central plam of the continent which is connected with 
the Mississippi. 

The northern limit of the tertiaries, so far as at present une- 
quivocally ascertained, is in the south-eastern corner of New 
Jersey, adjacent to the Delaware Bay. Here it appears to com- 
pose the greater part of the counties of Cape May, Cumberland, 
and the south-west corner of Salem. From that point it is be- 
lieved to extend almost continuously through the eastern por- 
tions of Delaware, Maryland, Virginia, and North Carolina, and 
in interrupted patches further south through South Carolina, 
Georgia, Alabama, and Mississippi into Louisiana, and the ter- 
ritory west of the Mississippi river. 

The following arrangement will show the range, as far as hi- 
therto discovered, of the tertiary and recent formations of this 
country. 

Synoptical Table of Recent and Tertiary Formations of the 
United States. 



Periods. 


Character of Formations. 


Localities of the Formations. 


Recent. 


Modem alluvium, consisting 
of sands, clays, and marshes, 
containing ti-unks of trees; 
and occasionally relics of 
human workmanship. 


Deltas of nearly all the rivers, 
especially the Mississippi. 




Terraced valleys of alluvial 
origin. 


Connecticut, and many other 
rivers, especially in the New 
England States. 


1. 


Loose shell rock, composed of 
comminuted fragments of 
shells, exclusively those now 
found recent on the coast. 


Anastasia Island, and the sea 
islands and beaches parallel 
to the coasts of Georgia and 
Florida generally. Probably 
most of the other sand 
beaches and islands also, 
which lie along the coast as 
far as Long Island. 


2. 


Raised estuary formation, 
formed almost entirely of 
shells of the Rangia Cyre- 
notdes in a suhfossil state. 


Extends along the whole shore 
of the Gulf of Mexico from 
Pensacola to Franklin in 
Louisiana, bends around 
]\Iobile Bay, Lake Pontchar- 
train, and ranges across the 
delta of the Mississippi, im- 
mediately above its marshes , 
a total distance of nearly 300 
miles, and probably much 
furtlier. 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 



31 



Periods. 



Character of Formations. 



Banks of oyster shells, ascribed 
to the Indians, contain oc- 
casionally fragments of older 
tertiary shells, as Pectens, 
&c. ; matrix generally sandy, 
like that of the beach. 



Diluvial. I Boulders.pebbles, and sand, de- 
rived from the primary and 
ancient secondary rocks of the 
interior. No organic remains. 



Localities of the Formations. 



New Jersey; Choptank River, 
Maryland; York River, 
Virginia, &c. 



Surface of the United States 
generally. 



Ancient Al- 
luvial. 



Beds of clay and variegated 
sands. One bed is a deep 
black tenacious clay, con- 
taining leaves, trunks of trees, 
lignite, amber, and vegetable 
products generally. It has 
all the aspect of having been 
once a saltwater marsh, si- 
milar to that now at the mouth 
of the Mississippi. No re- 
mains but such as are sup- 
posed to belong to existing 
species have hitherto been 
found in these clays, and they 
are therefore, for the present, 
put apart from the true ter- 
tiary formations. 



Martha's Vineyard ; Long Is- 
land ; greater part of New 
Jersey from Amboy Bay 
along the sections of the rail- 
road to Bordentown; Chesa- 
peake and Delaware Canal 
in Delaware; Telegraph Hill, 
Baltimore ; near the city of 
Richmond, Virginia; Cape 
Sable in the Chesapeake Bay, 
Maryland. There is little 
doubt that the same appears 
interruptedly the whole way 
to the Mississippi. 



Newer Plei- 

OCENE. 



Older Plei- 
ocENE and 
Meiocene. 



A lead-coloured clay. 



Mouth of the Potomac, St. 
Mary's County, Maryland. 



Alternating beds of sand and 
clay, the sandy beds often 
abounding in fossil shells, 
which are sometimes in a 
friable and pulverulent state, 
giving the bed the character 
of a shell marl. These fos- 
siliferous beds rest almost 
invariably on a bed of blue 
clay; sometimes the sands 
are greenish, but more usu- 
ally they are yellow with a 
slight admixture of clay. 



Cumberland Comity, New Jer- 
sey; Cantwell's Bridge, De- 
laware ; Chester Town ; East- 
on, and nearly all the eastern 
shore of Maryland; the whole 
of Charles, St. Mary's, Cal- 
vert, and part of Prince 
George Counties, Maryland. 
In Virginia, in Lancaster, 
Gloucester, and all the pen- 
insula between James and 
York rivers ; also nearly all 
Norfolk, Nansemond, Isle of 
Wight, Surrey, and Prince 
George Counties. In North 
Carolina, near the towns of 
Wilmington, Murfreesboro', 
and throughout the counties 
of Craven,Duplin, &c., across 
the State. In South Carolina, 
Vances ferry on Santee river 
seems to be about the termi- 
nation of the middle tertiary 
groups of the United States. 



39 



FOURTH REPORT — 1834. 



Periods. 



Character of Formations. 



Localities of the Formations. 



Eocene. 



A series of whitish and lead- 
coloured friable limestones, 
and ferruginous and siliceous 
sands, all abounding in ex- 
tinct species of shells and 
zoophytes. 

Occurs also very frequently in 
the form of a fine-grained 
siliceous rock, abounding in 
casts and impressions of 
shells. This is used as a burr 
stone in Georgia. 



Piscataway, near the Potomac 
River, Maryland; < Upper 
Marlboro', Maryland; Vance's 
Ferry, South Carolina; and 
across to Three Runs, on Sa- 
vanna River; Shell Bluff, 
Savanna River ; Silver Bluff 
on the same, inBurkisCounty, 
Georgia ; near Milledgeville 
in Georgia ; Early County, 
Georgia ; Wilcox County, 
Alabama; Clayborne, Ala- 
bama ; St. Stephens, Alaba- 
ma ; Munroe, on the Washi- 
taw River, west of the Mis- 
sissippi. All these localities 
are on the authority of Mr. 
Conrad, who has either seen 
them in person or received 
eocene fossils from them. 



It is necessary, perhaps, that T here explain in what sense I 
employ the very useful nomenclature of Lyell. I wish it to be 
understood that I apply the terms Pleiocene, Meiocene, and Eo- 
cene to our beds, not under the idea of any strict identity, either 
in geological character or age, being discoverable between them 
and the strata which have severally received those names in 
Europe, but to express simply their own comparative chrono- 
logical relations, and their connexion with the recent organic 
races of this country, independently of any direct comparison 
with formations elsewhere. It is possible, indeed it is very 
likely, that some of our formations, our newer pleiocene, for ex- 
ample, may exhibit in their organic remains nearly the same 
proportion of recent species as certain beds in Europe, and yet 
differ materially from the latter in positive age ; for I conceive 
it is a fair inference, that throughout a certain period of more or 
less duration, the relations of species, from general physical 
causes, must be more stable in some regions than in others, va- 
rying less rapidlj'^, for instance, upon the tranquil shores of the 
United States, than near the often agitated coasts of volcanic 
Sicily. If this view be granted, and I think it should not be 
overlooked in attempting to establish identity of period in di- 
stant strata, the tertiary formations of America will furnish an 
instance in illustration of the importance of the caution recently 
given us by Mr. Murchison and other eminent geologists of 
England, that we make out a classification of our rocks from 
their own relations, instead of ranking them, as we have hi- 
therto invariably done, merely as members of European types. 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 33 

More extended researches in our recent conchology will 
doubtless inform us, from time to time, of the existence in the 
living state of some shells which we now regard as occurring 
only in the extinct and fossil state ; and the natural tendency 
will therefore be, to lessen Xhe apparent antiquity of each for- 
mation. It is this prospect of being compelled to modify our 
arrangement of the tertiary beds, as the researches multiply, 
that has made me hesitate to fasten upon all of them the terms 
of the new nomenclature, which they might otherwise claim. 
I propose, therefore, to designate them for the present by the 
convenient synonyms of 'newer tertiary' for the newer pleiocene, 
* middle tertiary' for the older pleiocene and meiocene together, 
and ' older tertiary' for the eocene. The newer pleiocene and the 
eocene certainly exist in well-pronounced characters, and there 
will be little or no necessity, now at least, to employ their pro- 
posed synonyms ; but the case is very different with the less de- 
fined formations of an intermediate age, and I shall therefore find 
it of essential assistance to employ, for these, the term ' middle 
tertiary'. American geologists will be careful not to confound 
the middle tertiary beds, of which I am speaking, with those 
which Mr. Conrad has designated by the same name, and which 
are clearly of eocene date, as both that gentleman (in his re- 
searches among the fossils of Clairborne, Alabama,) and Mr. 
Lea have been prompt to show. 

Newer Pleioce?ie of St. Mary's County, Maryland. — In the 
tertiary mass now before us, the number of well-characterized 
shells is such as to enable us to examine their relations to the 
species now living in the neighbouring ocean, or peculiar to 
other formations. For our knowledge of the formation at the 
mouth of the Potomac, we are indebted exclusively to the re- 
searches of Mr. Conrad ; and it is mainly from his descriptions 
and on other information which he has been kind enough to im- 
part, that I am enabled to present the following brief account 
of the deposit. He justly pointed out its very modern character, 
by showing the identity of nearly all the species with the shells 
at present living on our coast. Mr. Conrad thus describes the 
formation : 

"About three miles north of the low sandy point which forms 
the southern extremity of the peninsula, the bank of the Poto- 
mac rises to an elevation of about fifteen feet at its highest 
point : the fossils are visible in this bank to the extent of a 
quarter of a mile. The inferior stratum is a lead-coloured clay, 
containing vast numbers of the Mactra lateralis of Say, which 
in many instances appear in nearly vertical veins, as though 
they had fallen into lissures. The Pholas costata is also nu- 

1834. D 



34 FOURTH REPORT — 1834. 

merous, and each individual remains in the position in which the 
living shell is usually buried in the sand or mud ; that is, ver- 
tical, with the short side pointing downwards : they are so fra- 
gile, that they can rarely be taken entire from the matrix. Upon 
this stratum of clay, in a matrix of sand, lies a bed of the Ostrea 
virginica, in some places a foot in thickness. It is nearly 
horizontal ; in some places at least eight or ten, and in others 
not more than four feet above high- water mark. The diluvium 
above exhibits a vein of small pebbles, traversing it horizontally, 
and at a distance resembling a stratum of shells. Not only are 
the fossils of this locality the same as existing species, but in 
some instances they retain their colour ; a circumstance com- 
mon to the later deposits of Europe. The distance fi*om the 
nearest point on the Atlantic Ocean is about forty-five miles, 
but it is at least one hundred by the course of the bay. It will 
be observed, that nearly all the shells are known to inhabit 
the shores of the United States at the present time : those of 
them which are now only known in the fossil state are extremely 
rare, or of minute dimensions." 

Mr. Conrad also mentions to me as an indication of the great 
tranquillity which has attended the deposition of these beds, that 
the miderlying blue clay is everywhere penetrated by the Pholas 
costata in its natural position. The upper bed contains Ostrea 
associated with Mytilus, a fragile shell, in a very entire and un- 
disturbed condition. It is not a little curious that the same fel- 
lowship of Ostrea virginica and Mytilus recurvus {hamatus. 
Say,) should subsist at the present day in the Gulf of Mexico, 
though the latter shell has never been seen in the more northern 
latitudes of our coast. The Rangia, likewise a gulf shell exclu- 
sively, occurs also in the same newer pleiocene, so that we seem 
to have indications of a higher temperature even so late as the 
newest of our tertiary periods. Several of the species, however, 
in the foregoing table were long supposed by our conchologists 
to inhabit, in the present day, only the most southern portions 
of our Atlantic coast, but the same have been since found as far 
north as the shores of Rhode Island. 

The bed of Ostrea virginica reposing upon the fossiliferous 
blue clay, has already been referred to a somewhat newer date, 
from the circumstance of its entire identity with the very recent 
beds of fossil oyster seen on the margins of some of our rivers 
and bays, in circumstances which prove them to be among the 
very newest of aU the upheaved accumulations of the waters of 
the coast. Considering these upper remains, therefore, as not 
quite contemporary with the subjacent and more diversified 
assemblage of marine shells, we may regard the latter as having 



REPORT ON THE GEOLOGY OP NORTH AMERICA. 35 

colonized a tract in the bed of the ocean, much deeper than 
would be compatible with the known habits of the oyster, until 
the occurrence of an alteration of the level, from what may be 
termed deep sea, to a shallow estuary; the clay enveloping 
the lower shells, indicating perhaps the ooze peculiar to the 
one, the oysters above lying in a sediment equally characteristic 
of the other, namely, sand. The supposed change of circum- 
stances would be just such as would tend to banish the pelagian 
shells and to introduce in abundance a race like the oyster, de- 
lighting in protected coves and shoals. A second elevation of 
the region must have taken place to bring both beds to their 
present position above high tide, and to expose them to receive 
their covering of diluvial pebbles, which is said to be thick and 
well characterized. The deposit at the mouth of the Potomac 
is the only one of its exact period at present discovered, though, 
from the appearance of successive small upheaves at various 
times, along nearly the whole Atlantic plain, it seems reason- 
able to look for the occurrence of beds of nearly similar age in 
other sections of the coast; if, indeed, we have not already 
found one at Charleston, and on the adjoining coast of South 
Carolina, 

Formations of the older Pleiocene and Meiocene periods. — 
These deposits which, before the appearance of Mr. Lyell's no- 
menclature, went under the name of the 'upper marine' formation, 
from a supposed identity with the beds of that name in certain 
basins in Europe, constitute by far the most extensively distri- 
buted portion of our tertiary beds yet explored. There is even, 
I think, reason to believe that we have deposits of a wide range 
w^hich may be separately classed, some in the meiocene, others 
in the older pleiocene period, though in many cases it is not 
possible, from the present limited catalogue of their fossils, al- 
ways to infer with precision their exact comparative age : on this 
account, and also from the circumstance that their mutal geo- 
graphical connexion has never been yet properly examined, I 
prefer, for temporary convenience, to treat them for the present 
under one head, as the deposits of one great middle tertiary 
group. These are clearly separated by a well-marked and per- 
haps wide interval from the more recent newer pleiocene on 
the one hand, and the more ancient eocene on the other, though 
there is some ground to believe that they will be found to blend 
into each other by various shades of approximation, — unless, 
indeed, future researches may point out among them an addi- 
tional number of distinguishing fossils. It is very probable, 
from present indications, that when we have investigated the 
deposits of these two periods we shall find it requisite to inter- 

D 2 



36 FOURTH REPORT — 1834. 

calate several subordinate new periods between the principal 
ones already recognised, fulfilling the plan and the predictions 
of Mr. Lyell. 

The proportion of species in the tables which are to follow 
will show how far these suggestions are pertinent. In the 
mean while I sliall content myself with establishing, from proper 
evidence, the existence of both the older pleiocene and meiocene 
in their broader limitations, being assisted by the tables and 
notes of Mr. Conrad, whose researches in this field, in Maryland 
and Virginia, constitute the chief of what we at present know 
touching these formations, and whose expression of concur- 
rence in some of my present general views gives me much 
satisfaction. 

Geographical Range of the older Pleiocene and Meiocene For- 
mations. — Commencing most probably, as I have already stated, 
in the southern extremity of New Jersey, these tertiary beds 
show themselves in a wide and, at present, imdefined belt con- 
tinuously through Delaware, Maryland, Virginia, and North 
Carolina, in the south of which State, and in part of the adjoin- 
ing State of South Carolina, they only occur in interrupted 
patches, thinning out and disappearing altogether after reaching 
the Santee river in South Carolina. 

New Jersey . — Hardly anything is known of these formations 
in this State, beyond what may be inferred from a small collec- 
tion of shells procured by Mr. Conrad, near Stone Creek, Cum- 
berland county, and by a few specimens of similar fossils received 
from Cape May and other places along the same shore of the 
Delawai'e Bay. In mineral character the middle tertiary beds of 
New Jersey appear, from the slight examination which they have 
had, to consist of yellowish siliceous sands, resting upon a lead- 
coloured clay, the chief receptacle of the fossil shells above enu- 
merated. There is reason to believe that tertiary beds are nearly 
continuous from Salem to Cape May and Great Egg Harbour, a 
tract of at least forty miles long by ten or fifteen broad. How 
much more of the peninsula of New Jersey may consist of ter- 
tiary beds, we cannot say, as the surface is deeply covered by 
diluvium and sea sand. 

Delaware. — In this State tertiary formations of the same 
period certainly exist, though it is a district which has received 
no attention. At Cantwell's Bridge, fossils have been procured, 
which Mr. Coni-ad is inclined to refer to the middle tertiary, 
though we consider the locality to require further investigation 
before we can pronounce even thus far. 

Maryland. — Formations, the major part at least of which 
are fairly of the middle tertiary age, occupy nearly the whole 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 37 

surface of both shores of the Chesapeake Bay south of an irre- 
gular line drawn from Kent county to a few miles below the 
city of Washington on the Potomac. Over this great area, 
which is nearly one hundred miles long from north to south, 
and more than fifty wide, the tertiary beds are seen under 
nearly uniform characters in almost every spot where the rivers 
or ravines have exposed sections. The upper layers are usually 
arenaceous and repose very generally upon a more argillaceous 
stratum, often developed as an almost pure lead-coloured clay. 
Both deposits are highly fossiliferous, and when seen on the 
side of a river, present, sometimes, little else than a bank of 
shells and zoophytes, often in a state of fine preservation. 

Some of the most conspicuous localities are on the Chester 
river, which is about the northern boundary ; also at Easton 
and Cambridge, all on the eastern shore; and again on the 
western shore of the bay, especially in St. Mary's county, 
where many of the fossils of this formation were first discovered. 
Mr. Conrad describes the fossiliferous mass as extending in the 
precipitous banks of St. Mary's river nearly a mile. This bed, 
he says, contains many extinct species; it furnishes a large 
number of genera, with very few species of each, while the in- 
dividuals are in the greatest abundance. The bank is elevated 
perhaps thirty feet in the highest point above tide, and there 
the stratum of shells rises fifteen feet above the river. Siliceous 
masses with imbedded shells are numerous, and are used for the 
foundations of buildings. The inferior stratum of these banks 
is clay, which appears to contain the same species of shells as 
the sand above it. On the eastern shore of Maryland in the 
banks of the Choptank, not far from Easton, Mr. Conrad ob- 
served the following section. 

1. Diluvium. Feet. 

2. Sand, with Pecten Madisonius and Balanus Proteus almost exclu- 

sively 2 

3. Cythe.rea marylandica, Corhula and Pecten Madisonius, in sand ... 7 

4. Cytkerea marylandica in vast numbers, in sand, with Crassatella 

marylandica in abundance 4 

5. Blue clay, with Perna maxillata. 

Virginia. — Tertiary deposits, apparently of the same middle 
group, occupy, it is believed, nearly all Virginia east of a few 
miles below the primary boundary, and are seen to put on all 
the varieties observable in Maryland, being continuous and 
identical with those just described as belonging to that region. 
The average breadth of the deposit in Virginia may be stated, 
therefore, at about sixty miles, and its length the \\'hole extent 
of the State, from the Potomac south to the State of North Ca- 



38' FOURTH REPORT — 1834. 

rolina. Throughout this great area it has scarcely received any- 
geological examination, our only accurate information being 
that procured by Conrad in his researches among the fossils in 
Suffolk county, and again at York town, and some recent exa- 
minations made by my brother, W. B. Rogers, along the James 
and York rivers and the peninsula embraced between them. The 
general distribution of the formation, however, is well known, 
because the fossiliferous parts of the deposit are soxight over 
nearly the whole region for the fertilizing action of their carbo- 
nate of lime and shells upon the soil, in consequence of which 
the whole deposit bears the name of marl in all the States in 
Avhich it occurs. I select for description the beds upon the 
James and York rivers, as being best known to us, and probably 
characteristic of the deposit generally. 

On the James river, along the cliffs in the counties of James 
city and Warwick, the fossiliferous strata are finely exposed. 
My brother. Professor Rogers, thus describes the locality : " By 
far the most striking exhibition of the tertiary strata which I 
have yet seen is on the bank of James river, from a little above 
King's Mill upwards. The bank has an average height of sixty 
feet, and from the water-line to a few feet from the top is occu- 
pied by shells : in some places huge blocks of the deposit have 
fallen down, exposing the specimens in a very perfect state. The 
mass in which the shells are imbedded is usually a stratum of 
sand, sometimes covered by, but mostly resting upon, blueish 
clay, which also includes the same fossils. The sand, as in 
Maryland, is mostly yellowish, though it has often a green hue, 
like that called turtia by the French. It is sometimes indu- 
rated into a rough concreted mass by the cementing action of the 
carbonate of lime of the shells. An interesting fact is, the oc- 
currence among it of the green grains so chai'acteristic of the 
secondary greensand of New Jersey." 

My brother states, that after examining at least thirty distinct 
localities, he has found the greensand an invariable ingredient 
in all, some having as much as thirty per cent, of this mineral. 
At Burwell's Mill the stratum over the shells for five feet is an 
olive and red clay, containing from thirty to forty per cent, of 
the greensand, from which it receives its colour, olive or green, 
precisely as certain beds of similar clay in the secondary tracts 
of New Jersey acquire the same tint. 

A section upon the side of a mill-pond recently drained near 
Williamsburgh, about midway between the York and James 
rivers, affords the following arrangement: 1st, reddish sand, 
about eight feet, containing near the bottom a stratum two feet 
thick of shells, chiefly Fenus and Area idonea, very large : 



REPORT ON THE GEOLOGY OP NORTH AMERICA. 39 

2nd, blue marl, full of Venus, twelve inches ; 3rd, blueish 
green marl, four feet thick, having at the bottom a mass of 
Pecten, and belovr this a crowded layer of Perna, all perfectly 
horizontal. 

On the York river the stratification, though it does not ex- 
hibit so lofty a precipice fiUed with shells as before described 
on the James river, presents the clay strata very beautifully. 
Immediately overlying the shells is a continuous bed of clay, 
many miles long, in some places forming a vertical wall, ten or 
fifteen feet high, and as smooth as masonry. It is of a blue 
colour, and divided by thin layers of sand, perfectly horizontal, 
into portions about eight to twelve inches thick, so that the ap- 
pearance is very much like that of a wall. The incumbent clay 
in some places thins out, and changes colour to a reddish brown, 
which makes it scarcely distinguishable from the diluvium above; 
sometimes it is subdivided into two strata, separated by sand 
and gravel. This clay is a very common deposit throughout 
the tertiary marl region, sometimes beneath, sometimes above 
the shells, and often both below and above, and also containing 
shells. In appearance it resembles a clay which is a member of 
the secondary greensand formation of New Jersey. From York 
town, six miles up the river, is the following interesting section : 
1st. Near York, a curious rock, containing shells, often in minute 
fragments, being somewhat like masses of the crag of England. 
Here the strata are not horizontal ; but in a ravine below the 
town they dip on opposite sides toAvards the ravine at an angle 
of more than thirty degrees. This shell rock is an indurated cal- 
careous sand, formed of shells, not partially decomposed, but 
comminuted by attrition. It had obviously been subjected, as 
Mr. Conrad observes, to a violent action of the waters at a pe- 
riod anterior to the tranquil deposition of the perfect shells it 
contains. 2nd. From York town to about three miles up the 
river, the principal stratum consists of shells, overlaid by the 
above-mentioned blue clay, separated near its western end into 
two strata. 3rd. At some distance higher up, the shell rock 
again takes the place both of the stratum of shells and the over- 
lying blue clay. 4th. Beyond this again, and still on the same 
level, the blue clay is seen resting once more on the unbroken 
shells. The appearance of the wall of clay in these places is 
very curious ; it is as smooth as if cut with a spade, and re- 
sembles the wall of a fortress. On the Nansemond river, in the 
immediate neighbourhood of Suffolk, very nearly the same series 
of strata is seen as described upon the York and James rivers. 
Yellowish sand reposes most generally upon the blue clay, both 
beds containing a profusion of shells, and rising from the rivei 



40 FOURTH REPORT — 1834. 

some fifteen or twenty feet. This would appear to be the pre- 
vailing order, not only in all the portion of Virginia here de- 
scribed but throughout the middle tertiary region, from whatever 
part of it accounts have reached us, whether from Maryland or 
North Carolina. 

North Carol hw. — The middle tertiary beds are prolonged 
through this State in a belt, the east and west boundaries of 
which are not at present ascertained, but which appears to con- 
tract both in width and thickness as we proceed south. 

Professor Mitchell, of the University of North Carolina, men- 
tions it as ranging through the following localities : Near the 
northern boundary of the State it appears on the Meherrin river 
at Murfreesboro' ; further south, on the banks of the Roanoke at 
Scotland Neck ; again on the banks of Fishing Creek near In- 
field, in Halifax county, and on the banks of the Tar river near 
Greenville, in Pitt countj^, and also a little below the falls of the 
Tar ; in several places in Craven county, and on the banks of the 
Neuse, below Newbern. It appears also in Duplin comity, and 
on the banks of Cape Fear river, at Walker's Bluffs, and eight 
miles above Elizabeth. Walker's Bluff, like all the other con- 
siderable bluffs in this State, is on the western or right bank of 
the river as we descend. It extends about three fourths of a mile 
along the river, and then recedes and loses itself in the general 
plain of the country above. The stratum of shells is from five 
to twelve or fifteen feet in thickness, and its upper surface 
seventy-five feet above the mean level of the water in the river. 
The tide flows a few miles above it. Beneath the shells are al- 
ternating and irregular strata of sand and blue tenacious clay, 
the latter predominating. Above the shells the surface rises as 
we recede from the river, until it gains a height of about one 
hundred feet, which is not far from the average level of the sur- 
face of this portion of the State above the sea. In Duplin and 
many parts of the south-eastern corner of the State, as along 
Cape Fear River, near Wilmington, this formation rests imme- 
diately upon the upper zoophitic limestone of our southern cre- 
taceous rocks. It is here in fact a mere capping, having a 
thickness of not more than a very few feet, but still abounding 
in characteristic fossils. 

South Carolina. — Mr. Conrad has the following observation 
in allusion to the southern extremity of these beds, which I have 
here termed middle tertiary : " The formation has not been 
found south of Vances Ferry, on the Santee river, in South 
Carolina ; nor do I believe it occurs in Georgia, Alabama, or 
Mississippi. I never myself observed it in any part of Soutli 
Carolina, though I explored the country between Charleston and 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 41 

the Eutaw springs, which is wholly secondary. The deposit 
therefore at Vances Ferry is probably very limited in extent, 
and extremely superficial, capping the cretaceous rocks in the 
same manner as at Wilmington. 

" The pleiocene probably occurs on the Santee river, near the 
junction of the Congaree and Wateree rivers, as Mr. Say de- 
scribes two species of Area, evidently pleiocene fossils, from a 
locality near the junction of these two rivers." 

Such, then, are the principal localities at present known of the 
middle tertiary formations in their apparently continuous range 
from the Delaware to the Santee, over a tract perhaps eighty 
miles in breadth from the coast. In external character, mineral 
contents, and organic remains, the sedimentary deposits over 
this great tract exhibit a most marked uniformity, and were it 
not that the principle has been furnished us whereby, through 
a comparison of recent and extinct fossils, the relative antiquity 
of each locality may be determined, at least approximately, we 
should, vrithout a doubt, regard the whole tract as one simul- 
taneous formation. I look confidently, however, for both older 
pleiocene and meiocene proportions among the species, and shall 
not be surprised if we discover, ultimately, almost every inter- 
mediate ratio. For this intimate association of the two periods 
there would seem to exist a natural and obvious cause. The 
whole of our tertiary, and even cretaceous groups, are all de- 
posits effected under the same general physical exposures, all 
accumulations upon the same coast, bearing traces of no con- 
vulsions, and therefore interrupted by no hiatus. These for- 
mations occupy one extensive plain, where the stratification is 
amazingly horizontal, which is crossed by no ridges, and there- 
fore subdivided into no basins ; so that the whole may be con- 
sidered as having resulted from a set of causes continuing in ac- 
tivity throughout a long period. 

Having procured a table of all our middle tertiary fossils at 
present known to us, and with it an enumeration of the species, 
recent and extinct, from the more important localities which 
have been explored, I am enabled to attempt a determination of 
the relative age of these beds, from the numerical relations of 
the shells. 

The total number of species from our tertiary beds, excluding 
the eocene and the newer pleiocene, is about 195 ; of these, nearly 
forty are known as recent shells, inhabiting principally our own 
coast. This presents us with a proportion of rather more than 
twenty-one in one hvmdred, or about the ratio of the living spe- 
cies in the meiocene formations of Europe. 

From New Jersey to North Carolina there is every reason to 



42 FOURTH REPORT — 1834. 

suppose that the greater part of the tertiary tract will furnish 
even a less proportion of living species than one fifth, vphile the 
tertiary beds of North Carolina have contributed a group of shells 
of which nearly two thirds are of recent species. The latter 
territory would therefore most probably come within the plei- 
ocene epoch, while the former districts are pretty clearly of the 
American meiocene. It is an interesting fact, however, that our 
meiocene shells, if we can at present call them such, resemble 
most the species of the European older pleiocene. 

The following brief details embrace the results of a compari- 
son of the respective fossils of each principal locality of our 
middle strata, according to present data. 

New Jersey. — To begin with the locality in New Jersey, it 
will be shown that we can at present enumerate only thirteen 
species whose relations are established. Of these, twelve are 
extinct, and one is supposed to be recent. 

What is curious in this small list is its containing so small a 
proportion of species recent on our coast, though the deposit 
evidently does not belong to our older tertiary, or eocene. The 
species are either the same as those found in the meiocene or 
middle tertiary of Maryland, or where they differ they are mostly 
analogous. It is certainly not fair to reason from such very 
limited data as are furnished us by this small list of fossils. New 
additions to our present rather small catalogue of recent shells 
may materially lessen the proportion of the species regarded as 
extinct : anticipating this, I feel the less hesitation in separating 
the beds of New Jersey from the eocene period. I consider it, 
nevertheless, possible that some of the middle tertiary forma- 
tions of this country may ultimately exhibit very nearly eocene 
proportions, while the character of a majority of their fossils 
may mark them to be decidedly meiocene in their relations. 

St. Mary's, Maryland. — This place has furnished about fifty- 
six species, thirteen of which are recent on our coast, while the 
remaining forty-three are extinct. The proportion of recent 
species here is 23 per cent. 

Euston, Maryland. — The deposit upon the Choptank river, 
near Easton, has presented, so far, about twenty-six species, 
twenty-two of them extinct and four living. Among the extinct 
species, the Perna inaxillata is conspicuous, as it always is 
wherever the deposit shows a large preponderance of species no 
longer living. The recent species here are about 16 per cent, 
of the whole, placing the bed, like that of New Jersey, perhaps 
in the meiocene period. 

Siiffolk, Virginia. — Here the total number of species procured 
is forty-five, about thirty-five of which are extinct and ten re- 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 43 

cent on our coast. It is evident that here the proportion of 
living species is greater than in most of the preceding localities, 
the proportion being something like 22 per cent. Should this 
ratio not materially vary with new discoveries, the deposit must 
be ranked, like the preceding, with the meiocene period, notwith- 
standing that its shells are rather the analogues of the European 
older pleiocene. 

York, Virginia. — About forty-four species are known from 
this spot, thirty-six of which are extinct, and the remainder 
recent. The living species here are nearly 18 per cent, of the 
whole, which differs but little from the ratio at Suffolk. 

Smithfield, on the James River, Virginia. — The deposit at 
this place has furnished sixty-four species, fifty-five extinct and 
nine recent. This affords a proportion of about 14 per cent., 
which, if it be taken as the true expression of the relations of 
the species, would place the locality in the meiocene, and per- 
haps in an older division of the period than would belong to some 
of the preceding deposits. 

North Carolina. — Though the fossil shells of this State have 
been very little examined, the present list indicates a group of 
beds decidedly more modern than any detailed above. Of thirty- 
seven species at present known, twenty-four, or nearly two 
thirds, are recent : should this proportion remain nearly the 
same, after the catalogue has been duly augmented, we must 
rank some at least of the interesting deposits of North Carolina 
in our older pleiocene, placing them most probably late in the 
period. A certain modern aspect about these shells lends coun- 
tenance to this prediction. 

I shall terminate this account of our middle tertiary beds with 
a list of the fossil shells of this period, which are common to 
the strata of both America and Europe. They are: 

1. Liicina divaricata, Lam. 

2. Cerithium melanioideum, Sow. (In the London clay.) 

3. Ostrea Virginian a, Gmel. 

4. Dentalium dentalis, Linn. (D. alternatum, Say.) 

5. Venus rustica ? Sow. (Isocardia fraterna, 5a«/.) 

6. Pectunculus subovatus. Say. (P. variabilis, Sow.) 

Older Tertiary, or Eocene. — The first notice of eocene de- 
posits occurring in the United States, as characterized by organic 
remains, was published by Mr. Conrad in the Journal of the 
Academy of Natural Sciences in 1830, from observations he had 
made in the vicinity of Fort Washington, in Maryland : he also 
stated that such beds occurred at Vances Ferry, on the Santee 
river, where it is since ascertained that they are covered by a su- 
perficial deposit of the fossils of the pleiocene period. One cha- 
racteristic fossil of the eocene of Claiborne {Ostrea sellceformis, 



44 FOURTH REPORT — 1834. 

Conrad,) occurs at the Eutaw springs and at Nelson's Ferry on 
the Santee river, but it lies in a white limestone, associated with 
very different fossils from those which accompany this Ostrea at 
Claiborne. This limestone is doubtless analogous to that on 
which the tertiary of Claiborne is based, but its true character 
is given by Dr. Morton, in his Synopsis, now in the press. Eocene 
deposits commence in Maryland, and extending in a south-west 
direction, crop out at intervals in the States of Virginia (?) and 
North and South Carolina, and are always of very inconsiderable 
breadth. They meet the Savannah river at Shell BluflF, fifteen 
miles below Augusta, and appear at Silver Bluff and other 
places, occupying a space of about forty miles, following the 
course of the same river. According to Mr. Vanuxem, Shell 
Bluff is about " seventy feet high, formed of various beds of im- 
pure carbonate of lime, of comminuted shells, and having at its 
upper part the Ostrea gigantea ? in a bed nearly six feet in 
thickness." 

The eocene formation appears on the Oconee, below Mill- 
edgeville, judging from a few fossils which have been sent from 
that vicinity. The matrix is calcareous, whitish, and very fri- 
able. We know nothing of its appearance on Ocmulgee and 
Fhnt rivers, but it has been observed in various parts of Early 
county, and it occurs at Fort Gaines on the Chattahooche, where 
it constitutes a bluff from 150 to 200 feet in height, which has 
a close resemblance to that at Claiborne. Its extent on the 
river is about one mile. 

In Georgia it is common to find the fossiliferous beds of the 
eocene developed as a pure siliceous rock or Buhr stone. The 
calcareous and other matter originally in the rock has all disap- 
peared and been replaced by silica, preserving, however, the 
casts of shells so perfectly that they may often be readily recog- 
nised. 

The eocene next appears in Wilcox county, Alabama, in the 
state of a hard dark-coloured sandstone, containing the charac- 
teristic shells, which are not mineralized at all, but are chalky 
and imperfect. This formation only extends eight or nine miles 
along the Alabama river. Claiborne Bluff is about one mile in 
loigth : a similar bluff, of equal extent, occurs three miles below, 
and about three or four miles south of this the deposit termi- 
nates in a bluff of less elevation. Here the upper bed is charac- 
terized by Scntella Lyelli (Conrad), the stratum being about 
three feet in thickness, with a matrix of angular quartzose sand, 
tinged by oxide of iron. Nearly the whole country in the vi- 
cinity of Claiborne is secondary, the eocene having been traced 
only about one mile east of the village, in the banks of a small 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 45 

creek. The ridge dividing the waters of the Alabama and Tom- 
beckbe, also secondary, is composed of cretaceous limestone, full 
of Nummulites Mantelli (Morton). St. Stephens, on the 
Tombeckbe, is situated on a bluff of the same, about one hundred 
feet in height ; but the eocene appears a short distance north of 
it, separated from the secondary by a strip of alluvial soil. Here, 
however, the two upper strata only are visible, the superior bed 
of limestone being but a few feet in thickness, whilst at Clai- 
borne the corresponding one is about forty-five feet thick. The 
arenaceous stratum is precisely similar to that of Claiborne, but 
the fossils are not so well preserved, and are chalky and friable. 
We know of no locality west of this, in Alabama or Mississippi, 
where the eocene formation occurs ; but on the Washita river, 
near the town of Monroe, it is associated with the strata of the 
cretaceous group, as Mr. Conrad ascertained by examination of 
some fossils sent to the American Philosophical Society by Judge 
Bry. The most abundant fossil beds of the eocene at this place 
appears to be Corbula oniscus (Conrad), a shell very common 
in the arenaceous strata at Claiborne. 

No other information has been received of any other localities 
of eocene deposits, but doubtless many will be discovered when 
geology is pursued in a more systematic manner. 

The following diagram will explain the order of succession 
and the thickness of the strata in Claiborne Bluff, and to these 
are added the two members of the cretaceous group, which oc- 
cur in the vicinity. Those species are indicated which occur in 
both formations ; they are highly interesting, as they furnish in- 
dubitable evidence of the antiquity of these tertiary beds. Among 
more than two himdred species of shells at Claiborne, there is 
not one which is identical with a fossil of the pleiocene of this 
county ; one only is even an analogue : not one can be referred 
to any recent species, much less to a native of the coast of the 
United States. One only, Lutraria papyrea (Conrad), is the 
analogue to a species of our coast, L. canaliculata (Say), in its 
general appearance, but is very remarkable in having the um- 
bones turned in an opposite direction to those of the latter spe- 



46 



FOURTH REPORT — 1834. 



Diagram representing the Strata composing the Bluff" at Claiborne. 







Thickness. 


Observations. 


Range of certain Spe- 
cies. 




1. Diluvium. 


20 feet. 








2. Whitish friable 


45 feet. 


Contains casts of a few species 


Pecten calvatus. 






limestone. 




occurring in the next stratum. 
The most characteristic fossil is 
Scutella Lyelli. Some species 
oi Aiithaphyltum also occur. 


Scutella Lyelli. 




3. Ferruginous si- 


6 feet. 


This portion is indurated, and the 








liceous sand. 




fossils occur in casts. 






14 feet. 


Very friable, and contains about 


Cardita planicosta. 










70 genera and 200 species of 












shells : among them are Cardiia 












planicosta, Corbis lamellosa, Py- 












ramidella terebellata, of thecal- 












caire grossier; apparently no 












species now existing, and none 






^ 






identical with those of the plei- 






K 

o 






ocene of Maryland. 






4. Sand with acal- 


3 feet. 


Concretion of Oslrea sellaformis. 






careous cement. 












5. Soft lead-colour- 










70 feet. 


Contain 0. selleeformis in abun- 


Plagiostoma dumo- 




k. 


ed limestone. 




dance, but other fossils are rare ; 


sum. (Rare.) 










some casts of univalves, a Pec- 






O 






ten,Antkophyllum, Flustra, Tur- 
binolia, &c. Hardly a trace of 
those species of the strata Nos. 
3 and 6. 






6. Friable lead- 


Thickness 


Contains the same class of shells 


Cardita planicosta. 






coloured lime- 


unknown. 


as stratum No. 3 ; the most cha- 








stone. Level 




racteristic fossil Cardita plani- 








of the river. 




costa, a shell very characteristic 
of the eocene. 






7. Very white fri- 


Thickness 


Contains many casts of shells pe- 


Scutella Lyelli. 






able limestone. 


unknown. 


culiar to itself, and no other fos- 
sil of the next deposit than 
Gryphtea Vomer. Characteristic 
fossil, Nummulites Mantelli 
(Morton). 


Plagiostoma dumo- 

sum. 
Pecten calvatus. 
Ostrea sellaformis. 
Ostrea panda. 
Ostrea cretacea. 












Gryphaa Vomer. 




^ c 


8. Blueish lime- 


300 feet. 


The characteristic fossil is Exo- 


Ostrea panda. 




s fe 


stone, alternat- 




gyra costata. 


Ostrea cretacea. 




• 5 -*=» 


ing with friable 






Gryphaa Vomer. 




sS 


limestone, sili- 










i o 


ceous sand, and 










2 e 


marl. 










^ 













REPORT ON THE GEOLOGY OF NORTH AMERICA. 47 

** If the deposit at Fort Washington, Maryland, be correctly- 
referred to the eocene, it must be a newer member of that for- 
mation than Claiborne Bluff, in as much as the species are gene- 
rally distinct, and no secondary fossil occurs amongst them. 
The only recent species is Venus mercetiaria (Lam.) 5 and one 
of the most characteristic shells, Ostrea compressirostra (Say), 
is found in the middle tertiary on James river, Virginia. Per- 
haps the deposit at Fort Washington will be found to class itself 
in a more recent period than the eocene." 

The total number of our eocene shells is about 210, nearly 
all the species being from a single locality, namely, Claiborne, 
Alabama. Other deposits, as that of St. Stephens on the Tom- 
beckbe, present a large collection of species also, but they have 
been found not to diifer from the species at Claiborne. 

It is remarkable enough that the older tertiary or eocene strata 
of Alabama contain a profusion of specimens of four secondary 
species, and yet possess not one species common with our 
meiocene or middle tertiary. This is just the reverse of what 
occurs among the corresponding formations in Europe, the eo- 
cene and meiocene coalescing there by 42 common species 
in 1238 of eocene, and the cretaceous and eocene strata having 
nothing identical between them. From this, and the interesting 
fact that our formations of this period contain not a single known 
recent species, it seems pretty evident that our southern tertiary 
strata assume an earlier place in the American eocene period 
than the beds of the Paris basin occupy in the eocene period of 
Europe. 

A fact equally as curious and unexpected is, that out of about 
210 eocene fossils from Alabama, not more than six are disco- 
vered to be common to the same period in Europe. They are, 

1. Corbis lamellosa, Lam. 

2. Cardita planicosta, Blainv. 

3. Bulimus terebellatus, Lam, 

4. Solarium patiilutn. Lam. (S. scrobiculatum, Conrad.) 

5. canaliculatum, Lam. (S. ornatum, Lea.) 

6. Fistulana elongata, Desk. 

It is not improbable, however, for reasons formerly advanced, 
that the number of identical species will augment as our strata 
and coast are more explored. 

Several other species show a resemblance to fossils of the 
eocene beds of the Paris and London basins, though they are 
obviously specifically different. 

Connected with the foregoing comparisons among our tertiary 
shells ought to be an inquiry into the number of shells which 
frequent our coast, and their relations to the living species of 



48 FQURTH REPORT 1834. 

European seas. I have accordingly procured from my friend 
Mr. Conrad a catalogue of the known marine shells inhabiting 
our coast from Louisiana to Maine. This I should have been 
glad to insert, as such a list has not before been made, but 
for the length to which this Report has grown under my hands. 
It is important to know, however, that the whole number of 
marine species, excluding those of the West Indies and the 
southern region of the Gulf of Mexico, does not much exceed 
200. It is possible that by dredging our coast a large accession 
to the list might accrue, yet it is apparent that the North Ame- 
rican border of the Atlantic is not prolific in Testacea ; and the 
same seems to have been equally the fact during the several 
tertiary periods. 

Mr. Conrad and Dr. Morton have arranged with care the fol- 
lowing viseful table of recent species common to the European 
and American coasts of the Atlantic. 

1. Purpura Lapillus. 17. Thracia convexa. 

2. Buccinum undatum. 18. Solecurtus fragilis. 

3. Natica canrena. 1!). Glycimeris siliqiia. 

4. Fusus islandicus. 20. Cardium islandicum. 

5. Cyprina islandica. 21. groenlandicum. 

6. Saxicava rugosa. 22. Tellina punicea. 

7. Lucina divaricata. 23. Venus niercenaria. 

8. Pholas cvispata. 24. Pecten islandicus. 
9. costata. 25. Strigilla carnaria. 

10. Anomia Ephippium. 26. Balanus ovularis. 

11. Solen ensis. 27. elongatus. 

12. Mya arenaria. 28. Anatifera dentata. 

13. Mytilus edulis. 29. vitrea. 

14. Modiola papuana. 30. laevis. 

15. Mactra deaurata. 31. Teredo navalis. 

16. Spirorbis nautiloides. 32. Serpula . 

The above list is likely to be sensibly augmented as fresh 
species are discovered. 

Here are 32 species in 200 (or one sixth) common to the two 
sides of the Atlantic, while, as we have seen, in 195 fossils of 
our middle tertiary there are but 6 ; and in 210 eocene fossils 
also only 6 which inhabited both continents during those re- 
moter {eras. We shall presently see, that during a still earlier 
period, that of the secondary cretaceous group, there was but a 
single species in 102 described which had this wide dispersion 
over both continents. Whether we shall discover a like dis- 
similarity in the organic remains of yet older formations is a 
question still to be solved, and it will require much preliminary 
labour and research. 

In concluding this survey of our tertiary formations, I ought 



REPORT OX THE GEOLOGY OF NORTH AMERICA. 40 

not to omit the curious and important fact, in harmony, I believe, 
with all the views here advanced, that among the organic re- 
mains of these deposits no traces of anything of freshwater or 
terrestrial origin have ever been discovered. 

Stepa in the History of the Tertiary Formations of the United 
States. — The whole of that large tract of the Atlantic plain and 
the basin of the Mississippi now found to be occupied by the 
tertiary and cretaceous formations, was originallj- laid down by 
M'CIure as alluvial. The first approach to a just knowledge of 
its geology commenced with the determination of about fortj/^ 
species of fossil shells collected in Maryland by Mr. Finch. 
Neither of these gentlemen, however, drew any geological in- 
ferences from the organic remains they examined. Dr. Van 
Ransaellar afterwards i-eferred the deposits in question to the 
age of the upper marine tertiary formation of England. Dr. 
Morton supported the same opinion, pointing out several species 
of fossil shells common to both sides of the Atlantic. After- 
wards, in 1830, Mr. Conrad visited Maryland, discovered the 
newer pleiocene at the mouth of the Potomac, which however he 
did not pronounce to be tertiary, examined the fossils of the 
formations which I have called middle tertiary or older pleiocene 
and meiocene, and which he had previously named upper marine, 
and also those of Fort Washington on the Potomac, which he 
ventured to suggest were of the age of the London clay. In 
1832, after a visit to Suffolk, James river, and York, to collect 
tertiary shells, Mr. Conrad commenced his work on the fossil 
shells of the tertiary formations of this country, retaining the 
term ' upper marine ' for the older pleiocene, using the title 
' middle tertiary ' for what he had shown to belong to the age 
of the London clay, and which he now shows to be our eocene, 
and applying the name 'lower tertiary' to a class of beds de- 
scribed as the plastic clay formation, first by Mr. Finch, and 
afterwards by Hitchcock, and Morton, and as subordinate to the 
secondary by Vanuxem, but which I have recently shown, under 
the appellation of ' ancient alluvium', to be of much more recent 
formation. Not long after, Mr. Conrad visited the eastern shore 
of Maryland, where, on the Choptank, he procured many new 
fossils, and made some interesting observations upon the beds 
in which they occur. In 1833 he visited Alabama, where he 
found the eocene very largely developed. His discoveries among 
the organic remains of that quarter constitute the largest con- 
tribution yet made to our tertiary geology. More recentlj^, my 
brother and myself have begun the development of the pleiocene 
and meiocene in Virginia. In 1834, Mr. Lea published his 
Contributions to American Geoloqy, describing about two 

1834. E 



50 FOURTH REPORT — 1834. 

hundred shells from the eocene of Alabama, the right of priority 
to the discovery of many of which, however, Mr. Conrad and he 
dispute. 

Many scattered descriptions of parts of our tertiary field have 
appeared from time to time in our Journals ; but as they have 
contained little or no scientific geology, I do not deem it neces- 
sary here to mention them. 

Cretaceous Formatio7is. — The survey just given of our ter- 
tiary formations is calculated, I think, to show how greatly 
formations of the same or nearly the same period, occurring in 
remote regions, may differ both in mineralogical characters and 
in organic remains. The peculiarities which distinguish the 
tertiary rocks of this country from those of Europe are clearly 
traceable to the general dissimilarity in the physical structure 
of the two continents, particularl)^ in the almost total absence 
of volcanic formations in the United States. 

This country, for a long series of periods, seems to have suf- 
fered less repeated and powerful convulsions than the opposite 
shores of Europe ; so that the same comparative exemption 
from disturbances is as apparent in om- secondary as I have al- 
ready shown it to be in our tertiary periods. I have already 
noticed the remarkably small number of species of fossils com- 
mon to the tertiaries of the two continents, and I doubt if we 
shall ultimately establish any closer identity in those of the 
group now before us. While the cretaceous formations of Eu- 
rope, from Ireland to Russia, are characterized throughout by 
a numerous class of peculiar fossils, it is not a little singular that 
so few of the same species should present themselves in the 
rocks of the corresponding period in America — not more than 
two perhaps of the 108 which are known. This fact, in con- 
junction with the no less striking one that we have yet disco- 
vered no true chalk in North America, has made me hesitate to 
apply without some qualification the received European names 
to these formations. For our information regarding this groiip, 
which embraces at present, perhaps, the most advanced portion 
of our geology, we are mainly indebted to the writings and re- 
searches of Dr. Samuel G. Morton, a new edition of whose work 
having just appeared, I am enabled to present this branch of the 
subject in its most complete state. 

Dr. Morton entitles these newest of our secondary beds the 
* cretaceous gi'oup', and regards them as divisible into two forma- 
tions, the lowest of which he calls the ferruginous sand, and the 
upper the calcareous strata. A very few years ago the group in 
question was not known to extend beyond the peninsula of New 
Jersey and a small part of Delaware. Subsequent discoveries. 



REPORT OX THE GEOLOGY OF NORTH AMERICA. 51 

however, mainly due to Mr. Conrad, have shown it to exist in 
nearly all the Southern States ; and from specimens brought, 
from time to time, from the interior of the continent, it would 
appear to occur abundantly on the Missouri far across towards 
the Rocky Mountains. From observations made by Professor 
Hitchcock upon the clay and satid strata of Martha's Vineyard, 
there seems little reason to doubt its existence either beneath 
that island or somewhere in the vichiity ; and it is more thaii 
probable, from appearances, that it underlies Long Island. " It 
is first unequivocally seen in New Jersey, whence it may be 
traced locally through Delaware, Maryland, Virginia, North 
and South Garohna, Georgia, Alabama, Mississippi, Tennessee, 
Louisiana, Arkansas, and Missouri." Dr. Morton remarks that 
" these various deposits, though seemingly insulated, are doubt- 
less continuous, or nearly so, forming an irregular crescent nearly 
three thousand miles in extent ; and, what is very remarkable, 
there is not only a generic accordance between the fossil shells 
scattered through this vast tract, but, in by far the greater num- 
ber of comparisons I have hitherto been able to make, the same 
species of fossils are found throughout : thus, the Ammonites 
placenta, Bamlites ovatus, Gryphcea Vomer, Ostrea falcata, 
Exogyra, &c., are found without a shadow of difference from 
New jersey to Louisiana, although some species have been found 
in the latter state that have not been noticed in the former, and 
vice versa." 

Calcareous Formations. — Beds of limestone and calcareous 
sandstones form the upper strata of the secondary class through- 
out the greater part of the marl region, as it is called, of New 
Jersey. They always occur in thin, horizontal, and rubbly lay- 
ers, either interstratified with blueish clay, or more commonly 
resting immediately upon the friable sands and marls of the 
formation beneath. The more calcareous beds are often highly 
fossiliferous and partially crystalline, reminding me strongly in 
their stratification and general appearance of some of the com- 
pact and thin oolites of England. Dr. Morton describes these 
calcareous strata as presenting the following varieties, — 

"An extremely friable mass, containing at least 37 per cent. 
of lime, with a considerable proportion of iron, silex, &c. It 
appears to be almost entirely composed of disintegrated zoo- 
ph^'tes — 

"A yellowish or straw-coloured limestone, as hard as the car- 
boniferous varieties, containing numerous organic remains, — 

" A granular or subcrystalline limestone, intermediate in 
structure between the former two, and including similar fos- 
sils. 



52 FOURTH REPORT — 1834. 

" A white soft limestone, not harder than some coarse chalks, 
which it much resembles, replete with fossils. 

" All these varieties occasionally contain infiltrations of sili- 
ceous matter, and considerable masses of chert are sometimes 
observed in them : they also present some appearances of the 
green grains so characteristic of the marls adjacent." 

These calcareous strata appear to be much less abundantly 
distributed in New Jersey than the friable sands and marls upon 
which they rest, for they have hitherto been found only at in- 
terrupted intervals along the south-eastern border of the marl 
region. 

Limestone strata, however, seem to compose nearly the whole 
of the cretaceous group in the Southern States, where they exist 
on a scale of vast extent and thickness, rising into bold undu- 
lating hills, which resemble in their features the surface of the 
chalk in Europe, and seldom or never repose upon the sands 
which form their substrata in New Jersey. In Alabama, Mr. 
Coni-ad states this formation to constitute nearly the whole bed 
of the country, the eocene occupying very limited patches in 
the valleys of some of the rivers. Generally throughout Georgia 
and the States south and west of it, these limestones are deve- 
loped as two distinct strata. That which is universally superior 
in position is a very white friable limestone, containing many 
casts of shells peculiar to itself, while beneath this is a compact 
blueish limestone, alternating with friable limestone and with 
greenish siliceous sand, which is indurated into a rock, and con- 
tains fossils and the peculiar green particles of silicate of iron. 
The thickness of the lower deposit is stated to be about 300 feet 
on the Alabama river. Its characteristic fossil is the Exogyra 
costata, the same shell which is so remarkably distinctive of the 
marl beds in the ferruginous sand formation of New Jersey and 
Delaware. 

In some places, as in Wilcox county, Alabama, this lower 
limestone is seen to rest upon a still inferior bed of a friable 
greenish sandstone, containing fossils, especially the Ostrca fal- 
cata, and also presenting, like the limestone above it, some of 
the green grains everywhei*e characteristic of these cretaceous 
formations. 

Ferruginous Sands of New Jersey . — These arenaceous strata 
compose tne chief mass of the secondary deposits in New Jersey, 
being buc partially overlaid by the very thin calcareous strata 
before mentioned. The mineralogical character of this deposit 
is extremely variable, though the most usual constituents are 
the following : 1st. Siliceous sand, mostly yellowish and ferru- 
ginous, though sometimes cf a green colour, answering to the 



REPOnT ON THE GEOLOGY OF NORTH AMERICA, 53 

glauconie sableuse of Brongniart. These sands occasionally 
occur in indurated strata containing fossils, when they form a 
rock ijrecisely the same in all respects as that which underlies 
the limestone in Alabama. 2ndly. The peculiar greenish chlo- 
ritic grains of the greensand formation of Europe. This mine- 
ral exists generally in the shape of small grains of about the 
size and form, and not unfrequently of the dark plumbago co- 
lour, of gunpowder. Sometimes it has a rich warm green, but 
more commonly an olive grey or dull blue, or even a very dark 
chocolate colour. 

The grains, although they contain about 50 per cent, of silica, 
are not gritty, can be easily bruised between the teeth, and when 
moistened some varieties can even be kneaded into a somewhat 
plastic mass. A pile of this marl, as the granular mineral is 
called by the inhabitants of New Jersey, after being somewhat 
exposed to the air, frequently contracts a light grey hue, from 
the exterior grains becoming coated with a white inflorescence, 
which, from some observations I have made, is most probably 
carbonate of lime. The following analysis by Mr. Seybert pre- 
sents a fair average of the composition of the green grains : — 
silica 49-83, alumina G'OO, magnesia 1-83, potash 10-12, prot- 
oxide of iron 21*53, water 9-80; loss 0*89 = 100 grains. Other 
analyses show occasionally as much as 5 per cent, of lime. 

Mica in minute scales mingles not unfrequently in the less pure 
varieties of the marl, which often contains more or less blue clay. 

Once or twice, in examining a mass of these mineral grains, 
I have detected numerous minute spicula of selenite. Almost 
every large heap of the marl exhales a distinct odour, closely 
resembling sulphur. These mineral grains occur in greater or 
less proportion in nearly all the strata, both arenaceous and 
calcareous, of the formation ; but what is remarkable, they occur 
alone, without any admixture of either sand or clay, in a homo- 
geneous deposit, which seems to underlie nearly the whole secon- 
dary tract of New Jersey, the stratum averaging ten or twelve 
feet in thickness. 

It is this stratum which is especially called the marl, rather 
from its highly fertilizing action upon the soil than for any re- 
semblance it has to marl strictly defined. I am not aware that 
the green chloritic substance has been found composing any 
extensive separate deposit, in such a state of entire purity, in any 
other region. I have met with no description of any such stra- 
tum out of New Jersey, either in Europe or among the creta- 
ceous masses of our Southern States. 

Beds of a dark blue tenacious clay, not unlike the gault of 
England, occur sometimes associated with these beds of marl, 



54' FOURTH REPORT— 1S.'34. 

and sometimes the clay and marl are mingled. Beneath the 
stratum of pure greensand or marl, a dark ferruginous sand- 
stone, containing many of the same cretaceous fossils which 
abound in the marl, has occasionally been reached. This, M'hich 
is the lowest bed of the group, exhibits a striking resemblance 
to some of the ferruginous sandstone and conglomerate of the 
lower greensand of England, and serves to indicate how similar 
in general the chemical and mechanical circumstances appear to 
have been during the same geological period on both sides of the 
Atlantic. 

Some localities in New Jersey present " beds of a siliceous 
gravel, the pebbles varying in size from coarse sand to an inch 
in diameter, and either loose, or cemented by brown oxide and 
green phosphate of iron ; the mass containing sometimes a pro- 
fusion of fossils." When it occurs, it usually rests above the 
marl. 

The last bed to be described is a sandstone deposit, resting 
above all the deposits here enumerated. It occurs rarely in situ, 
except as the top stratum on most of the detached ridges and out- 
lying hills, but it is found, mingled with the general diluvium, 
in worn and broken fragments over nearly all the denuded tracts. 
It consists of sand and minute pebbles of quartz united by a 
dark brown ferruginous cement, the whole rock having a very 
perfect resemblance to the ferruginous conglomerate of the lower 
greensand at Lockswell Heath in Wiltshire, England. It is 
destitute, however, of fossiliferous impressions and casts. Some- 
times it incloses a sensible quantity of the green grains, which, 
however, have no effect in modifying its colour. 

The sand composing the rock has often the character of a 
coarse triturated beach sand ; this is especially seen in the 
quarries about four miles east of Burlington, where it occurs in 
a regular horizontal bed many feet thick. 

The diversified deposits of sand, marl, clay, sandstone, gravel, 
&c., described above, assume a great variety of mineralogical 
character, resulting from their various conditions of induration, 
and their almost endless intermixture. The most fossiliferous 
beds are the marl, and the marly sand which usually reposes im- 
mediately upon it. In the marl the organic remains, consisting 
of shells, zoophytes, and bones oi Reptilia in great number, ap- 
pear to have been preserved in a very perfect state from the 
imperviousness of the greensand to water, which descends 
with facility through the ai-enaceous beds above, but is invariably 
arrested and thrown out along the upper surface of the marl. 
The water percolating through the overlying marly sands has 
effected a change upon the fossils, leaving them in this bed 



J 



REPORT ON THK GEOI.OGY OF NORTH AMERICA. 55 

either mere casts, or almost entirely obliterating them. In its 
descent it is seen to become charged with ferruginous matter, 
staining the fossils near the upper surface of the marl of a deep 
brown colour, and coating whatever it overflows with a ferrugi- 
nous incrustation. 

I have nowhere seen a better example of the changes which 
the infiltration of water can effect upon strata than may be wit- 
nessed in these marl deposits of New Jersey, where every variety 
of dissolving and cementing agency is in hourly operation upon 
a large scale. 

The mineral contents of these secondary strata of New Jersey 
are, iron pyrites in profusion, lenzinite, peculiar spheroidal 
masses of a dark green colour, carbonate and phosphate of lime 
occasionally replacing the fossils in the form of casts. Lignite 
is extremely abundant ; it is found in the lower strata of the 
Chesapeake and Delaware canal, in almost every variety from 
charred wood to well- characterized jet. 

The following appears to be the most usual order of the above- 
described cretaceous strata in New Jersey : 

1 . Dark ferruginous sandstone and conglomerate, consisting 
of limpid quartose sand, cemented by a dark brown ferruginous 
paste ; contains also some of the green grains. 

2. Rubbly calcareous stratum. 

3. Arenaceous stratum, being chiefly a yellow sand, mingled 
with a greater or less share of the green grains, or marl, and a 
small quantity of clay. Sometimes thirty or forty feet thick. 
Fossils usually in the state of casts. 

4. Marl. A mass of little else than the chloritic grains, loose 
and uncemented, 10 or 12 feet thick; full of fossils. 

5. A red ferruginous sandstone, full of the impressions and 
casts of shells ; — the particles being limpid quartz sand, and 
some green grains. 

With respect to the basis upon which the greensands of New 
Jersey rest, nothing is known with certainty. Although a sec- 
tion was made in cutting the Chesapeake and Delaware canal, 
of nearly one hundred feet deep, the upper part through the 
beds of the ancient alluvium, and the lower through those of the 
cretaceous period, no older formation was reached. There seems 
good reason to believe, however, from the nonappearance of 
any formations along the Atlantic plain of an age correspond- 
ing to the oolite and new red sandstone groups of Europe, that 
the superior secondary beds repose, wherever they are developed 
in the States north of Alabama, upon i-ocks of the primary class. 
In Alabama, on the other hand, where the primary formations 
do not extend, the probability is, that they rest upon rocks of 



56 FOURTH REPORT — 1834. 

the age of the gvair.vacke and carboniferous formations, in as 
much as the two have been seen by Mr. Conrad in the northern 
part of that State ahnost in contact. 

The whole of the above-described strata of North Jersey 
might seem to merit the name of the greensand formation of 
the United States, and I should propose applying this designa- 
tion to the deposit, in lieu of that of ferruginous sand, w^hich 
A\ as originallj^ appropriated to it by Dr. Morton, were it not, 
first, that the greensand being but little developed jmiong the 
beds of the same periods in the vast formations of the south, 
the name would not be expressive of the prevailing character of 
the group, except in the comparatively very limited area of 
New Jersey ; ami secondly, that in the present early stage of 
our discoveries, I am not entirely satisfied as to what are its 
true relations to the European formations, and therefore hesitate 
to appropriate to it the title of a formation with which there is 
little prospect of its ever being shown to be strictly identical 
either in mineral structure or organic contents. 

The following more detailed description of these formations 
in New Jersey is so well and succinctly given by Dr. Morton 
in the recent edition of his Si/nojisis, that I shall extract the 
accour.t almost entire. 

" Ferruginous Seoul. — In New Jersey the tract which has 
been known by the name of the marl district may be located as 
follows : Draw two lines, one fi'om Amboy to Trenton, the 
other from Deal to Salem ; let the Atlantic Ocean connect the 
eastern, and the Delaware river the western points of these 
lines : this irregular oblong tract incloses nearly the whole 
marl deposits of New Jersey, so far, at least, as it has hitherto 
been explored. There is reason, however, to suppose that it 
occupies a much larger proportion of the peninsula, especially 
in some places, overlaid by deep deposits of clay and sand, as 
at Bordentown, White Hill, &c. 

'■ In other localities, the older pleiocene (uiciocene) overlies the 
sccrndary, as is the case a few miles from Salem. 

'• The fossils, as will hereafter be shown, are of a very strik- 
ing character, occasionally grouped in vast numliers, and in 
other instances almost wholly absent. The genera Gri/p/iceOy 
I''!.vogi/ra, and Belemnites are found abimdantly thi'ougbout." 

" Calcareous Strata. — The calcareous beds have been traced 
as far south as Salem, and north to Vincent town, a tract of 
nearly sixtj^ miles in length, in a direction nearlj?^ parallel to the 
Delaware river, and from seven to ten miles east of it. They 
are marked throughout by the several varieties of calcareous 
VtH'k already described, and characterized by abundance of zo- 



RKDORT ON tHE GEOLOGY OK NORTH AMERICA. 5/ 

ophytes and Echini, and a few species of shells. These fossils, 
with a few exceptions, have also been found in the arenaceous 
bed ; but many of the organic remains of the latter are not ob- 
served in the limestone strata, which have not yielded any raul- 
tilocular univalves, unless the doubtful fossil Belemnites} am- 
biguiis be of this character : neither do they contain Terebra- 
tulce nor Exogyrce." 

Throughout the marl region of New Jersey, the traces of 
an extensive denudation of the former surface are everywhere 
conspicuous ; and, what is remarkable, the excavation has ex- 
tended almost invariably down to the marl stratum, but hardly 
in any case through it; the consequence of which is, that nearly 
all the meadows and low grounds, which are very numerous, 
expose this deposit immediately beneath the surface. These 
depressions in the surface are always occupied by creeks and 
streams, many of them receiving the tide, while the rest are 
only a few feet above it. The uplifting force must therefore 
have operated very equally over the whole i-egion, as the strata 
tliemselves sufficiently evince in their undisturbed features and 
luiiformly horizontal position, wherever they are seen, from 
Salem to their termination on the shores of Amboy Bay. The 
Neversink Hills, Mount Holly, and Mullica Hill, are low insu- 
lated outlying liills, from 100 to 200 feet elevation, having, 
like all the ridges in this region, their longer axes parallel with 
the Delaware river, or in other words, with the longitudinal 
diameter of the tract. These hills and ridges are almost inva- 
riablj'^ capped by a thin layer of the superficial ferruginous sand- 
stone or conglomerate, which I have before stated to be the 
general overlying rock of the marl deposits. The mineralogical 
nature of this rock, its uniform parallelism to the other second- 
ary beds wherever the surface has not sustained much denuda- 
tion, its universal occurrence in scattered fragments throughout 
all the intervening denuded tracts, and the quantity of the green 
grains in it, are all reasons to induce me to think that this rock 
is a true member, and the uppermost bed of the New Jersey 
secondary group. The whole formation expands towards its 
north-eastern extremity ; in approaching which it seems like- 
wise to increase regularly in elevation, attaining its greatest 
height in the Neversink Hills. As to the various upheaving 
and denuding actions which have brought this portion of New 
Jersey to its present configuration, I am not now prepared to 
speculate, but shall merely in this place remark, that the valleys 
adjoining the streams in this tract, like the valleys in the tertiary 
districts further south, are never covered by the diluvium which 
invests the general surface of the country. They are also of 



58 FOURTH RKPORT — 1834. 

such size and structure as to preclude the idea that the present 
puny streams could have had any part in excavating them. They 
must suggest to every geologist the conclusion that they have 
been filled by the tide from one escarpment to the other, so 
that each was a bi'oad bay or short tidal river. 

" Delaivare. Ferrtiginous Sand. — In this State, the blue and 
grey friable marls extend in the line of the Chesapeake and 
Delaware canal, from St. George's almost to the western lock. 
St. George's and its vicinity afford Gryphcea and E.vogyra in 
great numbers, with Ostrea falcata, and some Belemnites. 
The deep cut of the canal abounds in Ammonites, Hacu/ites, and 
Scaphites, without any of the fossils previously mentioned. This 
locality consists of a series of pyritous sands and clays, of which 
the shells are decomposed, leaving only the casts." 

" Maryland. — I am informed that the ferruginous sand oc- 
curs below Annapolis in this state, at which place it is chiefly 
characterized by Alcyonia. Mr. Conrad obtained at Fort Wash- 
ington, on the Potomac, a solitaiy valve of Exogyra, indicating 
the presence of this formation." 

" Virginia. — A writer in the American Journal of Science 
speaks of the occurrence of Beletnnites and Gryphcece on James 
river, but gives no locality." 

" North Carolina. Ferruginous Sand. — This is well developed 
at Ashwood, on Cape Fear river, where, according to the late 
Mr. William Bertram, there are several beds of dark-coloured 
marl containing JBelemnites, shark's teeth, pyritous lignite, &c. 
&c. These strata are surmounted by the usual diluvial mass 
to a depth of ten or twelve feet." At Wilmington, North Caro- 
lina, Mr. Conrad found the upper marine formation resting 
immediately on secondary limestone precisely like that described 
by Dr. Morton as occurring in New Jersey; it is in thin layers, 
and reposes directly on a hard rock, which is the equivalent of 
the ferruginous sand, as it abounds in E.vogyra costuta and other 
characteristic fossils. The calcareous strata are said by intel- 
ligent persons here, to extend sixty miles up Cape Fear river, 
and from its mouth coastwise as far north as Cape Hatteras. 

"South Carolina. — The ferruginous sand formation occurs 
near Effingham's Mill, on Lynch 's Creek. The fossils are 
chiefly Exogyra costata. Mar's Bluft", on Pedee river, and Nel- 
son's Ferry on Santee river, afford the Belemnites americanus. 

"Calcareous Strata. — The calcareous strata form an extensive 
basin to the west of the city of Charleston : this limestone, 
which is of the newest cretaceous formation, is mostly yellowish 
white, friable, and i-eplete with fossils, although the number 
of species hitherto discovered is inconsiderable. Among these 



KEPORT ON THIi GEOLOGY OF NORTH AMERICA. 59 

the Ostrea cretacea and Ostreu panda occur also in the ohlei- 
cretaceous deposits of Alabama." 

" Georgia. — The ferruginous sand appears to abound near 
Sandersville in this State, whence 1 have received a number of 
specimens of the Belemnites americaniis." 

"Alabama. — This State presents a vast deposit of both strata. 
Mr. Conrad informs us that the counties of Pickens, Bibb, 
Greene, Perry, Dallas, Marengo, Wilcox, Downes, Montgo- 
mery, and parts of Clarke, Monroe, and Conecute, are chiefly 
composed of the older cretaceous strata. In Clarke county the 
nevper cretaceous rock predominates. 

"One of the localities most prolific of fossils is Prairie Bluff, in 
Wilcox county. The following diagram will convey an idea of 
its strata : 

Feet 2. Loam. 

2. Ferruginous sand, generally indurated, with Exogyra and Gryphcea. 
70. Same deposit, in a friable state, with abundance of Oslreafalcata. 
River bed. 
" The older cretaceous rock constitutes the long and perpendi- 
cular bluff at Demopolis, where it has been ascertained by boring 
to be at least 500 feet thick. The more elevated blcff at Erie 
is chiefly composed of the same rock, which is here very friable, 
and well characterized by fine specimens of Pecten quinque- 
costattis, as well as abundance oi Exogyra costata. A short di- 
stance north of Erie, the cretaceous rocks terminate, following 
the course of the Black Warrior ; and at Tuscaloosa the old red 
sandstone with bituminous coal forms the bed of that river. 
The Tombeckbe and most of its tributaries run entirely through 
a region, the substratum of which is the cretaceous group, al- 
though it is probable that their sources originate in the carbo- 
niferous limestone, which may extend into the north-east section 
of Mississippi. We learn from travellers that the cretaceous 
rocks chiefly compose the countries of the Chickasaws and 
Choctaws, and it is highly probable that nearly the whole State 
of Mississippi is of the same formation. It is worthy of remark 
that all the prairies of Alabama and Mississippi have a sub- 
stratum of the older cretaceous rock. The newer cretaceous 
strata prevail only in the southern portion of Alabama, are 
never covered with a prairie soil, and have not been observed 
north of the central parts of Clarke and Monroe counties, 

" NummuUte Limestone. — 'After crossing the Alabama river 
at Claiborne,' says Mr. Conrad, ' I travelled over a level allu- 
vial country for two or three miles, when the surface became 
broken by gravelly hills, covered by a pine forest. Near Suggs- 



60 FOURTH UEPOKT — 1834. 

ville the hills are formed of the nummulite limestone, masses 
of which are scattered in every direction: it is porous, and con- 
tains spheroidal cavities, formed, no douht, by the decomposi- 
tion of organic remains, which leave loose casts tliat are easily 
washed out by the rains. The most characteristic fossil at this 
place is Ostreci panda. 

" These limestone hills occur at intervals to the vicinity of 
Jackson, on theTombeckbe : on Basset's Creek one of these hills 
rises probably to a height of .300 feet above the water level. St. 
Stephens is on a high bluff of this rock, wiiich, wherever it 
occurs, forms a very broken or undulating surface. A short 
distance above the village, the bluff rises nearly pei-pen- 
dicular from the river, and is about 100 feet high. Every- 
where in the vicinity this limestone crops out on the summits 
of the hills, and myriads of Nummidites Mantelli are scattered 
over the surface of the decomposing rock. The Gryphcca Vomer 
is occasionally found among them, and the Ostrea panda, is 
abundant; but no other fossils occur excepting what are pe- 
culiar to the limestone in question. On the hills the Pecten 
Poulsoni is in abundance. Near low-water mark in the bluff 
is a stratum of shells, consisting of Ostrea panda and Plagio- 
stoma diimosmn, both equally abundant. The surface of this 
rock is in many places very hard and of a blueish colour, com- 
pact and glittering when fractured, and is convertible into ex- 
cellent lime. 

" Again it is often white and friable, and so much resembles 
chalk that it is not surprising that it should have been mistaken 
for the real chalk of commerce, from Avhich it differs, in pos- 
sessing a coarse and more granulated structure, and in contain- 
ing a considerable proportion of argillaceous earth." 

" Mississlpjn. — This State has an extensive marl tract in the 
Chickasaw fields, near the borders of Tennessee." 

" Tennessee. — ^The south-western portion of Teimessee re- 
presents a continuation of the tract just mentioned, which takes 
a wcsterlj^ direction across the Mississippi River at the Chicka- 
saw Bluff's." 

" L,ouiskma.— 'Qx . Pitcher, in a recent letter, describes an 
extensive deposit of ferruginous sand between Alexandria and 
Natchitoches. Judge Bry has also noticed it near the township 
of Wachita, on the Wachita River, ^vhere it is recognised by 
Belenniites^ Ammonites, and GryphtEa." 

" ylrhansas. — Mr. Nuttall long ago found fossils of this for- 
mation on the calcareous platform of Red River, above and 
below the junction of the Kiameska ; and Dr. Pitcher, of the 



REronT ON THE GEOLOGY OF NORTH AMERICA. Gl 

United States army, now at Fort Gibson, has obtained speci- 
mens for my use, among which I readily identify the Gryphaa 
Vomer, Exogyra costata, &c." 

For the sake of exhibiting more fully the conditions of the 
comparison between the formations of the superior secondary, 
or cretaceous group of North America, and the equivalent group 
in Europe, I shall present the following summary of the or- 
ganic remains hitherto discovered in New Jersey, Delaware, 
and Alabama. 

Sauria. 
Mosasaurus. — Thought to be identical with the Mosasaurus of 

Europe. New Jersey. {Morton.) 
Geosaiirus. — Teeth and part of a jaw. New Jersey. {Defeat/.) 
Crocodile. — Teeth and other portions, indicating three species, 

from the marl region. New Jersey. 
Saurodon. — {Hays.) Portions of a jaw of an extinct animal, 
the relations of which are not very clearly known. It is 
thought to be analogous to the Saurians. (See American 
Philosophical Transactiotis.) 
Great Sauriati of Uonjleur. ? — I have recently described two 
vertebrae from Jersey, and another from Alabama, which I 
regard as either identical with, or very closely allied to, bones 
figured by Cuvier from Honfleur, which he considers to ap- 
proach nearer to the Plesiosaurus than to any other genus. 
(See Journ. of the Acad. Nat. Sci. of Philadelphia.) 

Testudo. 
Several bones from the marl deposit in New Jersey. {Morton.) 

Pisces. 
Squalus. — Teeth and vertebrae of several species of shark are 

abundant in New Jersey and Alabama. {Morton.) 
Sphyrcsna. — Some remains of this curious genus of fishes 
occur in the blue marl of New Jersey. {Morton.) 

AvES. 

A solitary tibia of a bird of the genus Scolopax has been found 
in the green marl in New Jersey. {Morton.) 

Testacea, &c. 

The whole number of Testacea, Echinodermata, and Zo- 
ophytes described by Dr. Morton in his Synopsis of the Organic 
Remains of the Cretaceous Group of the United States, is 108 
species. Of these, two belong to genera which are new, while 
one species only, the Pecten quinquecostatus, is thought to be 
common to the strata of both America and Europe. 

This latter fact is certainly not a little remarkable, as it goes 



6^ FOURTH REPORT— 1834. 

to prove, contrary to general opinion, that the organic races of 
remote regions diflfered as much during a part of the secondary 
sera as during the more modern tertiary and recent periods. 

It certainly seems difficult to explain, upon a distinction fre- 
quently admitted between secondary and tertiary formations, — 
namely, that the former are deep sea deposits, while the latter 
have been formed in more confined and local basins, — why the 
range of the species should have been actually less in the earlier 
aera than during the more modern dates of the tertiary. So far as 
relates to the superior secondary formations of the United States, 
I can perceive no evidence whatever that they were produced in 
a deeper sea than the tertiary beds which succeeded them. The 
secondary rocks have fully as much the appearance as the ter- 
tiary of having been the bed of a shallow sea, like that which en- 
circles our Atlantic coast with so wide a belt of soundings at the 
present day. It must be borne in mind that all this portion of 
North America is, and has been since the period of the coal forma- 
tion, remarkably exempt from agitation by volcanic causes ; so 
that the Atlantic plain offers no resemhlance, in its uni\ersally 
horizontal beds, to the broken, contorted, and denuded strata 
which diversify the tertiary and secondary scenery of the western 
regions of Europe. We are not likely ever to discover the 
modern formations of this country resting among the Alleg- 
hanies, as the cretaceous formations of Europe cap the Alps and 
Apennines. For the same reason we may look in vain over 
the whole of North America for a structure like that seen in 
the Weald, or in other well-known disturbed districts along the 
southern coast of, England. So many successive upheavings 
and submersions as those shores have experienced, betoken the 
long-continued activity of subterranean forces during a time 
when the similar actions upon this side of North America were 
almost dormant. 

We are presented with no pheenomena along the flat mono- 
tonous coast of the United States, like those which lend so 
high a charm to the geology and scenery of the cliff- lined coast 
of the English Channel. 

So small an amount of distvirbing action ought to favour the 
wide dispersion of the marine inhabitants of this region ; and 
we are therefore not to be astonished at seeing, as we do, many 
of the New Jersey fossils in Alabama, or at finding, as we have 
every reason to anticipate, the same group of species in the 
strata vipon the Missouri, 2000 miles west from the cretaceous 
formations vipon the Atlantic. 

Similar reasons should lead us to look for a somewhat gra- 
dual transition from the secondary to the tertiary series of 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 



63 



fossils ; and we do accordingly witness a manifest mingling of 
the races of the two periods, as the following Table will make 
apparent. 

Table showing the Species common to the Eocene and the 
Upper Cretaceous Strata, and also the Species common to 
the latter and the Lower Cretaceous Strata, in Alabama. 



Formations. 


Range of Species. 


Older tertiary, or 
eocene. 


Plagiostoma dumosum. 
Ostrea sellseformis. 
Pecten calvatus. 
Scutella Lyelli. 


Upper cretaceous 
limestone. 


Plagiostoma dumosum. 
Ostrea sellaeformis. 
Pecten calvatus. 
Scutella Lyelli. 
Ostrea cretacea. 
Ostrea panda. 
Gryphsea Vomer. 


Lower cretaceous 
limestone. 


Ostrea cretacea. 
Ostrea panda. 
Gryphsea \'^omer. 



After carefully reviewing, in a tabular form, the relations 
of the organic remains of our upper secondary group, I find 
that if we adopt for our data the 102 known species of Testacea 
and Ecluiiodermata (rejecting the zoophytes), we perceive that 
14 species are peculiar to the upper cretaceous formation of Ala- 
bama, and that only two or three of its species are found in 
the marl formation of New Jersey. We discover, however, 
that a much larger number are common to the New Jersey 
deposits, and the Imver limestone formation in Alabama. 

Subtracting the above 14 species, in order to make the 
comparison between the marl and this latter formation, we 
have of the two classes mentioned 88 species. Out of these 
88 species, 39 are peculiar to the marl formation of Jersey 
and Delaware, 32 to the older calcareous strata, and 17 
common to the two. These numbers show a want of identity 
in the fossils of the two regions worthy of notice. The 
two deposits, the ferruginous sand or marl of New Jersey, and 
the inferior calcareous strata of the south, are regarded by 
Dr. Morton as one formation. Though this opinion may 
very possibly be correct, to establish it in the present state 
of our data" would be difficult. It is possible, indeed, that 



64 FOURTH KEPORT — 1S34. 

while strata strictly synchronous are forming, as great a dif- 
ference may prevail between two groups of species inhabit- 
ing remote sections of the same coast as is observable in 
comparing those of our two secondary deposits. But on the 
Atlantic coast of North America such differences should be less 
than upon almost any other, from the influence of the gull- 
stream, and other causes elsewhere stated. 

We are therefore at present at a loss to know how much of 
this want of identity among the species we should ascribe to 
disparity of age in the formations ; how much to difference in 
the aqueous climate, and other circumstances controlling or- 
ganic life. 

Until a more extended list of fossils shall have been collected 
for the comparison, and, above all, until our geologists shall 
have examined more in detail the phsenomena of the stratifi- 
cation and structure of each region, I would recommend that 
the question of their relative age be not anticipated by the ap- 
plication of a common name, but that this point be left for a 
season sub judice. 

I think it not improbable that we shall ultimately regard the 
upper limestone of our superior secondary group in Alabama as 
a somewhat newer formation than the inferior calcareous strata 
of the same state on the arenaceous marl deposit of New Jersey. 
The occurrence of several of its fossils among the fossils of the 
overl}dng eocene seems to indicate that its true position is near 
the top of the secondary series. 

Taken in their mineralogical relations, the marls and sands 
of New Jersey would seem to occupy a place corresponding 
nearest to the greensand formation of Europe ; and the lime- 
stone strata of the south may be thought to harmonize imper- 
fectly with the chalk, or a portion, perhaps, more truly with 
the calcareous strata of Maestricht. Such certainly are their 
rather obvious analogies mineralogicallj'^, but it is doubtful if 
this ought to decide the question of their relative age. I would 
not have it understood, therefore, that I view the American 
upper secondary formations in any other light at present than 
as the loose eqviivalents of the great cretaceous group of Europe. 
I have already mentioned the existence of hut one, or at furthest 
two species, to link the organic remains of these strata in the 
two opposite continents. 

Another striking peculiarity, which also marks the want of 
that resemblance which we might expect, is the absence from 
these formations of any true chalk deposit. There would ap- 
pear to be no sufficient evidence of the existence of this remark- 
able formation in any known region of North America. May 



REPORT ON THE GEOLOGY OF NORTH AMERICA. 65 

not this be another result of the long dormant state of the vol- 
canic forces in this hemisphere ? It has been a received doc- 
trine, I believe, that igneous action has had much to do with 
giving solubility to so vast a mass of silica and carbonate of 
lime, which are regarded in the chalk formation as having been 
produced rather in the state of a chemical precipitate than in 
that of a mechanical sediment. 

The following recapitulation of the leading facts and deduc- 
tions brought forward in the foregoing survey of our superior 
secondary formations, will assist in elucidating more clearly the 
present state of this portion of our geology. 

1 . The deposits of New Jersey differ from those of the South- 
ern States in being chiefly arenaceous, and in containing an 
immense quantity of the pure chloritic mineral called green- 
sand. 

2. The organic remains hitherto discovered are nearly all, 
with the exception of one or two species, peculiar to this con- 
tinent. 

3. The existence of great quantities of lignite, of the remains 
of Scolopax, a shore bird, and the position of these beds in New 
Jersey, contiguous to the primary boundary or ancient coast, all 
indicate that they were deposited in a comparatively shallow 
sea, analogous in position to the present extensive line of sound- 
ings which skirts the coast. 

The obvious shallowness of the portion of the secondary 
ocean where these beds were formed, may perhaps help to ex- 
plain the remarkable discordance alluded to between the Ame- 
rican and European marine species of this period. 

4. The calcareous masses of Alabama, at least the upper 
beds, are probably different in age from the marls and arena- 
ceous beds of New Jersey. 

5. The marl formation of New Jersey is, perhaps, most nearly 
represented by the European greensands. The limestone de- 
posits of the South, on the other hand, resemble more the upper 
members of the cretaceous group ; for example, the formation 
of the plateau of Maestricht. 

6. Thus far there is no evidence of the existence of true chalk 
in North America. Genuine flints have not yet been found in 
any bed. 

7. Volcanic forces, during this period, seem to have been 
nearly dormant, which may perhaps assist in accounting for 
the absence of the chalk. 

8. The want of accordance, both in organic remains and 
mineral character, between these beds and the cretaceous group 
of Europe ; the difficulty of deciding their identity at present 

1834. F 



6(5 FOURTH RKI'ORT — 1834. 

for the want of a sufficient knowledge of the structure and su- 
perposition of our formations ; and, above all, the importance 
of pursuing our geology free from the shackles of a nomencla- 
ture originally adapted to another continent, — render it desi- 
rable that we reject the terms in use, and appropriate to this 
group of formations a name which shall be independent of old 
associations, and yet express their position in the geological 
series. 



REHO'.IT ON THE LAWS OF CONTAGION. 



Report on the State of our Knowledge of the Laws of Conta- 
gion. ^«/ William Henrv, M.D., F.R.S.,&;c., late Phy- 
sician to the Manchester Roy id Infirmary and Pever- ffards. 

The subject of the following pages may perhaps appear, on first 
view, not to fall Avithin those boundaries, wliich have been as- 
signed by the British Association to- the field of its labours. I 
hasten therefore to avow, at the outset, that it is no part of my 
object to trespass upon the province of practical medicine, or to 
treat the topic of contagion in any other light, than in that of a 
purely philosophical question. Under this point of view, the in- 
quiry is open to all, whose education has embraced the principles 
of chemical and physical science, and who possess a general ac- 
quaintance with the laws of the animal oeconomy. Much valu- 
able information has indeed been already contributed to the 
history of contagion by persons of this class ; among whom the 
late John Howard, the enlightened and devoted philanthropist, 
is an eminent example. 

The establishment of sound conclusions on this subject is of 
the highest importance, not only to individuals and to small 
communities, but to the interests of whole nations. On such 
principles alone can wise and salutary measures for obviating the 
importation, and checking the spread, of contagious m;iladies, 
be based ; and it is for want of them that legislators and execu- 
tive governments have enforced regulations, some of which are 
nugatory and absurd, and others positively mischievous. The 
quarantine law^s of every civilized country call, indeed, loudly 
for revisal and remodelling ; and this can only be effected by 
mutual agreement between different nations. In their present 
state, those laws are both inadequate and oppressive. They lay 
great stress upon observances that are of no value, and overlook 
others that would be really efficacious. They impose grievous 
restraints on personal freedom ; fetter our commerce ; abridge 
the demand for produce and manufactures ; and, by diminishing 
employment over wide and populous districts, increase the suf- 
ferings attendant on poverty, and give rise to inborn diseases, 
even more formidable than those,] against which they are in- 
tended to act as barriers. 

An inquiry into the laws of contagion, it must however be ad- 
mitted, is beset with many pressing difficulties. Our senses, the 
great inlets of our knowledge of the material world, give us no 
insight into the properties of this subtile agent ; nor do we derive 

F 2 



68 FOURTH REPORT — 1834, 

any assistance from the most refined instruments, or from the 
most delicate chemical tests. All that we perceive is a series of 
events, often faintly marked, the connexion of which with each 
other, even their order as to priority or sequence, can only be de- 
duced by processes of reasoning, that are open to more than usual 
sources of fallacy. In no one instance is the effect of an external 
agent upon living animals universally the same, but modified by 
peculiarities of structure; by temperament, age, sex, and habit; 
and above all, by those imperceptible changes to which the ner- 
vous system is perpetually liable. Even our mental constitution 
and habits, — the imagination, the affections, and the passions, — 
exercise a powerful sway over our susceptibility to contagious 
diseases ; and when such diseases do arise, often direct their 
course and determine their issues. The phsenomena of con- 
tagion, moreover, are in many cases extremely complex, being 
owing to a variety of causes which it is far from easy to ana- 
lyse, and separately to weigh and appreciate. The omission, too, 
of a single link in a chain of observations has frequently ren- 
dered the whole series valueless, as data for accurate reasoning. 
Difficult, however, as the investigation is in itself, it has been 
rendered still more so by the manner and temper in which it has 
been conducted. Every kind of error, that has obstructed the 
progress of philosophy, may be exemplified from writers on this 
subject. Observers have viewed phsenomena with the desire of 
establishing preconceived opinions. Facts have been described 
in language so highly coloured, or so mingled with hypotheses, 
that it is scarcely possible to discover its legitimate meaning. 
All that favours one side of an argument has been strongly in- 
sisted upon, while adverse evidence has been denied its due au- 
thority; and the love of truth has been sacrificed to the anxiety 
to baffle an adversary by ingenious sophistry. Such at least is 
a faithful picture of the greater part of what has been written 
on this subject in the spirit of controversy, excited, as it has 
generally been, by intemperate discussions of the quarantine 
laws. But it would be unjust not to except from this censure 
a numerous class of writers on contagious diseases, who have 
united an eminent capacity for observing and reasoning, with 
perfect singleness of purpose in tlie pursuit of truth. The names 
of Lind, Pringle, Cleghorn, Russell, Blane, Haygarth, Willan, 
Currie, Ferriar, and of many others who might be enumerated, 
are sufficient pledges for the accuracy of their reports of facts, 
and for the soundness of their conclusions. It is to authorities of 
this kind (in many instances confirmed, in a few corrected, by my 
own observation,) that I am chiefly indebted for the materials of 
the following pages, to which I have given the form of proposi- 



REPORT OX THE LAWS OF COXTAGIOX. 09 

tions or 'general laws'; not that I consider them as entitled to 
the weight of settled and invariable principles, but as open to be 
modified and amended by the results of further experience. 

Lmvs of Contagion. 

I. The animal body, when the seat of certain morbid actions, 
is known to elaborate within itself poisons, which are capable of 
imparting to healthy individuals the same diseased condition, 
and the power of generating similar poisons. These poisons 
have been called contagions, from contingOywhence, contactus; 
or INFECTIONS, from inftcio. A distinction between these terms 
has been attempted by some writers ; but, avoiding etymolo- 
gical discussions, I shall employ them in that general and po- 
pular sense, which regards them as synonymous or nearly so. 

II. It is consistent with the testimony of the best observers*, 
that some contagions (chiefly those of typhus, and its congenera,) 
may originate in the animal body when exposed to the action 
of certain external causes. Among these causes are confinement 
in overheated, close, and ill ventilated places ; scanty or bad 
food ; intemperance ; excessive fatigue ; long exposure to cold 
and moisture ', and, among mental influences, the whole train of 
depressing passions and emotions. It was doubted, however, 
by Mr. Howard f whether any of these causes singly be ade- 
quate to the production of contagious fever ; but, though they 
certainly operate more powerfully in conjunction, there is no 
reason to disbelieve their separate efficiency. For, 1. The 
crowding of numbers together without change of air has been 
known to occasion low fevers of the most formidable type. Out 
of 146 persons, shut up during a whole night of sultry weather 
at Calcutta, in a wretched prison called the Black Hole, (a cube 
with sides of only 18 feet,) not more than twenty- three survived, 
of whom several were affected with low fevers of a typhoid cha- 
racter, ending in carbuncular eruptions^. 2. Half a century has 
scarcely elapsed since our prisons and hospitals were almost 
constantly the seats of fevers of the worst character§, generated 
within their walls; and though banished from thence by an 
improved system of construction and management, yet similar 
fevers continue to originate in the crowded aijd squalid habita- 
tions of the abject poor. 3. Even among the lower animals, si- 
milar effects have been produced by the same causes. During a 

• Fordyce, HaygArth, Currie, Clark, Howard, Ferriar, Willan, &c. 

t On Lazarettos, 4to, p; 231. 

t See Mr. Holwell's interesting Narrative, Annual Register, 17.58, p. 278. 

§ Well described by Dr. Hunter, Medical Transactions, vol. iii. p. 345. 



70 FOURTH REPORT 1834. 

long voyage in a ship, the hold of which was densely crammed 
with swine and sheep arranged on different sides of the vessel, 
Dr. Fordyce observed that both those kinds of animals were at 
different times attacked with contagious fevers, the symptoms 
varying in the two species, and the disease not spreading from 
the one species to the other, nor at all affecting the passengers 
or crew*. 

III. Independently of crowding and confinement, contagious 
fevers do, however, occasionally arise without any immediate 
prototype. The recollection of every medical practitioner must 
furnish examples in which simple fevers, arising from cold and 
other causes, in persons well fed and well clad, have by neglect 
become contagious in their progress ; and if particular examples 
of this kind are seldom recorded, it is because of the notoriety 
of the general fact. An instance of typhus fever, thus origina- 
ting spontaneously, is related to have happened to one of the 
family of the late Dr. Jennerf. 

IV. Diseases which break out in a scattered manner, where 
the agency of contagion can neither be traced nor even suspected, 
have been called sporadic (from o-Tropaj, sparsus). This class 
therefore includes all disorders that are not produced by conta- 
gion ; nor by accidents or obvious injuries ; nor by any cause 
affecting numbers of individuals in common. 

V. There is an extensive class of acute diseases, which have 
never yet been proved to arise sporadically . These, from 
the greater distinctness and more uniform succession of their 
symptoms, have been considered as separate species. They 
have therefore been termed specffic diseases, and their causes 
SPECIFIC CONTAGIONS, or SPECIFIC INFECTIONS. Such are 
siphylis, measles, smallpox, cowpox, hooping-cough, scarla- 
tina, and a few others. 

VI. In a great proportion of instances, specific diseases may 
be traced to communication, either by contact or near proxi- 
mity, or intermediately, with some person suffering under the 
same disease. But it frequently happens that the most search- 
ing and diligent inquiry fails to trace a specific disease to its 
source. We are told that not one in twenty cases admitted into 
the Smallpox Hospital in London could be referred to any im- 
mediate original J. In a few instances, specific diseases have 
appeared within boundaries which might have been supposed to 
liave perfectly excluded them. In the Penitentiary at Millbank,- 
a prisoner was seized with smallpox, notwithstanding his ap- 

* First Dissertation on Fever, p. 112. 

f Baron's Life of Jenner, p. 106. 

X Dr. Gregory, Cholera Gazette, No. 2. 



REPORT ON THE LAWS OF CONTAGION. 71' 

parently perfect insulation*. But in this and all similar cases, 
the probability is much greater that a specific disease, like small- 
pox, should have been received from a pre-existing source, than 
that, contrary to all experience, the poison should have origin- 
ated afresh. Many instances too are on record, in which the pene- 
tration of contagious diseases,into situations supposed to be per- 
fectly isolated, has been traced to intercourse, though forbidden 
by the strictest rules, and even by menaced punishment. An- 
other mode of conveying infection, beside that of direct commu- 
nication, which will be pointed out in the sequel (§. xxii. et seq.), 
will account for a great part of the apparent exceptions. 

VII. The conclusion that ' contagious diseases of a specific 
kind never originate spontaneously,' is strengthened by the fol- 
lowing facts : — 1 . They have never been met with in any coun- 
try, when visited for the first time, after having been previously 
shut out from intercourse with the civilized world. 2. The hi- 
storical aeras may be fixed, when many of them first invaded the 
countries where they now prevail, and the line of their march 
may be distinctly traced outf. 3. Specific diseases have been 
known to become extinct for a time in certain situations, and 
their revival has been traced unequivocally to a foreign source. 
Thus, the smallpox disappeared several times from the island 
of Minorca, apparently from having already attacked all who 
were liable to it. In one instance the interval extended to se- 
venteen years ; in another, after having been absent for three 
years, its return was clearly traced to the crew of a ship of war 
which had arrived from the Levant. Seven similar intermissions 
of the same malady are recorded to have happened at Boston in 
New England, in three only of which the channel of its reintro- 
duction could be discovered. But these three instances render it 
much more probable that the poison, causing the disease, should 
in the remaining four have been imported anew, than that it 
should again have been generated. For though it cannot be 
denied that a poison may be again elaborated, by a concurrence 
of the same circumstances which originally produced it, yet, in 
assigning causes, we must be guided by actual observations, and 
not by possible contingencies %. 

* Fact communicated by Dr. Roget. 

t. Hawksworth's ^'byra^es, vol. iii. page 56. Siphylis was introduced by the 
crews of Bougainville's vessels into the Sandwich Islands, ii. 232. De Pauw, 
Recherches P hilosophiques stir IBs Am&ricains, torn. i. Robertson's History of 
America, book iv. 

■X The origin of new specific diseases is a topic too extensive to be entered 
upon here. The reader is referred, therefore, to an excellent essay by Dr. 
Ferriar, in the first volume of hh Medical Histoi'ies and Reflections; to the 
various publications of Dr. Jenner, John Hunter, Adams; &c. 



72 FOURTH REPORT 1834. 

VIII. It may be held as a general principle, that no specific 
poison ever gives rise to any other contagious malady, than that 
of which it is itself the product. The poison of smallpox never 
occasions measles ; nor that of measles smallpox. It must 
however be acknowledged, that the sequent disease is seldom an 
exact /ac simile of the antecedent, but often differs from it, not 
only in degree, but in the absence of one or more of the usual 
pheenomena, or in the addition of others not commonly ob- 
served. Scarlatina, it is well known, when connnunicated to 
numbers from a common source, may affect some severely and 
others slightly ; and the general fever, the eruption, and the af- 
rection of the fauces and throat, may exhibit almost infinite va- 
rieties. In like manner, the mild and distinct smallpox has 
often imparted a confluent and dangerous sorf ; and the reverse. 
It is needless to mvdtiply examples, because inconstancy of 
symptoms is observable, not of contagious disorders only, but 
of all others, whether acute or chronic. Our classifications and 
nomenclatures of diseases are in fact founded, not on constant 
and uniform characters, like those establishing the distinctions 
of natural history, but on general features, which are liable to 
be qualified by many exceptions, and which present almost in- 
finite varieties of aspect. 

IX. Of the nature of those processes, by M'hich a simple fever 
becomes contagious in its progress, we are totally ignorant. The 
opinion that. a contagious poison is, in any case, generated by a 
change in the animal fluids analogous to fermentation or to putre- 
faction, (a change veiled by Sydenham under the phrase commo- 
tio sangtmiis), is inconsistent with general reasoning as well as 
with observation. The tendency to putrescence in the solids or 
fluids of the animal body, at temperatures favourable to that pro- 
cess in dead matter, is counteracted by the undefinable principle 
of LIFE, so long as that principle retains sufficient energy. During 
a contagious fever, none of those gases are iiecessarily evolved, 
which are the constant products of animal putrefaction. A person 
sick of typhus fever, enjoying all the advantages of cleanliness and 
fresh air, and emitting no sensible odour, may yet impart a fatal 
infection. An instance is on record, in which a person under such 
circumstances was accompanied, for about half a mile, in a 
coach, by four individuals, none of whom perceived the slightest 
odour, but all caught the infection, and died in consequence*. 
It may be remarked also, that the odours, which arise from per- 
sons labouring under acute specific diseases, are not similar to 
those of common putrefying matter, but are distinct and pe- 

• Fordyce, Dissertation, p. 115. 



REPORT OX THE LAWS OF CONTAGION. iS 

culiar*. When we add to these arguments, that the perversion 
of a vital process, such as that of secretion, occasions, in at 
least one decided instance {rabies canina), the formation of a 
poison, by an organ which commonly secerns a bland and harm- 
less fluid, the weight of evidence must be allowed greatly to 
preponderate in favour of the opinion, that all morbid animal 
poisons are the results of vital operations; and that chemical 
changes, if concerned at all^ are under the control of the vital 
principle. 

X. Among contagious poisons, there are some that exist in a 
visible and tangible state, generally in that of liquids ; others 
are not at all perceptible by our senses, and are known to us 
only by their efffects. The liquid poisons are efficient, only when 
applied beneath the cuticle, or to parts where the cuticle is very 
thin, or to the surfaces of mucous membranes ; and if imme- 
diately and completely washed off, they inflict no injury. The 
action of some of those poisons, of siphylis for instance, does 
not necessarily extend beyond the part to which they are ap- 
plied. Other poisons, when inserted or inoculated, act locally 
in the first instance, and afterwards give rise to general febrile 
excitement, which is necessary to the formation of fresh poison 
in the inoculated part, or in the system. After inoculation for 
smallpox, the constitutional disturbance is generally well 
marked ; in cowpox, often so faintly as to be scarcely distin- 
guishable ; yet even in the latter, some degree of general fever 
seems to be essential to the perfect state of the pustule f. It 
is only at this period of full development (called the time of 
maturation) that the fluid contents of the pustule, (which in 
the cowpox is limpid, in smallpox purulent,) can be depended 
upon for producing its appropriate effect. Before maturation, 
the fluid is inert ; after that period, it is sometimes effete, and 
sometimes produces a modified disease;!:. All attempts to ex- 
cite smallpox or cowpox, by inoculating with the blood or 
with any other animal fluid, have been unsuccessful §. 

XI. When the liquid animal poisons are kept in a moist state, 
at temperatures not exceeding those of a warm atmosphere, they 
undergo spontaneous changes which materially affect their spe- 
cific properties. Variolous matter, thus negligently preserved, 
has been known to produce a train of symptoms resembling 
those of smallpox, but yet giving no security against the return of 

* The odours attending tlie plague, smallpox, and Asiatic cholera are in- 
stances. 

t Jenner, Inquiry, &c., 4to, 1798, p. 71. 
X Jenner's Further Observations. 
§ Darwin's Zoonomia, § xxxiii. 2, 



71. FOURTH REPORT — 1834. 

that disease*. But the liquid poisons, dried at the lowest tem- 
perature adequate to that purpose, may be kept in close vessels 
unimpaired for an indefinite time, and regain their infectious 
properties when moistened with very little water. The mixture 
of them, however, with a large proportion of water, renders them 
inefficient. Dr. Darwin relates that, in some experiments by 
Mr. Power, smallpox matter was found to be infectious after 
diffusion through five times its quantity of water; but that its 
dilution might be can-ied so far as to render it inertf. This is 
precisely analogous to what happens with common poisons, 
the most virulent of which is disarmed of its noxious power, 
when sufficiently diluted, 

XII. Of the chemical constitution of the liquid contagious 
poisons we are entirely ignorant ; nor is it probable that the 
knowledge, if we possessed it, would throw any light on their 
mode of action. We are well acquainted with the composition 
of many poisons (the prussic and arsenious acids, for example), 
without at all understanding in what way they act so powerfully 
upon the animal system. 

XIII. Beside the liquid poisons, requiring contact for their 
operation, there is another class which are independent of that 
mode of communication, and are transmitted to small distances 
through the atmosphere. Such are those of scai-latina, measles, 
hooping-cough, chicken-pox J, &c. In a few instances diseases 
imparted by contact are also caught by emanations or effluvia. 
The smallpox, it is well known, may be propagated in both 
ways ; and the plague, certainly infectious at small distances, 
has, of late years, been proved to be communicable by inocula- 
tion with the matter of the glandular abscesses. Dr. White, 
after two unsuccessful attempts to inoculate himself, caught the 
plague by the third, and died in three days; and Dr.Valli, in 
180.S, fell a victim to a similarly rash experiment §. 

* Jenner's Further Observations, p. 19. f Zoonomia, u. s. 

X Cliickcn-pox (varicella) is not inoculable. See Thomson's History of 
Smallpox, 8vo, p. 283. 

§ See Sir Robert Wilson's History of the Expedition to Egupt, p. 257; 
•Wittman's Travels in Turkey, pp. 516, 518 ; and Granville in the Pamphleteer, 
XXV. About the close of the sixteenth century a dispute arose, which has conti- 
nued almost to the present day, whether the plague be a contagious disease or 
not. Exclusion from that class has been extended also to typhus, yellow fever, 
and scarlatina. Indeed smallpox and measles are the only febrile maladies, 
which are admitted by some of the opponents of contagion to be propagated by 
a specific poison. All others, affecting numbers at one place and one time, have 
been by them classed with epidemics. It is needless to reply to the arguments 
in favour of this doctrine, because they have been already refuted, in a man- 
ner that should set the question at rest fqr ever, by Dr. Roget, in a Report 
presented to Parliament in 1825. {^lee Parliamentary History and Review, 



REPORT ON THE LAWS OF CONTAGION. 75 

XIV. There is only one form in which ponderable matter is ca- 
pable of being transmitted invisibly through the atmosphere, viz. 
in that of elastic fluids, either permanent at common tempera- 
tures, or existing as such veithin a certain range of temperature 
and pressure. The former are called gases, the latter vajwurs', 
but the distinction is one of convenience only, and is not marked 
by any well defined boundaries. Contagious poisons, when dif- 
fused through the atmosphere environing an animal body by 
which they are generated, can exist only in the form of vapour. 
Like all other vapours they must be governed, as respects their 
degree of concentration in a given space, chiefly by the existing 
atmospheric temperature. 

XV. Of the chemical constitution of contagious emanations, 
we are equally ignorant as of that of the liquid poisons. VTe 
may conclude, however, that they consist of the commonly 
known elements of animal matter, and that their diversities de- 
pend, as in several well known instances of gaseous compounds, 
on modifications of the proportions, or even of the molecular ar- 
rangement of like proportions, of those elements. Thus, the very 
same proportions of carbon and hydrogen are known to consti- 
tute no less than three elastic fluids, each distinguished by pe- 
culiar mechanical and chemical properties. From the little sta- 
bility of composition of contagious poisons, evinced by their 
being decomposed by temperatures not above 212°rahr., as well 
as, perhaps, by weak chemical agents, it appears that their ele- 
ments are held together by very fegble affinities. 

The notion, which appears to have originated with Kircher, 
that contagious emanations are at all connected with the diffu- 
sion of animalcula or acari through the atmosphere, is purely 
hypothetical. It has been defended, with a singular want of 
sound argument, by Nyander, in a dissertation which Linnaeus, 
with equal want of judgment, has admitted into the fifth volume 
of the Amoenitates Academiccs. All that can be conceded in 
favour of such an hypothesis, is, that the assigned cause is not 
impossible ; but not a single valid analogy has hitherto been 
advanced to confirm it. On the contrary, the opinion is at vari- 
ance with all that is known of the diffusion of volatile contagions. 

XVI. We have no decisive evidence, through what channels 
contagious emanations escape from the animal body. They may 
issue from the whole of its surface ; but it is probable that they 
transpire chiefly through that fine membrane, lining the air- 
cells of the lungs, which the pheenomena of respiration show to 

8vo, published in 1826j)y Longman and Co.) It is desirable that this vahi- 
able document sliould be made accessible to medical and general readers, by 
republication in some less voluminous work. 



76 FOURTH REPORT — 1834. 

be permeable, in both directions, by gaseous and vaporous fluids. 
Through the same membrane, it is probable that contagious 
emanations are chiefly admitted into the sanguiferous vessels. 
Certain poisons (prussic acid, for instance,) have been traced by 
their odour and chemical qualities into the blood*. But as we 
have no tests of contagious poisons, it must remain conjectural 
that they also are admitted into the blood-vessels, and circu- 
late with that fluid. Even were that point established, it would 
remain to be determined whether they act by producing che- 
mical changes, or by at once affecting the nervous expansions, 
and through them the great nervous centres. 

XVII. The theory which has been framed to account for the 
spread of contagious emanations, is founded on the same prin- 
ciple as that assumed to explain the diffusion of aqueous and 
other vapours, viz. that a chemical affinity exists between vapours 
and atmospheric air, producing a kind of solution analogous to 
that of saline bodies in water. But this theory, though inge- 
niously supportedf, is superseded by the more probable views of 
Dr. Dalton, that in all mixtures of elastic fluids, whether gases 
or vapours, with each other, chemical affinity has no share in 
the effect, but that they maintain their state of equilibrium by 
their respective elasticities alone J. In our atmosphere, for ex- 
ample, the oxygen and nitrogen gases, which are its constant 
ingredients, and the carbonic acid and aqueous vapour, which 
vary a little in their proportions, are diffused through each other 
by their respective elasticities, according to certain mechanical 
laws. This is not the fit place for a detail of the evidences, on 
which Dr. Dalton originally founded his opinion, nor of the ad- 
ditional arguments deducible from the experiments of Mr. Gra- 
ham §. It is sufficient to remark, that the probabilities are 
greatly in favour of the new theory, which, by analogy, may be 
extended to the contagious vapours. These effluvia, it is pro- 
bable, are also diffused through the atmosphere, not by a pro- 
cess of solution, but by the elasticities inherent in them as va- 
pours; which elasticities are amenable only to variations of 
temperature and pressure, and are totally independent of changes 
in the proportions of the ingredients of the atmosphere. 

XVIII. The activity of contagious emanations has been as- 
certained to be confined within very moderate distances from 

• Christison On Poisons, 8vo, 1829, p. 561. " Poisons," the same writer 
observes, " act on the mucous membrane of the pulmonary air-cells, with a ra- 
pidity not surpassed by their direct introduction into a vein." p. 22. 

f Chiefly by Dr. Haygarth. See his Inquiry, and also his Sketch. 

X Manchester Memoirs, vol. v. series i. 

§ Transactions of the lloyal Society of Edinburgh, 1832. 



REPORT OX THE LAWS OF CONTAGION. 77 

their source. As respects the emanations of the plague, this 
has been attested by several writers. 1. Dr. RusseU, the author 
of an excellent History of the Plague, preserved himself from 
that disease, during a residence of several years at Aleppo, by 
avoiding a nearer approach to the sick than four or five feet *. 
Mr. Howard's experience satisfied him that, in a still atmo- 
sphere, twelve feet was a perfectly safe distance f. Assalinitook 
no other precaution, than to avoid inhaling the breath of persons 
under that disease. 2. Smallpox infection was believed by Dr. 
Haygarth, not only from his own experience but from a series 
of experiments conducted by Dr. O'Ryan, of Lyons, not to ex- 
tend beyond half a yard from the patient ; and that of typhus 
to be at least as limited J. 3. Scarlatina, when introduced by 
a new comer into a school, has generally been observed to spread 
first to those associated in the same class, or otherwise, with the 
infected person. On these facts is founded the salutary practice 
of separating the sick from tlie healthy, on the first appearance 
of a contagious malady; by which, in numberless instances, its 
progress has been effectually stopped. It is a happy consequence, 
also, of the limited extent of the infectious circle, that in a well 
aired apartment, all those soothing and beneficial ministrations, 
that do not require a very close approach to the sick, may be 
performed with little if any danger to the attendants. 

XIX. It is impossible, however, to assign, to any species of 
contagious emanation, distinct and constant boundaries. Even in 
each particular instance, these limits are necessarily liable to fre- 
quent variation. For, 1. The more abundant the production of 
contagious effluvia, the wider, costeris paribus, will be the area 
over which they will be diffused. 2. Imperfect ventilation ex- 
tends the diameter of the infectious circle, and renders the poison 
efficient at distances where, by due dilution with atmospheric 
air, it would have been perfectly inert. Even the poisonous 
gases prepared by chemical processes, it is well known, may, if 
largely diluted with atmospheric air, be respired for a certain 
time, without even the slightest injury. By availing ourselves 
then of the law, which renders a certain state of concentration 
essential to the activity of volatile contagions, it is easy to ob^ 
tain complete exemption from their deleterious effects. Abun- 
dant dilution, indeed, effected by well planned and assiduous 
ventilation, is the most certain, if not the only, means of secu- 
rity against contagious emanations, as they issue from the sick. 

XX. The i^voce^&fli spontaneous diffusion is too slow to ac- 

« Russell On the Plague, 4to, 1791, p. 99. 
+ On Lazarettos, p. 34 ; and Appendix to that work, p. 31. 
X Inquiry, p. 97; and Sketch of a Plan to exterminate Smallpox, p. 237; 
also Letter to Dr.Percival, p. 9. 



78 KOUUTH REPOUT — 1834. 

count of itself for the spread of contagious emanations, and is ap- 
plicable chiefly to a quiescent condition of the atmosphere. But 
it is known that contagious poisons may be conveyed by the mo- 
tion of masses of air, which mechanically sweep those effluvia 
along with them, in a state consistent with their activity at mo- 
derate distances. Of this it is sufficient to cite the following, 
out of several similar examples : — 1. At the Old Bailey Sessions 
held in London in May 1750, the poisonof jail-fever was wafted 
by a current of air from a prisoner at the bar, in such a direc- 
tion as to infect the lord mayor, two of the judges, several of the 
barristers, and eight of the Middlesex jury, who all died in con- 
sequence ; but all the London jury, M'ho sat out of the current, 
escaped*. The black assizes at Exeter and Oxford were distin- 
guished by similar catastrophes. 2. Even in the open atmo- 
sphere, infection may be propagated to small distances. Dr. 
Haygarth relates an instance, the circumstances of vvhich were 
strictly investigated, in which a child was infected with small- 
pox, bypassing another sick of that disease on the walls of the 
city of Chester, where they are about a yard and a half broadf. 
3. Howard and Russell agree, that, in the open air the contagion 
of tlie plague lurks chiefly to leeward ; and they ascribe their own 
exemption from its effects, when examining patients out of 
doors, to the precaution of always standing to the windward of 
the sick. It is probable that currents of low degrees of force are 
more dangerous vehicles of contagion than strong gales or 
storms, since the latter must not only dilute the poisonous va- 
pours below their point of activity, but rapidly carry them oft", 
so diluted, to a distance. 

XXL There is no reason to believe that the atmosphere of an 
extensive district, or even of a city or open street, can be min- 
gled with such a proportion of animal contagion, as to become 
infectious to numbers. The extreme mobility of the particles of 
air among each other, and the almost unceasing variations of 
temperature at the earth's svirface, occasion constant though 
sometimes scarcely perceptible ciirrents, which mingle any poi- 
sonous vapours, that may be abroad, with the general atmospheric 
mass. All experience, indeed, as well as general reasoning, is 
against the ivide diffusion of animal contagion in an active state. 
The smallpox, we are assured by Dr. Haygarth, was never known 
to spread from house to house, even in the most confined parts 
of the city or suburbs of Chester, provided the rule of non-inter- 
course with infected families was strictly observed %. The plague 
does not cross the narrowest streets or alleys at Constantinople, 

• Gentleman's Magazine, 1750. f Inquiry, pp. 97 and 100. 

X Inquiry and Sketch of a Plan, Sec. 



REPORT ON THE LAWS OF COXTAGIOX. 79 

though not ten feet wide; and the English residents at that city 
live in perfect security within the walls of the Pera, even while 
the plague is raging around them*. Nor has it ever been known in 
a single instance that fever hospitals, which were at first violently 
opposed, and even indicted at law as dangerous nuisances, have 
spread infection to a contiguous house. On the contrary, those 
institutions have often cleared their immediate vicinity from 
fever, by extinguishing solitary cases, which would otherwise 
have multiplied rapidly in the midst of poverty and filth. It is 
due to Dr. Haygarth to state, that in the year 1775, he first re- 
commended the establishment of fever-wards as a practical in- 
ference from the law of the limited sphere of contagion, of which 
his inquiries had furnished many of the best illustrationsf. His 
proposal was soon afterwards sanctioned by Mr. Howard, who 
had learned, by his own experience, the limited sphere of conta- 
gion, and the great advantages of cleanliness and ventilation in 
suppressing the fevers of jails and hospitals. 

XXII. It has been long known that dry porous bodies, when 
exposed to the atmosphere, increase in weight by absorbing 
aqueous vapour. In like manner, there can be no doubt that 
contagious vapours or emanations are absorbed by porous sub- 
stances, and are again exhaled in an active state. Boyle remarked 
that " amber, musk, and civet perfume some bodies, though not 
brought into contact with them, as the same determinate disease 
is communicable to sound persons, not only by the immediate 
contact of one who is infected, but without itj." Contagious 
emanations, thus imbibed by porous bodies, have received the 
name oi fomites^. They are capable of issuing forth with 
unabated, and, it is even asserted on good authoritj^, augmented 
activity II . It is probable, therefore, that they are emitted in 
a state of increased concentration, the porous body having 
imbibed those vapours, in preference to the elastic fluids which 
constitute the atmosphere. The propagation of contagious poi- 
sons, in the state of fomites, is illustrated by the following among 
numberless similar instances : — 1. The contagion of the plague 
of 1665 was conveyed in a box of clotlies from London to Eyam, 
a small village in Derbyshire, out of whose scanty population 
it carried off two hundred and fifty persons**. 2. Smallpox 
infection has been transmitted from London to Liverpool, by 
means of new apparel made in a room where persons were sick 
of that malady. .3. Dr. Hildebrant introduced the poison of scar- 

* Clark's Collection of Papers ; and Macniichael, Pamphleteer, xxv. 
t Letter to Dr. Percival. % Boyle's Works, by Shaw, 4to, vol. i. 

§ The plural of fomes, fuel. || Cullen, Lind, Campbell, Clark, &c. 

•* Mead, quoted by Howard On Laxarcttos, p. 24. 



80 FOURTH REPORT — 1834. 

latina into Podolia, a distance of several hundred miles, by a suit 
of clothes, which he had worn at Vienna while attending persons 
sick of that disease, and had laid by for several months*. 4. Of 
the propagation of a fever of the typhoid character by fomites, 
Sir John Pringle has recorded a striking example. A number 
of old tents, wliich had been used as bedding by soldiers sick of 
low fever, were, on the disembarkation of the troops at Ghent, 
sent to be repaired. Twenty-three Flemish workmen were em- 
ployed in the business, out of whom seventeen took the fever 
and died, though they had no personal communication with 
the troopsf. 

XXIII. It has not been ascertained how long fomites may 
retain their activity ; but there is reason to believe that in arti- 
cles closely packed they may remain unaltered for several years. 
Sennertus relates an instance in which, after a violent plague at 
the city of Breslaw, in 1542, the pestilential contagion imbibed 
by linen cloth which was kept folded up, issued forth fourteen 
years afterwards in another city, and gave rise to a plague, which 
caused great devastation J. In Dr. Parr's Medical J)ictionary 
(art. Contagion), a fact is stated, which, if well authenticated, 
would indicate a much longer period for the durability of the con- 
tagion of plague. 

XXIV. The subject of fomites is well worthy of further in- 
vestigation. Hitherto we have acquired no information respect- 
ing the comparative powers of different porous bodies to absorb 
contagion. Technical distinctions into " more or less suscep- 
tible articles " are, it is true, recognised by the quarantine laws ; 
but they appear to be founded on loose analogies rather than on 
careful observations. 1. It is extremely probable that (Z?/^/*ew? 
porous bodies vary as to their powers of absorbing the same con- 
tagious emanation, as we know that they differ in their powers 
of imbibing a given elastic fluid. 2. In the same porous body, 
it is quite conceivable also, that the power of absorbing different 
contagions may vary with its states of dryness, temperature, 
mechanical aggregation, and other circumstances. A light 
and spongy material will probably be found a more active ab- 
sorbent of contagion, than the same substance when rendered 
dense by packing or by manufacturing operations. 3. A low 
temperature of the porous body will probably cause it to ab- 
sorb more contagion than an elevated one ; the dryness of the 
solid being supposed equal in both cases. When once im- 
pregnated also, an increased temperatui-e will probably act in 

• Diet, de Medecine, Paris, 1822, art. Contagion. 
t Pringle On the Diseases of the Army, part I. ch. iii. 
X Quoted by Boyle, Shaw's Abridgment, vol. i. 



I 



REPORT ON THE LAWS OF COXTAGIOX. 81 

disengaging fomites, just as odours lurk unperceived in a garment 
till the wearer enters a warm apartment. It is consistent with this 
opinion, that clothes, which have been in contact with persons 
suffering under typhus, sometimes infect those who wash them in 
hot water. 4. The distance from the source of contagious effluvia, 
at which porous bodies exert their absorbent power, is undeter- 
mined. There is probably a distance at which their elasticity 
may be so increased by dilution, as to be more than equivalent 
to the absorbent power of the solid. The more highly the atmo- 
sphere surrounding the sick is charged with contagious effluvia, 
the more abundantly, may it be expected, that those effluvia will 
be absorbed by solids. 5. The colours of porous bodies have been 
shown, by the experiments of Dr. Stark, to exert a decided influ- 
ence over their absorption of odours, the dark colours being most 
efficient. He has suggested, therefore, by a fair analogy, that 
colour may modify also the absorption of contagious effluvia*. 

XXV. In several well authenticated instances, persons convey- 
ing fomites with injurious and even fatal effects to others, havr 
themselves escaped infection. Prisoners discharged in theie 
usual health from Newgate, at the time when that jail was the 
seat of a contagious fever, have infected the keepers of shops and 
public-houses in the neighbourhoodf. The same consequences 
followed also the liberation of debtors from the jail at Gloucester. 
In the memorable instance, too, already cited, the criminals who, 
by the fomites lurking in their clothes, spread so fatal a pesti- 
lence through the court of assize, were in their ordinary state 
of health. Previous ablution of their bodies, and the putting on 
clean and uninfected clothing, would doubtless have prevented 
that extensive disaster. 

XXVI. Of contagious diseases, some attack the same individual 
repeatedly : such are siphilis, typhus, and the plague. The last- 
mentioned, however, rarely attacks twice during one season ; for 
out of 4400 cases. Dr. Russell observed reinfection to happen 
within that interval in 28 only J. Other contagious maladis, 
such as smallpox, cowpox, measles, hooping-cough, and scarla- 
tina, especially the first four, occasion some change in the human 
body, which, in a great majority of instances, secures it during 
life from a return of the same disorder. Smallpox and cowpox 
act as safeguards against each other ; or when (failing this) the 
one occurs in a person who has passed through the other, the 

* Philosophical Transactions, 1832. 

t Proceedings of the Board of Health at Manchester, p. 89— -100. Clark's 
Collection of Papers, p. 10. 

I Russell On the Plague, pp. 190, 305. 
1834. G 



82 FOURTH REPORT — 1834. 

second in order of sequence, whether smallpox or cowpox, as- 
sumes a modified, and generally a much milder form*. There 
can be little doubt, however, that those two diseases are essen- 
tially the same. We have no evidence that any one specific dis- 
ease affords a security against any other, which is distinguished 
from it by marked characters and a different succession of sym- 
ptoms. Neither smallpox nor cowpox gives a durable protection 
against measles, hooping-cough, or scarlatina. 

XXVII. It is in few instances only that two contagious poi- 
sons act together upon the human body, producing simultane- 
ously two distinct maladies. Scarlatina has been known to su- 
pervene on typhus ; and hence the precaution, in some fever 
hospitals, of distinct wards for those two diseases. Smallpox 
and cowpox may coexistf; so also may cowpox and measles J; 
but smallpox and measles are incompatible at the same time. 
Mr. Hunter inoculated for smallpox a child who, as afterwards 
appeared, had been previously exposed to the infection of mea- 
sles. The measles appeared and completed its course, before the 
inoculation took effect, after which the smallpox began, and 
passed through its usual stages §. Two similar instances are 
related by Dr. Darwin, in both of which the smallpox, after 
being suspended by the measles, exhibited an unusually mild 
character 1 1. 

XXVIII. A certain duration of exposure to contagious ema- 
nations is essential to their full effect. This is precisely analo- 
gous to what happens with respect to noxious gases, which may 
be breathed in mixture with common air, for a few moments, 
M'ithout injury. On this subject Dr. Haygarth's observations 
establish the conclusion, that air weakly impregnated with small- 
pox or typhus contagion, may be breathed for a long time, and 
air strongly charged with either, for a short time, with equal im- 
punity^. Medical practitioners who have sustained no injury 
from visits of ordinary duration, have been infected after staying 
unusually long in the apartments of persons suffering imder con- 
tagious fevers. A very dilute contagion, however, is known to 
disorder the health, when it does not produce the whole of the 
morbid phsenomena in their usual degree and order of suc- 
cession. 

XXIX. We have no observations suiSiciently correct to enable 

* For the fact that cowpox is milder after smallpox, see Jenner's Tract, 1798, 
p. 18. 

f Adams On Morbid Poisons, p. 398. J Jenner's Tract, 1799, p. 63. 

§ Hunter On the Blood, &c., Introduction. || Zoonomia, §. xxxiii. 

«i Letter to Dr.Percival, p. 41. 



REPORT ON THE LAWS OF CONTAGION. S3 

US to pronounce, of any one disease, at what period it begins to 
be infectious. Dr. Russell could not satisfy himself on this point 
as to the plague*. The smallpox was believed by Dr. Hay- 
garth not to be attended with contagious eflfiuvia until after the 
appearance of the eruption, and to diffuse its poison most abun- 
dantly when the pustules had reached the period of maturationf. 
Scarlatina is well known to spread by infection, before the cha- 
racteristic eruption on the skin shows itself. It is probable 
that the infectious period is not always the same for the same 
disease, but bears some proportion to the violence of the fever, 
and to other circumstances. 

XXX. It has not yet been decided respecting any one disease, 
when it ceases to be infectious. Dr. Russell coiUd not determine 
when convalescents from the plague ceased to infect others, nor 
when the fluid contained in the glandular abscesses was no longer 
dangerous. Persons, recovering from smallpox, infect others so 
long as the smallest scab is visible on the skin. Convalescents 
from scarlatina continue to impart that disease for ten days, or 
longer, after all the symptoms have disappeared, and even after 
the desquamation of the cuticle I . Hence, in part, the difficulty 
of eradicating that malady from any situation where numbers are 
subject to it. Asiatic cholera (a disease contagious under cer- 
tain circumstances,) emits the most active poison in its advanced 
stage, or rather in the state of consecutive fever. The infectious 
property of the bodies of persons who have died of that disease, 
though testified by several writers §, requires more accurate in- 
vestigation. If the affirmative should be established, the effect 
may still be imputed to a poison formed during life, and only 
exhaled after death. Infection from bodies dead of plague is 
denied by Howard, Desgenettes, and Wittman, and the infec- 
tious power of yellow fever is said to terminate with life. 

XXXI. It is seldom that the effects of contagious poisons, either 
liquid or vaporous, manifest themselves immediately after being 
received into the body. Well authenticated instances, however, 
are not wanting of the speedy and decided operation of the effluvia 
of plague, typhus, smallpox, &c.,when in a concentrated form. 
But in a great majority of cases, several days or weeks (in the 
instance of hydrophobia, even months) have elapsed, before the 
morbid phaenomena have appeared. The period differs for dif- 
ferent poisons, and is not always the same for the same poison. 
It has been called the latent period of infection, the time of in ■ 
cuhation, &c. The following intervals, though collected from 
the best sources, are to be considered merely as approximations. 

• Russell, p. 304. t Inquiry, p. 53. 

X Blackburn, pp. 5, 14, 36. § Becker On ChoJeru 



84 FOURTH REPORT — 1834. 

The plague, according to Dr. Russell, lies dormant about ten 
days. Among those inhabitants of Aleppo, who shut themselves 
up after having been previously in the way of being infected, no 
instance occurred of the appearance of the malady after the ninth 
or tenth day. 

In a number of cases of synallpox registered by Dr. Haygarth, 
the eruptive fever began on some day between the sixth and 
fourteenth after inoculation. Infection by emanations was not 
apparent until about two days later*. The latent period of 
chickenpox is, on an average, nine or ten daysf. The pustule 
of cowpux is distinguishable about the third day after vaccina- 
tion, and is perfected about the tenthj. 

The contagion of measles lies dormant for ten or fourteen 
days§. In scarlatina the interval does not exceed from two to 
six days II . No attempts to inoculate either of those diseases 
have yet succeeded^. 

Typhus makes its approaches in so gradual a manner, that it 
is scarcely possible to mark distinctly its latent period. The ob- 
servations of Dr. Haygarth indicate great latitude as to the time 
during which typhus infection may remain dormant in the sy- 
stem, viz. from less than ten days to even three or four weeks **. 
The peculiar difficulty, however, of ascertaining the interval, 
reduces greatly the value of the testimony of that careful ob- 
server in this instance. 

Asiatic cholera in Pioissia, according to Dr. Becker, indicated 
a latent period of from four to six days. Observations in this 
country tend to establish a similar interval. Among all the ves- 
sels that performed quarantine at Standgate Creek, not one ex- 
hibited an original case of cholera after the seventh dayff. 

XXXII. When a number of persons are exposed, apparently 
under precisely the same circumstances, to a contagious poison, 
it seldom happens that all are affected by it. It is to individual 
peculiarities influencing the state of the body at the time, that 
we are to look for the causes of these varieties. The circum- 
stances promoting the action of contagion have been classed to- 
gether under the name of predisposing causes, which agree 
generally in lowering the strength of the body, or depressing 
the energy of the mind. Among these maybe reckoned fatigue, 
want of sleep, extreme cold or heat, crowded or close places, 
air tainted by putrefying substances, scanty or bad food, or oc- 

• Inquiry. f Heberden, Comment, cap. 96. % Jenner. 

§ Heberden, cap. 63. |j Blackburn, p. 34 

i[ The experiments of Dr. Francis Home on the inoculation of measles, have 
not, I believe, succeeded in other hands. 

•• Haygarth's Letter to Dr. Percival. ft Cholera Gazette, No. 3. 



REPORT ON THE LAWS OP CONTAGION. 85 

casioual long fasts, excessive evacuations, and intemperate in- 
dulgences of every sort. The depressing passions of fear, grief, 
and anxiety are powerful auxiliaries of contagious poisons. So 
also are religious creeds that lead to gloom or despondency, or 
that inculcate observances requiring abstinence, or other prac- 
tices unfavourable to health*. But of all predisposing causes, 
poverty, with its attendant physical and moral evils, prepares 
the greatest numbers of victims to contagious diseases, and most 
widely spreads their destructive ravages. 

It may be received, then, as a general conclusion, to be applied 
to all our reasonings in special instances, that no one malady 
IS invariably and under all circumstances conta- 
gious ; in other words, that a contagious poison is such 
only in a limited and qualified sense. 

XXXIII. Beside the general causes promoting or counteract- 
ing the ef&ciency of contagious poisons, there are others of li- 
mited operation, affecting chiefly certain individuals or classes of 
men. 1. From peculiarities of structure or constitution not at 
all understood, some persons enjoy an exemption from particu- 
lar contagious diseases. Before the preventive powers of cow- 
pox were known, it was not unusual to meet with instances in 
which persons had entirely escaped the contagion of smallpox, 
though repeatedly exposed to it, and even after being inoculated 
with its virus. By diligent and careful inquiry. Dr. Haygarth 
was led to estimate the proportion of persons who had reached 
the middle age without taking the smallpox, at one in twenty- 
three ; and if it be admitted that in some instances the excep- 
tions were only apparent, there will still remain a sufl&cient num- 
ber to establish the general observation. During the prevalence 
of typhus fever a similar proportion of persons has been esti- 
mated to escapef. 2. Whole tribes and classes of men share in 
liability to be infected by some diseases, and in the power of 
resisting others. In hot climates the negro resists certain mor- 
bid poisons which the European is unable to withstand. The 
Bedouin Arabs, we are told, wear with impunity the cast-off 
clothes of persons who have died of plague, without even at- 
tempting to purify themj ; but the soldiers of the French army 
in Egypt fell victims to the same practice, which all the autho- 
rity of the General-in-chief could not suppress§. 3. Difi^erent 
periods of life modify the predisposition to infectious diseases. 
Old persons enjoy an exemption from some contagions, but not 

* Instance in Howard On Lazarettos, p. 25, and in the Doctrine of Fatalism. 
t Letter ioPercival, pp. 32, 33. J Blane's Medical Logic, p. 176, note. 

§ Larry, Memoires, p. 333. 



8G FOURTH REPORT — 1834. 

from others ; and infants at the breast show a remarkable in- 
sensibility to some contagious maladies. 

XXXIV. But of all the circumstances that impart the power of 
resisting contagion, the most remarkable is the force of habit. In 
this respect, as in many others, we find a close analogy between 
ordinary and contagious poisons. Large doses of opium, any one 
of which would be fatal to an uninitiated person, are habitually 
swallowed several times daily, by those accustomed to its use. 
In like manner, medical practitioners and the nurses of the sick 
breathe, with impunity, contagious emanations to which they 
are in the daily habit of being exposed. It was remarked by Dr. 
Ferriar, that the keepers of lodging-houses in Manchester, of the 
lowest and filthiest kind, from which typhus fever was seldom 
absent, were untouched by the reeking poison, Avhile the new- 
comers kept up a constant succession of victims to its effects*. 
To habit, also, the prisoners, who carried contagious poison in 
their clothes into a court of justice, owed their own protection. 

XXXV. The immunity acquired by habit is not, however, in 
all cases either permanent or absolute. 1. Medical practitioners 
and nurses, who have long discontinued their avocations, have 
again become liable to be infected by febrile contagionf. 2. Per- 
sons accustomed to breathe without injury atmospheres impreg- 
nated to a certain extent with contagion, yield to the influence of 
stronger doses. The late Dr. Clark, of Newcastle, though ren- 
dered by constant habit proof against typhus contagion of com- 
mon strength, caught that disease in a severe form by suddenly 
undrawing the bed-curtains of a patient, and thus subjecting him- 
self to a rush of air more than usually pestilential];. 3. Persons, 
who by habit are enabled to resist one kind of infection, do not 
on that accovmt enjoy a security against others. Of this, beside 
many other instances, we have a striking illustration in the havoc, 
which spread so rapidly among the medical practitioners in 
Prussia, when Asiatic cholera first appeared in that country §. 

XXXVI. There is reason to believe that contagious poisons 
may be received into the system, and may remain in it some time 
without manifesting their usual consequences, until some acci- 
dental cause calls them into full action, and gives birth to the 
usual train of symptoms. Circumstances of this kind have been 
called coxcuBRiNG or exciting causes. Generally speaking, 
they are identical with those which, acting upon the body before 
exposure to contagion, are termed predisposing causes, the enu- 

* Ferriar, Medical Histories, vol. i. p. 173. 

+ Haygarth's Letter, pp. 41, 44. % Clark's Collection of Papers. 

§ Dr. Wagner's "^Report of the Cholera in Prussia," Bibl, Brit., No. 51. 
p. 179; awA^WWrnmn American Journal, vol. .\xv, p. 17!). 



REPORT ON THE LAWS OF CONTAGION. 87 

nieratioii of which it is needless to repeat. Dr. Russell observed 
the plague to "hang ambiguously" for several days about per- 
sons. In this state, and even when there was no such evidence 
of being infected, an overheated bath or a sudden impression of 
fear, especially when the disease itself was the object, has ex- 
cited the lurking poison into activity*. The late Dr. Jenner, 
after having been much exposed to typhus contagion, experi- 
enced no ill effect until a long and fatiguing ride on horseback 
in extremely cold weather proved an exciting cause of that ma- 
lady, which he then underwent in its usual formf. Dr. Lind 
relates, that out of a number of sailors, all of whom had been in 
the way of febrile infection, a part only, who had been permit- 
ted to go ashore, and while there had been engaged in a debauch, 
fell sick of low fevers. 

XXXVII. Among causes influencing the spread of contagious 
diseases, climate has been reckoned, using that term in its en- 
larged sense, and not merely as applied to geographical position. 
There can be no doubt that climate modifies the jjredisjjosition 
of the human body to receive infections. In addition to this ef- 
fect, varieties of temperature, one of the principal elements 
of climate, must necessarily affect the elasticity of vaporous con- 
tagions, and consequently their diffusibilities. Certain poisons 
(those perhaps which appear to have low vaporising points, as 
smallpox, influenza, and Asiatic cholera,) exert their powers 
alike in the hottest and coldest regions. Other poisons demand 
a temperature not below 60° of Fahrenheit's thermometer]:. 
Such is that of plague ; while the yellow fever does not exist at 
temperatures below 80°, and in North America has been checked 
in its spread by a single frosty night. But an increase of tem- 
perature above a certain point (90") disarms the contagion of 
plague of its power§ ; and typhus (or hospital) fever is unknown 
in tropical regions||. Measles and scarlatina also are, in such 
countries, of very rare occurrence. It is not improbable that 
the highest temperatures observed in the atmosphere may ac-^ 
tually destroy or decompose contagious poisons, as I have en- 
deavoured to prove may be effected, so far as respects those of 
cowpox and scarlatina, by temperatures not greatly exceeding 
100° Fahr.^. 

The influence of weather over the spread of contagion has not 
been sufficiently examined. So far as respects predisposition, it 

* Howard, p. 33 ; and Russell, p. 303. f Baron's Life of Jenner, p. lOG, 

X Blane, Med. Log., p. 173. § Russell, Antes, &-c. 

II Dr. Hunter, Medical Transactions, vol. iii. p. 355. 

H Phil. Mag. and Ann. ofPhilos., November 1831, and January 1832. 



88 FOURTH REPORT — 1834. 

is probably considerable. Its direct effects upon contagious ef- 
fluvia are perhaps resolvable into temperature alone. 

XXXVIII. Such is a general outline of the facts that are 
known respecting contagion, and of the conclusions to which 
they lead. No one, however, who has inquired into this sub- 
ject, can fail to be struck wiuh the imperfections of our know- 
ledge respecting it, — with the paucity of observations sufficiently 
correct to serve as the foundations of general laws, — and with 
the number of questions which still remain to be solved*. A long 
course of diligent attention to phaenomena, and a persevering 
and rigid employment of the inductive logic, will doubtless sup- 
ply many of these deficiencies. But there is another mode of in- 
terrogating nature, hitherto little used in this department of phi- 
losophical inquiry, that of experiment, which, in the investi- 
gations of physiology, has supplied materials for the happiest 
generalizations. In exploring the nature and laws of contagion, 
experiment has hitherto done very little ; and extensive regions 
of discovery remain to be entered upon, with the aid of that 
powerful light. Difficulties and obstacles may be expected in 
the research, but none that, either in number or amount, would 
be insuperable by an ardent and inventive mind. Let it be re- 
membered, as an incitement, that the inquiry has a higher ob- 
ject than the gratification of speculative curiosity ; that its ten- 
dency to the advantage of mankind is direct and unquestion- 
able ; and that its success would add another triumph to those, 
which philosophy has already achieved over physical evil, — evil, 
no doubt, permitted to exist, among other reasons, that it may be 
overcome by the vigorous use of those intellectual powers and 
faculties, with which man is so preeminently endowed. 

XXXIX. This view of the subject of contagion would be in- 
complete, without noticing a class of diseases, which have been 
ascribed to causes of much more extensive operation, and are 
generally contrasted with those of a contagious nature. They 
are named endemic and epidemic DiSEASEsf. Both agree in 
attacking a number of individuals ; but the former are more li- 
mited than the latter as to the extent of their diflusion, and may 
often be traced to causes of local operation. 

XL. 1 . Acute or febrile endemics prevail, either constantly or 
periodically, over tracts of country of considerable area ; or they 
may be confined to a province, a district, a city, or street, or a par- 

• As these questions arise obviously out of the statements of what is ah-eady 
known, it appears unnecessary to collect them into a series of ' qitcBrenda.' 

f Endemic, from m in, and ovifio; the people ; Epidemic, from nrt tipon or 
among, and the same subslantive. The terms, therefore, differ only in the 
greater comprehensiveness given by the latter preposition. 



REPORT ON THE LAWS OF CONTAGION. 89 

ticular part of a street ; or to a single building, as a house, a jail, 
or a penitentiary. When spread over an extensive space, several 
circumstances hav^e been observed to be favourable to their pro- 
duction. Such are, situation with respect to the level of the sea, 
or that of the surrounding country ; the form of the surface, as 
inclined or flat ; the nature of the soil or substrata ; the quantity 
and quality of the water ; the state of drainage and cultivation ; 
the vicinity of forests, and of swamps and marshes. From 
marshy ground exhalations almost constantly ascend, which give 
rise to fevers of a peculiar type, called remittents when they oc- 
casionally abate, and intermittents when the symptoms are ab- 
sent for distinct intervals. In no instance has a remittent or 
intermittent been communicated from one individual to another; 
but intermittents are apt to pass into remittents, and the latter 
to assume a continued type, when they become decidedly con- 
tagious. 

2. Marshy exhalations, or miasms, as they may be exclusively 
called (to distinguish them from animal contagions), are evolved 
most abundantly in hot weather, from ground which is alter- 
nately moist and dry, or barely covered Avith water ; not if en- 
tirely or constantly inundated. Either fresh or sea- water is ade- 
quate to their production ; but the alternation of the two has, 
in certain situations, rendered miasms particularly virulent*. 
Marshy ground, however, is not essential ; for the half-dried 
gravelly beds of rivers have been observed to occasion fevers of 
a severe typef. In a few instances newly broken ground is re- 
corded to have had the same effectj. In general, miasms occupy 
low situations, insomuch that no greater an elevation than the 
upper stories of a house has afforded protection against them. 
But this is not universal, for they have been known to rise to 
considerable heights§, though in such instances the form of the 
ground indicates that they have been carried up inclined planes, 
by winds blowing from the place of their production. The 
sphere of the activity of marsh miasms surpasses beyond com- 
parison that of animal contagions, obviouslj' on account of the 
infinitely greater quantity in which they are generated. The 

* Giorgini (Mem. read to the Royal Academy of Sciences in July 1825) 
gives a frightful picture of the disease called Malatlie di Caltiva, caused by 
marshes of this kind at the foot of the Ligurian Apennines. 

•|- Ferguson, Edinhuryh Transactions, ix. 273. 

X A remarkable instance is related in one of the latter volumes of Silliman's 
American Journal. 

§ According to Monfalcon, {Hist, des Marais, Paris, 1824,) to 1400 or 1600 
English feet. See also Ferguson, loc. cit. 



90 FOURTH REPORT — 1834. 

Pontine marshes, covering an area of eight leagues by two, have 
spread their deleterious exhalations, in certain directions of the 
wind, to the mouth of the Tiber. In the West Indies miasms 
have affected the crews of vessels mooi-ed 1500 toises (3200 
English yards) from the shore (Monfalcon) ; but this is pro- 
bably much more than the usual distance. 

3. The chemical properties of marsh miasms have been in- 
vestigated by several writers, but with little other fruit than a 
catalogue of negative qualities*. Miasms are not the mere pro- 
ducts of putrefactionf, and have not necessarily a fetid odour. 
Experiment has not demonstrated any departure, in the air over 
marshes, from its usual proportions as to oxygen and azotic 
gases. Neither carburetted, sulphuretted, or phosphuretted hy- 
drogen, nor ammonia, has been detected in these exhalations. 
The principle on which their peculiar agency depends, still re- 
mains to be determined by experiment. 

4. There are several points of analogy between the operation of 
marsh miasms, and that of contagious poisons, upon the human 
body. Both require a certain predisposition in the persons ex- 
posed to them ; and this susceptibility is imparted by the same 
causes. The power of resisting miasms as well as contagions is 
acquired by habit, at least to a certain exjtent. But no continu- 
ance of usage ever protects persons, who are constantly exposed 
to an atmosphere impregnated with exhalations constituting 
malaria, from their pernicious effects. In some marshy coun- 
tries, the perfect and vigorous human form is never seen ; and 
a race of men inhabit them who are alike destitute of physical 
and mental energy, and who in middle life exhibit all the signs 
of old age. Strangers arriving there are doomed to inevitable 
destruction ; and all attempts to extend our geographical know- 
ledge of such regions, however well concerted, have been baffled 
by the overwhelming power of endemic pestilence. 

XLI. Epidemics are much more widely diffused than ende- 
mics ; so widely, indeed, that they have been imputed to certain 
conditions of the atmosphere, called epidemic constitutions of the 
air. To this term there can be no objection, provided it involve 
no hypothesis as to causes. The only legitimate meaning of the 
word epidemic is, an acute disease prevailing over the ivhole or 
a large portion of a community, at seasons not in general 

* The most elaborate and able work which I have seen on the subject, is the 
Recherches Historiques, Chimiques, et Aledicales sur I'Air Marecageux, par 
J. S. E. Julia. 8vo. Paris, 1823. 

f It has been suggested {Foreign Quarterly Review, No. XXI.) that miasms 
are the products of plants of the genus Chara. 



REPORT ON THE LAWS OF CONTAGION. 91 

marked by regular intervals, and not traced to local causes. 
Though the works of writers on epidemics give us no insight 
into their causes, yet they contain excellent descriptions of the 
phgenomena. Of these the following is a very general outline : 

1. Epidemic diseases do not observe any fixed cycles, nor can 
we at all anticipate the periods of their return. Some epidemics, 
however, are disposed to prevail most at particular seasons of the 
year, as in spring and autumn. 

2. Epidemics seldom spread suddenly over very extensive re- 
gions, but are observed to make a gradual, often a slow, progress 
from one kingdom to another, from province to province, and 
even from one locality to another not far remote. The influenza, 
(a catarrh, accompanied with extreme debility,) which was epi- 
demic in England in 1782, was noticed in the East Indies in 
October and November 1781 ; at Moscow in December of the 
same year; at St. Petersburgh in February 1782 ; in London it 
was in full force in May; in France in June and July; and in 
Italy in July and August. In the months of August and Sep- 
tember it prevailed in Portugal and Spain*. The Asiatic cho- 
lera, it is well known, made even a much more tardy progress 
from the East westwards, and did not appear in England until 
about fourteen years after it was known in British India. 

3. On the first appearance of epidemics, they are not always 
distinguished by those symptoms which mark them in subse- 
quent periods. The plague, for instance, for the few weeks after 
its first invasion, is frequently unaccompanied by bubos or car- 
buncles, which are seldom wanting when it has raged long in any 
place. 

4. When diseases of this kind attack any country, they con- 
tinue to spread until they have reached the period of their most 
general prevalence, called their acme, and then decline. These 
periods of commencement, acme, and decline, seldom coincide for 
the same epidemic at different places. Of three localities, for in- 
stance, not far remote from each other, the plague, which visited 
England in 1666, was often observed at the same time to be first 
showing itself in the one ; to be at its height in another ; and to 
be on the wane in the third. The Asiatic cholera exhibited si- 

-milar irregularities in this and other countries. 

5. Epidemic diseases of the same name diifer materially, both 
as to degree and to symptoms, at different visitations. The epi- 
demic of one year maybe almost universally a mild and tractable 
disease, and that of another extremely severe and dangerous. 

• See a general account of the Influenza, drawn up from the reports of me- 
dical practitioners residing in various parts of England, in the Medical Com- 
mioikalioiis, vol. i. 



92 FOURTH REPORT — 1834. 

6. All the predisposing causes enumerated as promoting the 
spread of contagious diseases, conti-ibute also to thatof epidemics. 
The latter, also, are propagated by some causes of general ope- 
ration, such as a scanty harvest, or produce of bad quality ; a 
severe winter ; a scarcity of fuel ; an unusually crowded popu- 
lation ; and, on some occasions, harassing and destructive wars. 
In some instances, the path has been prepared for one epidemic 
hy the previous ravages of another : in other examples, the new 
epidemic has acquired an ascendency over existing ones, and 
has either modified or entirely extinguished them. In 1666 the 
plague imparted much of its own form to a low petechial fe- 
ver prevailing in London, but minor diseases for a while disap- 
peared. Even the smallpox was superseded by the more power- 
ful malady. 

7. In what the influence of atmospheric changes in causing or 
diffusing epidemics consists, it is impossible, in the present state 
of our knowledge, to explain. The most diligent observation has 
not connected the prevalence of those maladies with any ascer- 
tained condition, either physical or chemical, of the general atmo- 
sphere. With respect to oxygen and nitrogen gases, which consti- 
tute, at a mean of the barometer and thermometer, 98-J- in 100 of 
its volume, an almost perfect uniformity is known to exist. In its 
carbonic acid no variation has been discovered by experiment, 
that can be supposed to affect the animal oeconomy. The varieties 
of proportion in its aqueous vapour are, however, much greater ; 
and when accompanied, as they often are, by sudden changes of 
temperature, and by disturbances of the electrical equilibrium, 
may interrupt the due performance of the bodily functions. But 
other causes are necessary to account for those epidemics (cho- 
lera, for instance,) which defy the influence of climate, seasons, 
and of all changes that are objects of meteorological research. It 
has been suggested that an ' epidemic constitution ' of the atmo- 
sphere may depend on the presence of some substance alien to 
its ordinary elements. No fact, however, confirms this suppo- 
sition, if we except an observation of Dr. Prout, that at a period 
coinciding with the appearance of cholera in London, the weight 
of a given volume of air, making due corrections for differences 
of pressure and temperature, seemed to rise to a small but sen- 
sible amount above the visual standard, and continued above it 
during six weeks*. This observation requires, however, to be 
frequently and carefully repeated, and extended to other epide- 
mics, as opportunities occur, before any sound conclusion can 
be founded upon it. 

8. Epidemics have been contrasted with contagious diseases, 

* Bridgewater Treatise, p. 350. 



REPORT ON THE LAWS OF CONTAGION. 93 

and supposed to form a distinct and separate class. But it must 
not be forgotten that certain specific diseases, which by universal 
consent are allowed to be contagious, at times prevail so gene- 
rally as to be with propriety said to be epidemic. Such are the 
smallpox, measles, scarlatina, and hooping-cough. But it is in- 
conceivable that the specific poison, which in each of these in- 
stances is the efficient cause of the disease, and which is the 
undoubted product of vital operations, can be generated by any 
' corruption of air,' or by any spontaneous changes in inanimate 
matter. The only way in which a general condition of the atmo- 
sphere can be supposed to influence the spread of specific dis- 
eases is, either by rendering it a better vehicle of their respective 
poisons, or by influencing the predisposition of the body to re- 
ceive them. But if the view which has been taken (§. XVII.) of 
the state in which contagions exist in the atmosphere be correct, 
temperature alone, by modifying the elasticity of those vapours, 
can affiect their diffusion. It is well known, however, that ascer- 
tainable conditions of the atmosphere, as to heat or cold, mois- 
ture or dryness, and sudden transitions from the one state to its 
opposite, produce in the animal body a predisposition to receive 
contagion. The same atmospheric variations may act also as 
exciting causes, calling into action contagious poisons already 
admitted into the system, but not yet manifested by the usual 
phsenomena ; and when they operate on numbers, may occasion 
those sudden and violent outbursts of epidemic diseases, of which 
several examples are on record. Other general influences, in- 
deed, may prove exciting causes of such outbursts. They have 
followed closely, for example, upon seasons of riot and intem- 
perance, and have spread rapidly in situations where those dis- 
eases were previously confined to few and scattered individuals. 
It is equally unfavourable to the progress of knowledge to over- 
estimate what we know, as to shrink from the just appreciation 
of difficulties opposed to its further advancement. On the sub- 
ject of epidemics, they who have inquired the most will be most 
ready to admit, that our actual knowledge is bounded by very 
narrow limits. But we are not on that account to despair. The 
genius of philosophers of our own age has imfolded the most 
astonishing truths with respect to the subtile agents — light, heat, 
electricity, and magnetism. Every new conquest, that science 
achieves, enlarges our powers over nature ; and we are fully en- 
titled by the past to hope, that the physical condition of man will 
in future be progressively improved by his acquiring a command 
over external agents, which have never yet been subjected to his 
knowledge and control. 



OI- FOUKTII REPORT — 1834. 



INDEX TO THE SUBJECTS OF THE REPORT ON CONTAGION. 

§ I. The animal body generates morbid poisons. 

II. Causes which, actino: on the body, produce those poisons. 

III. Originate independently of crowding and confinement. 

IV. Sporadic diseases. 
V. Specific diseases. 

VI. Specific diseases not always traceable. 

VII. do not now originate. 

VIII. produce only their own kind. 

IX. Conversion of sporadic into specific diseases. 

X. Liquid contagious poisons. — Inoculation. 
XI. Spontaneous changes in liquid poisons. 
XII. Chemical nature of liquid poisons. 

XIII. Modes of communication of morbid poisons. 

XIV. The volatile poisons are vapours, not gases. 

XV. Their chemical constitution unknown. — Not animated. 
XVI. Channels through which vaporous poisons issue. 
XVII. Emanations spread by diffusion, not by affinity. 
XVIII. Sphere of their activity limited. 
XIX. No constant boundaries assignable. 

XX. Emanations carried by currents. — Instances. 
XXI. The general atmosphere never infected. 
XXII. Porous bodies imbibe contagious vapours. — Fomites. 

XXIII. Fomites retain their properties durably. 

XXIV. Modifications of the power of porous bodies to absorb fomites. 
XXV. Persons convey fomites without injury to themselves. 

XXVI. Contagions acting once only, and oftener. 
XXVII. Two contagions seldom act at once. 
XXVIII. Contagions require to be applied for a certain time. 
XXIX. Period when diseases begin to be contagious. 

XXX. cease to be contagious. 

XXXI. Periods of latency or incubation. 
XXXII. Causes predisposing to the reception of contagion. 

XXXIII. preventing infection. — Natural exemptions. 

XXXIV. Effect of HABIT in protecting against infection. 
XXXV. But habit not an invariable security. 

XXXVI. Exciting causes. 
XXXVII. Influence of climate and weather. 
XXXVIII. General Remarks. — Experimental inquiry proposed. 
XXXIX. Diseases commonly contrasted with the contagious. 
XL. Endemics ; their production and causes ; miasms. 
XLI. Epidemics; their general phaenomena, and dependence on atmo- 
spheric changes. 



95 



Report on Animal Physiology ; comprising a Review of the 
Progress and Present State of Theory, and of our Informa- 
tion respecting the Blood, and the Powers which circulate it. 
By WiLLtAM Clark, M.D., F.R.C. F.G.S. F.C.P.S., 
late Fellow of Trinity College, and Professor of Anatomy 
in the University of Cambridge. 

That physiology should have been a science slow and uncertain 
in its progress is scarcely surprising, when we consider how ex- 
tensive are its objects. It pretends to nothing less than to explain 
the phaenomena of living nature, — the conditions upon which 
they depend, — the laws by which they are governed. Hence, it 
inquires not only into the relations of every component part of 
an individual to each other and to the whole, but also, as far as 
is possible, into the mutual relations of all living things to each 
other, and to the rest of the world. In its useful application, 
therefore, it is the foundation of agriculture, of husbandry, of 
medicine. Intentions thus ample can only be fulfilled when all 
particular sciences have gained their consummation. In earlier 
aeras it was included in those ideal assumptions, from which, as 
from axioms, it was conceived that all the pheenomena of nature 
might be deduced ; whilst, in later times, the attempt to treat it 
merely as a branch of the prevailing chemical or mechanical phi- 
losophy of the day favoured its advance in particular directions 
only, and with very confined conceptions of its nature and extent ; 
as if any two of these sciences had yet ascertained, by means of 
their ovra generalizations, a common proximate cause of their 
phaenomena ; or, as if particular sciences were something else 
than constructions of the intellect to explain phaenomena be- 
tween which similarity has been established. 

Physiology, as a positive science, can only be founded in obser- 
vation and experiment; and the value of these depends, as in other 
cases, not less upon the patience, the circumspection, the dispas- 
sionate, and unprejudiced character of the observer than upon his 
scientific and mental elevation. The multitude of physiological 
experiments daily accumulated, tells us how easily they may be 
made ; the facility with which one set of experiments so frequent- 
ly supersedes a former, how difficult it is to make experiments of 
real value. So numerous, indeed, are the conditions with which 
every vital phaenomenon is complicated, that the effect may really 
be referrible to one or more of these entirely diflferent from that 
to which the experimenter has referred it. And, since it is im- 



96 FOURTH REPORT 1834. 

possible to abstract many of the conditions without destroying 
life, innumerable modifications of the experiment can alone afford 
an approximation to certainty. It is to experiments, in the hands 
of able men, whei'e the condition may be suppressed without de- 
stroying life, that we owe a knowledge of various portions of the 
nervous system which is no longer problematical*. 

But we are not to expect too much frol^l experiment. It may 
jjoint out the variety and the extent of vital reactions, but can 
teach us (as Miiller has pointed out,) nothing of the nature or 
fundamental cause of these. For here the experiment is not like 
one in chemistry, where, the known agent which excites reaction 
in another unknown, entering as an element into the effect pro- 
duced and ascertained, we are able to infer from what is known of 
the nature of the one element that which was before unknown of 
the nature of the other. But although we are thus necessarily re- 
stricted to observation of the sequences of the phaenomena, and 
of the conditions under which they occur and are modified, yet we 
cannot suppose that they are without some fundamental cause, 
however it may be hidden from us. " Falso asseritur sensum 
humanum esse mensuram rerum ; quin contra omnes percep- 
tiones, tam senses, quam mentis, sunt ex analogic, hominis, non 
ex analogia universit." 

When physiological facts have been accumulated by observa- 
tion, extended through all living things, it is the object of the sci- 
ence to determine the general relations which subsist amongst 
them ; to ascertain what is common to these relations ; and thus, 
ascending constantly to more comprehensive generalizations, to 
arrive at that cause, least limited by conditions, which holds in- 
ferior causes in subordination. And this is all that any experi- 
mental science can pretend to. 

On the contrary, however, the first philosophy of nature was 
almost entirely deductive. The authors of it persuaded, as ra- 
tional creatures, that all parts of the creation are but portions of 
an harmonious whole — productions of the same intelligent first 
cause — were led to speculate on the nature of that cause, and 
thence deduced systems from assumed principles. The universal 
appeared to express itself hi particulars. It became the object of 
philosophy to begin with the essence of things, and from it to de- 
rive and explain all their phaenomena. Such a philosophy, deal- 
ing with abstractions, with primary essences of which the quali- 
ties and their relations were necessarilyhypothetical, could scarce- 
ly have any application to a particular creation — to the world as it 

• Miiller, Introductory Essay to his Vergleichende Physiologie des Gesicht- 
sinnes. 

t Novum Orgarmm, 41. 



REPORT ON ANIMAL PHYSIOLOGY. 97 

actually exists, however rigidly its conclusions might be de- 
duced. 

A different procedure was forced upon physicians : their very of- 
fice constrainedthem to observe the same vital phaenomenon under 
different circumstances, — to compare different phaenomena, — to 
separate what was common and essential from that which vyas 
merely contingent and partial. Thus was established a new prin- 
ciple of explanation, a principle little agreeing, perhaps, with 
that deduced in the former way. As observation and experiment 
extended the boundaries of this inductive knowledge of causes, it 
continually encroached more and more upon the limits of hypo- 
thetical belief. And the principles which were thus established, 
being founded in realities, were really the expression of the phae- 
nomena from which they were derived. It has been, however, by 
slow and gradual steps that men have become wilUng to abstain 
from assuming, as a privilege of the understanding, the power of 
creating that spontaneously which can only be supplied by the long 
and patient contemplation of nature. The two systems have been, 
more or less, in conflict from the earliest to the present times. 

Hippocrates was the first, whose writings have come down to 
us, who made experience the interpreter of nature. He collected 
a rich treasure of observations, the accumulated result of his own 
labours and of those of his family during 300 years. They relate 
to the investigation of the effect of changes in the external con- 
ditions of life, — viz. air, warmth, moisture, food, — upon its phae- 
nomena in man. On the other hand, his ideas of matter were 
founded on the speculations of the Pythagorean school. He taught 
that the four elements, variously combined, produced the four 
cardinal humours, and these again the different organs of the body. 
A vital principle, or principle of motion, i^va-is, or ivofiLmv, was. 
superadded, depending upon innate heat, its manifestations 
being excited by external things, &c. We see not how the theory 
has its application. Though Hippocrates did not, with many of 
the ancients, suppose that the vital phaenomena may be explained 
by the properties of matter alone, but referred them to a prin- 
ciple of life acting under external conditions ; yet his assumed; 
properties of living matter are nowhere verified, nor the altera-, 
tions asserted to be produced in such properties by alterations in. 
the conditions of life in any way established. 

Aristotle far excelled his predecessors in extending natural sci- 
ence by observation, and may be considered as the founder of com- 
parative anatomy and zoology. His anatomical descriptions of 
the elephant and the whale have merited the eulogy of Camper., 
Those portions of his works in which he records his observations 
of the mental faculties of animals, and compares them with those 

1834. H 



98 FOL'KTH REPORT— 1834. 

of man, are particularly valuable. These faculties he connected 
essentially with the organic body in which they are observed, and 
referred them to a principle entirely different from what was then 
considered elementarymatter, which was the cause of all the phae- 
nomena observed in living bodies, and which controlled the quali- 
ties of matter to its own destined purposes. On observing the 
modes in which this principle manifests itself, he distinguished 
them logically as faculties : the nutritive, the sensitive, the cogi- 
tative, the motive. He then reasons on these logical distinctions 
as if they were real independent existences ; and inquires whether 
they may not exist in different and in the same bodies as such. 
His conclusion is, that three of these faculties are faculties of one 
and the same real existence, wherever they are observed ; but that 
the fourth, the cogitative faculty, or rational soul, has a real and 
independent existence. Thus he defined living bodies to be those 
which contain within themselves the cause of their own motion. 
But, far from supposing, as others have done, that this cause of 
motion can move itself, he expressly states that the fundamental 
causes of its motions are to be found elsewhere — in a supreme 
animating principle, <^i;o-»j ; and asserted it to be the object of phi- 
losophy to ascertain them. These delegated powers, he contends, 
are four, — the material, the formal, the moving, the final causes. 
The imknown cause of volition and the mental faculties he di- 
stinguished as t\\eratio7ial soul; theunknown cause that produces 
and sustains the body, as the organic instrument of the former 
to effect its manifestations, he called the sentient soul*. Thus, 
primary matter (uAij TrpuiTYj, an abstraction,) is utterly devoid of 
properties ; it receives from ej'Soj all the shapes and powers 
which it possesses : and so are formed the various bodies observ- 
able in the universe with all their allotted qualities and energies. 

If we reflect on this theory of Aristotle, and divest it of its 
scholastic form, we shall find that its generalizations do not very 
materially differ from those which have, after strict observation 
in modern times, been presumed to be the most just, and are now 
the axioms of physiological science : viz. peculiar vital properties 
inherent in peculiar material textures : — a cause of living motions 
operating, by means of these textures, according to fixed laws : 
and phaenomena so remarkably distinguished as to lead to their 
(iivision into those of animal and of organic life, and indicative of 
powers directed to a pui'pose which, in the first instance, is the 
preservation of the body in which they are manifested. 

The Alexandrian school, founded by the Ptolemies, can scarcely 
be considered as having made an adequate scientific return. What 

• Barclay On Life and Organization. 



REPORT OX ANIMAL PHYSIOLOGY. 99 

was valuable in the doctrines which they had adopted from the 
philosophers of Greece and Ionia, became obscure and vitiated 
by the additions of sophists ; and experiment and anatomy, which 
had once been so highly cultivated by Erasistratus and Hero- 
philus, fell nearljMnto disuse. I pass over, therefore, the vaunted 
restoration of the Hippocratic method by Scrap ion, the pupil of 
Herophilus, in the empiric school which rejected reasoning al- 
together, and affected to rely upon experience. I pass over, also, 
the methodic school of Asclepiades, which attributed, after De- 
mocritus, all natural phasnomena to the fortuitous concourse of 
atoms, and the existence of bodies to the conjunction of these in 
a certain form, and their functions to the mechanical aggregation 
and separation of the same. Their doctrines have thrown no 
light on our science. Each of these schools, and others like them, 
had credit for a time ; because, as they arose, men hoped to re- 
pose in them, wearied with balancing theories which, being 
founded on no extensive induction, and few just analogies, were 
not unfrequently at the same time false generalizations of the 
scanty instances upon which they were raised, and therefore ne- 
cessarily contradictory. 

The school founded by Galen has a just claim to the title of 
eclectic, which had been assumed by another ; for its doctrines 
were a mixture of the philosophy of Plato, of the physics and 
logic of Aristotle, and of the practical knowledge of Hippocrates. 
He perceived the objection to Aristotle's theory, that it included 
under a generic term the organic functions of plants and animals, 
together with their inanifestations of sense and intelligence*. He 
therefore proposed another arrangement of the phaenomenaof life, 
which deserves to be recorded, in as much as it contains the germ 
of all those different classifications of the functions which have 
prevailed in modern times. It is founded on the essential differ- 
ence of the functions : first, that some are constantly necessary 
for the support of life, and can never be suspended ; secondly, 
that some ai'e accompanied by consciousness, and are subject to 
the will. The vital functions are those which cannot be inter- 
rupted without inducing death ; the animal, those which are 
perceived, and for the most part voluntary j the natural, those 
which proceed irresistibly, and without the consciousness of the 
individual. These logical abstractions gave rise, unfortunately, 
to the invention of corresponding imaginary principles as their 
cause. Galen considered the heart, the liver, the brain to be re- 
spectively the centres of these principles, — the occult powers dis- 
tributing their influences in proportion to the elementary qualities 
of those centres from which they emanated. He recognised, with 

• Thompson's Life of Cullen. 

h2 



100 FOURTH REPORT 1834. 

Aristotle, four elements ; tuid deduced, from the various propor- 
tions and mixtures of these, the elementary particles of the frame ; 
and secondary qualities, or cardinal humours founded on the 
greater or less prevalence of one or other of the elementary princi- 
ples, not greatly differing in this respect from Hippocrates. Ac- 
cording to Galen, Nature presides over the vegetative, and the 
soul over the voluntive faculties*. 

The theory of Galen prevailed through many successive cen- 
turies, its unestablished and mystical parts prevailing more or 
less over those which were founded on experience and reason, ac- 
cording to the degree of light and the character of the teachers 
during that long lapse of time so much disfigured by ignorance 
and barbarism. 

At length, in the seventeenth century, Harvey's great dis- 
covery of the circulation of the blood gave an importance to ana- 
tomical inquiry which the successive and valuable contributions 
it had hitherto received had failed to bestow ; whilst the dis- 
coveries of Hooke and of Boyle in pneumatic chemistry turned 
men's minds to study with increased ardour the minute details 
of every function, and to apply to the solution of the problem of 
life all those analogies which the advance of science in every di- 
rection so liberally afforded. Hence arose the chemical and the 
mathematical schools of physiology to eminence. The first in- 
cludes the names of Van Helmont, Sylvius, Willis, John Mayo, 
Croone, Helvetius. Its insufficiency was exposed byBoerhaave, 
Hoffmann, and Pitcairne, and in this country practically by Sy- 
denham. 

The mathematical school of physiology gained a better recep- 
tion. Its doctrines, recommended by the prevalence of the atomic 
theory of Descartes, gave the same direction to physiology and 
medicine with that in which science Avas principally advancing 
under the auspices of the Florentine Academy. The philosophy 
of Descartes appeared peculiarly applicable to such investiga- 
tions, since no reason apparently could be assigned which should 
render that law inapplicable to organic bodies which referred all 
changes in matter generally to the figure and motion of the ulti- 
mate particles of which they were composed f. Hence Ave find 
the followers of Descartes representing in their works, the mathe- 
matical forms of the ultimate particles, of which they supposed 
the various organs to be composed, as figures for the application 
of mathematical reasoning. The most distinguished disciple of 
this scliool was Borelli. He united to all the anatomical infor- 
mation of the day a depth of mathematical knowledge which 
enabled him, in appearance, to apply its reasonings and its results 

* Thompson's Life of Cnllen. t Ibid. 



REPORT ON ANIMAL PHYSIOLOGY. 101 

to explain the action of the organic machine. Thus, he submitted 
muscular motion to calculation on the principle of the lever ; ex- 
plained the action of the heart and the motion of the blood upon 
hydraulic principles ; and accounted for the secretions from the 
various diameters of the vessels. The proximate cause of mus- 
cular motion he asserted to be the rush of nervous fluid from the 
brain upon the muscular fibre. Bellini and Baglivi espoused the 
same theory, and extended its application by their writings ; but, 
as if internally aware of its insufficiency, and proving that they 
merely reposed in it as that which was least objectionable, they 
laboured to separate the theory from the practice of medicine. 
Thus Baglivi was in practice a follower of Hippocrates and of 
Sydenham. John Bernouilli was a celebrated disciple of this 
school. He considered the elementary geometry of the Italians 
insufficient in its application to the animal body, in as much as 
this represents neither line nor plane either in itself or in the ulti- 
mate particles into which it can be resolved. Hence he had re- 
course to the calculus lately invented by Newton and Leibnitz 
and the theory of curves. His theory of muscular motion gained 
great celebrity, as well as his application of the analysis to de- 
termine the decrement- of the body in consequence of the various 
transpirations and secretions. Another branch of the mathemati- 
cal school was founded on the Newtonian theory of attraction, 
and had for its supporters in this country Keill, the Robinsons, 
Wintringham, and Meade. 

These two schools, as may be well supposed, did not add very 
much directly to the science as a whole. But they prepared the 
way. each advancing it according to its own partial views. The 
intimate structure of parts and their connexions were sedulously 
ascertained by dissection, by the microscope, by chemical ana- 
lysis, in order to ascertain the data upon which chemical or mathe- 
matical constructions were to be founded. It is not unreasonable 
to attribute to the hypothesis of Willis and of Vieussens, which 
ascribed the cause of all the sympathies so remarkable in the 
human body to the physical connexion of parts by means of 
nerves, that great perfection which the anatomy of the nervous 
system attained in their hands. 

The followers of the chemical and mathematical schools either 
overlooked tfie necessity of having recourse to a vital cause for 
the operations they attempted to explain, or they had recourse to 
an animating principle as presiding over them. Hence arose what 
has been termed the dynamic school of phjsiology. In the sy- 
stem of Stahl the soul not only produces and forms the body, but 
maintains it in the performance of every voluntary and involun- 
tary act. Those motions, even, which he allowed to exist exclu- 



102 FOURTH REPORT — 1834. 

sive of muscular motion, wliich exemplify themselves by tension 
and relaxation of parts,ancl which he called tonic motions, — those, 
also, he considered as effects of the soul's power. He rejected 
the laws of physics or of chemistry, and the discoveries of ana- 
tomy, as throwing the least light upon the fundamental processes 
by which the corporeal manifestations are effected. He considered 
that the soul has no seat in any particular part, but that it is co- 
extensive with the body itself; that it perceives in the organs of 
sense, and operates in the muscles, independently of any con- 
nexion with the brain*. Had not Stahl failed to distinguish be- 
tween the manifestations of his vital principle, according as it ex- 
emplifies itself by means of those organs which it has formed, — 
had he not described it as the ' rational soul', — his system, con- 
firmed by subsequent observation as to the general principle 
upon which it would then have been founded, — that of vital pro- 
perties inherent in the several tissues, — could scarcely have been 
justly censured. It was received in a modified form by many of 
those whom T have instanced (from the mode in which they ap- 
plied it,) as disciples of other schools. In England it was de- 
fended by Bryan Robinson, and by Meade, and gained much ce- 
lebrity from the writings of Hartley, who assumed its principle 
to explain the association of ideas. It was received also, in a 
modified shape, by Sauvages in France, by Bonnet in Switzer- 
land, by Whytt in Edinburgh. The latter taught that the soul 
is the primary cause of all the motions observable in the body. 
These he divided into three kinds : natural motions, depending 
upon a gentle and equable supply of nervous influence (of which 
the tension of the sphincters and the general tone of parts are 
instances), and proceeding without the interference of the will or 
of stimuli ; involuntary, excitable by stimuli affecting the 
nerves (and he attempts to show that in all motions produced by 
stimuli, whether in the muscles of the limbs or of the viscera, 
the soul acts of necessity) ; voluntary motions, under the im- 
mediate influence of the soulf. James Johnstone greatly modi- 
fied this theory in England, but his opinions were not received 
by his own countrymen. He also assumed a vital principle to 
effect that which mechanical or chemical powers were obviously 
iniabie to perform. He placed its principal seat in the brain, 
thence to be propagated by the nerves, and pointed out an office 
of the ganglia, (which, indeed, had been hinted at by Winslow 
and Le Cat,) viz., that those organs which are supplied with 
nerves from the ganglia, performing their motions independently 
of the will, the ganglia are to "be considered as so many subsidiary 

• Thompson, op. cit. 

\ Whytt Oil the Fiial and Inooluntanj Motions, passim. 



REPORT ON ANIAIAL PIIYSIOI.O(- Y. 103 

brains, which continually supply the parts to which they distri- 
bute their nerves with new impulses and fresh activity, without 
immediate dependence upon the brain ; and that hence it is that 
the vital functions are continued when the influence of the brain 
is suspended, as in sleep or in paralysis. These opinions of 
Johnstone respecting the ganglia were the foundation of that 
hypothesis respecting the nerves of organic life which represents 
them as a system distinct from the cerebral system, and which, 
more fully developed by Bichat and by Reil, was pretty gene- 
rally received from them by physiologists, until it was shaken by 
the discoveries of Le Gallois and Wilson Philip. 

In this way the physical and dynamic theories came to be vari- 
ously combined. Their union gained its greatest perfection under 
Hoftmann and under Boerhaave, who insisted upon the primary 
influence of the nervous system in modifying and regulating all 
the organic functions, whether performed chemically or mechani- 
cally. Thus nervous power came to be considered as nearly 
equivalent to the anima of Stahl. But Stahl's system was not 
improved by the change; for nervous power, a manifestation of 
the vital energy by means of the peculiar matter of the nervous 
system which that energy has produced, and of which it is but a 
partial effect, cannot properly represent the entire cause ; and it 
affords no explanation of the organic life of plants. For the vital 
principle appears to manifest its several activities by means of 
the organs which it has produced : and Stahl's error seems to 
have been that he connected its vegetative processes, which are 
defined and necessitated, with those of consciousness and intel- 
ligence, which are free, and are developed only with the develop- 
ment of the brain*. 

The age of Haller, at which we have at length arrived, is the 
epoch from which modern physiology takes its date. The great 
object which that eminent person endeavoured to achieve, was 
to discover, experimentally, the conditions and the laws which 
govern those vital phsenomena which the assimiption neither of 
mechanical nor of chemical forces had been able to explain, and 
thus to I'ender physiology as certain as other physical sciences. 
For this purpose he excluded those metaphysical subtleties by 
which his predecessors had so frequently veiled ignorance ; ex- 
cluded also mathematical and chemical science in all cases in 
which it was impossible to ascertain the elements upon which 
their application could be founded. He was \villing, as he liim- 
self says, to confess himself ignorant of the manner in which the 
soul and body are united, and was content to proceed no further 
than those discoverable laws which the Creator has himself pre- 

* Miillcv, Physiologie. 



104 FOURTH REPORT — 1834. 

scribed, without inventing others unwarranted by experience. 
On this principle he instituted innumerable experiments to dis- 
cover and illustrate the properties of the vital powers. He proved 
the existence of a property in muscle, to which he restricted the 
term irrituhiliti/, which is only called into action by means of 
stimuli, which affects a much greater vivacity of motion than 
mere elasticity (a property of dead matter), the motions also con- 
sisting in alternate oscillations, with contraction, swelling, and 
wrinkling of the fibre, followed by extension, relaxation, and 
elongation of the same. He further attributed to the muscles a 
nervous power, distributed to them from the brain by means of 
the nerves, as a necessary condition of their irritability *, but 
which entirely diJTers from it. He concluded from his experi- 
ments, as detailed in his earlier works, that the following parts 
are destitute of irritability and nervous power : periosteum, peri- 
toneum, pleura, ligament, tendon, articular capsules, the cornea, 
parenchyma of the viscera. In these tissues he admitted a force 
analogous to elasticity, inherent in their organic texture, which 
solicits them to contract slowly M'hen divided, when exposed to 
cold, &c., and which only abandons them when entirely disorgan- 
ized. He proved that sensibility is inherent in the nerves, but 
that they are destitute of irritability. He denied that irritability 
could be imparted to the muscles by the nerves, because, seeing 
that a nerve, un being stimulated, may excite motion in the muscle 
to which it passes, but offers not the slightest motion itself, it is 
impossible to suppose they shovild be the source of that to others 
which they never possessed themselves ; and, more particularly, 
because he perceived that the excitement of muscles through 
nerves is a pheenomenon not true of all, but only of certain, 
muscles. 

He proved, universallj^, that irritability resides in all parts 
that have muscular fibre ; that this power differs in intensity 
and permanence in various parts ; that these qualities are most 
observable in the heart, more in the left ventricle than the 
right ; that next in order come the intestines, the diaphragm, 
the voluntary muscles. From reiterated experiments he concluded 
that the heart and other involuntary muscles are not excited to 
contract by stimulating the nerves with which they are supplied, 
but that they require specific stimuli ; thus, that the blood is to 
the heart what the Avill is to the voluntary muscles. 

• Si insita eonim organonnn (cordis, intestiiiorum, &c.) vis est, cur accipiunt 
nervos? li, nisi voluntatis imperia atferunt, quid aguiit aliud ? Primo sensum 
aflerunt, qui absque nervis nullus est. Adferunt etiam ex cerebro efficaeia im- 
peria non voluntatis, sed legum, corpori aniniato scriptannn, quae volunt, ad 
certos stiimilos ccrtos nasci motus. — Elem. PI'ys., toni. iv. p. 516. 



repout on animal physiology. 105 

In this way Haller restricted the vital powers to two, — sensi- 
bility and irritability ; the one exhibited in the brain and nerves, 
the other in muscular fibre. His doctrine was vehemently op- 
posed by Whytt, De Haen, Verschuir; and strenuously de- 
fended by himself, by Bonnet, and by Fontana. It was seen that 
many parts in the animal body to which neither irritability nor 
sensibility, in Haller's sense, could be extended, were not the 
less alive. Thus during the numerous controversies which arose, 
errors on each side were detected ; materials for more extended 
views were accumulated ; experiments were infinitely multiplied 
and eagerly criticised ; the excitability of various tissues, to which 
Haller had denied that quality, because he had not called it into 
action by an appropriate stimulus, was established on the one 
hand, and on the other the mistake of confounding nervous in- 
fluence with sensibility was made apparent. Thus the more pro- 
bable it became that irritability and innervation are separate 
powers, so did it follow the more necessarily that every different 
part should have its own excitability and its own degree of ner- 
vous power, and hence its own peculiar mode of life, — an opi- 
nion announced by Bordeu, Barthez, Blumenbach *. Indepen- 
dently of these expressions of vital energy in the various tissues, 
these physiologists admitted a fundamental power, which they 
termed vitality, or vis viice, of which the different degrees of 
excitability and sensibility were considered merely as modes, 
according to the organs in which the vital energy operated. But 
the analogies thus assumed between the ph«enomena were not 
established by any proof; the modifications of the original power 
were not accounted for ; and this theory, apparently philosophic, 
has no firm foundation when its partisans would represent vitality, 
or oxygen, or galvanism, as a proximate cause of all the phaeno- 
mena, residing in living matter as gravity does in deadf. 

It might have been foreseen that this analytical mode of treat- 
ing the living organism, — this isolation of powers which had 

• They liad all been anticipated by F. Glisson, who was President of the 
College of Physicians in 1677; but the opinions of a man who was a century in 
advance of the age in which he lived, and which were obscured by metaphysical 
subtleties and scholastic language, had no great influence, upon those who were 
engaged with mathematical or chemical theories of life. He proved the exist- 
ence of a peculiar quality of living bodies, which he first named Irritability; 
distinguished between perception and sensation, and adduced as instances of 
perception without sensation, the contraction under stimulation of the heart and 
muscles when separated from the body ; insisted that it was only through this 
natural perception and sensation, and not immediately, that the animal appetite 
on the one hand, and the mind on the other, puts the innate irritability in action, 
and so produces all motions, which are either natural and vital, or sensitive. 

t Thompson's Life of Ciillen. 



106 POURTH REPORT — 1834. 

been intended by their concurrent acts to produce the phaeno- 
mena of life, could scarcely lead to the detection of that control- 
ing cause whicii forced the whole to conspire to a common pur- 
pose. It became necessary, therefore, to consider the subject 
imder a different aspect ; to contemplate living bodies in their 
approach towards the possession of those powers which they ex- 
hibit when their organs are formed. The means for this have 
been supplied by the labours, extended through a long lapse of 
time, of Harvey, of Malpighi, of the Hunters, of G. F. Wolff, of 
Prevost and Dumas, of Meckel, of Tiedemann, of Serres, of G. 
de St. Ililaire, of Von Baer. The earliest examinations that 
can be made of plants or of animals present them as consisting 
of a minute globule of fluid, or a minute disc of slightly albumi- 
nous matter, i. e. under aspects not distinguishable in different 
future genera or species, as to properties or forms of their matter, 
by any tests which we possess. In the near neighbourhood of 
the disc is placed, in animals, a quantity of nutritive substance, 
by means of which it is destined to work. The effects, when 
produced, are definite for each species ; but none occur except 
under certain conditions. These conditions are, a due degree of 
moisture, of air, and of warmth. When they are supplied, the 
disc is capable of being affected by the matter in its neighbour- 
hood. It is excited, and it reacts. The consequence of the re- 
action is a gradual expansion of the disc to surround the nutrient 
matter ; a separation of it into different superposed portions, 
which come into view; and a gradual appropriation of the nutrient 
matter. Upon the external portion of the disc, the first trace of 
the nervous system is observed ; upon the internal portion, that 
of the intestinal canal ; intermediate betw^een them, that of the 
vascular system. Though at first simple, these objects have still 
a certain magnitude, and the later more complex formations are 
seen to arise from them as if by vegetation. " The first trace of 
the nervous system is not merely that of the spinal cord or of 
the ganglionic string, but is the potential whole of that system, 
of the brain and all its appendages. The first trace of the ab- 
dominal canal is not merely the rudiment of that canal, but of 
the w^hole glandular apparatus also, which may be seen gradually 
to spring from it*." And thus is the observed process of de- 
velopment altogether contradictory of the theory of Haller and 
of Bonnet, which represents each organ as absolutely existing in 
the germ, though in a miniature form. That the power which 
effects these changes, and thus controls the disposition of or- 
ganic molecules, resides in the disc, is ascertained from the facts, 

* Mullcr's PlnjFAologij, vol. i. p. 20 ct ^q. 



REPORT ON ANIMAL PHYSIOLOGY. 107 

that ova belonging to species the most different, are all develop- 
ed, according to their kinds, under similar external conditions, 
and that ova of the same species are true to their kinds under 
conditions which are not absolutely the same for any two indi- 
viduals. If we call this power vitality with modern writers, or 
the anima with Stahl, these words can teach us nothing physio- 
logically, unless we ascertain the law by which it operates : how- 
ever we may see that the final cause of its operation is plainly 
in every case the production of those numerous bodies, definite 
with respect to families, genera, and species, which it develops 
for its own manifestations in each. Our eyes inform us that 
these bodies arise by means of the assimilative process, and 
that the original power exhibits its faculties by means of the 
organs which it has produced through this process. Our idea 
then of the vital power is this,— that it is connected with the 
matter of the germ in the act of its formation, and resides in it 
as the potential whole, or sufficient cause, of the entire future 
organism ; that in consequence of the excitability of the or- 
ganic matter of the germ, imparted to it in the same act of its 
formation, the expansion of the germ into portions or members 
occurs by the visible process of assimilation or nutrition, each 
portion thus acquiring its own excitability and its own reactive 
energy, which are but partial manifestations of the original 
power ', and that in proportion as each part is developed, new 
internal conditions are introduced, in consequence of the new 
formation, which affect all that previously existed, by modifying 
the assimilative process in all. The phases of this process are 
strictly defined for each species, and the subsidiary means neces- 
sary for the purposed effect — as in the various forms of the re- 
spiratory organ in the foetal state of the same individual to mode- 
rate the condition of external air — are amongst the most beau- 
tiful instances of provision for a definite end. 

This formative act, this process of assimilation or nutrition, 
which is thus performed by animals and plants, and lias a rela- 
tion not only to the present, but the future also, appears to be 
the determination of a power acting according to Reason ; and 
hence it must have been that Stahl referred it to the rational soul. 
But, seeing that reason cannot exist without consciousness, — 
a faculty which manifests itself only by means of the brain, a 
late product of this very power by the act of assimilatioji, — seeing 
also that the effect may be modified, within limits, (as in cases 
of monstrosity,) when the conditions are altered, we rather con- 
clude with Harvey that it proceeds from a power acting accord- 
ing to fixed laws. " Vegetativae operationes potius videntur 



108 FOURTH REPORT — 1834. 

arte, electione et providentiS institui, quam animse rationalis 
mentisve actiones ; idque etiam in homine perfectissimo." 

A peculiar matter is necessary for the manifestation of vital 
phsenomena : this matter is called organic. It is not the cause 
of life, but rather is its act; a production by means of the assi- 
milative process, for the exemplification of the allotted faculties. 
The faculty is imperfectly manifested if the organ be imper- 
fectly formed : the organ and its energy both vary with varia- 
tions in the nutritive process*. 

Hence those subordinate expressions of vital force, called tie?'- 
voits power, force of secretion, tkc, cannot be considered as di- 
stinct and independent powers. They are produced, or evidenced, 
with their organs, by the force of assimilation, and are main- 
tained by the same. They depend upon it for their manifesta- 
tion and their due support f. 

Vital power imparted to organic matter (which is itself the 
product of the living power of the parents), and exemplifying 
its faculties by means of the organs which it has developed 
through the force of nutrition, seems to be the last step to which 
observation and induction has hitherto led us. The induction is 
verified by observation. If the assimilative process be altered in 
any organ, the expression of excitability and of vital reaction 
peculiar to that organ is altered in the same degree. 

There are then in living bodies as many species of excitability 
and as many modes of reaction as there are tissues. Every one 
of these has its own mode of both, which is called into action 
by its own appropriate stimuli. " Whatever these stimuli may 
be, — whether external, as air, light, warmth, food ; or internal 
stimuli, the blood, nervous influence, the secreted humours, — 
each organ reacts in its own peculiar manner ; a manner which 
supposes a peculiar organic power imparted to it in the act of 
its formation by the process of nutrition, and sustained by the 
same J." " The stimulus maybe that of a chemical, or mechani- 
cal, or organic substance ; the reaction, however, is always vital, 
and indicates the existence of an organic force, of which it is the 
effect. The physical properties of the one are in some sort in a 
constant conflict with the vital properties of the other, and living 
bodies only preserve their character of life so long as they are 
able to resist the physical impression. When it is said that or- 
ganic movements are occasioned by incitations, we do not admit 

• Tiedeniann, Pliysiulogie. f Tiedemann. 

J Tiedemann, Pliysiulogie, vol. ii. In this excellent work, worthy of the 
great name of its author, the theory, of which I have given this hasty notice, 
is fully developed. 



REPORT ON ANIMAL PHYSIOLOGY. 109 

that they are the immediate effects of the mechanical oi* chemical 
impressions, but assert that they are the ejRFects of powers which 
the external impression, be it mechanical or be it chemical, has 
thus solicited to act." 

Of these excitants some are necessary conditions of life, 
and are therefore called vital stimuli. Plants cannot live any 
considerable time without air, water, warmth, and light ; nor 
animals without the first three, and they become rickety when 
deprived of the last. These being indispensable for the due 
nutrition of parts, are necessary for the sustentation of those 
powers which are developed with the parts by the act of nutri- 
tion. But all animals are not dependent upon each of these 
excitants in an equal degree. Thus, the new-born of warm- 
blooded animals resist more easily the deprivation of air than of 
warmth. They are drowned more readily in cold water than in 
warm, within certain limits of warmth. They live longest 
under water between 20 — 30° R., and if the heat be above or 
below these limits die sooner. In general, the lower the place 
of the animal in the zoological scale, the longer can it bear to 
be deprived of these stimuli. Amphibia live from ten to thirty 
hours, in distilled water, under the air-pump ; and frogs, whose 
lungs have been extirpated, may survive thirty hours. 

With respect to the stimulus of food the same general rule 
prevails ; the intervals of supply may be greater without destroy- 
ing life in animals, according as their organization is less com- 
plicated, and their powers more limited. Thus, tortoises and 
sei'pents may be deprived of food for months, and many mollusca 
for yet longer periods. 

Some also of the internal conditions of life may, in the lower 
animals and in the imperfect states of the higher, be suppressed 
or greatly altered, and yet life be supported for a longer or a 
shorter period. The experiments of Legallois and others lead 
to the conclusion, that this period varies inversely as the per- 
fection of the organ whose action is suppressed. The Batrachia 
are found to live for many hours without the heart ; a tortoise, 
whose brain was i-emoved by Redi, lived after the operation for 
several months ; in new-born rabbits, if the heart be extirpated, 
sensibility persists for about fourteen minutes ; when they are 
fifteen days old, for only two and a half minutes ; thirty days old, 
one minute* ; and the young of man may, at the time of birth, 
be revived when the heart's action has ceased for a period after 
which, in the more adult state, it could not be restored. 

In the more perfect forms of life there is a necessary depend- 
ence of the whole organism upon each of its parts, and of the 

* Essai, Legallois, p. 142. 



110 FOURTH REPORT — 1834. 

parts upon the whole. Thus, for instance, respiration is neces- 
sary to the heart's action, the heart's action to the respiratory 
process ; neither can proceed after destruction of the nervous 
system, and this requires for the production of its energy a due 
supply of aerated blood. But this mutual relation of all and 
each, alternately as cause and effect, has been improperly as- 
sumed as a distinctive character of life. " The same is true of 
an automaton, in which the moving power is part of the thing 
moved : the same is also true of the planetary system as far as 
we are acquainted with it*." 

Thus does the vital power, manifesting itself in the assimila- 
tive process, occasion all the forms of life upon the earth. 
Each living thing, according to the nature of that original power 
(of which we can know nothing but by its effects), requires its 
own modifications of the common conditions of life, and presents 
an organization (upon which classification is based,) adapted to 
the region and the element in which it is destined to exist. Of 
these creatures, all that are not microscopic are observed to 
proceed from parents similar in structure to themselves by modes 
of propagation peculiar to the kind ; so that no one species, 
under any modification of external condition, has ever been 
known to assume the character or form which is distinctive of 
another. The consideration of the stratification of the earth 
assures us that all the families, genera, and species did not 
commence their existence at one and the same epoch. On the 
contrary, in the older strata are buried the remains of the sim- 
pler forms of life alone ; in the more recent those of more com- 
plex organization ; whilst the remains of the most perfect and 
of man have not been discovered in the most recent stratum. 
Of the remains which have thus been brought to light, some 
belong to species and genera which still exist, others to such as 
are lost. Some physiologists, taking their stand upon the 
general fact of this successive advance towards perfection of 
development in correspondence with the successive changes of 
the globe, have concluded that all the various modifications 
of life may be but successive metamorphoses of the first most 
simple form. 

The undoubted fact that existing species have been perpe- 
tuated unchanged for several thousands of years, would have 
rendered such an opinion in the highest degree impi-obable, but 
for the observations relative to the apparently spontaneous pro- 
duction of animals and of plants from ©rganic matter in solution 
— the apparent changes of species fi-om simpler to more complex 
vmder favourable external circumstances — and the interchange of 

• Treviramis, Erscheimtngen vnd Gesetxe des oryanhchen Lehens. 



REPORT OX ANIMAL PHySIOI.OGY. Ill 

animal and vegetable form. If the facts were really thus, then 
might the objection to the hypothesis of metamorphosis founded 
on the permanence of existing forms be encountered. It might 
be averred that, notwithstanding our ignorance of the means, 
the necessary conditions for such successive changes may have 
been supplied in the earlier periods of the world, at epochs so 
far removed, that the few thousands of years which have passed 
away since the appearance of man upon the globe bear no pro- 
portion to their immense distance, and only show that the rate 
according to which the conditions of change are produced is a 
very slow one. 

Let us see to what conclusion the latest obsei'vations on In- 
fusoria are tending. 

It is well known that the experiments of Redi and of Vallis- 
nieri were considered to have refuted the notions of the ancients 
concerning spontaneous generation, until those of Tuberville 
Needham, of O. F. Miiller and of Wrisberg, performed with the 
most considerate exclusion (if that be possible) of circumstances 
likely to throw a doubt upon the result, revived them. Miiller, 
repeating the experiments of Needham, concludes, that animal 
and vegetable matter, by solution in water, is reduced to minute 
membranous shreds, upon which, in a short time, are seen micro- 
scopic globular points. These enter into a tremulous motion, 
which gradually becomes more apparent ; the globules are de- 
tached, and Infusoria are produced from them. These first Infu- 
soria, he says, abound in all fluids, and are not to be confounded, 
as is usuallj^ done, with other Infusoria, being, on the contrary, 
elements which are the component molecules of all animals and 
plants. 

The conclusions Spallanzani drew from his experiments were 
opposed to those of the above-named naturalists. He found the 
structure of the infusory animals to vary with the nature of the 
infusion, and explained their appearance upon the supposition 
that ova had been introduced with the animal matter, or had 
been suspended in the air, whose admission, at least in some 
degree, is necessary for Ihe success of the experiment. 

The experiments of Priestley, of Ingenhouz, of Treviranus, 
appeared to prove that the green matter of Priestley, produced 
in organic infusions on exposure to light, is first a mass of ani- 
malcules ; then is resolved into green globules, which concrete 
into confervse ; then, after the solution of these, again becomes 
infusory animals and vegetables of a larger form. The organic 
particles appeared indestructible, and conmion to each form of 
life, passing from one to the other, and supplying the substance 



112 FOURTH REPORT 1834. 

from which each is formed, under the necessary external con- 
ditions*. 

The recent experiments and observations of Ehrenberg have, 
however, tended to increase our doubts concerning the validity 
of these conclusions. He has not succeeded, as Spallanzani con- 
ceived he did, in producing definite forms of animalcules from 
definite infusions. On the contrary, he has found the forms to 
vary under circumstances the most similar. He has explained, 
however, how it is that Spallanzani might be mistaken in his 
conclusion. The species pass through many gradations of form 
in their progress to maturity, each of which forms may have 
been readily mistaken for a distinct species. These are not so 
very numerous ; but the rate at which the individuals are multi- 
plied is altogether extraordinary. For instance, the Hydatina 
*ew^a, which was observedfor eighteen days, is capable of a fourfold 
increase in twenty-four hours, which may give more than a million 
of individuals from a single ancestor in ten days, and on the most 
moderate computation may give nearly seventeen millions in 
twenty-four days. According to Ehrenberg, infusories exist in 
all waters, (except rain and dew, in which he could not discover 
them,) and in some parts of plants, though here, probably, only 
in a diseased state of the plant. Further, he has succeeded in 
detecting a complex organization in those animalcules lately 
considei'ed of so simple a form. Even in the Monas, a creature 
not more than the twenty-thousandth part of an inch in diame- 
ter, the stomach is found to be of a compound structure, and 
its motions are effected by cilia. In others he observed ova, 
and propagation by means of them. If then, in the infusions 
of Treviranus and Needham, no animalcules were produced 
when the vessel was hermetically sealed, and the necessary 
quantity of air exposed to a high heat — if they were produced 
when fresh air was introduced after boiling — if the animalcules 
have been shown to be capable of producing ova, which, indeed, 
was jiever denied ; it seems more reasonable to suppose, that 
those observers who did not succeed in discovering the complex 
structure of the creature so extremely minute, might fail also 
in discovering the first ova, though they really existed in the 
infusion, than that the animal should arise spontaneously. 
Ehrenberg has not succeeded in detecting these first ova. No 
very violent improbability is included in the supposition that 
bodies so infinitely small have been conveyed by the air, like the 

• Vide a full critique of the experiments of previous authors, and an account 
of his own, in Treviranus, Biolor/ie, ii. 267, 403. 



REPORT ON AXIMA-L PHYSIOiOGY. 1 13 

motes visible in the sunbeam. We now know how numerous 
they must be*. 

In the case of parasitical worms, (the Distoma hepaticum, 
for instance,) the ova are too large to be either conveyed by the 
air, or to be absorbed by vessels from the food and carried to their 
nidus in the viscera. Such worms have even been fovind in the 
viscera of embryos. If we must have recourse to hypothesis to 
account for the origin of these, let our hypothesis be supported 
by analogy. It is not impossible that a portion of an ovum may 
be able, as has been supposed by many, to germinate and pro- 
duce a new individual, as a portion of a Polypus becomes a di- 
stinct and perfect animal of its kindf. 

The opinion of the gradual production of all creatures from 
an original simple form has received confirmation, in the minds 
of many, from their having observed that the embryo of the 
highest forms of life passes by gradations througli those which 
are permanent in inferior animals. They have, however, sup- 
posed this resemblance to be more complete than observation 
allows us to believe it to be. We have seen that the first ob- 
served embryo of all animals is extremely simple. With respect 
to this simplicity, which but implies the imperfection of our tests, 
a comparison may be allowed between embryos of a higher 
order and the simplest forms of life, when the animal presents 
no separation of distinct organs. As the development of the 

* " Although Dr. Ehrenberg, in refuting the notion of the extreme sim- 
plicity of these animals, has overthrown one great ai'gument in favour of their 
spontaneous origin, yet he has offered no explanation of their production in 
infusions which have been subjected to a heat sufficient to destroy any parent 
animals, or even ova, supposed to be present. In these cases, as is well known, 
the adversaries of the theory ascribe the origin of Infusoria to ova conveyed by 
the air ; an assumption which the supporters of the doctrine regard as highly 
improbable, and which, if admitted as true, they consider inadequate to explain 
the production of Infusoria in all the conditions under which it is reported to 
have taken place by observers worthy of credit. It is true that Dr. Ehrenberg 
never witnessed the spontaneous origin of Infusoria ; but before denying the pos- 
sibility of its occui'rence, and discarding the theory of spontaneous generation 
as unnecessary to account for the facts, it was incumbent on him to have sub- 
jected anew to a rigid examination the observations of those who have arrived 
at an opposite conclusion from himself, and either expose the fallacy of their 
experiments, or show how they were to be explained on a different view from 
that adopted by their authors. It is the more to be regretted that he has not 
favoured us with such a critical examination, as, from his extensive knowledge 
of the different species of the animals in question, his intimate acquaintance with 
their mode of life, and his superior methods of observation, he is singularly well 
fitted for the task." — Hr. Sharpey. Account of Professor Ehrenberg' s Researches 
on the Infusoria: Edinb. New Phil. Journal, Oct. 1833. 

t Entozoa have been found in embryos and in the eggs of birds : so also 
have pins and small pieces of flint. — Tiedemann's Anat. vnd Nat. Gesck. der 
Vogel, b. ii. s. 128. quoted by Treviranus. 
1834. I 



114 FOURTH REPORT — 1834. 

embryo advances, we observe some organs superadded, though 
still in a very simple form ; so that here also a certain resem- 
blance subsists between the embryo in this second stage and 
animals a little more complex. As we continue to observe 
the embryo of the higher family, we see organs come into 
view, some of which are meant only for a transitory purpose 
and disappear ; some which have no pvu-pose during fcetal 
life, but ai'e meant for an ulterior use. Here the resemblance 
between the eml)ryo of the higher form, and the animal of the 
lower form with which we may most favoiu'ably compare it, is 
found to be less close. We find that the animal has organs suited 
to the activities with which it is endowed, which are not to be 
found in the embryo. Even if the two exist under similar ex- 
ternal conditions of life, the organs adapted to these conditions 
are not the same in both. To instance these several state- 
ments : when no organs can be observed in the primitive streak 
of the embryo, it resembles the zoophyte, in which nutrition 
is performed by imbibition ; but we observe in addition that 
the primitive streak extends into a membrane which becomes 
the vascular area. If we attempt the comparison when the 
body resembles a worm, in as much as it is cylindrical and has 
no limbs for motion, the resemblance scarcely extends further. 
The worm has rings and contractile bands for its motions, 
whilst the embryo has neither ; and the simple tube, which re- 
presents the heart in both, gives indications of a higher organiza- 
tion in the embryo. If the worm resides in an aqueous medium 
like the embryo, it respires by means of gills, the embryo by a 
production of its abdominal tube — the umbilical vesicle (?), or 
the allantois, or the placenta. At another period remarkable 
apertures are observed, at regular distances, towards the head, 
between the imperfectly closed abdominal laminae in the higher 
embryos, in which they resemble some of the cartilaginous fishes. 
But with the former the vessels that follow the arches do not di- 
vide for any respiratory purpose, whilst in the latter they are the 
respiratory vessels of the gills. If, in a still further stage of ad- 
vancement, we compare the higher embryo with the turtle, we find 
that in both the double heart is rendered virtually single, but for 
very different purposes, and here the similarity is at an end*. 

In these analogies, therefore, we look in vain for that precision 
which can alone support the inference that has been deduced. 
Far rather do we infer gradations of original power, which 
manifest their different energies at different epochs, under ex- 
ternal conditions which may be similar according to a general 
plan, the expression of each that is superadded modifying that 
of all which preceded, and concurring with theirs to develop 

* Weber in Hildebrandt's Anatomy, vol. i. p. 125. 



REPORT ON ANIMAL PHYSIOLOGY. 115 

others which may be still latent. In the lower creature, a par- 
ticular organ or set of organs attain their purpose and are com- 
plete ; in the imperfect state of the higher, the corresponding 
organs may in general resemble them, and may even perform a 
similar office, yet still they are seen to be more than sufficient for 
this lower purpose : in the midst even of this general similarity, 
the indication of a higher destiny, yet unattained, is apparent. 

We are disposed to conclude, then, generally, that all the 
families, genera, and species of animated things were originally 
created in such forms as we observe them in at present ; and 
that they continue to produce the organs which are the instru- 
ments and the expression of their several powers by the process 
of assimilation as a proxiinate cause. Amongst these different 
organs the brain is peculiarly distinguished. We are sensible 
in ourselves of ideas, of emotions, of desires — of powers which 
present themselves to us as pure energies, without any interme- 
dium : we have self-consciousness. These activities are excited 
by our own will; we cannot contemplate them as observable 
processes in any other person. On the contrary, the energies 
of all the other organs are totally independent of our will ; we 
are aware of them only as their effects are matters of obser- 
vation by means of our outward senses, and we observe them 
better in other individuals than in ourselves. Life, thus pre- 
senting such remarkable differences in these two respects, has 
been distinguished as two forms. And this distinction is not 
merely logical, for in the vegetable kingdom we have an instance 
in which the one form of life exists totally separate from the other. 
But we find that even the higher form, the intellectual or purely 
animal life, requires for its manifestation a body*. In living 
creatures the two factors, though logically separable, exist as 
one reality. The two spheres approach and intermingle in va- 
rious degrees in the different families of the earth, the animal 
powers depending upon the vegetative for the formation of their 
material organ. The life of the lowest animal scarcely appears 
to differ from that of the vegetable. " From these animals, 
which obtain food without any act of volition, we come to those 
which can only obtain it by such an act, but who still, without 
any act of this kind, obtain the influence of air, yet more imme- 
diately necessary to their existence. We arrive at length at the 
most perfect class, which can neither obtain food nor air except 
by an act of the sensorium. In them the sensorial power is as 
necessary for the inhalation of air, as the ingestion of foodf." 

* Burdach, vol. iv. p. ."3. Burdach notices tlie impropriety of calling, with 
Bichat, the animal life ' vie externe,' and the organic ' interne.' 
t Wilson Philip, Phil. Tram. 1834. 



116 FOURTH REPORT 1834. 

And there enters, on the other hand, even into those organic mo- 
tions which we call voluntary, much that is neither willed nor is 
a matter of consciousness*. 

The following, therefore, I would signalize as the great achieve- 
ments of modern Ph}'siology : viz. 

The establishment of the general proposition, that peculiar 
vital powers are connected with, or inherent in, peculiar animal 
tissues ; — dating from Haller : 

The establishment of the theory of development ; — dating from 
G. F. Wolff: 

The further generalization which derives all the vital powers 
from modifications of the force of Assimilation; — more fully pro- 
pounded by Tiedemann. 

Having thus presented a rapid outline of theoretical phy- 
siology, in which I have purposely suppressed many details 
which may be introduced more conveniently in other parts 
of a review of the present state of physiology, I shall now 
proceed in that direction in which the science must for a long 
time attempt a progressive perfection, by endeavouring to as- 
certain, as far as is possible, the inferioi' rules by which the prox- 
imate cause operates. These include all the processes of vege- 
tative life ; and since they are all effected through a constant 
interchange between external matter and the matter of the vari- 
ous organs, I shall begin by pointing out the acquisitions added 
in late years to our knowledge concerning the vehicle of the for- 
mer — the blood. 

The Blood. — This fluid would be ill suited for its office, were 
not its constituent molecules held together, in the living state, 
by affinities so delicately balanced that they yield to every re- 
active energy that the different organs to which it is presented, 
can offer. Hence we account for the great discrepancies in the 
results of chemical inquiry concerning it, from the ease with 
which its components may be caused to combine in various pro- 
portions, and from the different effects which different quanti- 
ties of the same reagent are capable of producing. 

In the body it exists as a colourless transparent fluid, in which 
an infinite number of minute red bodies are equably diffused. 

Out of the body it shortly coagulates, or separates into serum 
and coagulum. 

It was the opinion of Home and Bauer, that the coagulum is 
formed by an aggregation of the corpuscles in the following way. 

• Burdach, vol. iv. p. 3, &c. 



REPORT ON ANIMAL PHYSIOLOGY, 117 

The corpuscles consist of a nucleus inclosed in a membrane of 
coloured matter, which membrane bursts, and the nuclei thus al- 
lowed to escape attract each other and form the solid coagulum, 
which is coloured by the broken membranes, and from which 
the colouring matter may be washed out by water. This opinion, 
which appeared to be confirmed by the observations of Prevost 
and Dumas, of Dutrochet, and of H. M. Edwards, has been 
very generally received. But it is certainly unfounded. For 
the fibrin may be separated from the blood by stirring, whilst 
the corpuscles remain in the serum unbroken and unchanged : 
the serum, far from effecting their solution, supplies the best 
medium in which they may be preserved for observation: if 
in human blood the coagulation be retarded by adding a few 
drops of solution of subcarb. potass., the corpuscles descend, 
from their superior weight, before coagulation takes place : in 
the course of half an hour a tender coagulum is formed, of which 
the lower part (as far as the corpuscles reach) is red, the upper 
pale and thready : operating on the blood of the frog, Miiller 
has succeeded in separating, by the filter*, the large corpuscles 
of that animal from the clear liquor, which last afterwards sepa- 
rates into fibrin and serum : fibrin is not soluble in water, the 
corpuscles are so in part ; and, in general, the two present some- 
what different chemical reagencies. 

The Corpuscles. — These bodies, called collectively cruor, 
have been objects of much interest ever since they were first 
observed by Malpighi. All that relates to them is even yet 
matter of controversy, — their form, their size, their composition, 
the cause of their colour. They have been too frequently ob- 
served in water, rather than in serum, by wliich the two first 
qualities are speedily altered. 

Form. — They exist in all vertebral animals as round or oval 
bodies, with well-defined edges. They are semi-transpai'ent 
and pale Avhen seen singly ; but present the colour of the 
blood when seen by reflected light or in masses. 
In all the Mammalia they are circular. 

In the other Vertebrata they are oblong. De Blainville has 
observed both these forms in Fishes, and Miiller in the 
Frog, who thinks that the round corpuscles, one sixth of 
the size of the others, belong to the lymph or the chyle. 
In all the Vertebrata they are flat. Rudolphi states, that they 
are flattest in the x\mphibia, less so in Birds, least of all in 
Man. 
Hodgkin and Lister find the proportion of axes in Man to 
be 1: 4-5. 

* Miiller, p. 106. The filter was composed of delicate animal membrane, 
moistened bladder, and covered a glass tube from which the air was exhausted. 



118 FOURTH REPORT — 1834. 

To the last-mentioned observers, as well as to Young, the 
corpuscles have not appeared uniformly flattened, but con- 
cave on their surfaces. Miiller, however, M'ho believes in 
the existence of a central nucleus, of which he finds the 
thickness to equal the lesser diameter of the corpuscle, has, 
if his observations admit not of another explanation, set 
that point at rest. 

Size. — As a rule, the size is constant in the same individual, 
and the same species ; and their measurement assumes an 
additional importance from the observation of Blundell, 
and of Prevost and Dumas, that death follows the transfu- 
sion of blood when its corpuscles differ in size from those 
of the animal which is operated upon. 

In Man the size of the corpuscle, according to 
Rudolphi,Sprengel,Hodgl\in, and Lister = 0"00033 in. -g-gV-o 

Kater, Prevost, and Dumas = 0'00025 toW 

WoUaston, Weber = 0-00028 ^oW 

Young = 0-00016 ^-iTTo 

If we take the mean of these, m'c find the size of the human 
corpuscle to be ^—o^dth part of an inch in diameter. 

In different Mammalia, (Prevost and Dumas,) 
the size of the corpuscle is the same as in 
Man, in the Dog, Hedgehog, Swine, Rab- 
bit, Dolphin = -00025 inch. 

Larger in Shuia Callithrix = -00030 

Smaller in Ass = -00022 

Cat = -00020 

Sheep = -00018 

Chamois = -00017 

Goat = -00014 

Hodgkin and Lister have, however, found it smaller in the 

Swine and Rabbit than in Man. 
Diameter in Man : major axis in Frog : : 1 : 4. 
The corpuscles are of equal magnitude in arterial and venous 

blood and similar in form. 

Stmcture. — Hewson, from observing the mode in which the 
fresh corpuscle appears to swell in water and to change, be- 
coming gradually colourless, and appearing as a central nu- 
cleus surrounded by an integument, concluded that it really 
exists in the blood in this complex form. In this opinion he 
has been followed by Home, Edwards, Dutrochet, Prevost, 
and Dumas. The integument has been represented as the 
colouring matter, and the nucleus as fibrin. Raspail, how- 
ever, gives it as the result of his observation, that when the 



REPORT ON ANIMAL PHYSIOIiOGY. 119 

homogeneous corpuscle comes in contact w ith water or an 
acid, then first a change is effected ; the density increas- 
ing towards the centre, and the colour, at first difi'used 
through the whole mass, being then confiTied to the surface. 
But however this may be, whether the nucleus have pre- 
existed or be now first formed, it is not soluble either in 
water or in dilute acetic acid, whilst the external portion 
with the colour is gradually removed by this. This has 
been pointed out by Miiller ^vith great precision in his late 
work : the subject of his examination, principally, was the 
blood of the Frog. 

Berzelius refers the insolubility of the corpuscles in serum to 
the albumen which it contains : but this is not the only cause. 
J. Miiller rather considers it to be an effect of the salts which 
the senuu holds in solution ; for he found, that on adding to a 
drop of Frog's blood under the microscope a drop of a solution 
of yolk of egg in water, the corpuscles lose their form ajid be- 
come round as quickly as in water, whilst a drop of a solution 
of such a salt as does not separate the blood (as subcarb. po- 
tass.) causes no such change to be effected. 

It has been stated by some that iron does not exist in greater 
quantity in the cruor of the blood than in its other essential com- 
ponents. Engelhardt has discovered a remarkable property of 
chlorine, confirmed by H. Rose, by which the incorrectness of 
that opinion has been proved, and the conclusion of Berzelius 
established, viz., that all the iron of the blood belongs to the 
cruor. The chlorine precipitates the animal matter from its solu- 
tion in Mater, and at the same time deprives it of the lime, soda, 
phosphorus, iron, which may have been connected with it. The 
liquor being strained, the oxide of iron may be precipitated by 
ammoiua : but that precaution is necessary, for otherwise, the 
ammonia redissolves the organic matter, and the iron recom- 
bines with it. Engelhardt could obtain no iron from similar 
operations with serum and fibrin, though he did all the otJ cr 
salts ; and there was no ash left on combustion. 

Berzelius 's estimate of the quantity of iron in the ash of the 
cruor was confirmed by these experiments. Of the entire blood 
metalUc iron forms only one part in 1000. 

It is yet undetermined whether the iron exists in the corpus- 
cles of the blood ui its reguline form or as an oxide, Engel- 
hardt and Berzelius supporting the former opinion, and H. Rose 
and Gmelin the latter. For the former opinion it has been con- 
tended, that chlorine has a strong affinity for the metals, but 
none for their oxides ; and that the oxide of iron, if present, 
would be dissolved by the mineral acids. But in Engelhardt's 



120 FOURTH REPORT — 1834. 

experiment, the affinity excited is between chlorine and animal 
matter, not iron and chlorine. And if the mineral acids have 
not the same effect, this does not prove the iron to be in a me- 
tallic state ; for if it were so, and unprotected by the animal 
matter, it would be oxidized, and then dissolved by the acid. 

The labours of chemists to explain the mode in which the 
elementary substances are united to produce the colour of the 
cruor, however they may be unsatisfactory in this respect, have 
thrown much light upon the reactions of these substances. Such 
expei'iments, on the other hand, have introduced as constituents 
of the blood, products which are perhaps merely the effects of 
the chemical operations ; or new combinations, not existing in 
nature, of its elements. The iron seems to enter in too small a 
quantity to form a metallic pigment for the cruor. Whatever 
changes the constitution of the blood, as a living product, also 
changes its colour. " Since its chemical composition is only a 
product of life, so are we unable by any aids derived from inoi'- 
ganic nature to produce it. The colour has its cause in the con- 
stitution of the blood as an organic whole ; and each of its ele- 
ments, iron amongst the rest, contributing to that constitution, 
enters into the production of its colour*." 

T/ie Lymph, or liquor sanguhds. — The clear fluid in which 
the cruor, or mass of corpuscles, is diffused. It separates spon- 
taneously into two portions, fibrin and serum. 

Fibrin. — I refer to Berzelius for all that is yet known con- 
cerning this substance. Since Miiller's discovery, it is distin- 
guished fi'om the corpuscles; and De Blainville and Hodgkin 
have shown that its fibres do not consist of strings of minute 
globules. 

Serum. — Lecanu has repeated the analysis of serum, and as- 
serts, that certain oily substances exist as components, which 
were unnoticed by Berzelius and Marcet. His mode was, after 
desiccating a known quantity by moderate heat, and thus deter- 
mining the quantity of water, to treat successively, with boiling 
water and boiling alcohol at 40°, the residue of desiccation. The 
Avater dissolved the soluble salts and extractive matters, the al- 
cohol the fat matters. The watery solution was evaporated ; the 
residue treated with alcohol to separate the extractive matters 
soluble in it. What was insoluble was calcined, to determine the 
proportion of organic matter it still contained ; the residue again 
treated with boiling alcohol to separate the hydrochlorates. 

The fatty matters taken up by the boiling alcohol were sepa- 
rated from each other by means of alcohol at 33°, which does 
not dissolve when cold the crystallizable fat, but does the oily. 

* Burdach, iv. 85, 



REPORT ON ANIMAL PHYSIOLOGY. 121 

The albumen procured by means of boiling water and cold al- 
cohol was dried, weighed, and calcined, and its salts determined. 
Traces of iron were found in such minute quantity in serum, 
that Lecanu presumes it would not furnish any if it were possi- 
ble to procure it entirely separate from the colouring matter. 

1000 parts of serum consist, according to this mode of ana- 
lysis, of First Second 

Analysis. Analysis. 

Water 90600 901-00 

Albumen 7800 81-20 

Organic matters soluble in alcohol and water .. 1-69 2-05 

Albumen combined with soda 2-10 2-55 

Crystallizable fatty matter 1-20 2-10 

Oily matter 1-00 1-30 

Chlorure of sodium ..." 



- potassium 



I 6-00 5-32 



Alkaline subcarbonate 

phosphate.... S 2-10 2-00 

sulphate j 

Subcarbonate of lime -i 

'■ magnesia. . 

Phosphate of lime >■ 0-91 0-87 

magnesia I 

iron J 

Loss 1-00 1-61 



1000-00 1000-00 

These fatty matters will be better understood by considering 
Lecanu's analysis of the entire blood. He poured alcohol in 
excess on venous blood, separated the precipitate, and treated it 
frequently with boiling alcohol, obtaining thus a mass insoluble 
in alcohol, and a slightly rose-coloured liquor. This liquor, 
subjected to evaporation, became turbid towards the end of the 
operation, in consequence of the separation of a fat matter in- 
soluble in the aqueous product. The residue of evaporation was 
treated with aether : a portion of it was dissolved. Hence an 
aethereal solution A, and a residue B. 

A, on spontaneous evaporation, gave a brownish residue, bit- 
ter, of a consistence similar to that of turpentine, formed of two 
distinct matters, one solid, the other liquid and like oil. The 
residue was incompletely soluble in cold alcohol, the solid por- 
tion remaining attached to the sides of the vessel. When this 
solid portion had been separated, and dissolved in boiling alcohol, 
it formed, on cooling, white nacreous laminae, similar to the fatty 
matter of brain. 

On evaporating the alcohol with which this had been washed, 
and in which the oily portion of the residue had been dissolved, 
another residue, of a bitter taste and turpentine consistence, was 
obtained 3 insoluble in hot or cold water, soluble in alcohol or 



122 FOUBTH REPORT — 1834. 

sether, inalterable by hydrochloric and nitric acids, rendered 
brown by sulphuric acid, soluble in potass with slight heat, and 
precipitated from the solution by hydrochloric acid in white 
flakes. If the excess of acid be washed off with water until the 
latter no longer reddens the vegetable blues, it comniimicates to 
alcohol, when essayed therewith, the property of reddening those 
colours. Hence the oily part of the blood appears to be con- 
vertible by potass into an acid substance, and is considered by 
Lecanu as an immediate principle of the same. 

From B treated with alcohol was obtained a brownish yellow 
liquid and a residvie C. 

-The liquid, on being evaporated, furnished an orange yellow 
mass, insoluble in aether, but soluble in water and alcohol, which 
then manifested alkaline properties. The watery solution af- 
forded a precipitate with hydrochloric and nitric acids, and 
Avith solution of galls ; — the same as that considered by Berze- 
lius to be a mixture of animal matter and lactic acid ; by other 
chemists as resembling osmazome. It is considered by Lecami 
to differ from osmazome in as much as the latter is not precipi- 
table from its solution by acids. 

C was found insoluble in aether and alcohol at 40° : treated 
frequently with boiling alcohol at 33°, it gave the hydrochlo- 
rates, and some extractive matter easily separable by alcohol at 
40°. This new residue, treated with cold distilled water, was 
nearly entirely dissolved, except a small quantity of a brown 
matter insoluble in boiling water and alcohol, and considered 
as a mixture of colouring matter, albumen, and fibrin. 

From a portion of the saline solution, white flakes were abun- 
dantly precipitated by acetic acid, — a gelatinous albumen, which 
Lecanu considers, from the mode in which he obtained it, to 
exist in this form in the blood. Another portion of the saline 
solution was evaporated, the residue calcined, and the salts de- 
termmed*. 

1000 parts of blood, according to the above, consist as fol- 
lows : — 

First Second 

Analysis. Analysis. 

Water 780-145 785-590 

Fibrin 2-100 3-565 

Albumen 60090 69415 

Colouring matter 133-000 119626 

Crystallizable fatty matter 2-430 4-300 

Oilymatter 1-310 2-270 

Extractive matters soluble in alcohol and water 1-790 1 -920 

Albumen combined with soda 1-265 2-010 

• Annalei de Chimie et de Physique, torn, xlviii. p. 310. 



REPORT ON ANIMAL PHYSIOLOGY. 123 

First Second 

Chlorure of sodium ") Analysis. Analysis. 



— potassiuni. 



Subcarbonate, "j )- 8-370 7-304 

Phosphate, ... >alkaline.. 



irbonate, ") 
)hate, ... >a 
late, J 



Sulphate, 

Subcarbonate of lime 1 

' magnesia 

Phosphate of lime [ 9. inn 

magnesia... f 



1-414 



iron 



Peroxide of iron J 

Loss 2-400 2-586 



1000-000 1000-000 

" Doubtless under various modes of applying heat, alcohol, 
the subcarbonates, &c., to the blood, many substances may be 
made to appear, which are but variations of its essential compo- 
nents — (albumen, fibrin, and cruor) . The knowledge of these 
may enrich animal chemistry, if the object were only to compre- 
hend, comparatively and in the gross, the series of changes which 
any matter may undergo under different agencies, and not to 
discover new materials and declare them to be real components 
of the organic body. Tiedemann reckons the peculiar matter 
of saliva amongst the components of the blood ; and lately urea 
has been coimted amongst the number, because it has been fovmd 
in the blood after extirpation of the kidneys. Incontestibly, in 
cei'tain cases of suppressed secretion or of inci'eased resorption, 
bile, the seminal fluid, &c., have been found there ; but no special 
product of secretion can yet, on sufficient gi-ounds, be proved to 
be a normal component of the blood, and from what we know of 
it, such a result is not to be expected*." Numerous colouring 
matters have been classed amongst the components of the blood, 
from the explanations of chemists respecting the causes of co- 
lour — as globulin, erythragin, &c. Burdach thinks that they are 
either the product of reagents acknowledged not to exist in the 
blood, or are modifications of albumen. Boudet, by treating very 
large quantities of blood, contends that all blood contains cho- 
lesterinf. 

Gas. — Under the air-pump, air has been observed to escape 
from recent blood ; its quantity has been variously computed. 
Most observers, as Sir Humphry Davy, Brande, Scudamore, Vogel, 
state that it is carbonic acid. The quantity is very variously esti- 
mated. Brande obtained two cubic inches from eight ounces of 

* Burdach, iv. 68. 

t Annales de Chimie et de Physique, torn. Hi. p. 342. 



124 FOURTH REPORT — 1834. 

blood; Scudamore half a cubic inch from six ounces; Sir Humphry 
Davy rather more than one cubic inch from twelve cubic inches 
of blood. Dr. Clanny finds that the gas developed is principally 
nitrogen. Dr. J. Davy asserts, from his experiments, that in no 
case is carbonic acid ever developed from fresh-drawn blood ; 
that, on the contrary, it absorbs one fourth of its bulli of carbo- 
nic acid, which becomes combined. Miiller has repeated the 
analysis, both with fresh sheep's blood and with that of man. 
Even under a heat which amounted to 200° F., one pound of the 
former gave oif only 1*8 cubic inch of gas : of this quantity 
not one fifth cubic inch was absorbed by lime water ; and this 
small quantity of carbonic acid he attributes to the action of the 
air contained in the tube of his apparatus upon the blood. He 
repeated the experiment in such a way as to exclude the air, and 
obtained no trace of carbonic acid, nor any, except the merest 
bubble, of any other gas. He further found, that blood artifi- 
cially impregnated with carbonic acid did not yield it again un- 
der the air-pvmip*, and thus has confirmed the same observation 
of Dr. J. Davy. Mitscherlich, Gmelin, and Tiedemann have lately 
performed another experiment with the same result. They in- 
troduced small metallic tubes, provided with stop-cocks, into the 
artery and vein of a Dog. After all air was evacuated from the 
tubes, by allowing the blood to flow, they were brought under 
glass cylinders inverted over mercury. The cylinders, half filled 
with blood, were placed under the air-pump. On exhausting, 
bubbles arose, so that the quicksilver, which had stood half an 
inch above that in the cup, sunk about an inch. But when 
the air was gradually readmitted to the bell of the pump, they 
disappeared ; showing that they did not consist of gas, but of 
watery vapour which had filled a vacuum. Both kinds of blood 
comported themselves similarly. The authors found that the 
blood contains carb. acid combined ; for blood mixed with vine- 
gar gave bubbles under the air-pump, which, when venous blood 
was emploj^ed, did not entirely disappear on readmission of the 
air : hence the alkaline nature of the blood depends not upon 
caustic alkalies, but upon their carbonates t> 

The proportion of solid to fluid matter in the blood has been 
determined by Prevost and Dumas, in agreatnumber of animals. 
They find that in Man the solid are to the fluid : : 1 : 9. 

In carnivorous animals there are more cruor and fibrin together 
than in graminivorous : in young animals less than in old of the 
same species :}:. 

* Miiller, Phys'wlogie, i. 313. 

t Archiv.fur Anat. utid Phys., Miiller, 1834, 103. J J.Davy. 



REPORT ON ANIMAL PHYSIOLOGY. 125 

In cold-blooded animals it is the quantity of cruor, not of 
fibrin, which is diminished*. 

Michaelis gives the following analysis of the components of 
arterial and venous blood into the elementary gases t- 

Albumen. 

Arterial. Venous. 



Nitrogen 15-562 

Carbonic acid 53-009 

Hydrogen 6-993 

Oxygen 24-436 



15-505 

52-652 

7-359 

24-484 



Nitrogen 17-587 

Carbonic acid 51-374 

Hydrogen 7-254 

Oxygen 23-785 



Fibrin. 

Arterial. Venous. 

17-267 

50-440 

8-288 

24-065 



Colouring Matter. 

Arterial. Venous. 

Nitrogen 17-253 I 17-392 

Carbonic acid 51-382 53-231 

Hydrogen 8-354 7-711 

Oxygen 23-011 | 21-666 

Arterial blood contains more niti'Ogen and oxygen, but less 
carbonic acid and hydrogen, than venous blood. 

Nit. C. Ac. Hyd. Oxyg. 

Arterial blood 16-800 I 51-920 I 7-534 I 23-746 

Venous blood 16-720 | 52-107 | 7-765 | 23-408 

Lecanu has made some interesting comparative analyses of the 
blood of individuals of diiferent ages, sexes, and temperaments. 
To determine the proportion of the essential principles, he dried 
a portion of the serum after having weighed it, and thus deter- 
mined its water, its extractive matter, and salts. He then divided 
the clot into two portions, dried one of them ; to determine, by 
the loss, the quantity of water of the serum involved in it : and 
washed the other, to obtain the quantity of fibrin. By the first 
part of the process he ascertained that part of the weight due to 
the extractive matter and salts left by the water of the serum 
evaporated: subducting this he had the weight of fibrin and 
colouring matter. By the second part of it he ascertained the 
weight of the fibrin alone. The difference was the weight of the 
colouring matter. In this way, examining the blood of twenty 
healthy persons, ten males and ten females, he found the water 
to vary in 1000 parts of blood— 

• Miiller. f Poggendorf, Annalen, 1832. 



126 FOURTH REPORT 1834. 

In the females from 853-135 to 790-394 : 
Mean of the 10 cases 804-371. 

In the males from 805-263 to 778-625 : 
Mean of the 10 cases 789-320. 

In diffei-ent temperaments : 

Females, lymphatic, mean of 5 cases 803-710. 
, sanguineous, 4 792-984. 

Males, lymphatic, 2 800-566. 

, sanguineous, 5 786-583. 

Female, mean quantity of clot from 10 cases 115-963. 
Male, 132-490. 

Hence there is more water in the blood of females than of males. 
The proportion of water was not found to depend upon age, at least 
between the limits of twenty and sixty years. In individuals of 
the same age, it is less in the sanguineous than in the lymphatic. 
The proportion of albumen is found to be sensibly the same 
in the male and female, and not to be proportional to the age 
between the same limits ; and nearly the same in quantity in 
sanguineous and lymphatic individuals of different sexes. The 
proportion of colouring matter is found to vary in the blood of 
individuals of diiferent sex and age, in individuals of same sex and 
different age : and to be greater in the male than in the female; and 
greater in sanguineous than in lymphatic persons of same sex. 

Denis found from comparison of his analyses, that in the blood 
of individuals ill nourished and accustomed to stimulant drinks, 
the proportion of colouring matter increases, and is even more 
abundant than in the blood of sanguineous subjects ; but that the 
albumen, on the contrary, is in very small quantity*. 

The principal change which J. Miiller foimd in the blood of 
cholera patients, he states to be its propensity to coagulate even 
during life. He therefore recommends the use of the subcar- 
bonates of soda and potass, particidarly the last, in large doses, 
on the immediate accession of the disorder. Dr. O'Shaugh- 
nessy. Dr. Clanny, and Mr. Bell found the salts and serum also 
greatly defective in quantity in this disease. 

There is no longer any question amongst physiologists as to 
the life of the blood. That which enters into the composition 
of all parts of the living body, from which they are produced, 
and sustained, and restored, and upon which the body itself re- 
acts, must possess life. Many have even supposed that its red 
particles possess spontaneity of motion, as in the instances 
quoted by Professor Alison ui the Appendix to his Physiology ; 
but the pheenomena alluded to appear to be explicable partly from 
acknowledged actions of the neighbouring living solids ', and 
• Majendie's Journal, ix. 221. 



REPORT ON ANIMAL PHYSIOLOGY. 127 

where they are not so, they are found to be not peculiar to mi- 
nute organic products, but are observed also in unorganized mo- 
lecules moving in fluids under the microscope*. 

How quickly the body reacts upon the blood, is proved by the 
direct experiments of Thackrah, Scudamore and J. Davy, who 
found the quantity of fibrin to vary in different portions of the 
blood during the same bleeding : generally diminish ing. 

That a due supply of arterial blood is necessary for svipport- 
ing the functions of the more important organs of the body, is 
seen from the singular anastomoses of the large arteries of the 
brain ; from the care taken to guard some of them from pres- 
sure ; from the imperfection observable in the muscular and ner- 
vous powers of persons in whom the septum of the heart is im- 
perfect, or the ductus arteriosus open ; and numerous other in- 

* Thus, Dr. Czermack of Vienna observed a peculiar motion of tlie particles 
of the blood when one of the vessels of the gills in the larva of the Salamandra 
atra was cut through. The particles, under the microscope, of the effused blood 
were seen to have an irregular motion backwards and forwards at some points, 
but generally to move round in circles or ellipses. Dr. Sharpey has shown 
{Edinburgh Medical Journal, 1 830,) that in the larva of the Frog and Salamander 
in the Mollusca and other inferior aquatic animals, the exterior covering of the 
body genei-ally, but especially of the respiratory organs, possesses the power of 
impelling the water contiguous to it in a determinate direction along the sur- 
face, by which a constant current is kept up, and successive portions of water 
brought in contact with the gills, replacing the action of the respiratory muscles 
in higher creatures. Drs. Purkinje and Valentin have lately published an in- 
teresting paper in Miiller's Archiven, Part V. 1 834, in which are detailed ad- 
ditional observations of the same kind. Whilst seeking for ovules in the tubes 
of Rabbits which had been impregnated three days, they observed by the micro- 
scope that minute particles of the mucous membrane of the tubes presented a 
lively motion under watei*, rolling round their axes, and recognised it as a mo- 
tion similar to that of the cilia of Infusories (Flimmerhewegung). Tl>e mucous 
membrane also of the entire uterus and generative passages exhibited similar 
motions, though with different degrees of vivacity. These distinguished observers 
were thus induced to inquire further. They found that in all Amphibia, as Ser- 
pents, Lizards, &c., in Birds, and in Mammalia, the entire surface of the mucous 
membrane of the oviduct presents this glittering motion (Flimmert) ; also the 
mucous membrane of the respiratory passages to their most minute subdivisions. 
It could not be observed in the mucous membrane of the glottis, of the vocal 
ligaments, of the mouth or gullet (Nasen-schleimhaut appears from the context 
to be a misprint for Rachen-sclileimhaut), of any part of the digestive tube or 
its appendages. So much the more remarkable was the observation of it in the 
nose, whilst the phasnomenon ceased exactly on the limits of these parts. Its 
presence serves as a sure criterion, where the membrane exactly begins to form 
a part of the respiratory organ. In the Amphibia, as the Salamander, where the 
mouth is not merely for swallowing, but is also a respiratory organ, the motion 
is very lively. The phenomenon could not be perceived in any fishes which 
were examined; but appeared to the authors, as far as their observations have 
hitherto extended, to be confined to the mucous surface of the respiratory organs, 
and of the female generative organs in Amphibia, Birds, and Mammalia. Such 
portions of the mucous membrane are provided with cilia, according to these 
observations. 



128 FOURTH REPORT — 1834. 

stances. But Blundell's experiments prove, that diminution of 
quantity is not so immediately hurtful to life as alteration of the 
quality of the blood. Three fourths or more of all the blood in 
the body may be removed, and the animal still live. When a 
Dog had been rendered apparently dead by the loss often ounces 
of blood, it Avas recovered bj'^ transfusion of two ounces. This 
vital influence of the blood is shown by Prevost and Dumas to 
depend not so much upon the serum as upon the red particles. 
An animal bled to insensibility, is not revived by serum of the 
proper temperature, but is by blood from which the fibrin has 
been removed by stirring. But with respect to qualitj'^, changes 
of this, slight in appearance, produce important effects. Blundell 
found, that when he had drawn blood from a Dog's artery, and 
reinjected it into a vein before coagulation had commenced, (per- 
forming the operation until more blood had been thus transfused 
than equalled the whole weight of the animal,) though it reco- 
vered, it was ill for several days with oppressed respiration and 
impeded action of the heart. When an animal, therefoi'e, is re- 
vived with blood of another of the same species, we may sup- 
pose that the operation is not entirely without danger of ill con- 
sequences. But when this is effected with blood from an animal 
of a different genus, the consequence is generally fatal. Of dogs 
revived with human blood, some died shortly after the operation, 
some on the following, others on the sixth day. When Pre- 
vost and Dumas transfused Calves' blood into Kittens or Rabbits, 
they seldom survived the sixth day : the pulse becoming quick, 
the warmth diminished, the evacuations bloody. The transfusion 
of the blood of an animal of another class, i.e. with differently 
shaped globules, almost always causes death. If blood with 
round particles be injected into the veins of a bird, it dies with 
symptoms of poisoning from substances which act on the ner- 
vous system*. 

With respect to transfusion we cannot but assent to the fol- 
lowing judicious observations of Burdach. The blood of every 
creature is in as special a relation to it as are any, the most im- 
portant, organs of its body, and is its own production as much 
as they are. It is vmder the necessity of making its own blood 
for its own purposes . When an animal, therefore, is saved from 
death by means of transfusion, it is saved by a mode which in- 
troduces into its system causes of derangement in all its func- 
tions, and which it must throw off by its powers of secretion be- 
fore healthy action can be restored. 

Nysten's experiments, and those lately detailed by Majendie 
in his lectures t, seem to prove, that air injected into the veins 

• Dieffenbach, quoted by Miiller. t Lancet, No. viii. 1834. 



REPORT ON ANIMAL PHYSIOLOGY. 129 

destroys life by mechanical interruption of the circulation. For 
small quantities even of irrespirable gases (except nitrous, sul- 
phuretted-hydrogen, and ammoniacal gases,) are not fatal. 

The interesting and difficult inquiry into the causes which 
produce coagulation of the blood has lately been ably resumed 
by Mr. Prater. His numerous comparative experiments show 
how important an element is the quantity of the agent which 
modifies that process : that the same agent which in a large 
quantity altogether prevents coagulation, in a small quantity 
favours it. He confirms also the fact, announced by Schroeder 
Van der Kolk, that as the proportion of serum is relatively in- 
creased, (as it is in blood last drawn,) so is the tendency to coagu- 
lation also increased. The impression derived from his works 
is one which strengthens our belief generally in the views of 
Hunter ; viz. that no theory can satisfactorily explain the phee- 
nomena of coagulation which has not a regard to the vital pro- 
perties of the blood ; properties whose variations v/e are not yet 
able to connect with those cori'esponding alterations in the com- 
position and aggregation of its molecules which we cannot but 
believe to accompany them, Mr. Prater attempts to infer from 
his experiments what the vital properties of the blood are which 
have hitherto been ascertained; viz. vital elasticity (irritability), 
and contractility. See Essay on the Blood, and Experimental 
Inquiries in Chemical Philosophy . 

The Powers ivhich circulate the Blood. — From the observa- 
tions of Prevost and Dumas, of Baer, and of Baumgsertner, we 
find that many important organs of the body are traced out in 
the primitive matter of the germ, before there is any indication 
of blood or of vessel to contain it. According to Baumgaertner*, 
the motion of the blood is first perceptible in the Frog and Sala- 
mander seven or eight days after the rudiments of the brain and 
cord are visible, and even twenty- five days after that time in the 
Trout. In the same way rudimentary shapes, corresponding to 
skin and organs of sense, muscle and bone, digestive and respi- 
ratory organs, are traced out in the original organic matter be- 
fore they receive any blood. The vessels and the blood which 
make up the first circulation between the vascular area and the 
heart, are formed simultaneovisly from the granular mass which 
has accumulated between the serous and mucous laminae of the 
germinal membrane. The granules, gathering together into iso- 
lated masses, present fissures between them containing a yellow- 
ish fluid which gradually becomes red. The fissures increase in 
number; the masses diminish in individual magnitude, whilst 
they extend the vascular area over a larger space. In these 
* Beohacldungen iiber das Bhit und die Nerven, quoted by Burdacli. 

1834. K 



130 FOURTH REPORT — 1834. 

fissures, G. F. WolfF first traced the gradual formation of the 
walls of the vessels, and the conversion of the fluid into blood 
by the included masses. The formation of the heart is effected 
similarly from the granular mass. 

When, therefore, the junction between the vascular area and 
heart has been effected, and the blood moves onwards by means 
of the heart's contractions, the direction which it takes is not in- 
determinate as it would be if left to the influence of that power 
alone. On the contrarj^, its course is determinate ; it seeks the 
different organs whose lineaments are perceptible, being soli- 
cited thereto by the vital attraction which is now established be- 
tween ihem. The streams which reach them vary in size, and sub- 
divide through their masses in a way so peculiar for each organ, 
that even in the adult and perfect form, each of them preserves 
a mode of branching for its main vessels, and a figure for its 
capillaries, which are found in no other. What, therefore, is es- 
sential in the circulation of the blood, is an attraction subsisting 
between the particles of each organ and the particles of the 
blood, and a subsequent repulsion between the same, that which 
is repelled by one set of organs being attracted by another. What 
are the physical conditions of the organs and of the blood under 
which thephEenomena are effected, has not been determined. 
Some have supposed that the particles of the organs and of the 
arterial blood are in different states of electric polarity. Accord- 
ing to them, the organ, as the more fixed, attracts the blood; 
communicates to it its ownelectric state, and then repels it. It fol- 
lows, therefore, that arterial and venous blood are in opposite elec- 
tric states. J. Midler, however, could discover no electric cur- 
rent by the galvanometer, M'hen one of its wires was placed in 
an artery, the other in a vein of a living animal. 

Though a negative experiment of this kind is not conclusive, — 
for the electric organ of the Silurus does not affect the galvano- 
meter, — yet Dutrochet's opinion that the red particles in the blood 
perform the olfice of galvanic plates, and his belief that he had 
effected the formation of muscular fibre by galvanizing a drop of 
serum, cannot be supported. His ingenious experiments are de- 
tailed in l\\eAnnales des Sciences NatureUes,\Sd\, p. 400. They 
have been repeated by Miiller, who has shown that the supposed 
muscular fibre is merely a collection of granules of albumen, with- 
out consistence, coagulated by the acid of the decomposed salts 
of the serum ; and that there is no sufficient reason for conclud- 
ing that colouring matter and fibrin (the nuclei of the red par- 
ticles according to Dutrochet,) are in opposite electric states*. 
It is on this principle, however, of vital attraction, as I conceive, 
* Miiller, Physiohgle, p. 132. 



REPORT ON ANIMAL PHYSIOLOGY. 131 

that the phaenomena of local inflammation, of determination of 
blood to particular regions, the emptiness of the arteries after 
death, &c., are to be explained*. It may be abnormal, as in 
many of these instances. It may also be suspended or destroyed. 
Nervous influence seems to be a condition of its continuance, 
where the animal has nerves. It is stated that when the main 
artery of a limb is tied, the circulation is not maintained by 
anastomosing branches if the nerve be also tiedf. Many have 
recorded that in persons bled to fainting, the blood which last 
issues from the vein is arterial in colour. 

The capillary vessels themselves seem to contribute nothing 
to the motion of the blood : the diameter of the small threads of 
blood in any of them is not seen to be in the least variable, whilst 
the heart's action continues the same and the muscles are at rest. 
They are intermediate between the minute arteries and the minute 
veins, and continually anastomose. Dr. Marshall Hall states that 
he has in vain sought for instances of the immediate termination 
of a minute artery in a minute vein : they all first pass into 
capillaries. In this way it is that the blood is brought into near 
contact with the parenchyme of the various tissues, and the pro- 
cesses of nutrition effected. It was the opinion of the older 
physiologists that all the minute arteries did not thus terminate, 
but that some ended by open mouths, thus allowing the blood 
itself to enter into the composition of the different organs of the 
body. If, however, the transparent parts of living animals be ob- 
served, all the particles of blood are observed to pass from the 
minute arteries through the network of the capillaries, and by 
these to enter into the veins. The minute anatomy of glands also 
shows that the last divisions of their ducts are closed tubules ; 
that on these the capillary vessels are largely distributed, but 
never pass into them. The smallest visible capillaries are those 
which convey red particles of the blood in single files ; their dia- 
meter therefore is about the :jy\y^dth part of an inch. That there 
are others so small as merely to convey the lymph of the blood 
is however the opinion of many physiologists. It was the opi- 
nion of Haller, and Bichat, and Bleuland that there are such 
vessels ; the contrary that of Mascagni and Prochaska, and of 
Soemmerring in his later writings. The primitive fibres both of 
muscle and of nerve are smaller, considerably, than the least vi- 
sible capillaries. 

In the lowest animals, this vital attraction between the mole- 
cules of their body and the nutrient fluid which penetrates, by 
imbibition, their uniform mass, appears to be sufficient for the 
purposes of their oeconomy. But in higher creatures, a moving 

* Kalken Brenner, Majendie's Journal, viii. 81. t Baumgsertner. 

K 2 



132 FOURTH REPORT — 1834. 

powei", afforded by the contraction of living solids, is necessary to 
bring the nutrient matter within the influence of this attraction. 
For in them the organs are gradually collected into distinct 
masses and individualized, and their life depends upon the reci- 
procal action of these. That their activities may be maintained, 
a common nutrient fluid is con^ejed to them on the one hand, 
and on the other, is brought into near contact with the air. 
Wherever the heart exists, it is the principal moving power ; but 
it does not exist until there is a distinct apparatus for aerating 
the fluid. In the Medusae and some Polypi, the nutrient fluid is 
the immediate product of digestion ; the digestive cavity supplies 
the place of a heart, and tubiiles proceed from it through their 
substance. In insects a single tube represents the heart : it pul- 
sates from behind forwards, and absorbs at every diastole a por- 
tion of a fluid mass which surrounds the intestine, and is the 
product of digestion. Here the vessel scarcely ramifies, that 
form being assmned by the respiratory apparatus which con- 
ducts the air to every part of the body. In the Crustacea the 
heart begins to be concentrated; there are arteries and veins : the 
single cavity of the heart receives the blood from the gills and 
distributes it to the body. In the ]Mollusca the heart consists 
of an auricle and ventricle. In the highest of this class, there- 
fore, it resembles the systemic heart of Mammalia ; but in 
some of the lowest it surrounds a part of the intestinal tube, 
and in this respect they form a link between the others and those 
animals in which the heart and digestive cavity are one and the 
same organ. In the Vertebrata, wherever the heart is single it 
belongs to the lungs; and here first the nutrient matter is ab- 
soi'bed from the digestive cavity by peculiar vessels, and then 
conveyed to the circulating system. As the pulsating vessel is 
gradually concentrated, so also is the nervous system. When 
the heart has the form of an oblong sac, the nervous system pre- 
sents a series of swellings connected by a single or double cord. 
In the Mollusca the heart becomes more globose, whilst a cen- 
tral mass of nervous matter represents the brain, and in many 
instances sui*rounds the oesophagus as the heart does the intes- 
tine in some. In vertebral animals the ganglionic chain becomes 
a spinal cord, the ring a brain of a spheroidal shape, whilst the 
heart is a more perfect central organ ; and here first a peculiar 
system of nerves is appropriated to the nutrient apparatus (the 
sympathetic), whilst there is a peculiar set of vessels for absorp- 
tion. Thus do the nervous and circulating systems appear to 
advance simultaneously towards perfection, the one being a con- 
dition, but not a cause, of the other's existence. In all the vei'- 
tebral animals the heart lies below the spinal cord and abdomi- 



REPORT ON ANIMAL PHYSIOLOGy. 133 

nal canal. In all the invertebral it is placed above the gangli- 
onic string, and above the abdominal canal*. 

Treviranus has given a table in v/hich the weight of the heart 
is compared with that of the body, in the different classes of ver- 
tebral animals. In the Mammalia it varies from ^\j to y^o ; in 
Birds, from yV to yi^ ; in Amphibia, from ^ io to ^ ig ; in Fishes, 
from gj-o to y|y. So that, assuming its power to circulate the 
blood through the body to be in proportion to its weight rela- 
tively to that of the body, he concludes that its influence de- 
creases with the descent of the animal in the series f- 

AVhether the arteries in any degree assist the heart in effecting 
the circulation of the blood, is a question upon which physiolo- 
gists are by no means agreed. That the heart is able to perform 
this office alone, is proved by those cases where the circulation 
in the limb was continued, though the main arteries were com- 
pletely ossified and incapable of contraction ; and that it does do 
so in all cases has been inferred, from the fact that there is no 
systole and diastole observable in the smaller arteries and ca- 
pillariesj whilst the blood is seen to flow more quickly in the 
veins on contraction of the heart. Poisseuillet has detailed ex- 
periments in which he has shown that the artery certainly dilates 
and contracts under the heart's action, which had been denied 
by Bichat and Parry, the cause of the pulse assigned by them 
being a motion of the entire artery in space, without alteration 
of diameter. By means of a metal cylinder capable of being 
opened like a box, he surrounded a portion of the carotid artery 
of a horse with water. A small graduated glass tube projected 
from the cylinder : the water rose and fell in the tube on expan- 
sion and contraction of the heart, thus evincing the varying vo- 
lume of the artery. With another apparatus he measured the 
recoil of the same artery, having detached a portion of it from 
the body. A glass tube was fixed to each extremity of the ar- 
tery laid horizontally. Both tubes then turned perpendicularly 
downwards for a space ; then one perpendicularly upwards, the 
other upwards at an angle of 45°. 'The former had a stop-cock 
at the extremity near the artery, the other at the distant extre- 
mity. The artery, filled with water, was submitted to a given 
pressure by mercury and water, which filled the oblique tube, 
and mercury alone, which balanced it in the other. The artery 
being thus distended, the stop-cocks were turned. When that 
at the extremity of the oblique tube was opened, the recoil of the 
artery caused the mercury to rise in it, and to drive off a portion 

* P'idc Buvdach, vol. iv. p. 451. 

t Erschcinuntjen unci Gesetse des Organischen Lehens, p. 225. 1831. 

X Mnjendie's Journal, vol. ix. p. 48. 



134 FOURTH REPORT — 1834. 

of the water. The perpendicular height of the remaining co- 
lumn of water appeared to show that the contractile power' of 
the artery was greater than the power which dilated it by fifteen 
millimetres of mercury. We suppose, however, that little can 
be concluded from this experiment respecting the quantity of the 
contractile force of the artery in the living body. It is placed 
in the experiment in very different conditions. Being forcibly 
dilated between fixed points, its coats represent in the longitu- 
dinal direction a series of elastic cords, M^hich are forced into 
curves, and the whole effect is due in part to the recoil of these, 
and in part to that of the circular fibres. 

The elasticitjr of arteries, which lasts after death until decom- 
position takes place, differs from that vital exertion of it called 
tonicity, which is soon extinguished. By means of the two, 
particularly the latter, the artery always adapts itself to its con- 
tents. In consequence of the latter alone, the artery is smaller 
shortly after death than after the lapse of several hours. I know 
of no experiments which satisfactorily indicate any rapid con- 
traction of arteries, which can be referred to muscularity. Their 
middle coat, in which that property has been supposed to reside, 
has been shown by Berzelius to differ from muscle, in being 
more elastic, in having less combined fluid, in being insoluble 
in acetic acid, soluble in mineral acids, but not precipitable from 
the solution by potass. Its fibre affords no trace of the trans- 
verse stri;e which Hodgkin and Lister regard as a peculiar cha- 
racteristic of muscle. 

The pulse, depending upon dilatation of the arteries from the 
force of the left ventricle, has until lately been by many supposed 
to be synchronous throughout the body. E.H.Weber, after 
Soemmerring,Majendie, Stocks and Carlisle, has shown that it is 
not exactly so ; and for the reason that the arteries are not rigid 
tubes. The blood driven by the heart into elastic tubes, distends 
them by an undulation which is progressive. The pulse, which 
is the distension of the vessel, is synchronous only at equal di- 
stances from the heart, and in arteries at considerable distances 
from the heart follows its beat by one sixth or one seventh of a 
second. 

Heart. — Poisseuille, in order to ascertain the force with which 
the heart drives the blood into the aorta, has repeated some of 
Hales's experiments in a more accurate manner. His appara- 
tus consisted of a glass tube, bent into a semicircle, so that its 
branches were parallel. The shorter of these was again bent at 
right angles, and nearly to this level the parallel branches were 
filled with mercury. What remained of the shorter still empty, 
together with its horizontal portion, was filled with a solution of 



REPCIRT ON ANIMAL PHYSIOLOGY. 135 

subcarbonate of soda, in order to prevent coagulation of the blood 
when the extremity of the horizontal portion was introduced into 
an arter}'. The instrument being so introduced, the mercury 
was found to oscillate in the parallel branches ; and the degree of 
oscillation and altitude of the mean point was measured by means 
of a graduated scale on the long limb, when the instrument was 
held so that this should be perpendicular. The oscillation was 
caused b)' the respiration of the animal, the mercury falling on 
inspiration and rising on expiration. The mid point was found 
(correction being made for the weight of the column of solution 
of subcarb. sod. in the short branch,) to stand always at the 
same place, whatever artery it might be into which the instru- 
ment was introduced, upon an average of many observations for 
each ; and gave the height of a column of mercury equal to the 
mean pressure of the heart, thus shown to exert the same force 
throughout the whole arterial system. This mean pressure^, mul- 
tiplied by the area of the aorta, gives the statical force of the left 
ventricle. 

The mean pressure was found to be in no degree proportional 
to the weight of the heart, and to differ so little in animals of 
very unequal size that Poisseuille is disposed to attribute the 
variations to individual circumstances of health, age, &c. ; and 
thinks it not unreasonable to conclude that the blood is moved 
in great and small animals, and in different species, Avith the same 
force. From such principles it will follow, that the statical force 
of the heart in different animals will be proportional to the 
square of the diameter of their aortas. The mean pressure in 
the Dog, the Horse, the Mare, was between the limits 140 and 
180 millimetres. Taking the mean of these limits, and measur- 
ing the aorta, the weight of a column of mercury equal to the 
statical force of the heart (that with which the blood moves in 
the aorta) is found in Man to equal 4lbs. 3oz. ; in the Horse, 
lOlbs. lOoz. The statical force with which the blood movies in 
the radial artery in man under the same pressure equals half an 
ounce. 

If the account which I have given of the beat of the pulse be 
correct, that of the heart against the sides of the chest will de- 
pend upon the contraction of the ventricles. I ought to men- 
tion, however, that Corrigan, and Carson, and Burdach are op- 
posed to this opinion, and rather deduce the beat from the dis- 
tension of the venti'icles, the contraction of the auricles imme- 
diately preceding that of the ventricles. The last experiment 
which I have found on this subject is that of Miiller*, per- 
formed in conjunction with Prof. Albers. The chest of a Goat 
* Physiologic, p. 165. 



136 FOURTH REPORT— 1834. 

was opened : whilst the animal lay on its back, the heart was vi- 
sibly elevated during the contraction of the ventricles, and even 
the apex tvu-ned upwards. When the hand was laid upon the 
heart, the perceptible quivering was so powerful and so momen- 
taneous, that it appeared impossible to assign the beat against 
the ribs to any other cause than the systole of the ventricles, for 
no agitation could be felt during the diastole. 

This conclusion agrees with that which Mr. Carlisle derived 
from his experiments. The dissections also of this gentleman 
account for the tilting of the apex of the heart. The muscular 
fibres, which pass from the basis to the apex, are found by him 
to be considerably longer on the front than on the back part. 
They contract therefore more : the apex is drawn towards the 
basis, but at the same time forward*. 

The causes of the two sounds which are perceptible by aus- 
cultation, and which occur between two consecutive beats of 
the heart, are scarcely yet determined to the satisfaction of phy- 
siologists. The dull and more enduring sound is quickly followed 
by one which is clearer and more brief, as was first well defined 
by Laennec. They follow each other v,ith a slight interval, and 
then there is a pause. Laennec attributed the first to the con- 
traction of the ventricles, the other to that of the auricles ; but 
the interval between the somids does not correspond to the in- 
terval between these contractions. All appear to be agreed that 
the first sound is synchronous with the pulse at the heart, and 
therefore they assign the cause of this as the cause also of the 
first sound. Thus, Corrigan and others deduce the first sound 
from the contraction of the auricles, the second from that of the 
ventricles ; Williams, the first from the contraction of the ven- 
tricles, the second from the action of the valves; Hope, the first 
from the contraction of the ventricles, the second from the ex- 
pansion of the ventricles by the bloodf. 

Majendie, in a memoir read before the Academy of Sciences 
of Paris, February 1834, has lately objected to all these explana- 
tions. He could perceive no sounds when the heart was laid 
bare; and therefore concludes that they cannot proceed from the 
respective play of its different cavities, nor from the action of the 
heart upon the blood, nor of the blood upon the heart. He then 
institutes a set of experiments, in order to discover the true 
cause of the phsenomena in question. He found that though all 
sound ceased when the sternum was removed, yet ^vhen elastic 
bodies were brought in contact with the heart, sounds, variable 
according to the nature of those bodies, were produced : when 

* Vide Reports of the British Association, vol. ii. p. 456. 
f Compare Carlisle, loc. cit., ]). 458. 



REPORT ON ANIMAL PHYSIOLOGY. 137 

the sternum of a Goose was raised and replaced, the sound was 
annihilated and reproduced at pleasure ; when air or water was 
injected into the left pleura, so as to keep the heart at a distance 
fi-om the thorax, no sound could be perceived. Further, he found 
that if he introduced a slip of metal, thin and flat, into the thorax 
of a Dog, so as to prevent the shock of the apex of the heart 
against the parietes of the thorax, though the heart acted vio- 
lently, the dull sound ceased ; if introduced so as to prevent the 
right ventricle touching the thorax, the clear sound ceased. 
Majendie hence deduces the first sound from resonance of the 
thorax, caused by the stroke of the apex ; and the second from 
resonance of the thorax, caused by the impulse afforded by the 
heart, under sudden dilatation from the influx of blood, to the 
anterior parietes of the right side of the chest. 

Bouilland, in a letter to the Academy of Sciences, has pro- 
tested against Majendie's explanation ; asserting that it does 
not satisfy the conditions, and raises a doubt concerning the va- 
lidity of that theory alone which assigns the double soimd to the 
play of the valves; (Romanet, in a recent inaugiu-al dissertation, 
having maintained that the one sound arises from the shock given 
by the blood to the tricuspid and mitral valves, the other to the 
shock on the sigmoid valves of the aorta and pulmonary artery ; 
and E. L. Bryan the same in the Lancet.) Bouilland further 
alleges his own experiments. No sounds were heard when the 
heart pulsated being emptied of its blood; they were heard when 
the heart in situ was laid bare, and had no connexion with the 
walls of the thorax. He further objects, that Majendie's theory 
does not account for the varieties of sound produced by organic 
lesions of the valves ; nor for the fact, that sounds may be heard, 
as though distant, when fluid fills the pericardium and prevents 
the heart from reaching the thorax. 

Here this subject rests for the present; but Majendie has un- 
dertaken to examine, in a second part of his memoir, whether his 
explanation will account for all the particular circumstances con- 
nected with each of the sounds of the heart. 

Cause of the Heart's Action. — Haller, from observing that the 
heart continues to beat for a considerable time even when re- 
moved from the body ; and that its contractions, in the body, 
may be affected by the direct application of mechanical and che- 
mical stimuli to its fibres, whilst he coiild not influence them by 
imtation of the cardiac nerves, concluded that its power of con- 
traction is inherent, and totally independent of the nervous sy- 
stem. His theory was afterwards fortified by the dissections of 
Scemmerring and Behrends, which appeared to show that the 
cardiac nerves are distributed to the vessels of the heart alone. 



138 FOURTH REPORT — 1834. 

And even after Fowler, Humboldt, and others had stated that the 
heart may be stimulated by galvanizing its nerves, and Scarpa 
had demonstrated that these are distributed to its substance as 
m other muscles, Haller's theorj', though vehemently opposed 
at first, came to be very generally received. It, however, met a 
formidable opponent in Le Gallois, who published, in 1812, an 
essay, containing results of numerous experiments, from which 
it appeared that the heart's power is altogether derived from the 
spinal cord. He found, that if a Rabbit be decapitated, the heart's 
action is continued, artificial respiration being performed ; that 
if a portion of the cord be destroyed, as in the lumbar region, 
the heart is unable to support the circulation, in a Rabbit twenty 
days old, longer than four minutes, whilst it is continued in one 
two days old ; and that the destruction of the cervical and dor- 
sal portions of the cord are still more suddenly fatal to the 
heart's action. He observed, on destroying successive portions 
of the cord, that even when the circulation is suddenly arrested 
life ceases, on the instant, only in those parts which derive their 
nerves from that portion of the cord which has been destroyed, 
continuing for a time in the rest of the body ; that this time is 
greater the nearer the animal is to the epoch of its birth, and is 
determinate for each species. He concluded that those parts 
which die last, on partial mutilation of the cord, die because the 
power of the heart has been so much weakened that the circula- 
tion through the entire arteries cannot be maintained. He hence 
inferred, that if the work to be performed by the heart were 
diminished in proportion as its power was lost, the circulation 
might be supported. He found, accordingly, that if the aorta 
was tied opposite to the part of the cord to be destroyed, the 
circulation was continued through the remaining portion of the 
trunk in connexion with the heart. His general conclusions 
were, that the heart has no intrinsic power, but that it derives 
its power from every part of the spinal cord ; that each part of 
the body is animated by that part of the cord from which its 
nerves arise ; that the spnpathetic system of nerves has its ori- 
gin in the spinal cord, and not in the ganglia, its office being to 
bring the parts to which it is distributed M'ithin the influence of 
the whole nervous power of the cord ; that the motions of the 
heart which are visible after excision from the body, are similar 
to those which may be excited in other muscles after they have 
been for some time dead, and are merely cadaveric phenomena. 
In 1818, Dr. Wilson Philip published his essay on the laws of 
the vital functions, and reviewed Le Gallois' experiments and 
observations*. By unexceptionable experiments he showed, 
* The first experiments of Dr. Philip are in the Phil. Trans, for 1815. 



REPORT ON ANIMAL PHYSIOLOGY. 139 

that if the sensibility of the Rabbit be destroyed by a blow on the 
head, the brain and spinal cord may be entirely removed, the 
heart still continuing to act. By other experiments he showed, 
that (the sensibility of the animal being destroyed,) the heart may 
be excited to act more powerfully by stimidi applied to any part 
of the brain and cord ; that if the stimulus be very powerful, as 
crushing the central parts of the nervous system suddenly, the 
action of the heart is suppressed. He infers from hence that 
the mode in which Le Gallois destroyed the cord exhausted at 
once the excitability of the heart in those instances in which it 
entirely ceased to act, and impaired it in others. He remarked 
that the increased action of the heart could generally be observed 
as long as the stimulus, whether chemical or mechanical, was 
applied, unless it was of a nature to produce the sedative after the 
stimulant effect; and inferred that the former is a direct opera- 
tion of the agent, when it is observed, and not a consequence of 
the latter. Dr. Philip therefore concludes, with Le Gallois, that 
the functions of the cord are independent of the brain ; and that 
the heart is acted upon by every part of the cord. But he dis- 
proves altogether Le Gallois' opinion that the irritability of the 
heart is a quality derived from the cord. He proves that it re- 
ceives no power from the central parts of the nervous system ; 
but that nervous influence, like any other stimulant, is capable 
of exhausting its excitability ; that it is acted upon not by the 
cord alone, but by every part of the central masses, the brain 
and cord : obeying a much less powerful stimulus than the mus- 
cles of voluntary motion, but that the stimulus must extend over 
a large surface of the brain or cord to affect the heart. 

Flourens*, from his experiments on fishes, concludes that the 
power of the heart is inherent, and is influenced only by destruc- 
tion of that part of the nervous system whose integrity is neces- 
sary for respiration, , the medulla oblongata. 

Dr. Marshall Hallf, making the Frog and Eel the subjects of 
his experiments, because the transparency of parts at different 
distances from the heart (in the former the web and lungs, 
in the latter the caudal, dorsal, and pectoral fins,) allowed him 
to test the varying power of the heart to circulate the blood, 
has deduced the following conclusions : that the heart's action 
is enfeebled from the moment it is deprived, at once, of the in- 
fluence of the brain and cord ; that it possesses an independent 
irritability, which however, like that of the voluntary muscles, 
is lost after the organ has been separated from the central masses 
of the nervous system ; that the circulation is first enfeebled, 
then lost, in the most distant parts of the body from the heart, 
• Mem. de I'Institut, torn. x. t Essay, 1831. 



140 FOURTH REPORT — 1834. 

then in parts less and less remote ; but that the power of ch'- 
culation in each part does not depend upon that portion of the 
cord from which it derives its nerves. He has proved, by de- 
cided experiments, that Flourens' opinion of the dependence of 
the power of the heart upon that part of the central nervous 
masses which supplies the nerves to the respiratory muscles is 
unfounded, if that could be doubtful after Cliffs experiments on 
the Carp, published in the Phil. Trcms. 1815. Dr. Marshall Hall 
could not observe that opium or spirit of wine, applied to the 
brain or cord, accelerated the circulation, as recorded by Dr. 
Wilson Philip. 

From these several experiments we conclude : that the heart's 
power is inherent, and not derived from the brain or cord ; that 
it is under the influence of every part of the brain and cord ; 
that it endures for a time, even when the heart is separated from 
the body. 

The rhythmical contraction of the heart is an instance of that 
periodicity which occurs in all involuntary motions, even in the 
minute oscillations of the fibre on which the contractions of 
those muscles depend which we call voluntary. The whole con- 
traction in the one case is periodical, for the stimulus is constantly 
recurring ; in the other the stimulus is dependent on the will. 
Though the successive presence of the blood in the different ca- 
vities of the heart may, as Haller explained, be the ordinary sti- 
mulus to its activity, yet it cannot be the only one, for the rhyth- 
mical contraction occurs when the heart is empty, and even when 
placed in vacuo. Why then does the heart continue to act under 
such circumstances, and what is the stimvilus ? We have seen, 
from consideration of the growth of the embryo, that organic 
activity depends upon the mode in which matter is compounded 
imder the assimilative process. Those organs which receive 
more blood, are more active than those which receive less ; and 
such as are liable to be called into siulden and excessive action, 
as the voluntary muscles, receive most blood of all : the blood 
is there for assimilation as it is wanted ; aerated blood, proper 
temperature, and most probably nervous influence being neces- 
sary conditions of the process by which each creature is enabled 
to maintain that form and mixture of its parts which is neces- 
sary to their life. Nutrition, then, or a constant interchange 
between the particles of the organ and of the blood, being neces- 
sarj-, it follows that something has occurred in the organ during 
its active state, some alteration, which requires repair. Activity 
has caused a change in that composition of its molecules which 
nutrition must restore. If the restoration do not occur, the sub- 
sequent reaction is different, or is impossible. The heart, when 



REPORT ON ANIMAL PHYSIOLOGY. 141 

removed from the body, responds to stimulation as long as the 
composition of its tissue is such as to render it capable of doing 
so. The stimulus may be the blood remaining in its vessels, if 
its cavities be empty ; or may be the nervous influence which, 
there is reason to suppose, remains in its nerves for a time after 
they have been cut oft" from communication with the brain and 
cord. Under these two conditions it is even possible that a low 
degree of assimilation may yet go on, which however can never 
completely restore the state which the fibre possessed at the 
time when any individual contraction was performed. The ex- 
citability at length ceases. But even without this supposition, 
stimuli which do not at the same time afford food for the nutri- 
tive process, can, if food be not otherwise supplied, merely 
exhaust. The final cause of this perdurance of a certain degree 
of irritability in the heart, even when nutritive supply and ner- 
vous energy are suspended or imperfect, is obvious. 

Dr. Carson has pointed out the effect which the empty state 
of the auricles produces upon the circulation in the veins, im- 
parting to the heart the power of a sucking instrument ; and 
also the effect of the resilient or elastic nature of the pulmonary 
tissue in subjecting the heart to a less atmospheric pressure 
than the rest of the body*. 

Poisseuille, by means of his barometrical instrument, has 
confirmed Sir J. Barry's conclusions respecting the effect of in- 
spiration on the venous circulation, as far as the large vessels 
near the heart are concerned. When the instrument was in- 
troduced into the vein of a Dog, towards the heart, the mercury 
rose 60 millimetres above the zero point during expiration, and 
fell 70 m. below it during inspiration ; the degree of rise and fall 
varying with the struggles of the animal, but occurring syn- 
chronously with the respiratory movements. He did not find 
that inspiration at all influenced the veins of the exti-emities j 
but he confirmed Majendie's observation, that expiration assists 
not only the motion of the blood in the arteries, but that its 
effect extends through the capillaries to the veins ; the blood 
rose in them all during expiration, (the instrument being at- 
tached to the peripheral portion in the case of the veins,) and 
during the systole of the heart. 

From all these experiments we conclude, that the heart sup- 
plies the power which effectually moves the blood in the higher 
animals, not only through the arteries (to which Bichat con- 
fined its effect), but also through the capillaries and the whole 
venous system ; that it is assisted by the elastic power of the 
arteries after they have been distended by the heart's action upon 
• Inquiry into the Causes of Respiration, Sfc. 



142 FOURTH REPORT — 1834. 

the blood ; assisted also by pressure, Avhether atmospheric or 
otherwise, on account of the disposition of the vah'es in the ar- 
teries and in the veins ; that the vis a tergo is more effectual 
during expiration ; and that the return of the blood to the heart 
is facilitated by the emptj- state of the auricles and by inspira- 
tion ; that the vital attraction and repulsion between the mole- 
cules of the organs and of the arterial and venous blood is a con- 
current cause. 

Hering has published some valuable experiments* made with 
a view to determine the time in which the circulation is effected. 
His method was to pour a solution of some harmless substance, 
easy of detection by tests, as prussiate of potass, into a vein ; and 
to determine, by observation of the blood taken from another 
distant vessel at short intervals, how soon the presence of the 
injected solution could be discovered in the latter. In Horses 
it passed from one jvigular vein through the lungs and great cir- 
culation, and Vv'as detected in the opposite jugular vein in a time 
varying from 20 to 25 and from 25 to 30 seconds ; from the 
jugular to the sapheena, in 20^; from the jugular to the external 
maxillary artery, in from 10^ to 15% and in another instance 
from 20^ to 25^; from the jugular to the metatarsal artery from 
20' to 25% and from 25= to 30'; once it required 40'. 

From other experimentsf Hering has concluded that the ve- 
locity of the blood is independent of the frequency of the heart's 
action. The prussiate of potass was not detected more quickly 
than usual when the heart's action had, in numerous instances, 
been greatly quickened by infusion of tinct. of white hellebore, 
camphorated spirit, &c. If, with Hales, we estimate the weight 
of a horse at SOOlbs., and his blood at 40lbs., which is certainly 
not too high an estimate, and allow ten ounces to be thrown 
from the heart at each systole, (the greatest possible quantitj^,) 
then 1"* 37^ will be the least time in which the whole mass of 
the blood will go through the heart*. And though the circula- 
tion consists not of one, but of many circles, the smallest being 
that of which the course through the coronary vessels of the 
heart forms part, and though each of these circles be performed 
in a different time, yet it appears difficult to make any probable 
supposition respecting the circuit taken by the substances in- 
jected in the above instances which will satisfy the rapidity 
with which they were detected. How then is their quick trans- 
ference to be explained ? Probably, as is suggested by Miiller, 
the foreign fluid diffuses itself through the mass of the blood 
more rapidly than the latter circulates. 

* Zeitschrift fiir Physiologic, vol. iii. f Zeitschrift, vol. v. part 1. 

X Burdach. 



14S 



Report on the Recent Progress and Presejit State of Zoology. 
—By the Rev. Leonard Jenyns, 3I.A., F.L.S. F.Z.S. 
F.C.P.S. 

The following Report has been drawn up at the request of the 
Section for Natural History of the British Association. I can- 
not but express my regret that the task has not devolved upon 
abler hands. The science of Zoology comprises such a wide 
field, and so much has been effected in that field by the researches 
of modern times, that it is difficult for any individual to obtain 
a correct knowledge of all that is going on in different coun- 
tries in its several particular departments. Still more difficult 
is it to form in all cases a true estimate of the relative import- 
ance of the many facts and discoveries which are every day com- 
ing to light, — to judge of their nuitual bearing on each other, 
and their more or less immediate tendency to advance the pro- 
gress of that science for the interests of which they are brought 
forward. I must therefore hope for much indulgence from those 
who may discover in this attempt, what it is almost impossible 
to avoid, many errors as well as omissions*. I have endeavoured 
to avail myself of whatever sources were open to me, in order to 
obtain the information requisite for the purpose ; but so numer- 
ous are the channels through which such information is now 
published, that I can hardly hope to have gleaned on this sub- 
ject all which may be expected of me. 

It is right, however, tlaat I should state in the outset, in what 
point of view, and within what limits, I propose to consider this 
subject. To follow it out in all its details would manifestly lead 
me far beyond the bounds to which a Report of this nature must 
necessarily be restricted. My intention, then, is principally to 
notice those researches which of late years have tended to eluci- 
date the characters and affinities of the larger groups of animals, 
and thereby to advance our knowledge of their natural arrange- 
ment. This will include the consideration of such systems as 
have been brought forwards in illustration of this part of the 
subject. With reference to this point, however, I do not pur- 
pose commencing from an eai'lier period than 1817, the year of 
publication oi the Regne Animal oi Cuv'iqv, whose general views 
respecting the classification of animals have been the basis of 
most of those which have appeared subsequently. I propose, 
nevertheless, in the first instance, to make a few general remarks 

* I fear that these omissions will be found rather numerous, with respect to 
German works, some of which I have been imable to procure, whilst there are 
probably others altogether unknown to me. 



144 FOURTH REPORT 1834. 

on the state of zoology in the early part of the present century, 
and the circumstances which have led to the introduction of those 
principles upon which it is now studied. 

I. Introduction. 

It is now generally acknowledged, that the true and legitimate 
ohject of zoology is the attainment of the Natural System ; and 
we may attribute it to this circumstance, and the consequent 
close investigation of structure and affinity to which it has led 
naturalists, that so striking a change has been effected of late 
years in this science, causing it to assume an aspect at once cha- 
racteristic of a distinct epoch in its history. Little else ap- 
peared to be the aim of Linnaeus and his followers beyond 
that of distinguishing sjiecies, and classing them simply in 
accordance with some law of arrangement arbitrarily assumed 
in the first instance, and too often pertinaciously adhered to in 
utter disregard of the general organization ; and although it may 
have been their endeavour to group together those species a- 
niongst which there appeared a certain resemblance, yet they 
did not hesitate in numberless instances to associate in the same 
class and order, and often in the same genus, beings of the most 
discordant nature, rather than renounce the principle which they 
had adopted for their guide. It is undoubtedly to Cuvier that 
we are most indebted for the striking improvements which be- 
gan to be made upon the Linnaean system towards the close of 
the last century*. This great master of modern zoology saw 
the importance of studying the entire organization of animals. 
He ti-aced the connexion which subsists between their internal 
and external structure, observed how these accorded with their 
habits and oeconomy, and perceived that in grounding a classi- 
fication of animals upon characters taken from these sources col- 
lectively, we should make a near approach towards grouping 
them according to their true and natural affinities. Daubenton 
and Pallas had already furnished some materials for such an un- 
dertaking, and by their exact descriptions, paved the way for a 
more complete knowledge of animal structure ; but it was re- 
served for Cuvier to erect the building of which they may be 
said to have only laid the foundation. Commencing with a re- 
investigation of the invertebrate animals, which, according to the 
statement of the French naturalist, Linnaeus had left in a state 

• It is not meant that there were none others besides Cuvier who had any 
share in effecting this change, but only that he appears the most prominent. 
Bruguieres, Geoifroy St. Hilaire, Latreille, and Lamarck, especially the last, all 
contributed to this end in their several departments. The labours of some of 
these naturalists will be alluded to further on. 



REPORT ON ZOOLOGY. 145 

of worse arrangement than that of Aristotle, he afterwards passed 
on to that of the higher classes*, carrying with him that reform 
which the new principles he had adopted pointed out to be ne- 
cessary. Cuvier's first memoir on the Invertehrata was offered 
to the notice of the Natural History Society of Paris in 1795, 
and the time should be remarked as commencing the sera of a most 
important revolution in zoological science. His Tableau Elemen- 
taire de V Hist. Nat. des Aninumx, containing a still further 
development of his views, was only two years posterior to it. 
This was followed by the Leqons d' Anatomie Comparee, pub- 
lished in 1800 and 1805 ; a rich series of memoirs on the mollus- 
cous animals, which appeared in the earlier volumes of the An- 
nalesdu Museum; the Recherches sur les Ossemens Fossiles, of as 
great service to zoology as geology, and much of which was also 
firstpublished in that collection; and lastly, in 18l7,by the^^^we 
Animal, in which it was attempted to arrange all known animals 
according to their natural affinities, as deduced from a compara- 
tive view of their M'hole organization. 

The above works, of some of which 1 shall have occasion to 
speak further hereafter, were not only important in themselves, 
but in the consequences to which they led. 

In the first place, it is worthy of remark, that since these ad- 
mirable endeavours on the part of Cuvier to elucidate the true 
relations of animals by reference to their internal as well as ex- 
ternal structure, and to the modifications, not of one or two ar- 
bitrarily selected organs, but of all the organs considered jointly, 
naturalists have everywhere felt the necessity of guiding their 
researches after the same manner, and building upon a similar 
foundation. If zoology has made much progress, as undoubtedly 
it has, since the publication of the first edition of the R^gne Ani- 
mal; if more enlarged views have been acquired of the science 
as a whole, and a more correct knowledge gained of some of its 
subordinate branches ; if new forms of structure have been dis- 
covered, and affinities brought to light, which at that time were 
not even suspected to exist by its illustrious author ; this is great- 
ly due to the assistance which the science has derived fi-om com- 
parative anatomy : and it must never be forgotten, that it was 
Cuvier principally who first taught us, in the works above alluded 
to, how to bring this great and powerful instrument to bear 
upon the researches of the naturalist. Yet it must not be sup- 
posed from the intimate connexion which subsists between these 
two sciences, that there is no line of distinction to be drawn 

• In the arrangement of the Mammalia, Cuvier was much assisted by Geof- 
froy. Their joint labours in this department form the subject of a memoir pub- 
lished in the Magasin Encyr.lopedique, torn. ii. p. 164. 
1834. L 



1 16 FOURTH REPORT — 1834. 

between theui. It is the object of the anatomist to investigate 
the details of structure, and to record all facts connected with 
the relative organization of animals. That of the zoologist is to 
arrange these facts, and to make them subservient towards de- 
termining the natural affinities of animals. Hence the latter is 
but little concerned with any details Avhich do not exercise a 
marked influence upon the manner of life, or with those minute 
differences of structure which are not accompanied by corre- 
sponding differences in the rest of the organization*. What he 
seeks for is a subordination of characters, selected in the order 
of their importance, on which to build his system ; and to judge 
of the value of any one in particular which anatomy pi'esents to 
him, he must trace by observation how far it is connected with 
others, whether external or internal, or derived from the oecono- 
my and mode of life, of which the value is knowTi. On such a 
comparison, it may prove of too small importance to assist in 
determining the affinities of a single species. Yet we can hardly 
pronounce that it may not be found of some value hereafter ; 
for although it may not in itself be sufficient to establish an affi- 
nity, it may tend to cori'oborate our ideas respecting those which 
M'ould seem already indicated by other characters. And con- 
sidered in this view, even the minutest anatomical details may 
prove of service to zoology. As an instance in point, we may 
refer to Mr, Owen's recent discovery of a peculiar modification 
of the stomach in the genus Semnopithecus\ . This genus had 
been originally established by Geoffroy upon a slight difference 

* It has been a complaint with some natm-alists that zoologjf has of late 
years been too much invaded by comparative anatomy, and that it has been in 
danger of suflering from the encroachments of that allied science which was 
originally called in to its assistance. i"or remarks on this subject the reader is 
referred to the article Zoologie in the Diet. Class. d'Hist. Nat. (p. 727), and the 
Introduction to the Hist. Nat. des Mammiferes, (p. 2, &c.) by M. Fred. Cuvier. 
Mr. Swainson would also seem to say as much in \\\& Preliminary Discourse on 
the Study of Nat. Hist. (pp. 84, 169, &c.), published since this Report was read. 
To a certain extent there may perhaps be some ground for the complaint; but 
it appears to me that it is only called for in those cases in which it has been 
attempted to arrange animals solely from anatomical characters, no considera- 
tion being paid either to external form or to the habits and manner of life. We 
may fall into the error of attaching too much importance to differences of inter- 
nal structure, as easily as we may in the case of those of external. The fact is, 
the whole must be considered collectively, and it is the relative value of the or- 
gans, when viewed in their mutual dependencies, which alone should decide 
on which of them we are to base our system. But after having determined our 
groups in this manner, we may generally succeed in finding, at least amongst 
the higher animals, some external character by which they may be distin- 
guished. And wherever this is the case, I fully agree with Mr. Swainson 
(pp. 169 and 247), that for convenience sake such external characters should 
be exclusively employed. 

f Zool. Trans., vol. i. p. 65. 



REPORT ON ZOOLOGY, 147 

onl)^ in the dental system, and there were some doubts as to whe- 
ther it should be retained. Now, however, that we find it also 
characterized by an accompanying difference in the internal or- 
ganization, its claims to be admitted as a distinct group in the 
system are considerably strengthened. In another communica- 
tion this able anatomist has expressed an opinion*, that even 
such details as tracing the convolutions of the brain "may ad- 
vance zoology, by bringing to light additional instances of affi- 
nities between the different groups of Mammalia;" and he 
grounds this opinion upon the fact of his having observed a re- 
markable uniformity of structure in this organ, in groups which 
have been long since well established upon other characters. 
At the present day, however, it is amongst the lower animals 
that the researches of the anatomist will most assist zoology. 
The structure of the higher classes is in general well understood, 
and it is not likely that any future discoveries in anatomy will 
much affect our present arrangement of the leadnig groups in 
those classes, however they may contribute to the perfecting the 
details of the system. But amongst the Invertebrata it is far 
otherwise. There we not only find large groups of animals of 
whose internal structure we know but little, but they are often 
groups in which the external characters cannot be tiaisted, and 
in which it becomes necessary to resort to the same organs for 
distinguishing orders, families, and even genera, which in the 
Vertehrata would only be employed in characterizing classes, or 
groups of a still higher denomination. This arises from the much 
more variable structure of the lower animals, with which there- 
fore it becomes the more necessary for the zoologist to be ac- 
quainted. 

Another circumstance which has in some measure resulted 
from Cuvier's labours relates to the country in which these la- 
bours were exerted, and their fruits made public. His works 
have had a manifest influence over his countrymen. Those who 
surrounded him quickly adopted his new views and principles ; 
and partly to this circumstance, partly to the magnificent esta- 
blishment of the Jardin ties Plantes, are we to attribute the 
gradual rise of a school of zoology ia France, which has ever 
since maintained the highest reputation. It is only necessary 
to refer to some of the many valuable works which appeared 
during the early part of the present centviry, in order to appre- 
ciate the zeal and success with which zoology was cultivated in 
that country. Lamarck's Systbme des Animaux sans Vertehres 
and Philosophic Zoologique, Dumeril's Zoologie Analytique, 
LatreiUe's Hist. Nat. des Crustaces et des Insectes, the Genera 
* Zool. Trans., vol. i. p. 136. 

l2 



148 FOURTH REPORT — 1834. 

Crtistaceomm et Insectorum by the same aiithor, Broiigiiiart's 
EssaicVime Classification NutureUe des Reptiles, Savigny's J/e- 
moires snr les ^■inimau.v sans T''ert^bres, Lamoiiroux's Histoire 
des Pull/piers CoraUighies Flexihhs*, (not to dwell upon a rich 
series of memoirs in the Aimales dn Museum, Journal de Phy- 
sique,hc., byGeoflfroy, Fred.Cuvier,Blainville, Peron, Lessuem*, 
and others,) all appeared before the publication of the JR^gne 
Animal, and not only contributed greatly to the further illustra- 
tion of the natural system, but furnished manj' valuable hints to 
Cuvierhimself whilst engaged in that undertaking. England, we 
fear, has but little to produce as the result of her labours in zoo- 
logy during the same period. Our countrymen were too much 
riveted to the principles of the Linnjean school to appreciate 
the value of the natural system. Although there were some good 
descriptive works in different departments, and a few excellent 
observers, amongst whom Montagu will ever hold a distinguished 
place, there was in general but little attention paid to structure 
with a view to elucidate the natural affinities of animals. The 
most remarkable, if not the only exception is undoubtedly to be 
found in Kirby's Monographia Apuni Anglice, a work which, 
though exclusively devoted to the illustration of a single Linnaean 
genus of insects, presents a model for naturalists in all depart- 
ments, from the profoimd views of its vei*y illustrious author. 
There were few, ho^vever, who followed up the path which was 
thus opened to them. There was a general repugnance to everj'- 
thing that appeared like an innovation on the system of Linnaeus; 
and for many years subsequently to the publication of the above 
work, which ajjpeared as far back as in 1802, zoology, which 
was making rapid strides in France and other parts of the Con- 
tinent, remained in this country nearly stationary. It is mainly 
to Dr. Leach that we are indebted for having opened the eyes of 
English zoologists to the importance of those principles which 
had long guided the French naturalists. Whilst he greatly con- 
tributed to the advancement of the natural system by his own 
researches, he gave a turn to those of others, and made the first 
step towards weaning his countrymen from the school they had so 
long adhered to. The following are the principal works which re- 
sulted from Dr. Leach's labours in zoology about the period of time 
referred to. In 1813, he published the article Crustaceology 
in the Edinburgh Encyclojicedia, in which he gave the system 
of Latreille, with some slight modifications. In 1814, he gave, 
in a paper to the Linntean Society, " A tabular View of the ex- 

* In the above list I have not included the splendid volumes by Desmarest, 
Vieillot, Audebert, &c., the object of which was more to illustrate species by 
coloured plates than to treat of their systematic arrangement. 



REPORT ON ZOOLOGY. 149 

tei'ual Characters of the four Classes of Cnistaced, BIyriupoda, 
Araclmida^ and Insecta, with the Orders and other Subdivisions 
of the three first of these Classes." In the same year he com- 
menced the Zoological Miscellany, which, though principally- 
intended for the illustration of new or little known species, con- 
tains (the 3rd vol. especially, published in 1817,) an indication 
of many new groups in different classes of zoology, with their 
characters and natural affinities. In 1 8 15, he published the article 
Entomology in the Edinburgh Encyclopccdia-, and in the same 
year he commenced th.e Malacostraca Podophthalma Britannice, 
which tended so much to our further knowledge of the Crustacea. 
Besides the above. Dr. Leach also wrote the articles Annxjlosa 
andCiRRiPEDES in the Supplement to the jEncyclop{edia£rita7i- 
nica, the latter containing an entirely new classification of these 
animals. It is much to be regretted, that soon afterwards the la- 
bours of this distinguished naturalist were interrupted by illness. 
He had prepared and nearly completed a valuable work on the 
British Molhisca, to the natural arrangement of which group he 
had devoted great attention. Part of it was printed, though 
never published. His other works, however, sufficiently testify 
the obligations conferred by him on zoologj^ At the same time 
they form a marked epoch in the history of this science, as con- 
nected with our own country. Since the time of their publica- 
tion many other excellent naturalists have arisen amongst us to 
contribute to its advancement, to whom I need make no further 
allusion at present, as of some I shall find occasion to speak 
hereafter. 

II. Of the primary Types of Form, and other leading Divisions, 
in the Animal Kingdom. 

Cuvier considered the animal kingdom as exhibiting four pri- 
mary types of form, to which he gave the names of Vertebrata, 
Mollusca, Annulosa, and Radiata. The leading characters are 
derived from the nervous system, which Virey was the first to point 
out* as the most important part of their organization, and there- 
fore the most fit to be selected as the groundwork of the system. 
Cuvier's first enunciation of this arrangement was in a memoir 
published in the 19th vol. of the Ann. du Mus. in 1812, being five 
years before the appearance of the R^gne Animal. In it he ob- 
serves, that he regards these four types or general plans as those 
after which all animals appear to have been modelled, and of 
which the subordinate divisions are only comparatively slight mo- 
difications, founded on the development or addition of certain 
parts, which produce no essential change in the original plan, 
* Nouv. Diet, d'llist. Nat., Art. Animal. 



150 FOCRTH RKI'ORT 1834, 

Before the date of this memoir, naturaUsts had generally a- 
dopted Lamarck's primary division of Vertebrate and Inverte- 
brate animals. Cuvier objected to this, on the ground that there 
were as great differences of structure amongst these last, as any 
of those by which they were separated from the vertebrate divi- 
sion. In his Hist. Nat. des An. sans Verthb. (the first volume of 
which was published in 1815), Lamarck somewhat modified his 
former views, by distributing animals under the three divisions 
of Intelligent, Sensible, and Apathetic. As this arrangement, 
however, is obviously objectionable, and has not met with much 
reception, I do not consider it necessary to dwell further on it*. 
I shall proceed, therefore, to notice some modifications of Cuvier 's 
system which have been proposed by different authors, as well 
as some new systems and principles of arrangement which 
have appeared since the publication of the R^gne A>iimal, and 
which from their impoi'tance appear deserving of consideration. 

The first in order of time, with which I am acquainted, is a 
modification of Cuvier's primary divisions proposed by Geoffroy 
in 1820, and which arose from his peculiar views respecting the 
unity of composition in animals. It is not necessary at the pre- 
sent day to enter into any detailed analysis of these views, which 
have been so long associated with the name of this distinguished 
naturalist, and which belong more to the department of compa- 
rative anatomy than zoology. It is sufficient to state that Geof- 
froy, who had previously endeavoured to show that all vertebrate 
animals were constructed so exactly upon the same plan as to 
preserve the strictest analogy of parts in respect to their osteo- 
logy f, thought to extend this unity of plan by demonstrating, 
as it appeared to him, that the hard parts of Crustacea and In- 
sects were still only modifications of the skeleton of higher ani- 
mals, and that therefore the type of Veriebrata must be made to 
include them also. It is impossible in this Report to follow up 
the train of reasoning and anatomical research which guided 
Geoffroy in his attempt to establish this theory. The general 
results at which he arrives are, that the segments of the Annu- 
losa are strictly analogous to the vertebrae of the higher animals, 

* Although Lamarck's leading divisions are ohjectionahle, there is much in 
his system which is extremely valuable, particularly as i-espects the arrangement 
of the Invertehrata. He was the first to point out that these last, if placed ac- 
cording to their true affinities, must be considered as forming two distinct sub- 
ramose series, one consisting of the articulated, and the other of the inarticu- 
lated invertebrate animals. — See the Supplement to his first volume, p. 4o7. 

■\ Geoflfroy's principal memoirs relating to this subject were collected into one 
volume, and published in 1818 under the title oi Philosophie Anatomiqiie. Se- 
veral others however, more or less connected with it, are to be found in the Ann. 
du Mus. 



REPORT ON ZOOLOGY. 151 

and that the former live within their vertebral column, in the 
same manner as the latter do tvithout. It is clear that, assiun- 
ing the correctness of these views, it becomes necessarj'^ to make 
some alteration in the leading divisions of Cmder's system. The 
following is the arrangement proposed by Geotfroy : 

rv f K ' / Hants- Vertebres. {Vertebres, C\xv.) 
I verteDves. j Dermo-Vert6br^s. {ArticvUs, Cuv.) 
Aiiimaux < ,., , ( Mollusques. {Mollusques, Cuv.) 

( inverteDres. | R^yonn^s. {Rayonnes, Cuv.) 

Thus we have a primary division into vertebrate and inverte- 
brate animals, before arriving at Cuvier's four types, talcing 
however the term vertebrate in a much more extended sense 
than did Lamarck, or any other previous author, and likewise 
that of invertebrate in a more restricted one. Geoffroy's me- 
moirs on this subject were published, as already stated, in 1820, 
in the Jonrnal Complementaire* , &c. He subsequently fol- 
lowed up the same views in some other publications, more 
especially in a paper in the 3Iem. du Mas. for 1822t, in which 
he entered into a strict analysis of the structure of the -vertebra, 
first as it occurs in the higher animals, and afterwards as it ap- 
pears, though modified, in the segments of the AnmdosaX. His 
theory, I believe, has been adopted by many of the French and 
German naturalists, as well as by some in other countries. 
Amongst the former, I may particularly mention Robineau- 
Desvoidy, who in 1828 published a work§ in order to substan- 
tiate, by still further illustration, the vertebral structure of the 
Crustacea, Arachnida, and Insecta. Towards the conclusion, he 
has pointed out the necessity (as it appears to him) of institut- 
ing several new classes amongst the annulose animals. It may 
be much doubted, however, whether these new classes will ever 
be adopted generally, whatever may be the fate of those theore- 
tical views which have alone suggested them ||. 

, * " M^moires sur 1 'Organisation des Insectes," Journ. CompUm. du Diet, 
des Set. Med., torn. v. p. 340; and torn. vi. pp. 31 and 138. 

+ tom.ix. 

X See also his Cours de V Hist. Nat. des Mammiferes, Le^. o^, published in 
1829. 

§ Rec/ierches sur V Organisation vertehrale des Crustaces, des Ai-achnides, et 
des Insectes. Paris, 1828, Svo. 

II As connected with the subject of the differences and resemblances between 
vertebrate and invertebrate animals, I ma)' refer to two recent memoirs, of 
which abstracts will be found in L'lnstitttt. The first, entitled " Recherches sur 
les Parties dures des Animaux Invertebres, par M. Dupuy," was read to the Aca- 
dem5' at Toulouse, Jan. 1833. {L'Institut, 1833, p. 3.) ' The other is a memoir 
by Dutrochet, " Sur I'Opposition qui existe entre les Animaux Vertebres et les 
Animaux Invertebres," read to the Academy of Sciences at Paris in March 
last. (See L'Jnstit. 1834, p. 90.) 



152 f'OURTH UEPORT — 1834. 

A slight moditiciitiou of Geoffroy's views has been adopted by 
M. Dumortier, and recently published in a memoir on the com- 
parative structure of plants and animals, in the 16th vol. of 
the jVov. Act. S)C. Nat. Cur.'*. Like Geoffro)^, he considers 
the hard parts of Crustacea and Insects as strictly analogous to 
the osseous system of the Fertebrata ; but instead of the two pri- 
mary groups into which he distributes animals, M. Dumortier 
would adopt the three divisions oi Endosceleta, Exosceleta, and 
Asceleta, the second answering to Geoffroy's Dernio-Vertthres, 
and the third to his Invertebres. These are given in a tabular 
form, with the secondary groups into which he thinks the animal 
kingdom shbuld be divided, amounting to twelve in number, also 
annexed. In a former part of his paper, M. Dumortier has 
entered into considerable details on the subject of the analogies 
which may be observed between the above three primary groups 
of animals, and the corresponding primary groups in the vege- 
table kingdom. It would, however, occupy too much room to 
enter into any more extended analysis of his views. 

In 1821, Mr. MacLeay published the second part of his Horce 
EiitoinologiccB, in which he proposed a new arrangement of the 
leading groups of the animal kingdom, and considered them as 
referrible to five primary types, instead of four, the number 
adopted by Cuvier. The new type, which he has called Acrita, 
he intended should include the least organized of the Entozoa 
of Rudolphi, as well as Cuvier's classes of Folypi and Infusoria, 
all which he considered as not sufficiently showing the true ra- 
diated structure characteristic of the type to which Cuvier referred 
them. Mr. MacLeay observed, that the necessity for this step had 
been previously pointed out, though indirectly, by Lamarck and 
Blainville. The establishing of this new group was not, however, 
the most importantfeature in the Horce Entomologicce. Mr. Mac- 
Leay announced some new principles connected with the clas- 
sification of animals, which, from the circumstance of their having 
led to a peculiar school of zoologists in England, it will be ne- 
cessary to consider a little more in detail. The most important 
of these principlesf are : 1st, That all natural groups, of ichut- 
ever detioinination, return into themselves, forming circles; 
iindly, That eachof these circular groups isresolvahle intoexactli/ 
Jive others; 3rdly, That these Jive groups always admit of a 
binary arrangement, two of them being what he calls tj'pical, 
the other three aberrant; 4thly, That while proximate groups 

* p. 306. 

t It may be observed, that Mr. MacLeay lias nowhere formally stated these 
principles as above. They are only gathered I'rom what he has written on the 
subject. 



REPORT ON ZOOLOGY. 153 

in any circle are connected hy relations of affinity, corre- 
sponding groups in two co)itigt(ous circles are connected by 
relations of analogy. Mr. MacLeay has also observed*, that, 
in almost every group, one of the Jive minor groups, into 
which it is resolvable, bears a resemblance to all the rest ; or, 
more strictly speaking, consists of types ivhich rejjresent those 
of each of the four other groups, together with a type peculiar 
to itself. These principles had been partly brought forward by 
Mr, MacLeay, two years before, in the first part of the work 
above mentioned. It was then, however, with exclusive refer- 
ence to the natural arrangement of the Lamellicorn Insects, in 
which group we are told it was that he was first led to detect 
them. It was not till 1821 that he applied them more generally, 
in showing that a tendency to circles prevailed throughout na- 
ture, and that the same principles which he had observed to re- 
gulate the natural arrangement of the above group, appeared to 
regulate that of the entire animal kingdom. It is somewhat re- 
markable, and certainly tending to confirm Mr.MacLeay's views, 
that in the same year, and apparently without any knowledge 
of the first part of the Hone Entomologicce, M. Fries, in Ger- 
many, published his Systema Mycologicum, in which he an- 
nounced principles somewhat similar to those above stated, as 
regulating the natural distribution of Fungi. This gave rise to 
a paper from Mr. MacLeay, read the following year to the Lin- 
naean Societyf, in which he commented on this identity (so ftir 
as the identity prevailed,) of the principles which they had 
respectively adopted. He also pointed out wherein they dif- 
fered; one difference consisting in the determinate number, which 
M. Fries considei-ed as four, being the same as that formerly ad- 
vanced by Oken. Mr. MacLeay's arrangement of the Lamel- 
licorn Insects in the first part of the HorcB Entomologica; was 
the result of rigid analysis, and is therefore deserving of the 
greatest attention ; that however of the entire animal kingdom 
in the second, was chiefly deduced from synthetical investigation, 
and was moreover confined to the larger and more important 
groups. It is not, therefore, surprising that many endeavours 
should be made subsequently by himself, as well as by those 
who had adopted more or less of his theory, to illustrate 
his new principles by a more close application of them to 
different departments of zoology. The first result was a paper 
by Mr. Kirby, in 1822:|:, in which he described some insects that 
appeared to exemplify Mr. MacLeay's doctrine of affinity and 
• Hor. Ent., p. 518. f Linn. Trans., \<A. xiv. p. 16. 

X Linn. Trans., vol. xiv. p. 93. 



154 FOUKTH llEPORT — 1834. 

analogy. In 1823*, Mr. Vigors made an application of Mr. Mac- 

Leay's principles to the class of Birds, pointed out the orders 
and families, and endeavoured to show that the natural affinities 
which connect the several groups in that class obeyed the same 
laws as those laid down in the Horce Entomologiccc. The same 
author subsequently followed up this inquiry in some particular 
families of the same classf. In 1824 J, Mr. MacLeay applied his 
own principles to the arrangement of the Molhisca Tunicata. 
In the same year Mr. Swainson endeavoured§, with reference 
to the circular and quinary system, to work out the natural 
affinities of the family of LaniidcB in ornithology. In 1825, 
appeared the first number of the Annulosa Javanica, in which 
Mr. MacLeay again brought his views to the test by appUang 
them to the natui'al arrangement of the insects collected in Java 
by Dr. Horsfield. Circumstances prevented Mr. MacLeay from 
proceeding with this arrangement beyond that of a small portion 
of the Coleoptera ; but Dr. Horsfield himself subsequently pro- 
ceeded to publish the Lejndopfera || classed according to the 
same principles. In the same year, (1825,) Mr. Gray published an 
attempt at the natural distribution of the Mammalia into tribes 
and families^, and likewise of the genera of the classes Reptilia 
and Amphibia** . Both these, but the former more especially, 
were intended to illustrate Mr.MacLeay's principles. In 1826ff, 
Mr. MacLeay gave the i-esult of some anatomical investigations, 
which tended to confirm the accuracy of Mr.Vigors's arrange- 
ment of Birds. In the same paper he considered the affinities 
which connect the various orders of Mammalia, the point of 
transition from this class to Aves, and -the true analogies 
existing between the respective orders of the two classes. 
In 1827^^5 Mr. Swainson gave a sketch of the natural affi- 
nities of the Lepidoptera diurna of Latreille, being also an 
application of Mr. MacLeay's principles. Lastly, in 1831, ap- 
peared the second part of the Fauna Soreali-Amencaiia, in 
which Mr. Swainson, still adopting Mr. MacLeay's views in 
part, but modifying them according to what (since his former 

* Linn. Trans., vol. xiv. p. 395. 

-f- Zool. Journ., vol. i. p. 312. and vol. ii. p. 368. 

X Linn. Trans., vol. xiv. p. 527. § Zool. Journ., vol. i. p. 289. 

II Descriptive Catalogue of the Lepidopterous Insects contained in the Mu- 
seum of the Hon. E. India Company, ^-c, with introductory Observations on a 
general Arrangement of this Order of Insects. 4to, 1828, &c. 

t Ann. Phil., vol. xxvi. p. 337. ** Id., vol. xxvl. p. 193. 

W Litin. Trans., vol. xvi. p. 1. 

XX Ann. Phil., vol. i. p. 180. 



RKl'ORT ON ZOOLOGY. 155 

papers) he has conceived to make a nearer approach to the true 
natural system, endeavoured to work out an amended arrange- 
ment of some of the principal groups of birds. The modifica- 
tions which Mr. Swainson has been led to make in this work of 
Mr. MacLeay's principles are these. He conceives, that although 
every natural group is resolvable into five others, the primary 
division is into three, each of M'hich forms its own circle : he 
thus rejects Mr. MacLeay's binary distribution of his five groups 
into typical and aberrant, which last not forming circles, would 
seem to be rather at variance with his own principles. He has 
also stated more precisely the law by which it appears to him 
the relations of analogy are governed. It is thus given : The 
contents of every circle or group are symholically represented, 
by the contents o/all other circles in the same class of animals ; 
this resemblance being strong or remote, in proportion to the 
proximity or the distance of the groups compared* . This prin- 
ciple, which Mr. Swainson terms the theory of representation, 
he considers as affording the only certain test of a natural group. 
Mr. MacLeay had considered such a test to be afforded by a 
group returning into itself, which Mr. Swainson thinks not 
suflBcient, on the ground that there is not one group in three 
which c«n be so tested ; this arising partly from our superficial 
acquaintance with forms, and partly, as he believes, from there 
being many real gaps in the chain of continuity. It will be 
observed that Mr. Swainson has been the first to bring forward 
any nevt^ laws of arrangement at all analogous to those originally 
developed in the Horce Entomologies ; and it is right to state, 
that the above are not mere hypothetical deductions, but have 
resulted from eight years' close analysis of the order Insessores 
in the class of birds, with reference to which order principally 
it is that he has illustrated them in the Fauna Boreali-Ame- 
ricana. 

It is evident that the necessary limits of this Report foi'bid any 
further analysis of Mr. MacLeay's theory, or of the several works 
and memoirs above referred to. To some of these last I shall 
have further occasion to allude afterwards. What has been ad- 
vanced may tend, however, to point out the influence which this 
theory has had over our own naturalists ; and if they have not 
been all equally successful in their endeavours to apply it to 

• M. Isidore Geoffroy St. Hilaire, in France, has also attended to the subject 
of analogies in zoology, and endeavoured to refer them to some general law. The 
reader is referred to a note attached to a memoir published by him in the Nouv. 
Ann. (hi Miis., torn. i. p. 380, in which he has given a slight sketch of his views 
on this point. He proposes to make it the subject of a distinct paper at some 
future opportunity. 



15G FOURTH RE TOUT 1834. 

different branches of zoology, these attempts have on the whole 
certainly advanced our knowledge of natural groups, and deve- 
loped many affinities before unsuspected. At the same time it 
is difficult to believe that there is not some truth at the bottom 
of this theory, however erroneous it may be in its details ; and 
that some of its details are erroneous, as w^ell as many of the 
subordinate arrangements in the system which has been built 
upon it, is almost certain, from many facts which have been 
brought forwards of late years, as well as from that difference 
of opinion* which exists with respect to these details amongst 
those who admit the fundamental principles. Neither are these 
fundamental principles entirely new. Mr. MacLeay has himself 
shownf that his doctrines have all been in some measure ad- 
vanced by authors prior to the publication of the Horce Ento- 
mologicce ; which circumstance, while it tends to strengthen our 
conviction that they have more or less of truth in them, does not 
detract from Mr. MacLeay's mei'its in having developed them 
far beyond what any of his predecessors had done. To him we 
are certainly indebted for having pointed out the exact nature of 
the difference between affinity and analogy in natural history, 
however these two kinds of relation may have been observed by 
former authors^. He was also the first to establish by proof 
circular affinities. He has sufficiently demonstrated their exist- 
ence in certain groups, to lead us to suspect that it is only our 
as yet imperfect knowledge of forms, and the gaps necessarily 
arising from the circumstance of many foriiis having become 
extinct, which prevents us from tracing their existence gene- 
rally. And these are by far the most important of Mr. MacLeay's 
principles. Whatever of error there may be in the rest of his 
views, whatever modifications already have been, or may yet 
further be made in them, by the help of the above principles he 
appears to have approached nearer than any before him to the 

• This difference of opinion more especially respects the determinate num- 
ber. While Mr. MacLeay considers it as five, and Mr. Swainson as three, Mr. 
Kirby is of opinion that it will turn out to be seven. {Introd. to Ent., vol. iii.p. 15.) 
It must be stated that this gentleman has hitherto brought nothing forward in 
support of this last number. It has, however, found an advocate in Mr. New- 
man, who has also endeavoured to establish some other modifications of Mr. 
MacLeay's theory. See a small tract, called Sphinx Vespiformis, published in 
1832. 

f Linn. Trans., vol. xvi. p. 8. 

X I add this because, some time back, there was a controversy between M. 
Virey and Mr. MacLeay on the question of priority with respect to the above 
distinction. See a review, by the former, of some of Mr. MacLeay's opinions in 
Btdl. des Sci. 1825. tom. iv. p. 275, in which M. Virey states having made this 
distinction long before in the Notiv. Did. d'Hisl. Nat., Art. Animal. Mr. Mac- 
Leay has replied to M. Virey in Zool. Jottrn., vol. iv. p. 47. 



REPORT ON ZOOLOGY. 157 

true natural system, and (as has already been twice observed*) 
been enabled to " reconcile facts which upon no other plan can 
be reconciled." 

It is necessary now to revert in point of time, for the purpose 
of noticing some works which appeared on the Continent during 
the above period. In 1821, Oken published his Esquisse de 
Systhne d' Anatoinie, de Fhysiologie, et d'Histoire Naturelle. 
This celebrated German naturalist is well known to have im- 
bibed some very original views connected with the classification 
of animals, which have led to a peculiar school of zoology in 
Germany, in like manner as those of MacLeay have in England. 
I regret that I am unable to say much of his system, which how- 
ever I believe to be only a modification of one which he had 
before published in some of his earlier worksf. It is based 
upon a theory which supposes the animal kingdom to be deve- 
loped after the same order as that in which the organs are in 
the body. He considers that these organs form, characterize, 
and represent the classes ; and that there are the same number 
of classes as there are organs. He also attaches to them names 
derived from the organs. Fanciful as this theory appears, it 
has not only had many followers in Germany, but has given rise 
to several attempts at a natural classification of animals founded 
upon analogous principles. Such is the " Synoptic Table of the 
Animal Kingdom," published at Dresden,inl826, by Ficinus and 
Carus|, in which the leading divisions are based upon views 
somewhat similar to those of Oken. In 1827, Leuckhart also 
published, at Heidelburg, " An Attempt towards a Natural Clas- 
sification of Intestinal Worms, followed by a Table of the 
Affinities of Animals in general," constructed upon the same 
principles§. I am unable to notice these works more particu- 
larly, but I conceive that it would be unnecessary, were it in 
my power to do so. 

In 1822, Blainville published his Principes d' Anatomie Com- 
paree, annexed to which are some Synoptic Tables of the Ani- 
mal Kingdom, containing a slight modification of a new system 
first brought forward in 1816 in the Journal de Physique\\. 
In tliis system, the primary divisions, which are called sub- 
kingdoms, and are three in number, are established on characters 

* Kirby, Introd. to Entom., vol. iv. p. 359 ; and Swains. Fn. Bor. jIm., part 2. 
p. xlvi. 

t Philosophy of Nature, (in German,) Jena, 1809, 3 vols. 8vo. Also, Trea- 
tise on Natural History, (in German,) Jena, 1816. Oken is also the editor of 
a valuable German periodical, called Isis, containing many important papers iu 
zoology. He was the first in Germany to abandon the Linnsean system. 

X Bull, des Sci. 1829, torn. xvii. p. 258. § Id., 1829, torn. xvii. 

It torn. Ixxxiii. p. 244. 



158 FOURTH REV'ORT — 1834. 

taken from the general form, which Blainville finds in accord- 
ance with those derived from the nervous system when this is 
present. The first of these subkingdoms he terms Artiomorphes 
or Artiozoaires, being that in which the form is symmetri- 
cal, or the parts disposed symmetrically on each side of the 
body ; the second, Actinomorphes or Actitio-^oaires, in which 
the parts radiate from a common centre ; the third, Hete.ro- 
morphes or Heterozoaires, in which the form is indeterminate. 
The ArtiomorpJies are referred to three secondary types, cha- 
racterized from the arrangement of the locomotive organs : 
(1.) Osteozoaires, in which the body and limbs are composed of 
several pieces articulated together, the articulations not being 
visible from without; (2.) Entomozoaires, in which the body 
and limbs are likewise articulated, the articulations being exter- 
nally visible ; (3.) 3Ialacozoaires, in which the body is of one 
single piece, and not divided into several parts. The Osteo- 
zoaires are the same as the Vertehrata of Cuvier. The Ento- 
mozoaires answer nearly to his AtDiuhsa, including, besides the 
classes referred to that type in the liegiie Animal, the Entozoa, 
and likewise the Cirripeda and the genus Chiton. These two 
last groups, however, form a subtj^pe, which Blainville calls 
Malentozoaires or MoUuscarticiiUs. The Malacozoaires cor- 
respond to the Mollusca of Cuvier, excluding the Cin-ipeda 
and the genus Chiton just mentioned. "The second subking- 
dom, Actinomorphes, comprises the Hadiata of Cuvier, with the 
exception of the Sponges, Infusoria, and Stony Corallines, 
which compose the third subkingdom, or Heteromorphes. 
Blainville's system, though different from Cuvier's, deserves to 
be studied, from its indicating many new affinities which had 
not been before noticed. Its author however has adopted, and 
in many instances very unnecessarily, an entirely new nomen- 
clature, which alone has been sufficient to prevent it from having 
been generally received by naturalists. 

In 1825, Latreille published his Families Naturelles dii 
Regne Animal, in which he considers the animal kingdom as 
primarily divided into three great series : Vertehrata, the essen- 
tial character of which group he does not derive however from 
the vertebral column, so much as from the presence of a brain, 
consisting always of a cerebrum and cerebellum, and the great 
sympathetic nerve, whereby it is particularly distinguished from 
his second group, Cephalidia, in which the brain is only rudi- 
mentary, and the third, Acephala, in which it no longer exists. 
His Cephalidia embrace the Annulosa and Mollusca of Cuvier, 
with the exception of the Ac&phales sans coquilles. These, with 
the Zoophytes of the same author, constitute his Acephala. 



KEPORT ON ZOOLOCy. 159 

Before arriving at the classes of the Vertehrata, Latreille adopts 
a previous division of this series into Ha:matherm.a (with wai-m 
blood,) and Hcemacrytna (with cold blood) . This last is again 
divided into Pulmonea and Solibranchia, according as the re- 
spiration is carried on by lungs or gills. In like manner we 
find his second series, Cephalidia, divided into the three races 
of Mollusca, Elrninthoida (comprising the classes Cirripedes 
and Annelkles), and Condylopa (with articulated feet). The 
Acephala also into Gastrica and Agastrica. Few will probably 
prefer Latreiile's three primary divisions to Cuvier's four types, 
or judge his arrangement on the whole to be more natural than 
that of the Regne Animal. His Cejihalidia, in particular, bring 
together under one head two very distinct groups which are well 
separated by Cuvier. 

The above are some of the principal systems, or modifications 
of that of Cuvier, which have been brought forwards since the 
first edition of the Rigne Animal * , In 1829 appeared the 
second edition of the work just mentioned, in which however 
there is no material alteration, at least as far as regards the dis- 
tribution of the leading groups- 

It may be thought by some that the subject is hardly deserving 
so much notice ; that the consideration of different systems, 
some of which perhaps we feel sure are grounded upon errone- 
ous principles, may be passed over as of not much importance 
to zoology. Cuvier will teach us to judge otherwise. He ob- 
servest that the affinities of animals are so complicated, that 
we ought thankfully to receive every endeavour to set them be- 
fore us in a new point of view. There are few systems which do 
not contribute something to our knowledge on this subject, and 
which do not thereby enable us to make some further advance 
towards that which is the end and object of the science, the 
natural system itself J. 

III. Of the several Classes in the Animal Kingdom. 
In entering on the consideration of the several classes of ani- 

• I have been obliged to omit the notice of certain worlds which may per- 
haps contain some new views respecting the arrangement of animals, but which 
I have been unable to get sight of. Such are the Elements of Zoology, (in Ita- 
lian,) by Ranzani, published at Bologna in 1S19, &c. ; and the Manual of Zo- 
°l"9!/, (ill German,) by Goldfuss, published at Nuremberg in 1820. In 1828, 
V'an der Hoeven also published a Tabular View of the Animal Kingdom, equally 
unknown to me except by title. 

•f Hist. duProgres desSci. Nat., tom. iv. p. 182. 

t Mr. MacLeay has well observed that " every discovery of an affinity is, in 
part, a discovery of natural arrangement." {Hor. Ent., p. 324.) 



IGO^ FOURTH REPORT 1834. 

mills, I may ol)serve, thiit it is not mj^ intention to do more than to 
convey a general notion respecting the state of our knowledge 
of the principal groups contained in them. At the same time 
I shall notice any recent researches which appear to throw 
light on their affinities, or to illustrate more clearly either their 
external or internal characters. Of these last I confine myself 
to such as are of immediate importance to zoology. 

I. Vertkbrata, Cuv. 

1. Mnmmalki. — Cuvier and GeofFroy greatly contributed to 
our knowledge of this class during the early part of the present 
century. The former by his investigation of fossil species sup- 
plied us with many new forms, serving in several cases as links 
to connect groups which before were widely separated. He 
also found it necessary, in order to determine the above with 
accuracy, first to examine more closely the structure of such 
species as are living at the present day. Owing to this circum- 
stance his Ossemcns Fossiles has conferred a lasting benefit on 
this department of zoology. His researches served to elucidate 
the history of numberless genera, and even led to the establish- 
ment of one entire family*, of which the true affinities had pre- 
viously been quite misunderstood. Geoff"roy also laboured much, 
and indeed has continued to do so to the present time, at the 
natural arrangement of these animals. His various memoirs in 
the Annales dii Museum and other French periodicals, more 
particularly those on the Marsujrialia, Cheiroptera, and Qund- 
rumana ; his splendid work also, the Histoire des 3Iammiferes, 
undertaken conjointly with M. Fred. Cuvier, are well known, and 
deservedly celebrated. Yet notwithstanding the laborious re- 
searches of these, and many other eminent zoologists, perhaps 
it is not advancing too much to affirm, that we are still in many 
cases far from understanding the real affinities of the Blanimalia, 
and less agreed about the primary groups into which they ought 
to be distributed, than in the instance of some other classes lower 
down in the systemf. This will appear by referring to the 
principal classifications which have been published since that of 
the Regne Animal. Cuvier, in the work just mentioned, admits 
the following eight orders : Bimana, Qiiadnimana, Ferce (Car- 
nassiers), Rodentia, Edentata, Pachydermata, Ruminantia, 

* The Herhioorous Cetacea. 

t This probably arises in a great measure from the paucity of forms which 
this class presents compared with others. Mr. MacLeay has observed, {Aiinul, 
Javan., p. xi.) that we arc more likely to detect the natural arrangement 
amongst Insects, from the circumstance of their presenting such a multiplicity 
of species, than in any other part of the system. 



REPORT ON ZOOLOGY. IGI 

Cetacea. Desmarets, in his Mammalogie, published in 1820, 
follows Cuvier. Blainville* distributes the Mammalia pri- 
marily into the two subclasses of Monodelphes and Didelphes, 
this last being instituted for the reception of the Marsii- 
pialia, and Monotremata of Geoffroy. His subclass of Mono- 
delphes includes seven orders ; of these the first five are the 
same as Cuvier's, only the Rodentia and Edentata are trans- 
posed, and the latter includes the Cetaceous animals, with the 
exception of the Lamentines : these last, with the P roboscidiens 
of Cuvier, form his sixth order, called Gravigrades : his se- 
venth order, Ongulogrades, comprises the rest of Cuvier's 
Pachydermata and his Ruminantia. Latreillef considers the 
Monotremata as a distinct class altogether. His class Mam- 
malia comprises Cuvier's eight orders, besides the three ad- 
ditional ones of Cheiroptera, Amphibia, and Marsiipialia (in the 
R^gne Anim. only subordinate groups in the order CarnassiersX.) 
Mr. MacLeay, in a paper in the Linncean Transactions^ already 
alluded to in a former part of this Report, dated 1826-7, adopts 
as primary divisions the old groups Primates, Feraz, GUres, 
Ungulata, and Cetacea, the first three, and last, being identical 
with the four Linnaean orders bearing the same names, the fourth 
(adopted from Aristotle and Ray) including the Linnaean orders 
BriitcB, Pecora, and Belliice. Mr. MacLeay has made some im- 
portant and interesting remarks on the series of affinities con- 
necting the above orders which deserve to be consulted, but which 
would occupy too much room here. He attempts to show that 
the chain returns into itself, forming a circle. He considers 
the whole class as passing off to the Birds by the Glires\\, and 
as also indicating an affinity to the Reptilia in the Monotre- 
mata, In 1827, Temminck published the first part of his valu- 
able Monographies de Mammalogie, at the end of which he 
gives a systematic arrangement of the whole class. He adopts, 
in addition to Cuvier's orders, those of Cheiroptera and Mono- 
tremata : the former is inserted between the Quadrumana and 
Carnivora ; the latter is placed at the end of the whole series, 
as serving to pohit out the transition to Reptiles and Birds. 

* Principes, SfC, tab. 3. t Fam. Nat. 

X Latreille thinks that at the end of the Quadrumana, the Mammalia divide 
themselves into two series: one composed of the Cheiroptera, Marsupialia, 
Rodentia, and Edentata ; the other of the Fera; Amphibia, Pachydermata, 
Ruminantia, and Cetacea. See Fam. Nat., p. 59, note (}). 

§ voh xvi. p. 1. 

II The analogy which exists between the organization of the Mammalia 
Rodentia and that of Birds, was pointed out by Professor Otto of Breslau the 
same year. HeeBull. desSci. 1827, torn. xii. 
1834. M 



162 FOURTH REPORT — 1834. 

The same year Lesson published his Manuel de Mammalogie : 
his arrangement, however, is the same as that of Cuvier. In 
1829, appeared the 2nd edition of the R^gne Aniynal, in which 
the Marsiipialia are considered as a distinct order ; in all other 
respects the arrangement is the same as that of the first. The 
same j'^ear Fischer published his Synopsis 3Inmmalium. His 
orders approach more in character to those of Linnaeus : he 
adopts, however, two more than that author : one, C/ieiroj)teray 
placed between the Primates and Ferce ; the other, which he 
terms Besticc, and which includes the Insectivora and Marsiipi- 
alia of Cuvier, following the order last mentioned. Also in 
1829, appeared a valuable treatise on the Mammalia by Fred. 
Cuvier, in the 59th volume of the Diet, des Sci. Nat. His 
arrangement differs in one respect from that of all his prede- 
cessors, in as much as he has thrown together in one order the 
first two families of the Carnassiers oi the R^gne Anim. and the 
Insectivorous Marsupialia, while of the Frugivorons Marsupi- 
alia he has made a separate order. He has also made distinct 
orders of the Amphibia and Monotremata. 

In 1830, Wagler published his NatUrliches System del' Ani- 
phibien, to Avhich he has prefixed a classification of Mammalia 
as well as oiAves. His orders in the former of these classes, 
amounting to eighteen, are miich more numerous than those of 
any other author. It is hardly necessary to specify them, as few, 
I conceive, will be disposed to adopt them all as primary divisions. 
They more properly deserve the name of families. Wagler con- 
siders ^\e Monotremata as a distinctclass, to whichhe gives the 
name of Gryphi. It maybe observed, that he also includes in it 
the fossil Ichthyosauri and Plesiosavri, as well as the Ornitho- 
cephalus of Sommerring*. 

In 1831, Charles Lucien Bonaparte published an arrangement 
of the Vertebrata\ differing in some respects from that of his pre- 
decessors. T\\Q Mammalia are primarily divided into the two sub- 
classes of Quadrujjeda and Bipeda, the latter being intended to 
receive the Cetaceous animals. The Quadrupeda are again divided 
into the two sections of Unguiculata and Ungulata. His 
orders resemble those of Fischer, excepting that he isolates the 
Marsujnalia, referring the Insectivora (with which they are 
associated by this last author) to the order Ferae. He also 

* Mr. MacLeayhas suggested in his Hora Enlomologicte, p. 267, that possibly 
the OrnUhoceplialus may have been the connecting link between Mammalia and 
Birds. 

f Sagglodi una Dislribuzione metodica degli Animali Vertebrati. 8vo, Rom. 
1831. 



REPORT ON ZOOLOGY. 103 

makes a distinct order of the Amphibia. Tiie Munoiremata 
he considers as a separate class*. 

On a review of the above systems it w\\\ appear how much 
difference of opinion exists respecting the value of certain groups, 
more particularly the Cheiroptera, Marsupialia, and Monotre- 
mata. To the number of those systematists who regard the 
Cheiroptera as a distinct order, we may add Geoffroy, whose 
opinion will have weight, when we remember the particular 
study which for many years he is known to have made of these 
animals. We may refer to the twelfth and thirteenth Lectures 
in his Corel's de V Histoire Naturelle des Mammif^res, as pre- 
senting considerable details respecting the general organization 
of these animals and their several peculiarities. He regards 
them as holding an intermediate place between the Quadrumana 
and JFerce, but requiring to be separated from both. 

The Marsujiialia will continue to perplex us until we can 
determine the true value of that peculiar character by which 
they are so remarkably distinguished from all other Mammalia. 
Is it to controul the characters derived from the organs of mas- 
tication, digestion, and motion, which maybe referred almost to 
as many types as there exist genera amongst these animals ? 
Even adopting that it ought, as most naturalists seem disposed 
to do, we have still to decide, whether the MarsupiaUa consti- 
tute merely a peculiar order, or a group of any higher denomi- 
nation as supposed by Blainville. Although Cuvier has only 
admitted them to the former, he observes that they might almost 
be supposed to form a distinct class parallel to that of the ov- 
dlnaxy Mammalia, and divisible into similar orders. The solu- 
tion of these difficulties must probably be sought in a more pro- 
found study of the 7-elative internal organization of these and 
other Mammalia. This subject has, indeed, for some time al- 
ready engaged the attention of Geoffroyf^ and luore recently it 
has been taken up by Messrs. Morgan^ and Owen§. We may 
reasonably hope that by the combined researches of these emi- 
nent anatomists, some new light will liefore long be thrown 
upon the affinities of these singular animals. 

* Since this Report was read, I have seen a sketch of a new arrangement of 
the Mammalia recently proposed by M. Duvernoy. Like Blainville, he con- 
siders the MarsupiaUa, (under which series he incliules the Monofremata,') as 
a group equivalent to the rest of the Mammalia takon together, for which last 
he retains Blainville 's name of Monodelphes. His orders are very numerous. 
See L'Institut, No. Ixv. p. 261. 

t See the article Marsupiaux in the Diet, des Sci. Nat., torn. xxix. 

X Linn. Trans., vol. xvi. pp. 61 and 455. 

§ Proceedings of the Zool. Soc. 1831, p. 159; 1833, p. 128. 
M 2 



164 FOURTH REPORT — 1834. 

The Munotremata, which are involved in quite as much 
obscurity as the Marsujiialia, have been for some time, but 
particularly within the last two years, a subject of great contro- 
versy amongst the first naturalists. Although belonging more 
to the department of anatomy, it will be necessary to say some- 
thing of this discussion, from its great importance to the science 
we are considering. The controversy has chiefly turned upon 
the existence or not of true mammary glands in these animals, 
and their consequent claims to be admitted among the Mam- 
malia. 

Lamarck was the first to maintain, in 1809*, arguing from the 
supposed absence of these glands, and the consequent probability 
that the Monotremata\ were oviparous, that thej* ought to form 
a separate class. This opinion was subsequently adopted by 
Geoffroy in the Bulletin de la Soc. Phil. 1822 J ; and also by 
Van der Hoeven in a memoir on the Ornithot'Uynchns, pub- 
lished in 1823 in the Nov. Act. 8)C. Nat. Cur.'^. In 1824, 
Meckel announced, in Froriep's Notizen, that he had dis- 
covered these glands, and in 1826 he published his Anatomy 
of the OrnithorhynchusW, in which their nature and situation 
were more fully illustrated. In the course of the same year (1826) 
Geoffi-oy endeavoured to show^, that the supposed mammary 
glands seen by Meckel were not truly lactiferous, but analogous 
to certain glands which he had observed in the genus Sore.v**. 
In 1827tt Meckel replied to Geoffroy, adducing further argu- 
ments in support of his former opinion. The same year Geoff- 
roy published a memoir on the structure of the genital and 
urinary organs in the OrnithorhynchHs\1^, from an examination 
of which he was still led to infer that it was certainly oviparous. 
This belief was soon after much strengthened by the receipt of 
information from Dr. Grant of the supposed discovery of the 
eggs of the Ornithorhynchns^^, which circumstance gave rise to 

* Phil. Zool, torn. i. pp. 145 and 342. 

t The name of Monotrejnala dates from 1803, when Geoffroy, who first ap- 
plied it in consideration of the peculiar structure of the genital organs, made 
simply a new order of these animals. See Bull, de la Soc. Phil., tom. iii. p. 225. 

I p. 95. § tom. xi. part ii. p. 351. 

II Ornithorhynchi Paradoxi Descriptio Anatomica. fol. Lipsiae, 1826. 
^ yinn. des Set. Nat., tom. ix. p. 457. 

** These latter glands form the subject of a memoir published by Geoffroy, 
in 1815, in the first volume of the Memoires du Museicm ; to which I refer the 
reader. 

tt Archiv.fur AnaL, band x. p. 23. XX Mem. du Mus., tom. xv. p. 1. 

§§ See an account of the discoverj', accompanied by a description of these 
eggs, in the Edinb. New Phil. Journ. for Jan. 1830, p. 149. 



REPORT OX ZOOLOGY. 165 

another memoir on the part of Geoffroy, published in the ^nu. 
des Sci. for 1829*. In 1832^ the controversy respecting the 
existence of the mammary glands again arose. In June of that 
year, Mr. Owen read a paper to the Royal Societyf , in which 
he entered into a close investigation of the structure of these 
glands, and decided altogether in favour of Meckel's opinion 
that they were strictly lactiferous. This opinion was further 
confirmed by a statement made the following September by 
Dr. Weatherhead to the Zoological Society^, respecting the 
positive discovery of milk in the instance of a female Ornitho- 
rhynchus lately taken with its young in the interior of New South 
Wales. In October of the same year, Mr. Owen laid before 
the Zoological Society § the results of an anatomical investigation 
of the mammary glands of the Echidna Hyshix, in which ani- 
mal he was also led to believe that they were really lactiferous. 
In February 1 833, Geoffroy published a memoir in the Gazette 
MMicale\\, in which he stated that the secretion of these sup- 
posed mammary glands was not really milk, but mucus, destined 
for the nutriment of the newly hatched young. In the same 
month, Blainville read a memoir^ to the Academy of Sciences at 
Paris in support of Mr. Owen's opinion. In March, Geoffroy 
made a communication to the Zoological Society** on the subject 
of his last memoir, to which Mr. Owen replied, alleging argu- 
ments against the probability of the secretion being mucus as 
Geoffroy supposed. In July the controversy between these two 
individuals was resumedif . Several other memoirs:}:^ have been 

• torn, xviii. p. 157. t Phil, Trans. 1832, p. 517. 

X Proceedings of Zool. Soc, p. 145. § Proceedingn ofZool. Soc, p. 179. 
II See Proceedings of Zool. Soc. 1833, p. 28. 

If Nouv. Ann. die Mtis., torn. ii. p. 369. In this memoir, although Blainville 
considers the Monotremata as mammiferous, he retains his former opinion with 
respect to the propriety of instituting a subclass for them, as forming the trans- 
ition from viviparous to oviparous animals. In the same subclass he suspects 
the fossil Ichthyosaurus would claim a place. This, it will be observed, accords 
with the views of Wagler already alluded to. 

*• Proceed., p. 28. ft Proceed, of Zool. Soc, p. 91. 

XI For abstracts of these memoirs see Z'/ns^i<«<, Nos. 4, 7, 9, 32, 33,40, 45, 
and 46. From some of the later ones it will be seen that this controversy has 
not been confined to the subject of the Monotremata. Geoffroy endeavoured 
to make it appear prohable that the mammary glands of the Cetucea were of a 
similar nature with the Monotrematic glands (as he terms them) in the Orni- 
thorhynchus ; and that if this were proved to be the case, the Cetacea also should 
be made to constitute a distinct class. Several facts and statements', however, 
have been brought forward to demonstrate that these glands are certainly lac- 
tiferous in the Cetacea, and I believe Geoffroy himself has since changed his 
opinion on this head. 

» See an article by Dr. Traill in the Edinb. Neiv Phil. Journ. for July of the 
present year (1834), p. 177. 



166 FOURTH REPORT 1834. 

also read by Geoffrey to the Academy of Sciences at Paris, both 
during the last and the present year, connected with this question. 
Nothing, however, has as yet been brought forward serving to 
prove the incorrectness of Mr. Owen's views, whicli certainly 
on the whole appear far more probable than those of Geoffroy. 
We may add in conclusion, that Mr. Owen has recentlj^ dissected 
a young Ornithorhynchus, the stomach of which was found filled 
with coagulated milk*, which milk examined under a high mag- 
nifying power, and compared ivith that of the cow, was found 
strictly analogous to this last in respect to its ultimate globules. 
Tiiis seems uhnost decisive of the matter. At the same time 
the mode of generation in these animals, whether oviparous, or 
ovoviviparous as appears more likely, remains yet to be ascer- 
tained. 

No one has paid so much attention to those organs in the 
3Iummalia employed by zoologists in characterizing genera and 
species as M. Fred. Cuvicr. The teeth have been particularly 
studied by him with reference to this point. His memoirs on 
this subject in the Aiui. and Mtin. du Mus.f formed the basis 
of a complete work|, published in 1825, in which he has given 
an accurate description of the dental system in each of the prin- 
cipal genera thi-oughout the Mainmalia, illustrated by figures. 
He has observed a remarkable uniformity of character in the 
molares, in all those genera which are manifestly natural, and 
generally admitted to be such by naturalists §. With reference 
also to their zoological characters, he has more recently made a 
study of the various productions of the cuticle. As yet he has 
only treated of the structure of the spines of the Porcupine ||, 
which he selected in the first instance as most readily examined, 
and likely to throw much light on the structure and development 
of hair in general. His researches, as far as they have been 
hitherto conducted, lead him to regard the hair as furnishing 
the zoologist with characters of more importance than has been 
usually supposed. He proposes, however, to follow up this sub- 
ject on another occasion. In a memoir published in the same 
volume with the one just alluded to, F. Cuvier has pointed out 

* Proceed. &c. 1834, p. 43. 

\ toms. X. xii. and xix. of the former, and torn. ix. of the latter. 

X Dents des Mammiferes considerees comme Caracteres Zoologiques. 8vo, Par. 
1825. 

§ On the subject of the teeth of the Mammalia, their structure and zoological 
characters, see a memoir recently published by Geoffroy. {Mem. de I'lnslUiit, 
torn. xii. p. 181.) His chief object is to prove that the long anterior tcc'th of 
the Rodentia, usually considered as incisors, strictly represent the canine teeth. 

II Nouv. Ann. du Mus.., torn. i. p. 409. 



REPORT ON ZOOLOGY, 167 

some valuable characters for distinguishing the species of Fes- 
perti/ionidte. These are derived from the form of the head, 
which he refers to thi-ee distinct types ; the form and direction 
of the auricle, which he refers to seven types ; and the form of 
the tragus. He observes that in the restricted genus Vesper- 
tilio, the organs of mastication and motion present but little 
variation. 

2. ^ves. — The structure of birds in general is perhaps quite 
as well undei'stood as that of Mammalia, and the leading groups 
are on the whole better determined. It is also curious to observe 
that the orders most generally adopted at the present day nearly 
coincide with those of Linnasus, thus evincing the tact with 
which that great naturalist in some instances seized affinities. 
The only alterations which we find in the RPgne Aniin. consist 
in the union of the two Linnaean orders Picoi and Passeres, (be- 
tween which it is certainly not easy to define,) and the separa- 
tion of the Scansorial birds from the former to constitute a 
distinct order by themselves. It will be well, however, to notice 
the principal arrangements of this class whicli have appeared 
since Cuvier's, in some of which we shall find a desire to deviate 
more widely from the system of Linnaeus. This will also aftbrd 
an opportunity of pointing out those individuals who have most 
contributed to the recent progress of this department of zoology. 
The first is that of Vieillot, which appeared in 1818 in the 2nd 
edition oiilxeNouv. Diet. cV Hist. Nat. (Art. Ornithologie). 
Its author was previously well known for his many valuable 
works on ornithology, in one of which* he had already given 
a slight sketch of his arrangement. Vieillot' s orders are five in 
number, and similar to those of Linnaeus, excepting that with 
Cuvier he throAvs together the PiccB and Passeres to form one, 
which he calls Sylvicolce. For the terms GrallcB and Anseres, 
he also substitutes Illiger's names of Grallatores and Natatoi'es. 
In 1820, Temminck published the 2nd edition of his Manuel 
d' Ornithologie, to which is prefixed a sketch of a general ar- 
rangement of birds, professedly grounded on the habits and 
organization. Perhaps, however, this is the least valuable part 
of a work, exceedingly rich in practical information relating to 
this class, and indispensable to ornithologists on all other con- 
siderations. Temminck's system, which is a slight modifica- 
tion of that given in the first edition of his Manual, cannot be 
considered as natural. His orders, amounting to sixteen, are 
greatly overmultiplied, and are far from being groups of equal 
value. In fact, he has not distinguished between orders and 

'Analyse d'une nouvclle Ornithuloyie elimentaire. 8vo, Par. 1816. 



1G8 FOURTH REPORT — 1834. 

families. Blainville's arrangement of this class* is grounded 
upon the form of the sternum and its appendages {clavicle and 
OS fur cat ur ins), according to a plan first developed in a memoir 
read to the Institute in 1812. At the same time, for the sake of 
convenience, its author has had recourse to the usual external 
characters for distinguishing the groups. As the sternum gives 
attachment to the principal muscles of flight, and thereby ne- 
cessarily exercises a certain influence over the ceconomy, it may 
assist in determining many natural affinities which would other- 
wise escape us. Hence Blainville's system deserves to be i-e- 
garded, although we may not be disposed to adopt it entirely. 
One of its chief peculiarities consists in the forming a distinct 
order of the Parrots, which stand first in the arrangement. 
Blainville thinks that not only the form of the sternum, but the 
whole organization and habits of these birds justify this step. 
With the rest of the Scaiisores, which are separated from the 
above by the intervention of the Birds of Prey, he associates the 
Syndactyli and Capritnulgidce, groups not referred by Cuvier 
to this order. He has also made distinct orders of the Pigeons 
and Ostriches. His other orders nearly coincide with those of 
the R^gne Anim. Although not immediately following in point 
of time, I may here notice an elaborate memoir on the sternum 
of birds by M. L'Herminier, published, in 1827, in the Ann. de 
la Soc. Linn, de Paris f, in which he has endeavoured to draw 
the attention of naturalists afresh to the great importance of this 
part. He has studied its structure in a large number of species, 
and founded upon it a new classification entirely different from 
all former ones excepting that of Blainville. He divides birds 
into two subclasses ; the first comprises all those io which the 
sternum is constantly furnished with a keel, and is distributed 
into thirty-three families ; the second forms but a single family, 
containing the Ostrich, Cassuary, and a few others, in which the 
keel is always wanting. M. L'Herminier thinks that the birds 
just mentioned conduct to the Reptiles, and not to the 3Iam- 
malia as is generally supposed. In 1823 appeared Mr. Vigors's 
*' Observations on the natural Affinities connecting the Orders 
and Families of Birds;}:," to which allusion has been already made, 
as containing an application of Mr. MacLeay's principles. His 
primary divisions are the same as Cuvier's, excepting that he 
sinks the order Scansoi'es, which he considers as only a subor- 
dinate group of his order Insessores, which name he has sub- 
stituted for that of Passeres. The names adopted for his other 

• Priiicipes, &c., tab. 4. f torn. v. p. 3 — 93. 

J Linn. Trans., vol. xiv. p. 395. 



REPORT ON ZOOLOGY. 169 

four orders are taken from lUiger*, viz. Raptores {Raptatores, 
111.), Rasores, Grallatores, and Natatores\. Mr. Vigors has 
traced out the chain of affinities which connects the above 
groups, and endeavoured to show that it returns into itself, 
forming a circle. Latreille in his arrangement^ follows Cuvier, 
with some slight modifications. Thus, he has a primary divi- 
sion of the whole class into the two sections of Terrestres 
and Aqiiatici : he has also made a distinct order of the Co- 
lumbcB and Alectrides, Vieill., to which he gives the name 
of Passerigalli. Wagler's orders § are more numerous than 
even those of Temminck, and deserve to be considered in many 
cases rather as natural families. He has annexed a synop- 
sis of the genera of birds, arranged in the order of their affi- 
nities||. In 1831, M. Lesson published his Trait4 (V Ornitho- 
logie, containing the result of a careful examination of the col- 
lections at Paris, to which in some measure it serves as an 
accompanying catalogue. In this arrangement, which professes 
to be according to the natural system, we have a primary division 
of birds into Anomalous and Normal, these groups being ana- 
logous toM. L'Herminier's subclasses, and characterized in like 
manner from the sternum and its appendages. The former com- 
prises the five genera of Struthio, Rhea, Casuarius, Dromaius 
and Apteryx^, The latter is divided into orders, on the whole 
similar to Cuvier's, the Scansores, however, forming only a sub- 
order among the Passeres. The Columhce and genus Penelope, 
Merr., which Cuvier associates with his Gallinaces, are also 
referred to the Passeres, where they form a portion of another 
suborder, called from Latreille Passerigalli. In the same year 
(1831), Mr. Swainson published the second volume of the Faun. 
Bar. Amer., in which he has stated his views with respect to the 
natural cirrangement of birds, although he has only illustrated 
them at length with reference to one order. Mr. Swainson's 
principles, which have been before alluded to, lead him to re- 

• C. lUigeri Prodromus Systematis Mammalium et Avium. Berol. 1811. 
A work extremely useful even at the present day, on account of its containing 
a very complete terminology with reference to the above two classes. 

t Mr. Vigors places the Strutliionidcs among the Rasores. By Cuvier they 
are associated with the tvading birds. 

X Fayn. Nat. § Natiirliches System, SfC. 

II Wagler had previously pubUshed, in 1827, a portion of a work entitled 
Systema Avium. It was not so much, however, a systematic arrangement of 
birds, as a collection of treatises on different genera, those being selected in the 
first instance which he had studied most thoroughly. It was his intention to have 
arranged them afterwards in a systematic table. The work, however, was never 
completed, and its talented author has recently met with a premature death. 

H See a paper by Mr. Yarrell on this anomalous genus iu Zool. Trans., vol. i. 
p. 71. 



I TO FOUKTH REPORT 1831. 

cognise three primary groups into which the class Aves is divisi- 
ble. To these he does not affix names, hut merely designates 
them as the typical, the siibtypical, and the aberrant. His 
secondary divisions, at least those adopted in the above work, 
which are equivalent to the orders of other authors, are the 
same as those of Mr. Vigors. In the details of the arrangement 
the systems of these two authors are in many respects different. 
The latest arrangement of this class with which I am acquainted 
is that of C.L. Bonaparte, in his Saggio di una Distribuzione,hc. 
He divides it into the two subclasses of Insessores and Gralla- 
tores : the former containing the orders Accipitres and Passeres, 
Cuv. ; the latter those of GalUncE, Grallce, and Anseres. 

The above are the principal authors who have treated of the 
systematic arrangement of this class of late years. The general 
leaning seems to be towards the adoption of the same orders as 
those just mentioned*. The group which presents most diffi- 
culties in the way of a natural classification is undoubtedly that 
of Scansores, on the value of which naturalists are not agreed. 
Latreille considers it as forming a parallel order to that of the 
Passeres. It will probably, however, be allowed ultimately to be 
only a subordinate group in this last order, as is already the 
opinion of Vigors, Lesson, and others. In the details of the 
system there is still much inicertainty, though more in some 
groups than others. And this uncertainty can only be cleared 
up by a more rigorous analysis of external characters, combined 
with anatomical investigation. This last has already been suc- 
cessfully resorted to in some families, for the detei-mination of 
true affinities. Thus, Mr. Yarrell, by studying the internal struc- 
ture of the Anatkke, has sketched out an arrangement of this 
group t, which Mr. Swainson finds in accordance with his own 
views on the subject J derived from the external characters and 
habits. The same gentleman has recoi'ded some important notes§ 
respecting the internal organization of Cereopsis and some allied 
species, serving in like manner to confirm the notions previously 
entertained respecting the affinities of these birds. There can 
be no doubt also that we may derive much assistance from study- 
ing the systems of those authors who, like Blainville and 
L'Herminier, have taken some one of the internal organs as the 
basis of their arrangement. For however it may be true that 
no such arrangement can be natural in itself, founded upon "cha- 
racters derived from one organ exclusively, yet it affords an in- 

* I speak of the groups themselves without reference to any particular names 
for them. 

t Linn. Trans., vol. xv. p. 378. J Fn. Bor. Am., vol. ii. p. 430. 

§ Proceed, of Zool. Soc. 1831, p. 25. 



REPORT ON ZOOLOGY. 171 

sight into the method of variation of that organ, teaches us in 
consequence its exact value, and when viewed in connexion with 
other systems previously established upon other characters, may 
serve to correct and perfect many details in these last beyond 
what we might be able to do by anj'^ other method. With re- 
ference to this end, besides the above, I may refer to a system 
of Dr. Ritgen, in the Transactions of the Ceesarean Academy at 
Bonn*, established upon the characters of the pelvis, as one, 
not to be adopted entire, but capable perhaps of furnishing some 
valuable hints which might otherwise be lostf. 

The external characters of birds have recently received much 
attention from M. Isidore Geoffroy St. Hilaire, who has published 
a memoir on this subject in the Nouv. Ann, du Miis.X which de- 
serves to be consulted by all ornithologists. He has reviewed 
those in most general use, and pointed out several of wliich he 
thinks the proper value has not been correctly appreciated. He 
particulai'ly mentions the emargination of the bill, so much 
trusted to in characterizing the Dentirostres, as one to which too 
much importance has been attached. On the other hand, he 
regards the disposition of the toes, in the Passeres more parti- 
cularly, as not having been sufficiently studied in a general point 
of view. His researches indeed on this point have led him to 
propose a new arrangement of the order just mentioned, which 
he divides into the three groups of Zt/godactyles, SyndactyleSy 
and Deodactyles, this last comprising the great bulk of the 
genera, which have the toes divided in the regular way. Hence 
it will be seen that he does not side with those who regard the 
Scansores as forming a distinct order. The feet of the Passeres, 
and the characters which they furnish, have likewise been much 
attended to by M. Dela Fresnaye, who has also proposed a new 
arrangement of this order §, though not exactly upon the same 
plan as Geoffroy's. The year previously to that in which Isidore 
Geoffroy published the above memoir, he gave some new obser- 
vations in the ^?M«a/e5 rfe* 'S't?e«6'cs|| relating to the characters 
of the Strigidce in particular, to which however it Avould occupy 
too much room to alhide more particularly. 

The structure and mode of development of feathers, which has 
been so ably illustrated by Fred. Cuvier*[[, and subsequently by 

* torn. xiv. p. 217. 

t The jielvis of birds has been recently studied bj' M. Bourjot St. Hilaire, 
and made the subject of a memoir, read to the Royal Academy of Sciences at 
Paris in August last. See Ulnstitut, No. 66, p. 266. J torn. i. p. 357. 

§ See an abstract of M. De la Fresnaye's memoir in the report of the French 
Congress held at Caen in 1833, p. 69. Sec also other memoirs by him on the 
same subject in Guerin's Magasiii de Zoologie for 1832 and 1833. 

Ij 1830i torn. xxi. p. li)l. ^ Mem. du Mus. 1825, torn. xiii. p. 327. 



172 FOURTH REPORT — 1834. 

other observers*, is perhaps too much within the province of 
pure animal physiology to require notice here. The laws, how- 
ever, which i-egulate the assumption and changes of plumage are 
of the utmost consequence for the exact discrimination of species. 
These laws have received great attention from Mr. Yarrell, who 
has lately added one to those previously establishedf, viz. that 
" Whenever adult birds assume a plumage durmg the breeding- 
season decidedly different in colour from that ivliich they bear in 
the wilder, the young have a plumage intermediate in the gene- 
ral tone of its colour compared with the tivo periodical states of 
the parent birds, and bearing also indications of the colours to be 
afterwards attained at either period." In the same paper Mr. 
Yarrell has stated some experiments, the results of which fully 
establish the point that in many cases a change of plumage is 
certainly occasioned by a change of colour in the feather itself J, 
quite independently of moulting. 

The difficulty of finding specific characters for birds which 
shall be applicable to both sexes and all ages, particularly in 
those groups in which the changes of plumage above alluded to 
are most prevalent, has been severely felt by ornithologists. Mr. 
Macgillivray has considered this subject in a paper published in 
the 4th volume of the Wernerian Memoirs^. He has pointed 
out the insufficiency of some of those in common use, particu- 
larly such as are derived from coloiu". He thinks it would be 
possible to obtain others, from the situation, form, and position 
of the feathers, which would be more preferable, as being of 
general application and founded upon permanent and essential 
organs. Mr. Macgillivray has annexed, as examples, the cha- 
racters of several species drawn up in this manner. His sug- 
gestions deserve to be considered, although it may be questioned 
whether such characters will be foimd " sufficiently diversified " 
to admit of being adopted in all cases. 

3. Repttilia, Cuv. — The study of the animals belonging to 
this division of the Vertebrata is difficult, and has received far 
less attention from naturalists than that of either of the preced- 
ing classes. Hence we are at present but little advanced in the 
details of their natural arrangement. The propi'iety of separat- 
ing off the Amphibia, and considering these last as a distinct 
class, is becoming every day more generally acknowledged. This 
separation was first proposed by Latreille || so long ago as in 

• See more particularly Macgillivray in Ed'inh. Netv Phil. Joitrn. 1827. 

f Zool. Irans., vol. i. p. 13. 

X This had been often suspected to be the case, (see Whitear in Linn. Trans., 
vol. xii. p. 524, and Fleming in Edinh. Phil. Journ.,\o\. ii. p. 271,) but never 
before ascertained by direct experiment. 

§ p. 517. II Nouv. Diet. d'Hisi. Nat., 1st edition. 



REPORT ON ZOOLOGY. 173 

1 804. It has not been adopted however by Cuvier, who divides 
the whole group into four orders, Cheloniens, Sauriens, Ophi- 
diens, and Batraciens, being the same arrangement as that of 
Brongniart*. Blainvillet follows Latreille in considering the 
Reptilia and Amphibia as distinct classes, but differs from all 
his predecessors in his subordinate groups. Attaching more im- 
portance to the organs of generation than those of locomotion, 
he has thought fit to unite the Saurians and Ophidians under 
the name of JBispeniens ; at the same time detaching the Croco- 
diles to form a distinct order, which he calls Emydosauriens. 
The class Amphibia he divides into four orders, Batraciens, 
Pseudosauriens or Salamanders, Subichthyens {Proteus, Siren, 
&c.), and Pseudophydiens {Ccecilia). In 1820, Merrem pub- 
lished his arrangement of the AmphibiaX, under which name, 
although he includes both the above classes, he considers these 
as forming two divisions, which he calls Pholidota and Batra- 
chia respectively. His Pholidota are distributed into three or- 
ders, which correspond with those of Blainville, but are called 
Testudinata, Loricata, and Squamata. The Batrachia include 
the three subordinate groups of Apoda {Ccecilia), Salientia 
{Rana, &c.), and Gradientia {Triton, Proteus, &c.). Mr. Mac- 
Leay§, adopting the Amphibia as a distinct class, would divide 
the true Reptilia into the five groups of Chelonians, Emydo- 
saurians, Saurians, Dipod Ophidians, and Aj)od Ophidiasis. 
He considers the first and last of these groups as meeting in 
the Emys longicoUis, thus causing the five to unite and form a 
circle. He looks upon the whole class as connected with that 
of Aves by means of the Chelonians. Latreille ||, preserv- 
ing the Reptilia and Amphibia as distinct classes, divides 
the former into the two sections of Cataphracta and Squamosa. 
His Cataphracta include Blainville's two orders of Chelonians 
and Emydosaurians. The Squamosa, answering to the Bisjie- 
niens of Blainville, comprise, as two other orders, his Sauri- 
ans and Ophidians. The Amjihibia are divided into the two 
orders of Caducibra)ichia and Perennihranchia. In 1825, Mr. 
Gray published in the Anti. of Phil, an arrangement of the 
c\&%^Q& Reptilia and Amphibia, in conformity with MacLeay's 
principles. As his primary groups are slightly modified in a 
later treatise on these animals, to be alluded to presently, perhaps 
it is unnecessary to specify them particularly. In 1826, Fitz- 

* Essai d'une Classification naturelle des Reptiles. Paris, 1805. 
t Principes, &c., tab. 5. 

X Tent amen Systematis Amphihiorum. Marpurg. 1820, 8vo. This work is, 
strictly speaking, a second edition of one published by the same author in 1800. 
§ Hor. Ent., p. 263. || Fam. Nat. 



174 FOURTH HKPORT — 1834. 

inger published a new classification of these animals* founded 
upon their natural affinities. He considers the Bejjtilia and 
Amphibia of Latreille in the light of orders only, to which he 
affixes the names of Motiopnoa (Reptiles breathing all their life 
by lungs only), and Dipnoa (breathing by lungs and gills at 
the same time). It will be seen that these two groups corre- 
spond to the Pholidnta and Batracliia of Merrem. The Mono- 
pnoa he divides into four tribes, the first three being the same as 
Merrem's orders, with the same names ; the fourth, called Nuda, 
embracing the single family of CcEcilice. The Dipnoa he sepa- 
rates into the two tribes of MutahHia and Immutahilia, the 
former comprising those Amphibia which do, and the latter 
those which do not, undergo metamorphosis. In the Nov. Act. 
8^c. Nut. Cur. for 1828, Dr. Ritgen has published an arrange- 
ment of the Amphibia in which he admits but three orders, an- 
swering to the Ophidia, Chelonia, and Sauriaoi other authors. 
This last, however, is made to include the Batrachia as well as 
the true Saurians. He has selected for most of his groups new 
terms, wliich from their great length will never be adopted gene- 
rally. Waglerf has very much augmented the orders of this 
class, in like manner as he has done those of the Mammalia and 
Birds. He adopts eight : Testudines, Crocodili, L,acertce, Ser- 
pcntes,Angues (comprising the genera Aconfias, Chirotes, Chal- 
cides, and AmphisbcBna of the RPgne Anim.), CcEcilicE, Ranee, 
and Ichthr/odi {Subichthyens of Blainville). In 1831, Mr. Gray 
published his Si/nopsis Reptilium, of which only the first part 
has as yet appeared, comprising the Cataphracta of Latreille, 
whose arrangement is for the most part adopted, with the ex- 
ception of a new order instituted for the reception of the Ophio- 
sauri, the second division of Latreille's order Saurii. C. L. 
Bonaparte, in his Saggio di una Distribuzione, Sec, published 
the same year, adopts the term Amphibia as a general name for 
the whole group of which we are treating. These he divides 
into the two sxibclasses of Reptilia and Batrachia, which are 
again divided into sections, the former into four, and the latter 
into two, before arriving at the orders. Thus we have Sect. 1. 
Testudinata, comprising the single order of Chelonii ; Sect. 2. 
Loricata, comprising the two orders of Enaliosaurii {Ichfki/o- 
sauras and Plesiosuiirus,) and Efinydosaiirii, Blainv. ; Sect. 3. 
Squamata, comprising the three orders of Saurii, Saurophidii 
{Amj)hisba:na), and Ophidii ; Sect. 4. Nnda, comprising the 
single order of Batrachophidii ( Ccecilia) . In the subclass Ba- 
trachia, we have Sect. 1 . Mutabilia, comprising the order Ca- 

* Neue Classification der Replilien, &c. 4to, Vienn. 1826. 
+ Natiirliches System, &c. 



REPORT ON ZOOLOGY. l75 

ducihranchia ; and Sect. 2. Amphipneusta {Immulahilia), com- 
prising the two orders of Cryptohranchia and Perennihranchia. 
The most recent work in this department is that by Dumeril 
and Bibron*, of which only the first volume has appeared hi- 
therto, containing remarks on the organization of Reptiles in 
general, and the Chelonians in particular. There is also a very 
complete Bibliography with reference to this branch of zoology. 
The systematic portion of the work is not yet entered upon. 
The authors, however, have it in view to adopt the same orders 
as those of Cuvier. 

The above are the principal authors who have treated of this 
class as a whole, but some of its orders have received the par- 
ticular attention of different naturalists, and derived much illus- 
tration from their researches. No one has contributed so much 
to our knowledge of the Chelonian Reptiles as Mr. Thomas Bell. 
Several memoirs from him on these animals are to be found in 
the Linnoean Transactions and Zool. Journal, amongst which 
I may more particularly mention his " Monograph of the Tor- 
toises having a moveable Sternum " published in 1825 f, and his 
'*C haracters of the O rder, Fam ilies, and Genera of the J<^5^^<fZm«/a " 
published in 1828 J. More recently (1833) Mr. Bell has com- 
menced a splendid work § on this order, in which it is intended 
to describe and figure all the known species, arranged according 
to their affinities. Seven parts have already appeared, which 
for beauty and accuracy of illustration it is impossible to surpass. 
Before quitting this group I may just allude to a paper in the 
Ann. des Set. for 1828||, by MM. Isid. Geoffroy St. Hilaire and 
J. G. Martin, on some parts of the internal organization of these 
Reptiles. Being purely anatomical, I should not have noticed it, 
did it not contain the statement of a curious fact respecting the 
affinity well known to exist between the Chelonia and the Mo- 
notremata. It is observed, that with regard to the urinary ap- 
paratus, the analogy between the Ornithorhynclms and the Tes~ 
tudo Indira is even much greater than that which is found be- 
tween this last species and many other reptiles belonging to the 
same order. 

The Emydosauria were closely investigated by Cuvier and 
Geoffroy, by the former more especially, in the early part of 
the present century, and since their researches %, I am not 

• Erpetologie generale, ou Histoire Naturelle Complete des Reptiles, torn. i. 
Paris, 1834. 

+ Zool. Journ., vol. ii. p. 299. J Zool. Journ., vol. iii. p. 513. 

§ Monograph of the Tesfudinata. fol. 1833, &c. || torn. xiii. p. 153. 

If See tlie earlier volumes of the y/ww. du Miis., more particularly vol. x., con- 
taining a valuable memoir by Cuvier on the different species of living Crocodiles, 
and their distinctive characters. For the structure of these animals, sec his 
Ossemem Fossiles. 



176 POURTII REPORT — 1834. 

aware that much addition has been made to our knowledge of 
this group. Nevertheless there is great need of further exami- 
nation in order to determine the value of those characters which 
have been hitherto employed in distinguishing the species. It 
may reasonably be questioned whether these have not been over- 
miUtiplied, from placing too great reliance upon slight differences 
in the form and number of the nuchal, cervical, and dorsal plates. 
I may mention a memoir by Geoffroy on the Gaviah, as more 
recent than his others, published in 1825*, in which he has 
treated largely of their organization and affinities. He consi- 
ders the former as offering sufficient peculiarities to warrant the 
establishing of a distinct genus of this group, which Cuvier re- 
garded as merely a subgenus of Crocodilus. 

The Saurian Reptiles have been much attended to by Mr. 
Gray. In the Ann. of Phil, for 1827 1, he has given a synopsis 
of tlie genera belonging to this group. In a subsequent paper 
published in the same volume J he has made some additions 
and corrections to his first communication. He has made it a par- 
ticular object to revise the species of Chamcsleon. To M. Milne 
Edwards we are indebted for a paper in the Ann. des Sci. for 
1829§, which though relating only to the restricted genus Xo- 
certa, may be found valuable in a general point of view from 
the remarks which it contains on the zoological characters of 
this group. Those who have studied these reptiles know what 
difficulty attends the discrimination of species. Milne Edwards 
has sought to remove this difficult}'. He has ascertained that 
in this geiuTS the best distinguishing characters are derived from 
the different kinds of scales, more especially the large squamous 
plates which cover the upper part of the head. He particularly 
dwells on the relative size of the occipital and parietal plates, 
and the forms of the scales between the eye and the ear||. He 
does not place much reliance on the character derived from the 
number of femoral pores, which he finds often varying in the 
same species, although considered as constant by Merrem and 
Blainville. In the same voliune with the above memoir is one 
by M. Duges, treating partly of the same subject ; and it is sa- 
tisfactory to find that he confirms what Edwards says respect- 
ing the characters of the scales. It may be observed that Wagler 
appears to have derived much assistance from the teeth in cha- 
racterizing both the Emydosavrian and Saurian Reptiles. In 
one portion of his work he has treated of this subject in great 

* Mem. du Mus., torn. xii. t vol. ii. N.S. p. 54. 

X p. 207. § torn. xvi. p. 50. 

II Merrem and others had previouslj' availed themselves of these characters, 
but according to Edwards, they have not made a judicious use of them, or se- 
lected those scales on which any reliance can be placed. 



REPORT ON ZOOLOGY. 177 

detail, and given minute descriptions of the teeth as they occur 
in all the different genera in the above two orders. 

Among the Ophidia more perhaps remains to be done than 
in any other order of Reptiles. Many new genera and species 
have been discovered of late years, and described by different 
authors ; but of several the characters and synonyms are ill 
determined, and their affinities still more so. Mayer has pro- 
posed a new arrangement of this group*, fomided on the pre- 
sence or absence of rudimentary posterior extremities, which he 
has succeeded in detecting in many genera in which they were 
not before known to exist. He would adopt as three subordi- 
nate divisions : 1. Phcenopoda, \n which these, extremities are 
externally visible ; 2. Cryjitopoda, in which they are entirely 
concealed beneath the skin ; 3. Chondropoda, in which the ru- 
dimental feet are reduced to mere cartilaginous slips, and Apoda, 
in which they are entirely wanting. M. Duvernoy, in the Ann. 
des Scien. for 1832t, has entered upon the consideration of the 
anatomical characters which serve to distinguish the venomous 
from the innocuous serpents. As these groups are kept distinct 
by Cuvier, as well as by some others, in their systematic ar- 
rangement of the Ophidia, such researches may prove service- 
able to the zoologist in helping him to the true situation of some 
genera. In a later volume of the same work+, M. Duvernoy 
has followed up this inquiry, as well as treated of some other 
parts of the internal organization of serpents in general. On 
the subject of the alimentary canal, he particularly observes that 
it offers sensible differences in different genera, and such as may 
serve to confirm or lessen the propriety of adopting some of those 
which have been established by naturalists. In this last com- 
munication, he has also made some remarks § on the forms and 
arrangement of the scales on the head and body considered as 
zoological characters. He thinks that such characters require 
to be compared afresh with those derived from the internal 
structure, in order that their true value may be more correctly 
ascertained. The genus Ccocilia, which by some has been asso- 
ciated with the true Reptiles, by others with the Amphibia, has 
been recently discovered by M.Miiller|| to possess gills in the 
very young state, which fact seems to corroborate its claims to 
a place in the class last mentioned. 

The structure of the Amphibia has been much studied of late 
years, and has given rise to many excellent memoirs on the part 
of different observers. As these, however, are for the most part 

* Nom Acta Acad. Nat. Cur., torn. xii. p. 819. f torn. xxvi. p. 113. 

X toni. XXX. pp. 5 and 113. § p. 25. 

Il Ann. des Scien. 1832, torn, xxv. p. 89. 
1834. N 



178 FOURTH REPORT — 1834, 

purely anatomical, it would be out of place to dwell on them in 
this Repoi't. Yet we may allude to one as of more impoilance 
to zoology than some others. I refer to Dr. Davy's discovery 
of a second auricle in the heart of these animals, which will lead 
us to correct what was always considered as one of their distin- 
fifuishing characters, viz., their having a single heart like Fishes *. 
The Perennihranchiate Amjihihia received some time back much 
illustration from Cuvier, whose researches on this subject will 
be found in the first volume of Humboldt's Comparative Anato- 
myt He was led to regard the Siren and Proteus as adult 
animals, bat suspected the Axolotl to be a larva. In 1819, 
MM. Configliachi and Rusconi published a valuable monograph % 
on the Proteus anguinus, containing a full account of the struc- 
tvire and natural history of this singular animal. Dr. Rusconi is 
the author of another work, published in 1821 §, in which he has 
treated of the tiquatic Salamanders, detailing some interesting 
observations respecting the mode of development of these Rep- 
tiles. This subject had not been previously followed up with 
so much closeness of research. It may be stated that in this last 
work Dr. Rusconi has doubted the accuracy of Cuvier's views 
respecting the Siren being an adult animal. Cuvier has recon- 
sidered the subject in his Ossemeus FossiIes\\ ; but still adheres 
to his former opinion on this point. From examining the os- 
teology of this reptile, he feels satisfied that it never acquires 
hind feet, as Rusconi supposes, and deems it very improbable 
that it ever changes its form or loses its branchiae. That the 
Siren is not the larva state of the Amphiuma of Garden, as 
some imagine, Cuvier has endeavoured to prove in a memoir 
upon this last genus published in the Mem. du Mus.% for 1827- 

* Edlnh. New Phil. Journ. 1828, p. 160. Dr. Davy's researches went no 
further than to show the existence of a second auricle in several species of the 
genus Rana; but reasoning from analogy, he thought it probable that the same 
would be the case in all the other genera of this group. These suspicions have 
been since partly confirmed by Mr. Owen, {Proceed. ofZool. Soc. 1834, p. 31,) 
who has lately given the results of an examination of the hearts of several ge- 
nera of the Perennibranchiate Ampbihia, in all of which he finds it consisting 
of three distinct cavities, as in the higher Reptilia. 

f " Recherches anatomiquessurlesReptiJbs regardes encore commedouteux 
par les Naturalistes ; faites a I'occasion de I'Axolotl, par M. Cuvier." — Humb. 
Anat. Comp., tom. i. p. 93 — 126. 

X Del Proteo Anguino di Laurenti Monografia. Pavia, 1819. An excellent 
analysis of this work will be found in the Edinb. Phil. Journ. for 1821, vols. iv. 
and V. 

§ Amours des Salamandres aquatiques, et Developpement du Teiard de ce,<t 
Salamandres, depiiix VCEvf jiisqu' a V Animal farf ait. Milan, 1821. An analysis 
of this work also will be found in the Edinb. Phil. Journ. for 1823, vol. ix. 

II tom. V. Pt. II. p. 418, &c. 1[ tom. xiv. p. 1. 



REPORT OX ZOOLOGY. 179 

4. Pisces. — It is generally allowed that this class is connocted 
by close affinity with those Batrachian Reptiles which have 
permanent gills. That it also leads back to the Mammalia by 
means of the viviparous sharks, which approach the cetaceous 
animals, will scarcely be doubted by any who have considered 
the relative organizations of these last groups. Yet no one ap- 
pears to have thought of placing the Fish between the Mamma- 
lia and Amphibia before Mr. MacLeay, whose circular arrange- 
ment of the classes of Vertebrata is certainly the only one yet 
given that conforms itself to nature. As a class, the Fish have 
received but comparatively fittle attention from naturalists ; and 
from the time of the appearance of the first edition of the M^gne 
Animal of Cuvier, to that of the Hist. Nat. ties Poissons by the 
same illustrious author, but few attempts have been made by 
other individuals to elucidate their true affinities. Several works 
of great merit, descriptive of the fish of different countries have 
appeared, and many detached memoirs on particular genera and 
species, but no work of a regvUar systematic character since that 
of Lacepede. 

Cuvier's system, as developed in the first edition of the JR^gne 
Animal, is very different from that of Lacepede, which he objects 
to as having all the secondary groups established upon charac- 
ters drawn from the presence or absence of the opercle and 
branchiostegous rays, which Cuvier observes will often lead to 
glaring violations of natural affinity, not to mention the circum- 
stance that in many instances Lacepede has assumed these parts 
to be wanting where they are really present. Cuvier adopts as 
primary divisions the two groups of Cartilaginous and Osseous 
Fishes, commencing with the former, which he divides into the 
two orders of Chondrojjteri/giens a branchies fixes and Chondro- 
pterygiens a branchies libres. The osseous fishes he divides into 
six orders. The first of these, Plectognathe^, is characterized 
by a peculiar mode of articulation of the jaws, and comprises 
some of the genera before included in the old order of Branchi- 
ostegi, which is here abolished. The second, hophobranches, is 
founded upon a peculiar form of the gills, and includes but the 
two genera Syngnathus and Pegasus of Linnaeus. The remain- 
ing orders comprise the Malacopterygii and Acanthopterygii of 
Artedi, the former group being divided into three orders ac- 
cording to the position of the ventrals, the latter kept entire as 
one order. 

Blainville's arrangement of this class * does not differ materially 
from that of Gmelin, excepting that the leading groups have 
new names affixed to them, and new distinguishing characters. 
* Priiiclpes, S)C., tab. 6. 



180 FOURTH RKPORT — 1834. 

Thus, the osseous fishes he terms Poissons Gnathodontes, from 
having their teeth implanted in the jaws, in contradistinction to 
the cartilaginous fishes, which he calls Dermodontes, from the 
teeth in this group adhering simply to the skin. In like man- 
ner he calls the Branchiostegi of Gmelin by the name of H4t4- 
rodermes, or fish in which the structure of the skin is variable 
in its nature, as opposed to the ordinary fish, which he terms 
Sqiiamodermes. The subordinate groups are established upon 
the presence or absence, and on the position (either jugular, 
thoracic, or abdominal,) of the ventrals, leading in too many 
instances to unnatural combinations as well as separations. 

Latreille in his Families Naturelles considers the cartilagi- 
nous and osseous fishes as forming two distinct classes in his 
great division of SolibrancMci, which he terms Ichthyodera and 
Pisces respectively. He removes, however, the chondroptery- 
gious fishes with free gills into the latter class, which is pri- 
marily divided into the two groups of Anomalia and Normalia. 
The Anomalia comprise, besides the Sturionii of Cuvier, his 
two orders Plectognathes and Lophohranches. The Normalia 
include the remaining orders of that naturalist, arranged how- 
ever somewhat differently from what they are in the Rigne 
Animal. In the order Acanthopterygietis, before arriving at 
the families, he adopts a primary division into the two sections 
Kystophora and Akystica, characterized respectively by the 
presence or absence of a swimming bladder. 

Risso, in the 3rd volume of his Hist. Nat. de V Enr. MMd., 
published in 1826, has given an arrangement of this class ac- 
cording to his own views. His orders, however, are nearly the 
same as those of Gmelin. He only substitutes the orders 
Plectogtiathes and Lophohranches of Cuvier for the Branchio- 
stegi of the former author. 

Besides the above, I am not acquainted with any systematic 
arrangements of this class, deserving notice, prior to that of the 
Hist. Nat. des Po/.wo/«*byMM.Cuvier and Valenciennes. In this 
work, of which the first volume appeared in 1828, the leading 
groups remain the same as in the Rhgne Animal. The details 
of the arrangement are however slightly modified*. And un- 

• One alteration consists in the commencing with the osseous, instead of the 
cartilaginous fishes. Cuvier observes, however, with reference to this point, that, 
strictly speaking, these groups form two parallel series, neither being superior 
or inferior to the other. See Hist. Nat. des Poiss., torn. i. p. 419, and Regne 
Animal (second edit.), tom. ii. p. 376. — Latreille seems to consider the Fish as 
forming two series, which, after a time, unite and become one. His arrange- 
ment of the groups in these parallel lines is, however, different from Cuvier'*. 
See Fam. Nat. p. 115, note (1). 



REPORT ON ZOOLOGY. 181 

doubtedly much, very much remains still to be done before we 
can consider these details as not susceptible of any further im- 
provement. Cuvier's groups are on the whole natural and 
well characterized ; but the true position of many of them is 
extremely doubtful *, and their relative value as yet undeter- 
mined. He has done much, however, towards determining the 
value of certain characters which had been considered in very 
different points of view by former ichthyologists, especially that 
derived from the structure of the dorsal Vays, He states it to be his 
firm opinion, deduced from a careful study of the entire organi- 
zation in several hundred species, that the acanthopterygious 
fishes ought to be kept quite distinct from the others, and that 
whatever characters may be resorted to for the further svibdivision 
of the normal fishes, they must be held subordinate to the one 
above mentioned. It is mainly in consequence of having attached 
too little importance to this character, and set too high a value 
upon that derived from the position of the ventrals, that Lin- 
naeus and several of the more recent authors have entirely failed 
in their attempts at a natural arrangement of this class. No one 
has made better use than Cuvier of the characters derived from 
the structure of the jaws f, and the nature and position of the 
teeth ; and perhaps in certain groups we can hardly select any 
of more importance. For the teeth he has adopted a peculiar 
set of terms, expressive of the different forms which they assume. 
These terms are, however, better adapted to the French than to 
the English language. On the whole, it may be observed, that 
although there may be some parts of his arrangement found de- 
fective, Cuvier has done more for this department of zoology 
than any one else. His Histoire des Poissons must ever be 
considered as forming a real epoch in ichthyology. If we look 
to the profound erudition it displays, the thorough knowledge 
of its author with respect to all that had been done by previous 
writers on this class, the close and accurate researches which 
he has made into every part of the internal as well as external 
organization of the subjects of which he treats, the minuteness 
of detail which characterizes the description of species, at the 

• It is more than probable that Cuvier has in some instances mistaken re- 
lations of analogy for those of affinity. One such instance has been pointed 
out by Mr. Bennett (see Zool. Journ., vol. iii. p. 372,) in the case of the genus 
Lophius. 

t Cuvier first called the attention of naturalists to this part in a memoir 
published in 1815, in the iirst volume of the Mem. du Museum (p. 102.). One 
of the conclusions at which he arrives is, that the characters derived from the 
pieces of the upper jaw and palatine arch, their various positions, proportions, 
&c., serve to indicate genera, but cannot be employed in distinguishing orders, 
if we wish to preserve natural affinities. 



18;2 FOURTH REPORT — 1834. 

siinie time that every attempt is made towards generalization, it 
will be thought impossible to speak too highly of its merits. It 
is almost a perfect model for works of this nature, and deserves 
to be consulted by all naturalists engaged in similar undertak- 
ings. It cannot but be a subject of deep regret that its talented 
author has not lived to complete a work, for which he tells us he 
had been forty years collecting materials. Let us hope, however, 
that this may be yet effected by M. Valenciennes, Mhom, fortu- 
nately for the scientific world, M. Cuvier had from the begin- 
ning engaged as his coadjutor. 

A slight modification of Cuvier's arrangement appears in the 
Saggio di una Diiitrihuzione,8)C., of C. L. Bonaparte, published 
in 1S31, principally as regards the value of some of the groups. 
In the first place, the osseous and cartilaginous fishes are con- 
sidered as two subclasses. The former are then primai'ily di- 
vided into three sections: 1. Pectinibranchii, comprising 
the two orders ^-Icaiithopten/gii and Maiacopterygii; 2. Lo- 
PUOBRANCHii, including the single order of Osteodermi {Syn- 
giiathus); and 3. Plectognathi, comprising the two orders 
Gymnodontes and Sclei'udermi. The Malacopterygii are sub- 
divided into the three tribes of Ahdomhudes, Suhbrachkmi, and 
uipodes. Thus we have two of Cuvier's orders raised to a higher 
rank than that Mhich he assigned to them ; while on the other 
hand there are three lowered to a subordinate denomination. 
In like manner we have the cartilaginous fishes divided into the 
two sections of Chismopnei and Trematopnei : the former 
comprising the two orders of Eleutheropomi [Sturiones) and 
Acanthorrhmi {Chimieriv), the latter those of Plagiostomi and 
Cyclostomi. A similar alteration in the value of some of Cuvier's 
groups will be found here. 

The most recent work on ichthyology, and one of the most 
important which has yet appeared, is that by M. Agassiz, now 
in course of publication*. Although the object of its author is 
more particularly to illustrate the fossil fishes, it is his intention 
to bring forward an entirely new classification of fish in general. 
The details of his arrangement are not yet published. He has, 
however, put forth a slight sketch of his system, such as will 
serve to show the striking changes which he contemplates in 

* Reclicrclies stir les Poissons Fossiles, par Louis Agassiz, 1833, &c. Only 
two numbcvs have hitherto appeared. — M. Agassiz was before known to ich- 
thyologists from having assisted Spix in the description of his Fishes of Brazif. 
This work was published in 1829 under tlie following title: Selecla Genera el 
Species Pisvium quos in Ilinere collegit Spix ; descripsit L. Jgassiz. fol. lu 
18;5f), M. Agassiz had also announced the prospectus of a work on the Fresh- 
iiater Fishes of Europe. This last has, however, not yet appeared. 



REPORT ON ZOOLOGY. 183 

this department of zoology. Thus, he adopts but four orders, 
in each of which are to be found both osseous and cartilaginous 
fishes, — both Acanthopterygians and Malacopterygians, — both 
apod and abdominal genera, — and, in two out of the four, tho- 
racic and jugular genera besides. Hence it will be seen that his 
principal divisions are founded neither on the degree of ossifica- 
tion of the skeleton, nor on the structure of the vertical fins, nor 
on the position of the ventrals, as is the case in those systems 
which have been hitherto most generally adopted. M. Agassiz 
thinks he finds in the differences of the scales the most exact 
indication of the natural affinities of all fish. Accordingly it 
is from the scales that he has drawn the diagnostic characters 
of his four orders, (which bear respectively the names of Pla- 
coides, Ganoides, Ctenoides, and Cycloides,) although in form- 
ing them he has kept in view all the rest of the organization. 
Ichthyologists will doubtless be impatient to see the full deve- 
lopment of a system founded upon views so entirely opposed to 
all those which they had previously entertained on the subject. 
The science of ichthyology has been so little cultivated, that 
there are but few individuals to whom it is necessary to refer in 
this Report, besides those who have been already mentioned. 
Many have made great contributions to the anatomy of fish, 
amongst whom Geoffroy St. Hilaire stands preeminent ; but I 
allude to such only as have thrown light upon the affinities of 
the larger groups, or helped us to a better knowledge of their 
zoological characters. I must not, however, omit to mention 
an important paper on the fishes of the Lake of Geneva by 
M. Jurine, published in 1825, in the third volume of the Mem. 
de la Soc. de Phys. et d'Hist. Ahit. de Geneve. It is not merely 
valuable as a local catalogue, but as containing several new cha- 
racters for distinguishing the species of Cy2)rinidce, which is per- 
haps one of the worst understood families in the whole class *. 
This memoir is accompanied by i-emarkably accurate figures of 
all the species found in the above locality. The scales of fish 
were, some years back, particularly studied by M. Kuntzmann, 
whose memoir t on this subject will have acquired fresh interest 
since naturalists have had their attention again directed to it by 
M. Agassiz. M. Kuntzmann has not only entered into consi- 
derable details with respect to the structure of these organs in 

• Cuvier lias somewhere observed that in general the freshwater fishes, at 
least those of foreign counuies, are much less known and understood tlian those 
lound on the coasts. 

+ Verhandlung der Gesell. Nat. Freunde in Berlin, vol. i. No. 5, 1824, p. 269. 
1 am, however, only acquainted with the analysis of it in Bull, des Set. Nat. 
1826, torn. vii. p. 118. 



184 FOUKTH REPORT — 1834. 

different groups, but considered their value as furnishing cha- 
racters for distinguishing species. He seems to think, that in 
general, if not in all cases, they are available for this purpose, 
and advises that selection be made of those which are placed on 
the middle of the sides of the body, and near the lateral line, not 
only as being the largest, but as those in which the form is most 
constant in a given species. M. Kuntzmann has instituted se- 
veral divisions or classes amongst scales, in which they are ar- 
ranged according to their form and structure. It would, how- 
ever, occupy too much I'oom to follow him in this part of his 
subject. Before quitting this class, I may just allude to two 
papers by Dr. Hancock, in the London Quarterly Journal of 
Science for 1830*, in which he has made some remarks on the 
composition of the fin rays in fishes. Dr. Hancock has dwelt 
much upon the importance of the character derived from the 
number of these rays, which he considers as oflPering the best 
diagnostic marks for the discrimination of species. This cha- 
racter, however, must be employed \^ith some limitation, since 
it will be found much more variable in some groups than others. 

IT. AxNULOSA, Cuv. 
Cuvier, in his B^gne Animal, places this division below that 
of the Mollusca, which last he appears to have regarded as 
standing higher in the scale of organization on account of its 
circulatory system. Geoffroy, gxiided by his peculiar views re- 
specting the vertebral structure of the Annulosa, to which allu- 
sion has been already made, has disputed the propriety of this 
arrangement t, and considers that the Mollusca shoidd decidedly 
give precedence. It is obvious, however, that these two groups 
are formed upon such entirely different plans, that they scarcely 
admit of direct coiiiparison in this respect. Each has its own 
peculiar marks of affinity with the higher animals ; and it is only 
by supposing two points of departure from the Vertehrata, and 
arranging the Invertehrata in a double series, that we shall pre- 
sent a system at aU conformable with nature. This double route, 
indeed, was long since pointed out by Lamarck J, and subse- 
quently by Latreille§, MacLeayll, and Blainville^. Latreille has 
reconsidered the subject in his latest work, the Cours cV En- 
tomologie, published in 1831. He there supposes** the In- 

• pp. 136, 287. 

t See his Cours dc I' Flist. Nat. des Mammif., Lecons 2 & 3. 
X Hist. Nat. des An. sans Vert., torn. i. p. 457. 

§ 111 a memoir published in 1820 under the title of Passage des Animaux 
Inoertelres aux Vertebres. 8vo. 

II Horte Entom. p. 206, and elsewhere. 

1J Principes d'Anat. Comp , tab. 2. •* p. 15. 



REPORT ON ZOOLOGY. 185 

vertebrata to be arranged on two lines, one occupied by the 
Crustacea, Arachnida, and Insecta, the other by the Mollusca 
and Zoophyta: he then supposes a lateral branch from the 
Mollusca to the Crustacea, passing successively through the 
Cirripeda, Annelida, and Entozoa, the connecting link at this 
end of the ramification being found in the LerncBce of Linnaeus. 
That this arrangement is, however, not quite correct, is rendered 
probable by discoveries connected with the Cirripeda to be here- 
after spoken of, and by the indisputable affinity between the 
Annelida and Cyclostornous Fishes, which affinity points to the 
former group as being necessarily at the head of one series, and 
therefore not forming part of any lateral ramification *. 

The following are the classes considered by Cuvier as belong- 
ing to the Annulose type : Annelida, Crustacea, Arachnida, 
and Insecta. 

Mr, MacLeay adopts five classes t independently of the-^wwe- 
lida, which he regards as an osculant group connecting the ver- 
tebrate and annulose animals. Two of these are the Crustacea 
and Arachnida of Cuvier. Two others are formed out of the 
old class Insecta, and are the same as Clairville's groups of 
Mandibulata and Haustellata. The fifth, to which the name 
of Ametabola is given, includes the Myriapoda and Thysanura 

* Latreille seems to consider, as he had done in his original memoir on this 
subject, that the Crustacea are the most perfect of the articulated animals, and 
that therefore they necessarily approach nearest to the Vertebrata. Mr. 
MacLeay has controverted both these points. He maintains that Insects are 
more highly organized than Crustacea. Furthermore he observes, that so far 
from its being by the most perfect, it is by the least perfect group in the series 
that we might naturally expect to find a passage to the Vertebrata. Every 
vertebrate animal would seem to " have been constructed with reference to one 
type, and every annulose with reference to another ; and as the former is more 
imperfect in its organization according as it approaches the annulose structure, 
so the latter is more imperfect in proportion as it possesses a distinct system of 
circulation and other characteristics of the Vertebrata. It thus follows that the 
animals which connect them ought to be extremely imperfect in their organi- 
zation." Such animals are the Cyclostornous Fishes on the one hand, and the 
Annelida on the other, the striking affinity between which groups has been 
noticed both by Lamarck and Cuvier. See Hor. Ent., p. 292, &c., for a further 
development of Mr. MacLeay's reasoning. It cannot be doubted that his views 
on this last point are correct. They likewise fall in with those of Straus-Durck- 
heim, who has touched on the same subject in the Introduction to his valuable 
work on the structure of the Articulated Animals {^Consid. Gen. sur I'Anat. 
Comp. des An. Artie, pp. 13, 15, 20.) published in 1828. Geoffroy, however, 
agrees with Latreille in thinking that the Crustacea should follow immediately 
after the Fish. See Mem. du Mia., tom. xvi. p. 2 ; also Cours de VHist. Nat. des 
Mammif., Lee. 3, p. 18. Robineau Desvoidy entertains the same opinion. 
Recherches, ^-c, p. 78. 

i Hor. Ent., pp. 288 and 390. 



186 FOURTH KBPORT — 1834. 

of Lutreille, the A)iuptura of Dr. Leach, and a portion of the 
Entozoa of Rudolphi. Mr. MacLeay has endeavoured to show 
that these five groups unite to form a circle. 

In Blainville's Principes, &c., we find the Aiinulosa forming 
his third type, Entomozoaires * , which he divides into eight 
chisses, characterized according to the presence or absence, 
and when present the number or nature, of the appendages for 
locomotion. The Annulosa with articulated feet he distributes 
under the six classes Hexapodes, Octopodes, D^capodes, HeM- 
ropodes, Tefradecapodes, and Myrkipodes ; the first including 
the true Insects, the second the Arachnida of Cuvier, the third, 
fourth, and fifth the Crustacea of that author. The inarticulated 
Annulosa, comprising the Annelida of Cuvier, form his seventh 
and eighth classes, called Clietopodes (with setiform appendages,) 
and Apodes (deprived of appendages altogether). The last of 
these two inclucles iilso some of the Entozoa. Few will pro- 
bably be disposed to adopt this arrangement, which leads to di- 
visions of very unequal value. 

In the Families Naturellcs of Latreille, the Annulosa (or, as 
they are there termed, Condylopa,) are primarily divided into 
the two sections of Hyperhexupi and Hexapoda, according as 
the feet are more than six, or six only, in the adult state, the 
former term being adopted from Savigny. The Hyperhexapi 
include the three classes Crustacea, Arachnida, and Mi/riapoda, 
this last being adopted from Dr. Leach, who first instituted it in 
a paper read to the Linnaian Society in 1814 f. The Hexapoda 
comprise the single class of Insecta. The Annelida are referred 
by Latreille to a different branch of his arrangement of the 
Animal Kingdom. 

Straus-Durckheim, in his Consid. Gen^r. sur VAnat. Comp. 
des Anim. uirtic. published in 1828, considers the articulated 
animals as including the five classes Annelida, Myriapoda, 
Insecta, Crustacea, and Arachnida. To the end of the Intro- 
duction of his work he has annexed two synoptic tables, in 
which he has represented what he conceives to be the true chain 
of affinities connecting these classes, and the principal groups 
contained in them. It would, however, occupy too much room 
to follow him in these details. 

In the Cours d' Entoniologie, published in 1831, Latreille 
has adopted the same divisions as in the Fam. Nat. He only 
substitutes the name of Apiropoda for that of Hyperhexapi. 

I shall now proceed to consider the progress and state of each 

* Tab. 7. t Linn. Trans., vol. xi. p. 306. 



REPORT ON ZOOLOGY. 187 

of the classes referred by Cuvier to this type of structure sepa- 
rately. To these I shall add Dr. Leach's class of Myriapoda. 

1, Annelida. — This class was established by Cuvier iu 1802. 
Lamarck, who adopted it from him, was, however, the first to 
assign to it its present name. The animals which it includes, al- 
though possessing great intei-est fi'om the circumstance of their 
forming the passage from the Annulose to the Vertebrate type, 
have been comparatively but little studied, and have received the 
attention of only a few naturalists. It is principally to Cuvier, 
Savigny, Blainville, and to the more recent researches of Au- 
douin and Edwards, that we are indebted for what knowledge 
we have respecting them as a class. Cuvier more especially ex- 
amined their internal organization. His arrangement, in both 
editions of the R^gne Animal, is grounded upon the respiratory 
organs, which furnish him with the characters of three groups, 
which he terms orders : (1.) Tubicoles, in which the branchiae 
are in the form of tufts attached to the head or anterior part of 
the body, generally inhabiting shelly tubes ; (2.) Dorsibranches, 
in which they are arranged down the back or along the sides of 
the body; and (3.) Abranches, in which there are no distinct 
branchiae visible. Savigny, whose valuable memoirs on these 
animals * are inserted in the great French work on Egypt, paid 
more attention to their external structure. He particularly 
studied the conformation of those elastic and often brilliant 
metallic-like seta;, which in a great number of genera serve as 
organs of motion. He also entered into a detailed examination of 
the jaws, antennae, branchiae, and the membranaceous append- 
ages attached to the several articulations. His arrangement of 
this class is very different from Cuvier's. He divides it into 
five orders : (1.) Nereidi^es, comprising such genei'a as have re- 
tractile feet furnished with setae, a distinct head, and a mouth in 
the form of a proboscis, generally armed with jaws ; (2.) Ser- 
piilees, in which there are also feet furnished with setae, some 
of these being hooked, but no distinct head ; (3.) Lombricines, 
M'ithout feet or distinct head, but nevertheless furnished with 
small setae ; (4.) Hirudinees, without distinct head, feet, or setae, 
but with a mouth in the form of a sucker; (5.) The last order, 
of which he has not treated, he has left without a name. The 
result of Blainville's researches into the structure of these ani- 
mals, which form his class Chetopodes, will be found in the 

* Recherches pour servir a la Classification des Annelides ; and Tableau 
si/slemaligue tie la Classe des Awielides. The first of these memoirs was pre- 
sented to the Royal Academy of Sciences in 1817. An analysis of them both 
will be found in Latreille's Report, published in the il/m. c^k JV/?(5e!(7«, tom. vi. 
p. 93. 



188 FOURTH REPORT— 1834. 

Bull, de la Soc. Phil, for 1818. He divides them into three 
orders, the characters of which are drawn from the similarity or 
dissimilarity of the segments of the body with relation to the 
appendages, and the more or less marked separation of these 
segments into head, thorax, and abdomen. It is not necessary 
to give the names of his orders, as he has changed them in a 
more recent dissertation on these animals published in the 
Diet, lies Scien. Nut. *, and to which I refer the reader for 
a full development of his views respecting their organization 
and arrangement. 

The memoirs of MM. Audouin and Edwards on the Annelida, 
which are the most recent, and at the same time the most 
valuable that have yet appeared, are contained in the Annules 
des Sciences for 1832-33. These acute observers liave not only 
discovered a vast many new species, but found some exhibiting 
such peculiar characters, as render it necessary to institute 
several new groups, and to remodel entirely the classification of 
former authors. They remark that the system of Cuvier, although 
adapted to the small number of species then known, cannot be 
employed for the arrangement of many which have been since 
discovered, without entailing violations of natural affinity. In 
fact, they find that the presence or absence of the appendages 
termed branchice does not by any means constantly coincide 
with the true characteristic marks of the different types of 
organization presented by these animals, and that moi'e than 
one instance might be adduced of species presenting these two 
modifications of structure, yet identical in all other respects, 
and indisputably belonging to the same family, if not to the 
same genus. The systems of Savigny and Blainville they state 
to be attended by similar difficulties. What they pi-opose is, 
instead of confining their attention to the hrancliicB only as the 
basis of their classification, to take into account the different 
membranaceous appendages in general, the consideration of 
which will lead to more natural divisions. It would seem indeed 
from their researches, that although the branchiae are occa- 
sionally much developed, so that it is impossible to mistake their 
function, or to confound them with the cirri and tentacula, yet in 
other cases respiration is carried on by some of the other mem- 
branaceous appendages, all of which take up this function by 
turns in different cases. Hence by considering these organs col- 
lectively, and attaching the same value to all of them, we shall 
obtain characters of the first importance for the classification of 
the Annelida. It is accordingly from these organs, which the 

* toin. Ivii., Art. Vers. Also published separately under the title of Manuel 
d' Helminlhohgie. 



REPORT ON ZOOLOGY. 189 

authors term the soft appendages of the body, that they derive 
the characters of their four primary divisions or orders, to which 
they attach the names of Annelides errantes, Annelkles tubicoles 
ou sedentaires, Annelides terricoles, and Annelides suceuses. 
Audouin and Edwards have paid particular attention to the ex- 
ternal organization of the Annelida, and have made some inter- 
esting discoveries with respect to the structure and use of the 
setcB with which the feet are provided in the animals of their 
first division, being those in which the organization is most com- 
plex. They have observed that these setae are not mere orna- 
ments or organs of motion, but offensive weapons of a very par- 
ticular structure, and such as can only be compared to the stingg 
of bees or the spines of certain fish. Savigny had noticed that 
they were in general capable of being exserted from the body 
and retracted at pleasure, but does not appear to have entered 
so deeply into the details of their structure as these authors. 
MM. Audouin and Edwards have submitted them to a close 
and microscopic examination, and have ascertained, that while 
some are simple, assuming a great variety of different forms, 
others are compound, always consisting of two parts, united by 
an articulation, which gives way when the seta is employed for 
offensive purposes, leaving the apical portion in the body of the 
animal attacked. 

From giving a detailed account of the external organization of 
the Annelida in general, MM. Audouin and Edwards proceed 
to the subordinate groups. So far as they have hitherto ad- 
vanced in the subject, they have described at length the charac- 
ters of all the families and genera ; but in regard to species, of 
those only found on the coasts of France. To give any further 
analysis of their labours would, however, be inconsistent with 
the limits to which this Report must be restricted. It is, more- 
over, necessary that we should proceed to notice several indi- 
viduals who, though they have not written on this class as a 
whole, have thrown great light upon some particular parts of it. 

The Hirudinid(B especially have received more general atten- 
tion than any other group, which is doubtless owing to the valu- 
able services of these animals in medicine. Dr. Rawlins Johnson 
is the author of two memoirs in the Philosophical Transac- 
tions for 18 17, in one of which he has detailed some interesting 
observations with respect to the habits and mode of propagation 
of the Hinido vulgaris ; in the other he has instituted the ge- 
nus Glossopora * for those species in which the mouth is fur- 
nished with a projectile tubular tongue, including the H. com- 

* The same as the genus Clepsine of Savigny. 



190 FOURTH REPORT — 1S34. 

planata and H. stagnalis of authors, and some others. Dr. 
Jolinson has also written two treatises on the 3Iedicinul Leech, 
to the last of which is appended a reprint of the memoirs above 
alluded to. In the Turin Memoirs for 1820*, Professor Ca- 
rena has published a complete monograph of the genus Hirndo, 
in which, notwithstanding the labours of Savigny, who paid great 
attention to this family, he has described several new species, 
besides elucidating the history and synonyms of others known 
before. A supplement to Carena's mojiograph will be found in 
the twenty-eighth volume of the same Memoirs. In the ^nn. 
des Scien. for 1825 f, M. Rayer has published some interesting 
observations with respect to the capsules and ova of several 
species of Hirndo, and the gradual development of the joung. 
In 1827 appeared nearly at the same time two other valuable 
monographs on this family, one by Moquin-Tandon J, the other 
by Blainville §, this last being in part an extract from the Diet, 
des Scieu. A^cif. In these works, which may serve as points of 
departure to future observers, the history of these animals is 
nearly complete up to the above time. In both will be found 
considerable details with respect to their anatomy, physiology, 
and habits, and likewise with respect to species. Of these last 
Blainville enumerates thirty-six. Moquin-Tandon describes 
thirty-seven, besides four which he considers as doubtful. It 
may be stated that Derheims has also written upon this family ; 
but Moquin-Tandon does not speak favourably of his work ||, 
which I have not seen myself. 

The Lnmbrici, which received a large share of Savigny's at- 
tention, and of which he has described upwards of twenty 
species % (as he considers them), before confounded under the 
general name of L. terrestris, have been since much attended 
to by Leon-Dufour, Duges, and Morren. Leon-Dufour's ob- 
servations, contained in two memoirs in the Ann. des Scien. 
for 1825 and 1828, chiefly respect the mode of reproduction, 
which he asserts to be oviparous, and not viviparous as sup- 
posed byMontegre** and SirEverard Home ft . He has disco- 
vered the capsules at the depth of five or six feet in the earth, 
and found them analogous to those of the genus Hirudo. 
M. Duges is the author of an elaborate memoir in the Ann. des 

* vol. XXV. p. 273. f torn. iv. p. 184. 

X Monographie de la Famille des Hirudinees, par Alfred Moquin-Tandon. 
Paris, 1827. 4to. 

§ Essai d'une Monographie de la Famille des Hirudinees. Paris, 1827. Svo. 

II Histoire Naturelle et Medicale des Sangsites. Paris, 1825. Svo. 

i[ The characters of these species will be found in Cuvier's Analyse des Tra- 
vaux for 1821. 

** Mem. dii Mus., torn. i. p. 242. -jf ^^I'l- Trans. 1823, p. 143. 



JtEPOBT ON ZOOLOGY. 191 

Scien. for 1828 *, which has prmcipally for its object the 
anatomy of Cuvier's entire group of Annelides Ahranches. So 
far as respects the HinulinidcB, he has added little to what 
may be found in Moquin-Tandou's work on this subject ; but he 
has thrown much vahiable light on the structure and physiology 
of Cuvier's first family. His researches, which relate to the 
organs of circulation, respiration, and reproduction, have been 
made on two species of Nais and six of Lumbriciis, which he 
commences by characterizing. The latter he does not appear to 
be able to identify in all cases with those of Savigny. Like 
Leon-Dufour, he considers these animals as oviparous, and 
thinks that what Montegre took for living young were only 
intestinal worms. Morren's work f, which was crowned by 
the University of Ghent, was published in 1829, and is of the 
most elaborate nature. Taken in connexion with the researches 
of the French naturalists, it leaves scarcely anything to be de- 
sired as far as i*egards the anatomy and phj'^siology of the Lxim- 
brici. Its author seems in doubt, however, about the numerous 
species described by Savigny and others. He is more inclined 
to regard them as simple varieties. He in some measure recon- 
ciles the conflicting testimonies of Montegre and Leon-Dufour 
with respect to the mode of reproduction, by asserting it to be 
both oviparous and ovoviviparous. 

The structure of the genus Nais has been also investigated 
by Dr. Gruithuisen. He has published two memoirs on the 
anatomy of certain species belonging to this group in the Nova 
Acta S)C. Nat. Cur-X. 

Before quitting this class, it may be remarked that the true 
situation of the genus Dentalium, placed by Cuvier amongst 
his Annelides tuhicoles, is undetermined. M. Deshayes, who 
has made it the subject of a monograph published in the Mem. 
de la Soc. d' Hist. Nat. de Paris§, and who has entered into much 
detail with respect to its anatomy, seems to regard it as belong- 
ing to the Afolhiscous type. Further researches are, however, 
necessary in order to establish this opinion as correct. 

2. Crustacea. — Until within these few years Latreille and 
Dr. Leach were almost the only naturalists who had studied the 
animals of this class collectively with any degree of care or 
minuteness of detail. The latter gentleman is well known to 
have devoted a great deal of his attention to their arrangement 
and natural affinities. His treatises in this department, consisting 

• torn. XV. p. 284. 

t De Lumbrici Terresiris Historia Naturali nee non Anatomia J'ractatits. 
Bruxell. 1829. 4to. 

X torn. xi. p. 235, and torn. xiv. p. 397. § torn. ii. p. 321. 



192 FOURTH REPORT — 1834. 

of the article Crustaceology in the Edinb. Encyclop., a pa- 
per in the Linn. Trans. *', and the Malacostraca Podophthalma 
Britannia, this last giving descriptions and coloured represen- 
tations of a large portion of the British species, have been already 
alluded to in a former part of this Report. These works were 
all published before the first edition of ih^ R^gne Animal of Cu- 
vier. Nevertheless it may be well to give a slight sketch of Dr. 
Leach's arrangement, which, though founded upon Latreille's f, 
is somewhat different from that proposed subsequently by this 
last author. 

In the LinncEan Transactions, ahove referred to. Dr. Leach 
distributes the Crustacea primarily into the two large groups or 
subclasses of Malacostraca and Entomostraca. The Malaco- 
straca are then divided into two other groups, or legions as they 
are called, bearing the names of Podophthalma and Edrioph- 
thalma, according as the eyes are either pedunculated or sessile. 
The Podophthalma include the two orders Brachyiira and 
Macroura, comprising, the former thirty-three, and the latter 
twenty-two genera. The Edriophthalma are not di\ided into 
orders, but merely distributed into thirty-eight genera, which 
are grouped according to the form of the body, and other cha- 
racters derived from the antennae and feet. In this division are 
several new and curious genera, entirely unknown till Dr. Leach 
first made them public. The Entomostraca had received so 
little attention when Dr. Leach published his system, that he 
did not attempt to arrange them according to their true affini- 
ties, but merely gave an artificial distribution of the genera, to 
serve till such time as we were made better acquainted with 
their structure. 

The arrangement of Latreille in the third volume of the first 
edition of the Rbgne Animal % is different, as already alluded 
to, from that adopted formerlj'' by this author. In this work 
the Crustacea are divided into five orders : Decapodes, Stoma- 
podes, Amphipodes, Isopodes, and Branchipodes ; the charac- 
ters of which are taken from the situation and form of the 
branchicc, the mode of articulation of the head with the trunk, 
and the organs of manducation. The Decapoda are divided into 
the two families of Brachyiires and Macroiires, answering to 
Dr. Leach's two orders bearing the same names. The Stoma- 
poda include one family, formed out of the Fabrician genus 

* vol. xi. p. 306. 

f I allude to the system given by Latreille in his Genera Crustaceorum et 
Insecforum. 4 vols. 8vo. Paris, 1806. ' 

X Latreille undertook all that portion of the above work which treats of the 
jinnulose Animals with Articulated Feet, comprising the classes Crustacea, 
Arachnida, and Insecta. 



REPORT ON ZOOLOGY. 193 

Squilla. The Amphipoda consist principally of such Crustacea 
as were referred bj'^ Fabricius to his genus Gammarus. The 
Isopoda answer to the Onisci of Linnaeus. The Amphipoda 
and Isopoda together constitute Dr. Leach's second legion, 
Edriophthalma. Latreiile's fifth order, Branchiopoda, includes 
the Entomostraca of Miiller and Leach, referred by Linnaeus 
to his genus Monoculus *. 

Since the appearance of the R^gne Animal, other naturalists 
have occupied themselves with this class. Latreille has also 
modified his own arrangement in some subsequent publications, 
availing himself of many valuable researches on the part of differ- 
ent individuals, relating more particularly to the Entomostraca. 

In the Families Naturelles, published in 1825, we find the 
Crustacea divided primarily into the two sections of Maxillosa 
and Edentata. The former comprises, in addition to the old 
orders Decapoda, Stomapoda, Amphipoda, and Isopoda, three 
new orders, — one, Lcemodipoda, for the reception of the Isopodes 
Cystihranches oi the R^gne Animal, placed between the Stoma- 
poda and Amphipoda ; the other two, Lophyropoda and Phyllo- 
joorfa, taken out of the old order 5rancAiopoJa,andterminatingthe 
first division. The second section contains the remainder of the 
Branchiopoda arranged under the two new orders Xyphosura 
and Siphonostoma. Thus we have the Entomostraca, which 
before constituted but one order, here forming four. Latreille 
in his last work, Cours d' Entomologie, has increased the orders 
still further. He has adopted three other new ones, called Dicla- 
dopa, Ostrapoda, and Trilobita. The first of these, inserted 
between the Isopoda and Lophyropoda, includes the genera 
Nebalia, Pontia, Condylura, and Cuma. The second, insti- 
tuted by Straus, comprises the genera Cypris and Cytherea, and 
is placed between the Lophyropoda and Phyllopoda. The third, 
adopted for the fossil Trilohites, forms the last order in his first 
division of Maxillosa. In other respects his system is the same 
as that in the Families Naturelles. 

The same year as that in which the Fam. Nat. of Latreille ap- 
peared, Desmarest published his Consideratio^is Generales sur 
la Classe des Crustac^s. In this work, which is one of consider- 
able merit as well as utility f, we have the systems of Latreille 
and Leach in some measure combined. Thus, the Malacostraca 

• The above arrangement by Latreille was adopted, with some slight modi- 
fications, by Lamarck in the 5th vol. of his Hist. Nat. des An. sans Vert. 

\ M. Desmarest was the first to draw the attention of naturalists to the dif- 
ferent regions marked out on the upper surface of the carapace in the Decapoda 
Brachyura, and to show their exact accordance with the internal organs which 
they respectively cover. 

1834. a 



194 FOURTH REPORT — 1834. 

and Entomostraca of this last author are retained as primary 
divisions, and the former is still divided into the two secondary 
groups of Podophthalma and Edriophthalma ; but the groups 
next in succession are the same as Latreille's orders. At the 
satne time there is a slight modification of these orders among 
the Entomostraca . 

Risso, who has paid considerable attention to the Crustacea, 
adopts, in his Hist. Nat. de I'Eur. Merid., published in 1826*, 
nearly the same arrangement as that of Desmarest. 

The most important, as well as most recent, additions which 
have been made to our knowledge of the Crustacea are due to 
the researches of MM. Audouin and Edwards, who have for some 
years back, the latter gentleman more especially, given particular 
attention to this class of animals. Indeed it is impossible to 
speak too highly of their labours in this department. Bearing 
in mind the close connexion which subsists between zoology 
properly so called, and comparative anatomy and physiology, 
they have commenced by studying closely the internal as well as 
external organization of the Crustacea, before proceeding to in- 
vestigate their natural affinities. The results of their researches 
on this branch of the subject are contained in a series of me- 
moirs published in the Annales des Sciences, of which anylengthr 
ened analysis here would lead too much into anatomical details. 
It may be just stated, that in their first two memoirs, published 
in 1827t, they have treated of the circulation of the blood, con- 
cerning the true course of which there prevailed before much 
difference of opinion. They have determined with accuracy the 
exact method in which the circulation is effected, and found it 
to be in some respects analogous to that which is known to pre- 
vail in the molluscous animals^. In a third memoir, published 
in 1 828 §, they have entered into considerable details with respect 

* The Crustacea are contained in the fifth volume. Risso had published 
some years previously a work entitled, Histoire Naturelle des Crtistaces det 
Environs de Nice, 8vo, Paris, 1816. 

t Ann. des Scien., torn. xi. 

J Two memoirs on the circulation of the Crustacea have been also published 
in Germany by M. Lund, the one prior, the other subsequent, to those of Au- 
douin and Edwards. In the first {his, 1825,) the author observes that he has 
never been able to discover the slightest trace of veins in the Crustacea, which 
he thinks are without them, and in consequence deprived of a complete circu- 
lation. In the second (Isis, 1829,) he confines himself to some remarks on the 
researches of Audoxiin and Edwards, who have arrived at such difl^erent results 
from himself. He allows that they have discovered a system analogous to the 
venous system of the Vertebrata and Mollusca, but does not agree with them as 
to a near affinity between the Crustacea and Mollusca in regard to their circula- 
tory organ*; 

§ Ann., torn. xiv. p. 77j 



REPORT ON ZOOLOGY. J 95 

to the nervous system. Their particular object is to show that 
in the Crustacea this system exhibits a unity of composition, and 
that all the different modifications which it presents in different 
families may be easily referred to one type, these modifications 
depending simply on a greater or less approximation, and ten- 
dency towards centralization of the medullary ganglions. In a 
fourth memoir, read the same year to the Royal Academy of Sci- 
ences*, they have considered the respiratory organs of these ani- 
mals, their researches on which head have led them to discover the 
true method of respiration in those Crustacea which are capable 
of living for a considerable time out of water. They have as- 
certained that it is not by any organ analogous to lungs, as was 
formerly supposed, but by the help of a peculiar structure, ena- 
bling them to retain the water within the respiratory cavity as in 
a reservoir, from whence is supplied the necessary moisture for 
a free exercise of the branchial laminae. In a subsequent me- 
moir on this subjectf, published in 1830, M. Edwards has ex- 
pressed an opinion that the respiratory apparatus will be found 
to afford some valuable characters for the determination of natural 
groups. 

The above memoirs on the anatomy of the Crustacea, with 
the exception of the last, were undertaken by MM. Audouin 
and Edwards jointly. During the present year (1834), M. Ed- 
wards has published singly the first volume of a general work | 
gn the natural history of this class, in which he has embodied 
the researches just alluded to, as well as treated of the classifica- 
tion and systematic description of these animals. The following 
is a sketch of his arrangement. He divides the Crustacea pri- 
marily into the three subclasses of Crustaces Maxilles, Crust. 
Suceurs, and Crust. Xyphosuriens. The first of these groups 
conunences with the legion Podophthalmiens, including the two 
orders Decapodes and Stomapodes ; then follows the legion 
Edriophthalmes, comprisiiig the three orders Amphipodes, Iso- 
podes, and Lcemipodes; next in succession are the legions 
Branchiopodes and Entomostracts, which he thinks form two 
parallel series, the former containing the two orders of Phyllo- 
podes and Cladoc^res, the latter those of Ostrapodes and Cope- 
podes, this last being nearly the same as the order Dicladopes 
of Latreille. The legion Trilobites is placed provisionally at 
the end of the first subclass. The second subclass is divided 

• A report by Cuvier and Dumeril on this memoir will be found in the Ann. 
des Sci. l^at., torn. xv. p. 85. 

t Ann. des Set., torn. xix. p. 451. 

J Histoire Naturelle des Crustaces, comprenant V Anatomie, la Physiologic, et, 
la Classification de ces Animanx, par Milne Edwards, torn, i., Paris, 1834. 

o2 



196 FOURTH REPORT 1834. 

into the two legions of Parasites Marcheurs and Parasites 
Nagetirs, the former comprising the single order Araneiformes, 
the latter the two orders Siphonostomes and Lemeens. The 
third • suhclass consists of the single order Xyjihosures. It will 
be seen that Edwards has adopted a large number of Latreille's 
principal groups. At the same time he has introduced some 
changes in the arrangement of this author. He has augmented 
the nmnber of orders, and likewise altered the limits of some of 
these divisions. Two of the additional orders are for the recep- 
tion of the Pt/cnogonida and LerncecB, w^hich Latreille does not 
include in the present class. In the descriptive portion of his 
work, M. Edwards has as yet pnjceeded but a little way. In 
fact he has only got through the first two families of the Decw 
poda Brachyura. A few years back, however, he published a 
monograph on the Crustacea Amphipoda, to which those may 
be referred who want information on that particular order. An 
extract from it will be found in the Ann. des Scien. for 1830*. 

Some researches on the Crustacea by a naturalist of this 
country, of great importance, though leading to results which it 
would be w'ell to have confirmed by other observers, may be 
noticed in this place. I allude to Mr. Thompson's supposed 
discovery of a metamorphosis in the animals of this class, an- 
nounced in 1828, in the first number of his Zoological Re- 
searckesf. It is stated by this gentleman, that having examined 
the newly hatched young of the common Crab ( Cancer Pagujnts), 
he found them presenting exactly the appearance of the Zoea 
Taurus, the Monocuhis Taurus of Slabber, which animal he 
conceives to be the first state of the species above mentioned. 
From this circumstance he was led to conclude, that metamor- 
phosis was general throughout the Decapod Crustacea ; that in 
the first stage of their existence they are essentially natatory, 
but that after a time the greater number of them lose the power 
of swimming, acquire chelae, and have their feet adapted for 
crawling only. In a communication made by letter to the Zoo- 
logical Society in 1830:}:, Mr. Thompson stated, in support of 
the universality of this metamorphosis, that he had ascertained 
the newly hatched animal to be a Zoea in eight genera of the 
DecupodaBrachyura,\\z. Cancer, Carcinus, Portimus, Mryphiay 

• torn. XX. 

t Zoological Researches, and Illustrations ; or Natural History of Nondescript 
or imperfectly known Animals. By J. V. Thompson. Cork, 1828, &c. — Of this 
work only five numbers have as yet appeared. In it will be found some other 
valuable memoirs relating to the Crustacea besides that above alluded to, more 
particularly one on the genus Mysis, and another on the Shixopoda. 

X Proceed, of Zool. Soc, p. 17, 



REPORT ON ZOOLOGY. 19/ 

Gecarcinus, Thelphusa ?, Pinnotheres, and Inachus ; and in 
seven genera of the Macroura, viz. Pagurus, Porcellana, Ga~ 
lathea, Crangon, Palcemon, Uomarus, and Astacus. 

No direct observations have been as yet made by other natu- 
ralists sufficient to establish the existence of any error in these 
results at which Mr. Thompson has arrived. There is, how- 
ever, enough on record to prove that this metamorphosis is not 
universal ; and some excellent observers have been led by their 
own inquiries to regard it as rather improbable altogether. 
The researches of Rathke are decidedly opposed to it. This 
profound anatomist is the author of an elaborate treatise on the 
development of the young Cray- fish* , which he has traced 
through all its stages from its earliest existence ; and so far from 
observing any metamorphosis in this species, he particularly 
states that the young at birth scarcely differ externally from the 
adult except in size. M. Edwards has made some remarks upon 
Mr. Thompson's theory, which he does not consider as tenable, 
without the support of further and more accurate observation. 
At the same time he thinks it very possible that none of the in- 
dividuals of the genus Zoea hitherto observed by naturalists had 
reached their adult statef . We are informed by Latreille J, that 
this gentleman had it in view to institute some particular re- 
searches under the hope of throwing light on this matter. I 
am not aware that any decisive results have been hitherto made 
public. The subject, however, is undergoing investigation in 
our own country, and will probably before long be satisfactorily 
cleared up. 

The above doubts respecting the metamorphosis of the Crus- 
tacea relate only to its existence amongst the Decapoda. That 
it takes place in some of the other orders in this class is quite 
certain. Jurine long since detected it in the case of some of the 
Entomostraca. More recently M. Edwards has observed strik- 
ing changes of foi-m, almost, if not quite amounting to meta- 
morphosis, taking place in several genera of the Crustacea Iso- 
poda, in one genus (Cy amies, Latr.) of the L^modipoda, and in 
one genus {Phrotiima, Latr.) of the Amphipoda^. At the same 
time he has fully ascertained, that in other genera, more parti- 
cularly Gammarus and Idotea, this kind of metamorphosis does 

• See an analysis of this memoir in ^e Ann. des Set. Nal. for 1830, torn. xx. 
p. 442. 

+ Ann. des ScL, torn. xix. p. 459. See also Hist. Nat. des Crust., toni. i. 
p. 199 ; and Diet. Class, d' Hist. Nat., Art. Zoe. 

X Cours d' EntomoL, p. 385. 

§ These researches are contained in a memoir, of which an analysis will be 
found in the Ann. des Scien. for Dec. 1833, p. 360. 



1S8 FOURTH REPORT — 1834. 

not occur. The genus in which the change of form is most con- 
spicuous appears to be that of Cymothoa. In this instance he 
has observed the young to be not only deficient in some parts 
which are developed in the adult, — thus, having six instead of se- 
ven thoracic segments, and consequently only twelve instead of 
fourteen feet, — but possessed of others well developed, which in 
the adult state are merely rudimentary. Thus, the adult has the 
head extremely small, and the eyes scarcely perceptible exter- 
nally. The young, on the contrary, have the head large, and the 
eyes remai-kably conspicuous. A similar difference occurs in 
the segments of the abdomen, which in the adult are very short 
and almost linear, whereas in the young they spread out almost 
as much as those of the thorax*. 

Naturalists who have studied this class have too frequently 
confined their researches to the Malacostraca. The Entomo- 
straca, although everywhere to be met with, like some other 
equally neglected gi-oiips, have received, at least of late years, 
but comparatively little attention. In this country they have 
been scarcely noticed at all. The works of Miillerf and Jurine| 
still retain their value as the great storehouses of original ob- 
servations relating to these animals, and are indispensable to 
those who may feel induced to study them. The latter, which 
is of recent date compared with Miiller's, deserves especially to 
be pointed out, as, though well known and duly appreciated on 
the Continent, it does not appear to be familiar to our own na- 
turalists. It embraces the history of Miiller's genera Cyclops, 
Daphnia, Polyphemus, Lynceus, and Cyjiris, including descrip- 
tions of such species as are found in the neighbourhood of 
Geneva. Jurine has paid the most scrupulous attention to the 
habits and ceconomy of these minute animals. Many of them he 
has traced through every stage of their existence ; and, amongst 
other valuable researches, has ascertained that the genera Amy- 
mone and Nrnqtlius of the Danish naturalist are only young 
states of the genus Cyclops. This work is illustrated with beau- 
tifully coloured figures of all the species. There is also ap- 
pended to it a detailed and valuable memoir by Benedict Prt'vost 

• M. Edwards has sought to i-efer to some general principles these and other 
similar facts which he has observed relating to change of form in the Crustacea. 
He has arrived at the following generalization : That " the different changes 
of form which the Malacostraca (or higher Crustacea) may experience after 
quitting the egg, tend always, whatever be their nature or importance, to alienate 
the animal from the type common to the greater number of these beings, and in 
some measure to individuate it more and more." See Ann. des Scieii., 1. c. 

f Entomostraca, seu Insecta Testacea, S^-c. 4to, Lips, et Haun. 1785. 

J Histoire des Monocles qui se trouvent aux Environs de Geneve. 4to, Geneve, 
1820. 



REPORT ON ZOOLOGY. 109 

on the Branchipus of Latreille, or, as the author here calls it, 
Chirocephalus* . 

If to the above works we add a few separate memoirs devoted 
to particular genera by different individuals, — that of the younger 
Jurine on Argulus foliaceus published in 1806f, Straus's two 
memoirs on the genus Daphnia published in 1819 and 1820 J, 
a third the year following by the same author on the genus Cy- 
pris§, and Brongniart's memoir on the Limnadia Hermanni 
published in 1820||, — we shall have enumerated by far the most 
valuable contributions which have been yet made to our know- 
ledge of this portion of the Crustacea*^. Straus's memoirs in 
particular, which for patient research and close anatomical in- 
vestigation, considering the minuteness of these animals, can 
scarcely be equalled, deserve the highest commendation . It was 
principally in consequence of the labours of this observer and 
those of Jurine, which were subsequent to the appearance of 
the first edition of the R^gne Animal, that Latreille was led to 
make such striking alterations in the arrangement of the Ento- 
mostraca in his Families JVaturelles. These alterations have 
been already pointed out ; and they clearly show what we may 
yet expect from further researches into the structure of other 
groups which have not hitherto received so close an examination. 
The only recent contributions of any moment, at present known 
to me, are, a memoir by Dr. Gruithuisen on the Anatomy of 
Daphnia Sima published in 1828**, a second by Milne Edwards 
on the structure of the mouth in the Siphonostomous Entomo- 
straca published in 1833ff, and a third published within these 
few months by Mr. Thompson on the Artemis salinusXt- The 
principal object of M. Edwards's essay is to show that notwith- 
standing the apparent differences between the mouth of the 
Siphonostoma and that of the rest of the Crustacea, the parts 
are strictly analogous in the two cases, and there is still kept up 
a unity of composition. Thompson's memoir contains observa- 
tions on the gradual development of the j^oung of the Artemis 
salinus, and the metamorphoses which it undergoes before arriv- 
ing at an adult state. These metamorphoses are found to cor- 

* This memoir had been previously published in the Journal de Physique for 
1803, torn. Ivii. t Ann. du Mus., torn. vii. p. 431. 

+ Mim. du Mus., torn. v. p. 380, and torn. vi. p. 149. 

§ Id., torn. vii. p. 33. || Id., torn. vi. p. 83. 

If A treatise on the Monoculi was published at Halle, in 1805, by Ramd'hor, 
who, according to Latreille, has anticipated Straus and Jurine in somfe of their 
anatomical researches. I have not seen the work myself. 

•• Nov. Jet. i^-c. Nat. Cur., torn. xiv. p. 368. 

tt -^nfi. des Scien, Nat., torn, xxviii. p. 87. 

XX Zool. Researches, No. 5, Mem. 6. 



200 FOURTH REPORT — 1834. 

respond with those noticed in Branchipus, Apus, and other 
genera of the Phi/Uopoda, to which the Artemis is allied. Mr. 
Thompson has endeavoured to prove that there is a close affinity 
ht\.v<&en the Artemis salinus and the fossil Eyeless Trilobites. 

I may also refer to a paper by Audouin and Edwards in the 
Annates des Scien. for 1826*, containing an account of a very 
singularly organized animal, forming a new genus {Nicothoe) 
among the Siphonostoma of Latreille. It is of parasitic habits, 
and was discovered firmly attached to the gills of the Lobster. 
Perhaps there is no group in the Entomostraca in which we 
may expect so many new forms yet to occur, and of whose 
oeconomy in general we know so little, as that just mentioned. 
With reference to this last point we may, however, except the 
genus Argidus, Jurine's memoir before spoken of leaving us 
scarcely anything further to be desired in the history of that 
animal. 

3. Arachnidu. — This class, which Lamarck was the first to 
separate from that of Insects, has until very recently been much 
neglected by naturalists. The consequence is that our know- 
ledge of many of the groups contained in it is extremely imper- 
fect. Even its limits are far from being determined ; and some 
are of opinion that it ought to be resolved into two classes, on 
account of the great difl"erences which occur in the respiratory 
organs. Dr. Leach was the first to entertain this last idea, in 
the third volume of his Zoological JMiscellam/, published in 
181 7. In an article in this workf " On the Characters of the 
Arach/tides," he has restricted this class to the five families 
of Scorpionidce, Tarantididie, Phalangidce, Solpugidce, and 
Araneidce, in all of which respiration is effected by means of 
pulmonar)- sacs. The Trachean Arachnida of Latreille, except- 
ing the genera Pycnogonum, Phoxichilus, Ammothea, and 
JS'^ymp/iKm, (whose situation he considers doubtful,) and the 
genera. P/ialangium,So/puga, and Trogulus, (and perhaps Siro,) 
he thinks constitute a peculiar class, which he proposes to name 
Acari. 

Although Lati'eille himself subsequently adopted this same 
opinion respecting the propriety of forming two classes of the 
Pulmonary and Trachean ArachnidaX, he has not acted upon it in 
any of his published works. In the Regne Animal these groups 
simply stand as two orders, the first including the two families 
of Filenses {Aranea, Linn.) and Pedipalpes {Tarantula, Fab., 
and Scorpio, Linn.), the second those of Faux Scorpions, Pyc- 

• torn. ix. p. 345. \ p. 46. 

X Fam. Nat., p. 317, note ('). Coins d'Entom., p. 161. 



REPORT OX ZOOLOGY. 201 

nogomdes,2Li\(\. Holetree {Phalangium andiAcarus, Linn,). In 
the Families Naturelles his arrangement is nearly the same. 
There is simply a change with respect to the order in which the 
families stand, with the addition of some new ones amongst the 
Trachean Arachnida. But in the Cours d' Entomo logic we find a 
third ordei', termed Aporohranches, occupying a middle station 
between the other two. This new group, which is characterized 
by having gills without any external opening, Latreille intends 
should include the Pyaiogonida. It has been already mentioned 
that these anomalous animals, which seem to form the passage 
from the Arachnida to the Crustacea, are considered by Ed- 
wards as belonging to the class last mentioned. 

It may be stated that Mr. Kirby appears likewise to be of 
opinion that the Pulmonary and Trachean Arachnida should 
not be included in the same class*. 

Mr. MacLeay has, however, expressed himself differently. He 
maintains " that the division of the organs of respiration and 
circulation is not to be depended on in the classical arrangement 
of the Annulosaf." 

This last opinion, which will probably in the end be generally 
assented to, has been adopted by Duges in a valuable memoir on 
the Acari, published during the present year;}:. In the intro- 
duction to this memoir Duges has made some observations on 
the relation which subsists between the Acari and the rest of 
the Arachnida. He remarks that there is nothing in the external 
structure of these animals at all corresponding to those differ- 
ences in the respiratory and circulatory organs which some au- 
thors have made the basis of their arrangement. He thinks that 
the value of the characters derived from these organs has been 
overrated ; and in proof of this, that it is only necessary to 
observe the striking changes which such organs undergo (in the 
case of the Batrachian Reptiles and aquatic insects) in the same 
individual at different stages of its life. 

Instead, then, of making the external form subordinate to the 
organs of respiration and circulation, M. Duges adopts the for- 
mer as the groundwork upon which he establishes his principal 
divisions. The following are what he considers as the true di- 
stinguishing characters of the class Arachnida : Istly, the pre- 
sence of eight feet adapted for walking ; 2ndly, the absence of 
antennae§ and reticulated eyes ; 3rdly, the constant union of one 

• Introd. to Entom., vol. iii. p. 21. + Hor. Enf.,Tp. 382. 

J " Recherches sur I'Ordre des Acariens" Ann. des Scien. Nat. for Jan. 1834, 

§ Lamarck had observed, and formerly Latreille also, how strikingly the true 
Arachnida were distinguished from the two classes of Crustacea and Insects by 



202 FOURTH BKPORT 1834. 

or more segments of the thorax with the head. The class thus 
characterized, which, according to a new nomenclature of his 
own*, he calls Aranistes, he divides into the two subclasses of 
Acarulistes and Armmlistes ; the former containing the single 
order Acariens ; the latter the three orders of Phalangiens, 
Ar aniens, and Scorjnoniens. Each of these orders is again 
divided into several families. 

The rest of Dug^s's memoir is restricted to the investigation 
of the Acari, and contains some novel and highly important re- 
searches on this group of animals. These relate more espe- 
cially to the gradual development of the young, and the meta- 
morphoses which many of them undergo before arriving at the 
adult state. M. Duges has satisfactorily ascertained that many 
of the hexapod genera constituting Latreille's family of Micro- 
phthira are only the larvfe of others, and he has sufficiently 
multiplied his observations to lead him to suspect that this will 
be found ultimately to be the case with all of them ; that is to 
say, that there will be found no instance of any of the Arachnida 
having only six feet in the adult state. He has proved Leptiis 
to be only the young of Trombidium, and he has strong reasons 
for supposing Ocypete and Astoma to be so likewise. The genus 
Achlysia of Audouinf he has shown to be the larva of Hy- 
drachna : the genus Caris he suspects to be the larva of Argas. 
Although these striking researches necessarily lead to the sup- 
pression of many genera instituted by former naturalists, Duges 
has discovered or established others more than sufficient to make 
compensation. In his arrangement of these animals we still 
find twenty-four genera, distributed under seven families, the 
former exceeding by five the number adopted by Latreille. It 
is his intention to treat of each of these genera separately. As 
yet, however, his valuable memoir remains unfinished. 

But few individuals besides Duges have hitherto devoted much 
of their attention to the Acari. In 1826, Heyden published a 
systematic arrangement of this grouplj:, in which he increased 

the want of antennfe. Latreille, however, was led subsequently to take a dif- 
ferent view of the subject, and to regard what are usually called the mandibles 
or chejiform palpi in the Arachnida as representing the intermediate pair of an- 
tennae in the Crustacea Decapoda, only in the former class exercising a different 
function and being always adapted for manducation. Thus the deficient parts he 
considered to be the true mandibles, and not the antennae. See jFVijw. Nat., p. 307. 
See also some remarks on this hypothesis of Latreille, by MacLeay {Hot. Ent., 
p. 383,) and likewise by Duges {I. c, p. 9.). 

• In this and some other instances Duges has very unnecessarily changed 
names which had long been consecrated by time, and adopted generally. 

t Mem. de laSoc. d'Hist. Nat. de Paris, torn. i. p. .98. 

t his, 1826, p. 608. 



REPORT ON ZOOLOGY. 203 

the number of genera to sixty-nine, but in the opinion of Duges 
many of these rest on doubtful if not erroneous characters. 
Leon-Dufour, Audouin, and De Theis have all contributed me- 
moirs to the Ann. des Sci. Nat. on particular genera*. Accord- 
ing to LatreiUef , this last gentleman is engaged in a new work 
on these animals, to be illustrated by plates. 

The most important group among the Pulmonary Arachnida 
is that of the Araneidee. Nevertheless, like all the others in this 
class, it has been greatly neglected. Walckenaer, Latreille, 
and Leon-Dufour in France, De Hahn in Germany, and Mr. 
Blackwall in our own countiy, are almost the only individuals 
who have given it any attention of late years. Walckenaer, who 
has studied it most deeply, and whose Tableau des Aran^ides, 
published in 1805, has been hitherto the only guide for naturalists 
in this department, has recently proposed a new arrangement of 
these animals in a memoir read to the Entomological Society 
of France j. The principal groundwork of his system is the 
same as in his Tableau, and he still adopts the two large divisions 
of Theraphoses and Araignees, founded upon the position of the 
jaws with respect to the rest of the body, and the articulation of 
the mandibles. The number and position of the eyes serve 
afterwards for characterizing some well-marked groups subordi- 
nate to these two large tribes. Walckenaer observes that the 
species of Spiders have been greatly overmultiplied, from suf- 
ficient regard not having been paid to the changes incident to 
different ages with respect to size and colour. Leon-Dufour 
has more particularly occupied himself with the structure and 
internal anatomy of the Araneidee. He is the author of some 
important memoirs§ on this part of the subject, in one of which 
he has instituted a new division of this group into the two sec- 
tions of Tetrapneumones and Dipneumoiies, founded on the 
number of pulmonary sacs, which he was the first to discover 
are double on each side of the abdomen in certain species, amount- 
ing to four in all. The Tetrapneumones, which comprise the 
Th4raphoses of Walckenaer, as well as a small portion of his 
Araignees, form the subject of a memoir in the Nouv. Ann. du 
Mus.\\ by Latreille, who speaks highly of this new principle of 
arrangement. He thinks that it will serve as an immutable 



• Ann. des Set., torn, xxv., xxvi., and xxvii. f Cours d'Entom., p. 546. 

X An extract from this memoir will be found in L'Institute, 1833, No. 18. 
M. Walckenaer has also lately commenced the publication of a work entitled, 
Les Araneides de France classees par lettr Organisation, 8fC. (L'Instit. 1834, 
No, 53.) 

S Ann. des Scien. Physiques de Bruxelles, torn. v. and vi. i| torn. i. p. 61. 



204 FOURTH IlEPORT 1834. 

foundation for a natural distribution of the genera In this exten- 
sive family. Latreille has adopted it in the second edition of the 
R^gne Anifmal, as he had previously done in his Families JVatu- 
relles. It must be observed, however, that Walckenaer does not 
attach so much importance to this modification of the respira- 
tory organs. He states that it is not accompanied by anj^ cor- 
responding differences in other parts of the structure, and that, 
taken as the basis of a division, it leads to the separation of cer- 
tain genera which, according to his views, are connected by the 
closest affinity. Besides the above memoirs on the structure of 
the Aranece, Leon-Dufour has published several others descrip- 
tive of new or ill- understood species*. He has particularly 
attended to the species found in Spain, as well as to the species 
of Phalangium met with in the same countryf. He has dis- 
covered a new method of preserving the Arane(s\, which it is 
to be hoped may induce fresh labourers to enter upon this field. 
It is greatly owing to the difficulty which has been hitherto 
experienced in preventing the changes which occur after death 
in these animals, that they have been so much neglected by 
naturalists. 

De Hahn is the author of a work now in course of publication, 
the object of which is to illustrate by coloured plates the genera 
and principal species of this family§. Mr. Blackwall has pub- 
lished some important memoirs on subjects connected with the 
structure and oeconomy of the Araneidce\\, as well as others de- 
scriptive of some undescribed genera and species^. 

Before leaving this class it may be mentioned that in the third 
volume of the Zoological Miscellany** , Dr. Leach has published 
an article on the characters of the genera of the family Scorpi- 
onidcB, accompanied by descriptions and coloured representations 
of all the British species of Chelifer and Obisiiim. Some ad- 
ditions to these genera by Tlieis will be found in the Ann. des 
Sci. for 1832t-i-. 

4. Myriapoila. — There can be no doubt that a certain affinity 
exists between this class and the Annelida, as Latreille was the 
first to point out in a memoir on the articulated animals pub- 
lished in 1820:J:|. The Myriapoda have not been much attended 
to. In the third volume of the Zoolog. Miscell. is a valuable 
paper by Dr. Leach on these animals, in which he has given the 

• Ann. des Sci. Phys., torn. iv. Ann. des Sci. Nat., tomes ii. and torn. xxii. 
f Ann. des Sci. Nat., torn. xxii. + Id. 

§ Die Arackiiiden getreu nacli der Natur ahgebildet und besehriehen, von 
C. W. Hahn, 1831, &c. || Linn. Trans., vols. xv. andxvi. 

^ Land, and Edinb. PJiil. Mug. and Journ., J 83.3, vol. iii. 
»* p. 48. t+ toni- xxvii. p. 57. %% Mem. du Mus., torn. vi. p. 116. 



REPOKT ON ZOOLOGY. 205 

characters of the genera which it comprises, as well as descrip- 
tions of all the British species*. He divides the class into the 
two orders of Chilogtiatha and Syng7iatha, the former answering 
to the Linnsean genus lulus, the latter to that of Scolopendra. 
This arrangement is adopted hy Latreille. Savi has made a 
particular study of the luli. In two memoirs, one published in 
I8I7, the other in 1819f , he has recorded some valuable observa- 
tions relating to the ceconomy of certain species of this family. 
I am not aware of any recent contributions to our knowledge of 
this class excepting a paper by L^on-Dufour on the internal 
structure of the Lithohius forficatus and the Scutigera lineata. 
This memoir is published in the Ann. des Set. Nat. for 1824. 

5. Insecta. — It is impossible to do more than to treat of this 
class in the moat general manner. Indeed from its great extent, 
the immense additions which have been made to it of late years, 
and the large number of individuals who have contributed to its 
progress, it may well deserve to be made the subject of a separate 
report. I shall simply state, Istly, the leading groups which 
have been adopted or proposed in this class ; 2ndly, the most 
important works and memoirs which have appeared in illustra- 
tion of its structure ; 3rdly, the principal authors who have con- 
tributed to the advancement of particular parts of it. As the 
chain of affinities connecting the several orders is far from being 
determined with certainty, and much difference of opinion exists 
on this subject, to discuss which would lead to considerable 
details, I shall be silent on this point altogether. 

(1.) Inthefirst edition of theii^^Tie^wma^thefollowingorders 
are adopted by Latreille, exclusively of the Myriapoda, which 
he afterwards acknowledged as a distinct class. 1. Thysanura, 
Latr.J ; 2. Parasitu, Latr.J ; 3. Suctoria, De Geer ; 4. Coleo- 
ptera,iAnn.; 5 .Orthoptera,Ol[v.', 6. Herniptera, Linn. ; 7- Neu- 
roptera, Liinn.; 8. Hy)nenoptera,hmn.; 9. Lepidoptera, Linn.; 
10. Rhipiptera, Latr. {Strepsiptera,'K\x:h.)', W. Diptera,lAnn. 

In the same year (1817), Dr. Leach published his amended 
arrangement of the orders of the class Insecta in the third volume 
of his Zool. Miscellany. In this work we have a primary di- 
vision into the two subclasses of Ametabolia and Metabolia. 
The former includes the Thysanura and Parasita of Latreille, 
the name of this last order being changed to Anoplura : the 
latter, Latreille's remaining orders, with the five additional or- 
ders oi Dermaptera, De Geer, (gen. Forficula,'L\im.) ; Dictyo-- 

* Dr. Leach has described several new species of Tultis from the South of 
Europe in the Transactions of the Plymouth Institution, 1830, p. 158. 
t See Bull, des Set. Nat., 1823, torn. iv. p. 330. 
J These two orders were established by Latreille in some of his earlier works. 



206 FOURTH REPORT — 1834. 

pterUy (gen. Blatta, Linn.) ; Omoptera, (gen. Cicada, Thrips, 
Aphis, &c., Linn.) ; Trichoptera, Kirb. (gen. Phryganea, Linn.) ; 
and Gmaloptera, (gen. Hippohosca, Linn.) ; amounting in all 
to sixteen. Latreille's name of Suctoria is changed to that of 
Apt era. 

Mr.MacLeay in his HorcB Entoni. (1821) has proposed Bom- 
hoptera, Megalopteru, and Rhaphioptera as three new oscu- 
lant orders in his class Mandihulata, including the genera Sirex, 
Linn., Sialis, Latr., and Boreas, Latr., respectively. The first he 
considers as connecting the Hymenojitera and Trichoptera; 
the second, this last and Neuroptera ; the third, this last and 
Orthoptera. He regards Dermaptera and Strepsiptera like- 
wise as osculant orders, the former connecting Orthoptera and 
Coleoptera, the latter this last and Hymenoptera. 

Blainville* divides the Insects (forming with him his class 
Hexapuda) into thi'ee subclasses, Tetraptera, Diptera, and 
Aptera. The first of these contains as subordinate groups the 
orders Coleoptera, Orthoptera, Hemiptera, Lepidoptera, Neu- 
roptera, and Hymenoptera. 

In 1823, Dumeril published his Considerations G ene rales sur 
la Classe des Insectes. His work, however, which is of an ele- 
mentary nature, oifers nothing new on the subject of classifica- 
tion. His orders, eight in number, are the same as those of 
Linnaeus, with the addition of Orthoptera. M. Dumeril advo- 
cates very strongly the dichotomous, or, as he terms it, the ana- 
lytical method of arrangement, which he had adopted in his 
former works. 

In the Fain. Nat. (1825) Latreille adopts as a primary divi- 
sion of this class the two sections of Aptera and Alata. The 
former comprises the orders Thysanura, Parasita, and Siphon- 
aptera (name substituted for that of Suctoria) ; the latter, the 
remaining orders of the Regne Animal. 

In 1826 appeared the fourth volume of the Introduction to En- 
tomology, in which Mr. Kirby proposes to adopt twelve orders. 
Seven oi" these are the same as those of Linnaeus ; the remaining 
five are Strepsiptera, Dermaptera, Orthoptera, Trichoptera, 
and Aphaniptera (Siphonaptera, Latr.). 

In the second edition of the Regne Ani7nal,Li-dtre\\\e' s ari'ange- 
ment is the same as in the first. But in his last work, the Cours 
d' Entomologie (1831), he has again taken that of the Families 
Naturelles, excepting that he has adopted one additional order, 
the Dermaptera of Leach. 

(2.) Our knowledge of the structure of Insects, both external 
and internal, has been greatly advanced of late years by the re- 

• Principes, ^-c, tab. 7. 



BBPORT ON ZOOLOGY. 20/ 

searches of many excellent observers. Some of the most im- 
portant contributions on the subject of their external anatomy 
have arisen out of an endeavour to trace analogies of structure 
in the relative conformation of different groups in this class, as 
well as in that of insects in general compared with the rest of 
the Annulosa. Savigny was the first to draw the attention of 
naturalists to inquiries of this nature in two memoirs on the 
structure of the mouth of the articulated animals, published in 
1816*. In one he demonstrated that the same parts were to be 
found, though modified, in this organ as it occurs both in the 
Mandibiilata and Haustellata, notwithstanding the apparent 
dissimilarity of its structure in these two groups. In the other 
he extended his researches, with the view of establishing similar 
analogies, to the mouth of the Arachnida, Crustacea, and En- 
tomostraca. The year 1820 was rich in memoirs of a similar 
nature to those just alluded to. Latreille first published one on 
the structure of the wings of Insectst, in which he sought to re- 
fer to some general law of conformation the organs of locomo- 
tion in this class, as well as in those oi Arachnida and Crustacea. 
Latreille' s memoir was followed by three from Geoffroy on the 
Organization of Insects, already referred to in a former part of 
this Report as containing the first enunciation of his views re- 
specting the vertebrate structure of Insects and CrustaceaX. 
The same year two memoirs were brought forwards by Audouin 
on the same subject. The object of one was to point out ana- 
logies of structure between the true Insects and the Crustacea 
and Arachnida, more particularly as regards the head and its 
appendages, and the relative development of the segments of 
the trunk§. That of the other was to generalize an extensive 
series of observations with respect to the various parts which 
enter into the composition of the thorax in the different orders 
of Insects II . Latreille also published two other memoirs besides 

• " Theorie des Organes de laBouche des Crustaces et des Insectes," Mim. 
sur Us An. sans Vert., Part I. 

+ De la Formation des Ailes des Insectes. 8vo. 

X Journ. Comp. du Diet, des Sci. MM., tomes v. and vi. It was in conse- 
quence of GeofFroy's first memoiron this subject, read to the Academy of Sciences 
Jan. 3, 1820, that Latreille was induced to write his memoir (before alluded to) 
entitled Passage des Animaux Invertebres aux Vertebres, which memoir of 
Latreille was published, together with his former one, De la Formation des Ailes 
des Insectes, as an Svo pamphlet. 

§ I am ignorant as to where this memoir was published, or whether it was 
ever published at all. I know it only fronv Cuvier's Report in the Analyse des 
Travaux. 

II This memoir was subsequently published in the Ann. des Sci. Nat. for 1824, 
torn. i. pp. 97 and 416. A short analysis of it had appeared previously in the 
Bull, de la Soc. Phil, (or 1820. 



fJ08 FOURTH REPORT — 1834. 

that already alluded to ; one on the supposed elytra of the Stre- 
psiptera, and on the appendices of the trunk of Insects in gene- 
ral* ; the other on the general relations of the external structure 
of the articulated Invertebrataf. In 1821 Latreille published 
a memoir containing further observations on the external struc- 
ture of the Atinulosa, principally with a view to fix the nomen- 
clature of the principal parts J. The same year appeared the 
first of a series of elaborate memoirs by Chabrier on the organs 
of flight in insects, with a detailed account of all the parts con- 
tributing to the motion and articulation of the wings §. In 1825 
an important memoir was brought forward by Mr. MacLeay on 
the structure of the tarsus in the Tetramerous and Trimerous 
Coleoptera of the French entomologists ||. Its object was to 
show the defects of an arrangement founded on this part, and to 
prove that such arrangement must necessarily lead to the viola- 
tion of natural affinities. In 1826 appeared an elaborate dis- 
sertation on the external anatomy of Insects in the third volume 
of the Introduction to Entomology by Kirby and Spence. In this 
work there is given a collected view of the researches of previous 
naturalists on this subject ; at the same time there are some 
material additions made to what had been already done by others. 
In the Bull, des Set. Nat. for 1828, is an abstract of a memoir 
by Haan on the organs of manducation and motion in the arti- 
culated animals^!- It was during that year that Straus-Durck- 
heim published his great work on the Comparative Anatomy of 
the Articulated Animals **. This last is perhaps the most im- 
portant and elaborate treatise of its kind that has hitherto ap- 
peared. It is the first of a series of monographs which the au- 
thor intends publishing on the structvire of the different orders 
of insects. It contains some general remarks on the organiza- 
tion of the Annulosa, after which the author proceeds to the 
investigation of that of the Coleoptera in particular, the Melo- 
lontha vulgaris being taken as the type. In the first part of his 
subject, Straus-Durckheim has endeavoured to refer the different 
modifications of structure which the organs undergo in passing 
through different groups of articulated animals, to general laws. 
In 1830 Straus-Durckheim read to the Royal Academy of Sciences 
at Paris a portion of another work, treating in like manner of the 
structure of the Hymenopterous Insects, the common Hornet 

• • Mem. du Mus., torn. vii. p. 1. f Id., torn. vi. p. 116. 

X Id., torn. viii. p. 169. § Id., tomes vi., vii., and viii. 

II Linn. Trans., vol. xv. p. 63. ^ torn. xiii. p. 443. 

•• Considerations generales siir V Analomie Comparee des Animaux ArticuUs, 
auxquelles on a joint V Anatomie descriptive du Melulontha vulgaris (Hanneton), 
donnee comme exemple de V Organisation des Coleopteres. Paris, 1828, 4to. 



REPORT ON ZOOLOGY. 209 

(Vespa Crahro, Linn.) being selected as the type. I am not 
aware that this second monograph has been yet published*. 
During the same year an elaborate memoir appeared in this 
country by Mr. MacLeay on the structure of the thorax in winged 
insects, in which he has not only given the result of his own 
inquiries, but reviewed the previous labours of Audouin and 
Kirby on this subject, especially the nomenclature of the dif- 
ferent parts of the thorax as assigned by these authors respec- 
tivelyf. Lithe Annales des Scien. for 1832J:, is a memoir by 
Duges on the structure of the genus Pulex, with the particular 
view of discovering its true affinities. This genus constituting in 
itself an entire order of insects, the memoir is of considerable im- 
portance. In the Entomological Magazine^, Mr.Westwood has 
also made some remarks on these insects more particularly relating 
to the structure of their antennae. In the Notiv. Ann. dti 3Ii(s. 
for the same year||, Latreille has published a valuable memoir 
on the external structure and affinities of the Thysaniira, which 
his researches lead him to think form the transition from the 
Myriapoda to the true Insects. They are the only insects in 
which Latreille has not been able to discover stigmata ; the ab- 
sence of which he regards as one of the distinguishing charac- 
ters of this order^. Lastly, I may refer to some papers by Mr. 
Newman on the external anatomy of Insects in general, recently 
published in the Entomol. Mag** Latreille has also treated of 
the whole subject in his Cours d'Entomologieff. 

It would be out of place to dwell much on the internal ana- 
tomy of insects in this Report. I shall do little more than ob- 
serve that it is principally to the researches of Marcel de Serres, 
L^on-Dufour, Duges, and Straus-Durckheim in France, and to 
those of Herold, Gaede, CarusJI, Suckow, Meckel, and Miiller 

• An analysis of it will be found in the Bull, des Sci. Nat. for 1 830, (torn, 
xxii. p. 347,) also in Cuvier's Analyse des Travaux for the same year. 

t Zool. Journ., vol. v. p. 145. J torn, xxvii. p. 145. 

§ vol. i. p. 359. II torn. i. p. 16'l. 

1[ The Thysaniira have been sadly neglected by entomologists. Latreille 
observes that with respect to the Poduree there has appeared nothing new since 
the time of De Geer. ** vols. i. and ii. 

tt I may state in this place that two general introductory works on entomo- 
logy have appeared recently which I have not seen, both entering into details 
on the subject of the organization of insects. One of these is the Handbuch 
der Entomologie, published by Burmeister at Berlin in 1832. The other is the 
Introduction a l' Entomologie by Lacordaire, of which the first volume has only 
just appeared. See L'Insiit., No. 73, p. 324. 

XI Carus has the particular merit of having discovered the circulation of the 
blood in Insects. This remarkable fact, which was observed in the lai-vae of 
certain Neuroptera, was first announced at the meeting of German naturalists 
held at Dresden in 1826. 

1834. P 



^10 FOURTH REPORT — 1884. 

in Germany, that we are indebted for the recent progress which 
has been made in this department. Mr. Newport in our own 
country has also lately entered upon this subject*. There can 
be no doubt that our knowledge of the natural affinities of In- 
sects will be idtimately much benefited by the laborious investi- 
gations of such observ'ers, although there may not have been 
acquired hitherto a sufficient number of facts to Avarrant any 
extensive generalizations. Those of Leon-Dufour may be more 
particularly alluded to as throwing some light on this subject. 
This patient anatomist, in one of a series of the most elaborate 
memoirs on the internal structure of the Coleopteraf, observes 
that by dissecting insects he has been enabled to determine the 
value of many purely entomological characters, to clear up doubts 
with respect to the distinction of the sexes in certain cases, 
and to add to the number of those characteristic marks which 
had already been acquired from a study of the mouth, antennae, 
and feet, and employed as the foundation of families and genera. 
His researches have satisfied him that the system of LatreiUe is 
for the most part in perfect harmony with anatomical facts. 

(3.) Since the science of entomology has become so extensively 
cultivated, and the field which it embraces been found to be so 
extremely large J, naturalists have given up all attempt at a com- 
plete Species Insectornm. They have even in many cases found 
it impracticable to obtain a correct knowledge of any particular 
order, regard being paid to all the included species. Hence they 
have generally confined their researches to the more subordinate 
groups, or to the insects of particular countries : and it is to such 
works that we must have recourse, in order to learn the present 
state of our knowledge of the different orders which are com- 
prised in this class. It is not my intention, indeed it is not 
practicable on the present occasion, to do more than indicate in 
a general manner a few of the most valuable of such works which 
have appeared of late years. 

It is to the Count De Jean that we are indebted for the most 
extensive work which has been published on the order of Coleo- 
pteraf, although it has not extended as yet beyond the Cicinde- 
lidoi and CarabidcB. In a separate publication he has undertaken, 
conjointly with M. Boisduval, the illustration of such species as 
are found in Europe ||. Several important monographs have, 

• Phii. Trans. 1832. t ^«n- des Sci. Nat. 1824, &c. 

J Messrs. Kirby and Spence have estimated the probable number o£ existing 
species of Insects at not less than 400,000. See IiUrod. to Entom., vol. iv. 
p. 477. See also^ some remarks on this subject by Mr. Westwood in Loudon's 
Magazine of Natural History, vol. vi. p. 116. 

§ Species general des Colcopteres. Svo, Par., 1825, &c. 

II Iconog. et Hist. Nat. des Coleop., 1827, &c. 



REPORT ON ZOOLOGV. 211 

however, appeared upon particular families, some of which are 
now in course of publication. Thus, Zimmermann has made a 
study of the CarabidcB *; Erichson of the Di/ticidcBf ; Gory and 
Percheron of the Cetonice and some allied genera J. Schon- 
herr has published two valuable works on the CurcidionidcB ; 
one§ giving a general view of the subordinate groups in this 
extensive family ; the other ||, which has been only recently 
commenced, entering into the details of species. Lastly, I may 
refer to an important monograph on the Staphylinidcs by Count 
Mannerheim^. 

The Orthoptera have been made the subject of particular 
works by Zetterstedt** and Audinet Servilleff. Toussaint de 
Charpentier has also published a monograph on he European 
species of this order in his HorcB Entomologicce . 

Hahn has undertaken an illustrated work on the HemipteraXX- 
Schummei has written a monograph on the particular genera 
Hydrometra, Velia, and Gerris, constituting LatreiUe's family 
Ploteres^^. 

The Lepidoptera, at least the European species, have been 
particularly treated of by Treitschke, Godart, and Duponchel. 
The first has continued the valuable and well-known work of 
Ochsenheimer||||. Godart is the author of a work on the Lepi- 
doptera of France, which was commenced in 1822, but inter- 
rupted in 1825 by his death. Duponchel has carried it on from 
that time^^. Boisduval has published a valuable monograph on 
the ZygcenidcB*** . He has also commenced two other works on 
this order, one serving to illustrate the Lepidoptera of North 
Americafttj the other the caterpillars and metamorphosis of the 
species found in Europelt:}:. In the former he is assisted by 

* Monographie der CaraUden. Berlin and Halle, 1831. See Entomolog. Mag., 
vol. i. p. 306 ; a work to which I am indebted for the only knowledge I have of 
some of these monographs. 

t Genera Dyticeorum. Beriin, 1832. (See Ent. Mag., vol. i. p. 501.) 

I Monog. des Cetoines, et Genres voisins, S^c, 1833. (See Ent. Mag., vol. i, 
p. 418. § Curculionidum Dispositio methodica, Sfc. Lips., 1826. 

II Genera et Species Curculionidum, 8(C., 1833, &c. 

ij Precis d'un nouvel /irrangement de laFamille des BracMlytres, de VOrdredes 
Inseetes CoUopteres. St.Petersb. 1830. ** Orthoptera Sueoice. Lund., 1821. 

tt Revue Methodique des Inseetes de VOrdre des Orthopteres. (See Ent. 
Mag., vol. i. p. 304.) 

XX Die Wanzenartigen Insecten, ^c, Niirnberg, 1831, &c. (See^w^ Mag., 
vol. i. p. 308.) §§ See Ent. Mag., vol. i. p. 307. 

nil Die Schmetterlinge Europ., mit Fortsetzung von F. Treitschke. 1 825, &c. 

il^ Godart and Duponchel, Hist. Nat. des Lepidopteres, ou Papillons de 
France. 8vo, Par., 1822, &c. 

*•* Essai sur une Monographie des Zygenides. Par., 1829, 8vo. 

+tt Hist. Gener. et Iconograph. de tous les Lepidop. et Chenilles de I'Amer, 
Septentrionale. 8vo. tXX See Ent. Mag., vol. ii. p. 110, 

P 2 



212 FOURTH REPORT — 1834. 

L^conte, in the latter by Rambur and Graslin. Dr. Horsfield 
has thrown much Ught upon the arrangement and affinities of 
these insects in his Lepidoptera Javanica, already alluded to in 
a former part of this Report. 

The Neuroptera have been particularly attended to by Tous- 
saint Charpentier and Vander Linden, who have each published 
a inonograph on the European LiheUulcE : that of the former 
is contained in his Horce JEntomologiae. The Phryganece 
{Trichoptera, Kirb.) form the subject of an elaborate and valu- 
able work recently published by M. Pictet of Geneva*. 

The only recent works devoted to the Hymenoptera, with 
which I am acquainted, are those of Lepelletier de St. Fargeau, 
Gravenhorst, and Nees ab Esenbeck. The first has published a 
monograph on the Tenthredinida;f. The second has treated at 
great length of the European species of IchneumonidcBX- The 
third has written upon the more aberrant groups of the family 
just mentioned§. 

The Diptera have received great attention of late years from 
several excellent entomologists. Fallen's Diptera Suecice is 
rather anterior to the period of time we are considering. Wiede- 
mann's Diptera Exotica ||, Meigen's Diptera of Europe^, and 
Macquart's Diptera of the North of France**, are of more re- 
cent date, and have greatly contributed, the last two especiallj^, 
to advance our knowledge of this order of insects. I may also 
allude to a most elaborate work by Robineau-Desvoidy, which 
though treating only of the Fabrician genus Miisca, contains 
descriptions of nearly 1800 species, referred to nearly 600 
genera. This astonishing production, which is entitled JEssai 
sur les Myodaires, occupies the entire second volume of the 
Mem. des Savans E'trang., published in 1830. 

Besides the above works, I may mention Stephens's Illustra- 
tions of British Entomology, now in course of publication in 
our own country, as one which promises great additions to all 
the orders. The Coleoptera and Lepidoptera have already 
appeared. Curtis's British Entomology is confined to the il- 
lustration of the genera of British Insects, but as a work in the 

• Recherches pour servir a VHhtoire et a I'Anatomie des Phryganides. 4to, 
Geneve, 1834. (For an analysis of this work, see L'Instit., No. 73.) 

t Monographta Tenthredinetarum Synonymia extricata. Par., 1823, 8vo. 

X Ic.hneumoitologia EuropcBa. Vratislav., 1829, 3 vols. 8vo. 

§ Hymenopterorum Ichneumonibus affinhim, MonogrupkitB, Genera Europaa 
et Species illustrantes. vol. i. Stuttgart, et Tubing, 1834. 

II A usseretiropaisclie ZweiflugeUge Insecten. Hamm, 1828 — 1830, 2 vola. 8vo. 

^ Systeniatische Beschreibung der bekannten Europaischen Zweijlugeligen 
Insecten. Aachen, 1818— 1830, 6 vols. 8vo. 

*• Published in the Recueildes Travanxde la Society d'Amat. des Sciences, 8fC., 
de Lille. 1826—1829. 



REPORT ON ZOOLOGY. 213 

illustrative department, is unrivalled in the beauty and accuracy 
of its delineations. It is also extremely valuable from the num- 
ber of dissections which it contains. 

There are also many other valuable monographs, not published 
separately like those already alluded to, to be found in Germar's 
Magazin tier Entomologie, Guerin's Magasin de Zoologie, 
Silbermann's R^vue Entomologiqiie, in the Entomological Ma- 
gazine, and in t\\eAnnales de la Soc. Entomologique de France. 

In concluding my remarks on this department of zoology, 
I may observe that it has received a powerful impulse from the 
recent establishment of two Entomological Societies, one in 
France, and the other in our own country. This last was only 
instituted in 1833*. 

III. MOLLUSCA, CuV. 

It is undoubtedly to the researches of Poli, Cuvier, Lamarck, 
Ferussac, and Blainville that we are to attribute the great advance 
which has been made of late years in our knowledge of the ani- 
mals belonging to this tj^e. Poli's work, consisting of two 
volumes, on the anatomy of the Bivalve and Multivalve Testacea, 
is well known. In 1826, a third volume was published by 
Chiage, in which the anatomy of the Univalves was commenced 
upon the same plan as that adopted in the two former volumes. 
Cuvier's Memoirs on the Mollusca, most of which had been pre- 
viously inserted in the Annates dii Blusdiim, were in 1816 col- 
lected by himself into one volume and published separately. 
They contributed greatly to our better knowledge of the natural 
affinities of these animals, and furnished the basis of the system 
developed the year following in the R^gne Animal. In this 
last work the Mollusca are divided into six classesf , Cephalo- 
poda, Pteropoda, Gasteropoda, Acephala, Rrachiopoda, and 
Cirrhopoda, the characters being derived from the general form, 
between which and the internal structure Cuvier observes there 
is a pretty constant relation. The Cephalopoda are simply 
divided into genera according to the nature of the shell. The 
Pteropoda, a class instituted by himself in 1804 for the recep- 
tion of the genera Clio, Pneumoderma, and Hyale, are divided 
into two sections, founded on the presence or absence of a di- 
stinct head. The Gasteropoda are distributed under seven orders, 
characterized according to the position and form of the respira- 
tory organs. The Acephala comprise the two orders of Testa- 
ceous and Naked Acephala. The JBrachiopoda include the genera 

* Since this Report was read, the Entomological Society of London has pub- 
lished the first part of a volume of Transactions, containing several interesting 
and important communications on this branch of Zoology. 

t Three of these classes, Cephalopoda, Gasteropoda, and Acephala, had been 
established by Cuvier in his 2abl. E'lem. de I'llkt. Nat, in 1798. 



214 FOURTH REPORT — 1834. 

Lingula, Terebratula, an d OrAiCM^a, which had previously formed 
a part of the class last mentioned. The Cirrhopoda comprise 
the two genera Anatifa and Balanus, which Cuvier considers 
as in some respects intermediate to the Molluscous and Articu- 
lated Animals. 

The benefits conferred upon this department of zoology by 
Lamarck belong to a period of time somewhat anterior to the 
publication of the R^rpie Animal. We may, however, make a 
few remarks on the system adopted in the fifth and two suc- 
ceeding volumes of the second edition of the Animanx sans 
Vert^bres, which appeared in the years 1818 — 1822. Perhaps 
it is in the details of the science, the grouping of genera, and the 
characterizing an immense number of new species, that Lamarck's 
tact and penetration appear most conspicuous. His leading di- 
visions present several peculiarities which are scarcely warranted 
by the organization of these animals. Thus, he has separated 
altogether from the Mollusca the Naked Acephala, and made 
of them a distinct class mider the name of Tuniciers, which he 
refers to quite another place in his system, below the Articulated 
Animals which intervene. Again, the rest of Cuvier's Mollusca 
he divides into only three classes, which we are naturally led to 
infer he considers therefore as groups of equal value. The first is 
that of CirripMes. The second, or Conchif^res, answers to the 
Testaceous Acephala of Cuvier, including also the Brachiopoda. 
The third, to which Lamarck restricts the name of Mollusques, 
comprises all the remaining classes of the R^gne Animal. The 
groundof primary subdivision in Lamarck's second class is more 
entitled to our regard than that on which his higher groups are 
established, although not particularly noticed by Cuvier. It is 
the niunber of the muscles of attachment and the impressions 
caused by them on the shell, points to which Lamarck was the 
first to call the attention of naturalists in a memoir in the Ann. 
du Mus. for 1807- These give rise to the two orders of Dimy. 
aires and Monomyaires. The secondary groups in this class 
are founded on the form and structure of the shell, the situation 
of the ligament, and the form of the foot of the animal ; the 
families resulting from these principles of arrangement being on 
the whole natural, though not in all cases distinguished by cha- 
racters of the same importance. The third class, Mollusques, 
is divided into five orders, one of which answers to the class 
Pteropoda of Cuvier, and another to the Cephalopoda of the 
same author : the remaining three are formed out of Cuvier's 
class Gastet'opoda, and bear the names of Gast^ro/jodes, Tra- 
chelipodes, and H.et4ropodes respectively. Li this part of his 
system Lamarck has not only altered the value of some of 
Cuvier's groups_, but adopted peculiar views with regard to their 



REPORT ON ZOOLOGY. 215 

relative degrees of organization. Thus, he considers the Uete- 
roporfa,' comprising the genera Carinaria, Firola, &c., as de- 
serving to be placed at the head of all the MoUusca, and as 
forming the transition to the Fish, an opinion which few will 
be inclined to adopt besides himself. 

In 1819 appeared the first numbers of that splendid work 
which M. de Ferussac has devoted to the Land and Freshwater 
MoUusca, a work which for beauty as well as accuracy of illus- 
tration has perhaps never been surpassed. It is principally, 
indeed, to this department of the subject that De F(^russac's 
labours have been directed, and no one has done more towards 
elucidating the history of that immense assemblage of species 
which belong to the Linnwean genus Helix. In order, however, 
to point out the relation between the land and freshwater genera 
and the rest of the MoUusca, he has added a general arrange- 
ment of all the Molluscous animals, which though nearly the 
same as that of Cuvier, presents nevertheless two or three slight 
modifications. Thus, before arriving at the classes, we have a 
primary division into two sections, grounded on the presence or 
absence of the head. The first section, or that of Cephalous 
MoUusca, includes the first three classes of Cuvier. The se- 
cond, or Acephalous section, comprises the classes Cirrijieda, 
Brachiopoda, Lamellihranchia (name taken from Blainville), 
and Tunicata, this last being admitted as a group of a higher 
denomination than that assigned to it by Cuvier. There is also 
a slight difference in the subordinate divisions. Thus, the Cepha- 
lopoda are divided into the two orders of Decapoda and Octo- 
poda*. Amongst the Gasteropoda, we find a new order esta- 
blished for the reception of the Operculated Pulmonifera. It 
may be stated that Ferussac's work, which for some time was 
interrupted, has been recently recommenced, and it is much to 
be desired that it may yet be completed according to the original 
plan. 

In 1820, Schweigger published in Germany a Manual of the 
Inarticulate Invertebrate Animalsf. In this work, which I have 
not seen, the arrangement of the MoUusca is said to be on the 
whole similar to that of the R^gne Animal. 

In 1821, Mr. Gray published in the London Medical Repo- 
sitoryX * new systematic arrangement of the MoUusca, founded 
upon the internal organization. In this system, one of the 
principal features is an entirely new nomenclature for the pri- 
mary divisions, which constitute seven classes, in other respects 

• These groups are adopted from Dr. Leach. See his " Synopsis of the Orders, 
Families, and Genera of the Class Cephalopoda," in his Zool Miscell., vol. iii. 
p. 137. \ Handbuch der Natargeschichte, Sfc. 8vo, Leips, 1820. 

X vo\. XV. p. 229. 



216 FOURTH REPORT — 1834. 

nearly the same as those of former authors. The Cirripeda, 
however, are not included. The groups subordhiate to the classes 
are established principally upon the organs of respiration. The 
arrangement of the families and genera of the Gasteropoda is 
grounded upon the form of the opercle, which leads in many 
cases to very natural relations. Mr. Gray has the merit of 
having studied this part more profoundly than any of his pre- 
decessors. 

In 1824, M. Latreille published in the Ann. des Sci. Nat.* 
a sketch of a new arrangement of the Mollusca, which was more 
developed the following year in the Families Natiirelles. In this 
last work, the primary division of these animals (from which the 
.Naked Acephala and Cirripeda are entirely excluded,) is into 
Phanerogama and Agama, the former including all those in 
which copulation is necessary in order to reproduction, the latter 
such as impregnate themselves. TYiq Phanerogama are further 
divided into two large sections, the characters of which are de- 
rived from the organs of motion. The first of these, which is 
termed Pterygia, includes two classes, the Cephalopoda and 
Pteropoda of Cuvier. The second, Apterygia, includes the 
class Gasteropoda of the same author. In this last class, be- 
fore arriving at the orders, which are characterized from the 
organs of respiration, there is a subdivision according as the 
sexes are separate, or united in the same individual. In the se- 
cond great division, or that of Agamoiis Mollusca, we likewise 
find two sections, grounded upon the presence or absence of an 
apparent head. The first, Exocephala, comprises a new class, 
calledPeltocochlides, established for the reception of the Gaste- 
rop. Scutibranchia and Cyclobranchia of Cuvier. The second, 
Endocephala, includes the Brachiopoda and Testaceous Ace- 
phala of Cuvier, Lamarck's name of Conchifera being adopted 
for the class last mentioned. 

In 1825 appeared the Malacologie \ of Blainville, who had 
already contributed many valuable memoirs to the Journ. de 
Physique and Bull, de la Soc. Phil, on this department of 
zoology. No one, after Poll and Cuvier, has done so much as 
Blainville in illustration of the anatomy of the Mollusca. At 
the same time his arrangement, which differs in several respects 
from all preceding ones, can hardly be considered as preferable 
to that of the Regne Animal. It has also the disadvantage, like 
all the rest of his system, of being attended by a peculiar nomen- 
clature, embracing many names for the primary groups entirely 

* toin. iii. p. 317. 

•f Manuel de Malacologie et de Conchyliologie. 8vo, Paris, 1 825. The greater 
part of this work had previously appeared in tlie Diet, des Sci. Nat. under the 
Art. MoLLusQUEs. 



REPORT ON ZOOLOGY. 217. 

different from those generally adopted. Blainville's primary 
subdivision of his type Malacozoaires is into three classes, esta- 
blished upon the characters of the head. In the first class, Ce- 
phalophores, which answers to the Cephalopoda of Cuvier, the 
head is well distinguished from the body. In the second, Para- 
c4phalophores, it is less strongly marked. In the third, Ac4- 
phalophores, it can be no longer observed. The Parac4phalo- 
phores include the Gasteropoda and Pteropoda of Cuvier, though 
arranged upon a very different plan, the characters of the sub- 
ordinate groups being derived in the first instance from the re- 
productive organs, and afterwards from the respiratory or- 
gans. Thus we have the three subclasses oiParac^ph. Dioiques, 
P.Monoiques, and P. Hermaphrodites, each of which is divided 
into two or more orders, according to the structure of the bran- 
chiae. The third class, Acephalophores, is divided immediately 
into four orders, which are likewise characterized from the re- 
spiratory organs. The first of these orders, Palliohranches, 
answers to the Brachiopoda of Cuvier ; the second, Rudistes, 
comprises the Lamarckian family of bivalve Mollusca bearing 
the same name ; the third, Lamellihranches^ includes the great 
bulk of Cuvier's Testaceous Acephala ; and the fourth, Het4ro^ 
branches, his Naked Acephala. Blaiuville does not include 
either the Cirripeda or the Chitones amongst his true Malaco- 
zoaires, but regards them as forming a subtype, Malentozoaires, 
leading directly off to the Articulate Animals. In this group 
they constitute the two orders of N4tnatopodes and Polyplaxi- 
phores respectively. 

The latest systematic work in this department with which 
I am acquainted, is the excellent little Manuel des Mollusques * 
by M. Rang, published in 1829. This gentleman is also the 
author of a valuable monograph on the genus Apli/siaf, as well 
as of some other important memoirs relating to the Mollusca. 
His arrangement of these animals is nearly the same as that of 
the R^gne Animal. At the same time there are some alterations 
with respect to the primary divisions. Thus, he sinks the class 
Brachiopoda, regarding that group as only an order among the 
Acephala, in which last class he admits as another additional 
order the Rudistes of Blainville. He has also adopted some 
new orders in the class Gasteropoda. Some of his families and 
other subordinate divisions he has borrowed from Lamarck and 
Ferussac. This work contains many new and original observa- 
tions. 

The arrangement of the Mollusca in the second edition of the 

• Manuel de VHistoire Naturelle des Mollusques et de leurs CoquUles, ^c. 
Paris, 1829. f Hisloire Naturelle des Aplysies. Paris, 1829, fol. 



218 FOURTH REPORT — 1834. 

Rhgiie Animal, also published in the year 1829, does not differ 
materially from that in the first. There are simply two additional 
orders in the class Gasteropoda ; one, named TuhuUhranches, 
including the genera Vermetus, Magilus, and Siliquaria ; the 
other, that of H^teropodes, adopted from Lamarck. 

From a review of the above systems, which have been briefly 
sketched out in the preceding pages, it would seem that even the 
primary groups in this branch of the animal kingdom are not 
all determined with certainty. At the same time it is probable 
that whatever alterations may be suggested by further researches, 
they will not greatly interfere with those established by Cuvier, 
and adopted with more or less modification by the generality of 
naturalists. What we most vrant is a more exact determination 
of their relative values. The ,Ci)'ripeda, however, probably do 
not belong to the Molluscous type at all, as appears from re- 
searches to be further alluded to hereafter. There is also great 
uncertainty with respect to the exact situation, as well as limits, 
of some of Cuvier's smaller groups, such, for instance, as his 
Gasterojjoda Cyclohranchiaund Scutibratic/iia, of which Latreille 
makes a distinct class. The genera Capiilus, Crepidula, Navi- 
cella, and Calyptrcea, which are by most authors referred to the 
Scutihranchia, and which Cuvier himself placed in that order in 
the first edition of the R^gne Animal , in the second hehas referred 
to the Pectinihranchia, stating it as his opinion that they come 
near the Trochidce. Indeed, in none of the classes has the chain 
of affinities been hitherto worked out with any degree of cer- 
tainty. We still require further anatomical investigations, both 
in order to determine with more exactness the actvial structure of 
many entire families, and to learn the relative importance of those 
organs from which naturalists have drawn their principal charac- 
ters. Where we find the organs of motion, circulation, and re- 
spiration, as well as the mode of I'eproduction, all varying to the 
degree they do in these animals, it is clear that we must proceed 
with great caution in endeavouring to ascertain the respective 
degrees in which they are entitled to our confidence. 

Before, however, quitting this division of the subject, it will be 
right to notice several important memoirs which have appeared 
of late years, connected with the structure and affinities of some 
of the above classes in particular. 

1. Cephalopoda. — All, except Lamarck, allow that this class 
stands at the head of the Inarticulate Invertehrata, although it 
is not decided to which of the Vertebrate classes it shows most 
affinity. Cuvier, who was the first to make us acquainted with 
the anatomical details of these animals, and who has particu- 
larly noticed the striking development of some parts of their 
organization, nevertheless does not allow that they conduct to 



REPORT ON ZOOLOGY. 219 

any other groups placed higher in the system *. Mr. MacLeay 
has endeavoured to show that in their general structure they 
make the nearest approach to the Chelonian Reptiles f. He 
allows, however, that the hiatus occurring between is very con- 
siderable. M. Latreille, in a memoir published in 1 823 J, has 
pointed out several resemblances between them and Fish, and 
thinks that they show considerable affinity to the Rays and other 
Cartilaginous Fishes. These resemblances refer exclusively to 
the external structure of the two classes. More recently the Ce- 
phalopoda have been much investigated by MM. Laurencet and 
Meyraux. In a memoir read to the Royal Academy of Sciences 
at Paris in 1830 §, these naturalists attempted to lessen the 
gap that was supposed to exist between them and the Vertebrata, 
in like manner as Geoflfroy had previously done with respect to 
the gap between these last and the Anniilosa. They would de- 
monstrate that the plan upon which the Cephalopoda are con- 
structed does not depart so widely as was imagined from that of 
the structure of the Vertebrata', that the same organs appear 
in both groups, though somewhat modified and transposed ; and 
that in order to make the structures conformable, we are only 
to suppose a vertebrate animal doubled back upon itself, when 
the relative position of the several organs in this last will be 
essentially the same as in a Cephalopod. Geoffroy, in his report 
on this memoir to the French Academy, took occasion to ob- 
serve how favourable the results at which these anatomists had 
arrived were to his peculiar views respecting the unity of com- 
position in the animal kingdom. Cuvier, who was opposed to 
these views, replied to Geoffroy ; and for some time after a sharp 
controversy was kept up between these two distinguished natu- 
ralists on this subject. To state the several memoirs, and verbal 
communications to the Royal Academy of Sciences, which 
arose on both sides of this question, would lead us too far from 
the present subject || . We may mention, however, one memoir 
by Cuvier, in which he states, with reference to the singular 
opinion advanced by Laurencet and Meyraux, the results of a 
rigid comparison which he actually made between a Cephalopod 
and a Vertebrate Animal doubled back in the manner they di- 

* Mem. sur les Ccphalop., 8fC., p. 43. f Hor. Ent., p. 254 to 258. 

X Mem. de la Soc. d'Hist. Nat. de Paris, torn. i. p. 269. 

§ Quelques Considerations sur l' Organisation des MoUusques. I am ignorant 
as to whether this memoir has heen hitherto published. 

II Geoffroy 's memoirs were afterwards collected by himself into one volume, 
and published under the following title : Principes de Philosophie Zoologique, 
discutis en Mars 1830, au sein de I' Acad. Roy. des Sciences. Par. 1830, 8vo. 
Cuvier also expressed a determination to publish his under the title of De la 
Variete de Composition des Animaux, I am not aware, however, that these 
last ever appeared. 



220 FOURTH REPORT 1834. 

rect. This memoir, which was published in tiie Ann. des Sci. 
Nat. *, is illustrated by coloured sections of the two animals, 
and its author shows that there are still many organs present in 
each not found in the other, and tliat many of those common to 
both are not, as was supposed wovild be the case, in the same 
relative situation. In short, he attempts to demonstrate that, 
pushed beyond a certain point, the analogy utterly fails. Du- 
ring last year (1833) a second memoir appears to have been read 
byM. Meyraux on these animals f, in which he still retains his 
former theory, and, moreover, expresses an opinion that the 
Cephalopoda ought to constitute an intermediate class between 
the 3Iollusca and the Vertehrata, their general organization de- 
parting much from the type of the former division, at the same 
time that it approaches that of the latter. This is in accordance 
with the opinion formerly advanced by Mr. MacLeay, who in his 
Hor. Entom. considered the Cephalopoda as constituting an 
osculant group between the two large divisions just mentioned %• 
Like Mr. MacLeay, M. Meyraux would seem also to consider 
them as showing considerable affinity to the Chelonian Rep- 
tiles. Perhaps, however, the final elucidation of this pohit must 
wait for the discovery of some intermediate form, which it is 
not too much to hope may yet occur at some future period. 

A few other memoirs require to be pointed out as valuable 
contributions to our knowledge of this class, although not con- 
nected with the subject particularly discussed in those just 
alluded to. Foremost amongst these is a memoir by Mr. Owen 
on the Pearly Nautilus, published in 1832 §. This very valu- 
able treatise contains a detailed account of the anatomy of the 
animal inhabitant of the above shell, so often sought for since 
the time of Rumphius, its original but imperfect describer. The 
specimen dissected, which is the only one that has been 
discovered in modern times ||, notwithstanding the frequent 
occurrence of the shell itself, was taken by Mr. George Bennett 
off the New Hebrides in 1829. Mr. Owen has shown that its 
organization, although exhibiting some differences, more par- 

* torn. xix. p. 241. 

t See L'Instttut, No. 21, p. 180. lonlyknow the memoir from the analysis 
which is there given of it. 

X Meckel is also stated to have proposed the making a distinct division of 
the Cephalopoda, intermediate to the Vertehrata and Invertehrata. I am un- 
able, however, to refer to the work in which he has advanced this proposal. 

§ Memoir on the Pearly Nautilus (Nautilus Pompilius, Linn.), with illustra- 
tions of its external form and internal structure. Lond. 1832, 4to. 

II A fragment of a Cephalopod animal, supposed to belong to the Nautilus 
Pompilius, was brought from the Moluccas by MM. Quoy and Gaimard, and 
described in the Ann. dcs Sci. Nat. (torn. x.'i. p. 470.), but there are great 
doubts as to its identity with that species. 



REPORT ON ZOOLOGY. 221 

ticularly in the respiratory and circulatory systems, is on the 
whole strictly conformable to that of the higher Cephalopoda, 
between which and the Gasteropoda it constitutes an osculant 
form*. At the conclusion of his memoir Mr. Owen has given 
the characters of two orders, Dibranchiata and Tetrahran- 
chiata, into which he proposes to divide the Cephalopoda, these 
characters being founded on the details of the organization of 
the Nautilus Pompilius. 

Dr. Grant has also added considerably to our knowledge of 
the structure of this class. In the New Edinb. Phil. Journ. \ 
he has given the anatomy and extei'nal characters of an appa- 
rently new species of Octopus % from the Frith of Forth. In 
the Zool. Trans. § he has also published an account of the genus 
Loligopsis of Lamarck, the very existence of which was before 
disputed by some naturalists : he has examined its structure, 
and found it to constitute a new form in this class, possessing 
characters hitherto known only in the Testaceous Cephalopods, 
with others common in the naked species. In the same volume [j 
is a second paper by this distinguished naturalist on the anatomy 
of the Sepiola vulgaris. 

The controversy respecting the animal inhabitant of the Argo-^ 
naut is not yet decided, at least not to the entire satisfaction 
of all parties. Future observation will, however, probably con- 
firm the opinion of Poli % and Ferussac **, that the animal 
hitherto alone found in that shell {OcythoU) strictly belongs to it. 
The former author expresses himself decidedly with respect to this 
point, asserting that he has traced the gradual development of 
the shell from the egg. Mr. Broderip appears still to entertain 
doubts on the subject, but the evidence which he has advanced 
on the other side of the question is simply negative ft- 

* This circumstance seems to point out the impropriety of considering the 
Cephalopoda as a distinct division of the animal kingdom, according to the 
views of Meckel, Laurencet, and Meyraux. ■ f 1827. 

X According to De Ferussac, under the names of Octopus vulgaris, Loligo 
vulgaris, and Sepia officinalis, several very distinct species of Cephalopoda have 
been hitherto confounded. § 1833, vol. i. p. 21. || p. 77. 

H See Ann. des Sci. Nat. (1825), torn. iv. p. 495. 

•* Mem. de la Soc. d'Hist. Nat. de Paris, tom. ii. p. 160. 

tt See Zool. Journ. vol. iv. p. 57. Mr. Gray is also of opinion that the 
Oeytkoe is only parasitic in the shell of the Argonauia \ and I may state, that 
since this Report was read he has brought forward what he considers as a new 
argument in support of this side of the question. This argument is founded on 
the size of what Mr. Gray terms the nucleus of the shell, or that original portion 
of it which covered the animal within the egg, and which in some specimens of 
young shells oi Argonauta Argo and A. hians, lately exhibited to the Zoological 
Society, he has shown to be many times larger than the largest eggs of the 
Ocythoe found within the Argonaut shells. From this Mr. Gray has inferred 



222 FOURTH REPORT — 1834. 

Great additions have been made to oar knowledge of the mi- 
nute Polythalamous Cephalopoda by M. D'Oi-bigny, whose me- 
moir on these animals, read to the French Academy of Sciences 
in 1825, will be found in the seventh volume of the Ann. des Set. 
Nat. He confirms the propriety of assigning them a place in 
this class, to which they had been referred previously, more 
from analogy than from any positive knowledge of their real cha- 
racters. He has studied far more closely than any former ob- 
server the structure and development of the shell in this group, 
as well as in many cases the structure of the animal. He has 
ascertained that the former is internal, or at least entirely 
covered by a membrane, and destitute of a siphon ; and that the 
latter is possessed of true arms, or tentacula, analogous to those 
of the larger Cephalopoda. He considers these animals as 
forming a large and well-marked group in the present class, to 
which he assigns the name of Foraminifera. He is acquainted 
with upwards of six hundred species, nearly half of which have 
been discovered by himself. 

M. D'Orbigny has undertaken an arrangement of these shells, 
which has led to a revision of that of the entire class of Cepha- 
lopoda by himself and De Ferussac jointly. It is the intention 
of these authors to publish an extensive work * on this class, 
which D'Orbigny divides into the three orders of Cryptodi- 
branchia, Siphonifera, and Foraminifera. In the first, the 
shell is either monothalamous, or internal and rudimentary, 
never polythalamous : in the second, polythalamous, external, 
or partiall}' covered by the animal, which is capable of retiring 
either wholly or in part within the chamber above the last sep- 
tum; a siphon always continuous from one chamber to another: 
in the third, the shell is polythalamous, and always internal ; 
the last septum terminal ; no siphon, but only one or more 
apertures causing a communication between the different cham- 
bers t- It may be observed that this arrangement by D'Or- 

that it must have been produced by an animal whose eggs are of much greater 
magnitude, and that therefore the Ocytho'e cannot he the true artificer of the 
shell in question. Mr. Gray's communication on this subject, which is not yet 
published, will shortly appear in the Proceedings of the Zoological Society. 

* Since this Report was read, I have seen the first three numbers of this 
splendid work which have recently appeared under the following title : Mono- 
graphic des Cephalopodes Cri/ptodibratiches, par AIM. De Feriissac et D'Or- 
bigny. Paris, 1834, fol. The plates are extremely beautiful. The Ceph. 
Siphonifera and the C. Foraminifera are to form the subjects of two other 
distinct monographs. 

■^ The same year in which D'Orbigny brought forward his memoir, De H*in 
published at Leyden an important treatise, entitled, Monographice Ammonile- 
oruni et Goniatiteorum Specimen. In this work, which I have not seen, there 
is said to be also a new arrangement of the Cephalopoda, and a similar division 



REPORT ON ZOOLOGY. 223 

bigny has been adopted by Rang in his Manuel des Mollusques 
already alluded to. 

2. Pteropoda. — De Ferussac has given a systematic arrange- 
ment of this class in the Bull, des Sci. Nat. for 1827 *. Rang 
has made several important additions to it, as well as recorded 
many valuable observations respecting genera and species which 
were already known. Nevertheless we have still but an imper- 
fect knowledge of this group. 

3. Gasteropoda. — This being the typical and the most exten- 
sive class among the Mollusca, it has received more general 
attention than any of the others. Many of the families and ge- 
nera contained in it have been made the subject of valuable 
monographs by different individuals, which, however, it would 
lead too much into detail to allude to more particularly. Na- 
turalists do not appear to be agreed as to the exact value of cha- 
racters derived from the shell in distinguishing the genera of 
this class. M. Deshayes, in a paper in the Ann. des Sci. 
Nat. for 1831 f, has recoi'ded some anatomical details, which 
would seem to have been undertaken with the view of throwing 
some light on this matter in the case of the Helices. His ob- 
ject is to discover whether there may not be found some pecu- 
liarity in the internal structure of the animal sufficient to war- 
rant the adoption of many genera in this family, which hav- 
ing been established solely upon the characters of the shell, have 
not hitherto been received by all naturalists. T am not aware, 
however, that he has carried on this investigation beyond the 
case of Draparnaud's genus Succinea, which is the only one 
treated of in the above paper. 

The opercle of shells, which, as already stated, has been much 
employed by Mr. Gray in his arrangement of the Gasteropoda, 
has been since studied with great care by Blainville, who in a 
memoir in the Bull, de la Soc. Philom. for 1825 +, proposes 
to adopt characters derived not merely from the presence or ab- 
sence of this part, but from its form and structure, its position, 
and mode of attachment to the animal. In the Ann. des Sci. 
for 1829 §, Duges has also a paper on this subject. His prin- 
cipal object is to trace the analogies between this part and the 
upper valve of the Inaequivalve Acephala, more particularly as 
respects its mode of growth, and the production of the striae on 

of the Testaceous genera into two groups, characterized by the presence or 
absence of a siphon. I believe De Haan was the first to make use of this cha- 
racter, although D'Orbigny is said to have had recourse to it without any know- 
ledge of De Haan's work. See Diet. Class. d'Hkt. Nat., torn. xi. p. 56. « 

• torn. xii. p. 345. f torn. xxii. p. 345. J pp. 91 and 108. 

^ tuiji. xviii. p. 113. 



SS* FOURTH REPORT — 1834. 

its surface. As these striae, however, have been used in some 
cases for characterizing the genera of the Pectinibranchiate 
Gasteropoda, this memoir is not without its importance to the 
systematist. During the last year Mr. Gray has again turned 
his attention to this subject. In a paper in the Phil. Trans. 
for 1833, he has detailed some observations on the structure of 
the part in question, as well as on the structure and oeconomy 
of shells in general. He considers that the mere fact of the pre- 
sence or absence of the opercle is of small importance, but that 
in its form and structure it offers some of the most constant 
characters for the distmction and arrangement of families and 
genera. 

4. Brachiopoda. — Mr. Owen has recently published * an im- 
portant memoir on the anatomy of this group, in which he has 
offered some remarks with respect to its value and affinities. 
He observes that in all essential points of structure these ani- 
mals closely correspond with the Acephalous Molliisca, al- 
though inferior to the Lamellihranchia as far as regards their 
respiratory and vascular systems. He considers them as hold- 
ing a middle place between these last and the Timicata; not, 
however, possessing characters of sufficient importance to justify 
their being regarded as a distinct class, but forming a separate 
group of equal value with those above mentioned. 

5. Tunicata. — Whether we admit this group as a class or 
only as an order, it is one which will always possess interest as 
affording a natural passage to the Radiatn of Cuvier. It is 
especially to the researches of the naturalist just mentioned, and 
to those of Savigny, that we are indebted for the first accurate 
knowledge obtained respecting these animals. While the struc- 
ture of the simple Tunicata was beautifully illustrated by the 
dissections of the former t, the latter had the merit of discover- 
ing the true organization of those singular compound AscidicB 
which until his time had always been confounded with the 
zoophj-tes %. Peron, Desmarest, and Lesueur have all likewise 
contributed to render this group better understood. What re- 
cent additions have been made to our knowledge of it are 
due principally to Mr. MacLeay, MM. Quoy and Gaimard, 
MM. Audouin and Edwards, and Dr. Meyen. Mr. MacLeay is 
the author of a paper, read to the Linnaean Society in 1824 §, in 
which he has given the anatomical details of some new forms 
from the Northern seas, at the same time that he has thrown 

• Zool. Tram. 1834, vol. i. p. 145. 

f See Ann. du Miis., torn, iv., and Mem. du Mus., torn. ii. p. 10. 

X Mem. sur les An. sans Verieb., Part 2. 

§ See Linn. Trans., torn. xiv. p. 527. 



REPORT ON ZOOLOGY. 225 

out several remarks respecting the arrangement and affinities of 
these animals in general. Quoy and Gaimard have communi- 
cated some new observations relating to the habits and anatomy of 
the Salpee which they made during their voyage withFreycinet*. 
Audouin and Edwards, who paid great attention to the Compound 
Jiscidice during their residence on the Chausey Islands, have 
made some interesting discoveries respecting the mode of de- 
velopment of these animals f . They have ascertained that, al- 
though in their adult state they are united to form one common 
mass, and are immoveably fixed to some rock or other marine 
substance, they enjoy at birth a separate individuality, and are, 
moreover, endued with the power of swimming freely in the 
water from place to place. It is not till after two days that this 
locomotion ceases. They then seek a place favourable to their 
further development ; and while some return to the parent mass 
from which they first emanated, others attach themselves afar 
off and found new colonies. These observations are of great 
value. They not only throw light upon the history of these ani- 
mals, but serve to establish very important relations between 
them and other groups in which similar facts have been noticed, 
connected with the early development of the young. Dr. Meyen's 
researches are confined to the genus Salpa, which forms the sub- 
ject of a memoir by him in the Nov. Act. &fc. Nat. Cur. for 
1832 X- He has revised the characters of more than thirty 
species. 

6. Cirripeda. — ^The doubtful situation of this class has been 
already alluded to. Indeed there are few groups whose true 
affinities have been involved in so much uncertainty. The most 
recent observations, however, seem decidedly in favour of the 
opinion of those naturalists who regard it as partaking more of 
the Annulose than the Molluscous structure, and approaching, 
on the whole, nearest to the Branchiopod Crustacea. Straus 
was the first to announce this affinity in his memoir on the genus 
Daphnia, published in 1819. He was led to observe it from a 
comparison of the relative structures of the genera Pentelasmis 
(Leach) and Limnadia (Brong.). Two years afterwards, Mr. 
MacLeay, apparently without knowledge of Straus's memoir, 
pointed out the same relationship §, dwelling, however, more 

articularly on the affinity between Pentelasmis and Daphnia. 

am not avvare that anything further was written on this sub- 
ject till 1830, in which year Mr. Thompson published the third 

• Ann. des Sci. Nat. (1825), torn. vi. p. 28. ; and Bull, de la Soc.Philom. 
(1826), p. 123. 

t See Ann. des Sci. Nat., torn. xv. p. 6. 

J torn. xvi. p. 363. § Hor. Ent., p. 308. 

1834. (i 



r 



22G FOURTH REPORT — 1834. 

number of his Zool. Researches, containing some observations 
on the Cirnpeda which appear to be quite decisive of their close 
affinity to i\ie Annulosa in general, and the Branchinpod Crus- 
tacea in particular. This gentleman asserts that he has ob- 
served that these animals undergo a metamorphosis. He states 
having discovered swimming freely in the sea a small crusta- 
ceous animal furnished v^^ith a shell composed of two valves like 
those of Daplinia ; that being desirous of watching it further, 
he kept it in water, and was much surprised, after a few days, 
at seeing it throw off its bivalve shell, attach itself to the bottom 
of the vessel, and become transformed into the Balanus piisillus 
of Pennant*. For some time afterwards these alleged facts 
were thought to require confirmation from other observers ; 
more esiiecially as in a commvmication made to the Zoological 
Society last yearf, Mr. Gray advanced some statements re- 
specting the condition of the j^oung oi Balanus Cranchii (Leach) 
observed in ovo, as well as of the young of the genera Pentelas- 
niis and Otion, which appeared to militate against the accuracy 
of Mr. Thompson's views. They have, however, been fully 
established by Dr. Burmeister, who has recently published a 
treatise on these animals annoiincing this circumstance j and 
judging from his own observations, combined with those which 
had been previously made by others, Dr. Burmeister infers that 
the Cirripeda ought to be arranged with the Crustacea, forming 
a particular tribe in that class J. 

It may be stated that M. Martin-St.-Ange is said to be en- 
gaged in a work on the organization and affinities of the Cirri- 
peda. The results of his researches have been already given to the 
public in a memoir read to the Royal Academy of Sciences at 
Paris towards the end of last year§. They likewise favour the 
opinion that these animals, at least the pedunculated genera, are 
truly articulated, and allied to the lower forms of Crustacea. 
M. Martin-St.-Ange thinks that they also show some points of 
affinity to the Annelida. 

* It is a curious fact that, according to Mr. Thompson, the young animal 
should not only possess the power of locomotion, which is denied to the adult, 
hwi distinct organs of sight, which, after the transformation into £a/a»i, gra- 
dually become obliterated. This is analogous to Edwards's observation (already 
alluded to) in the case of the development of the Cyinothoce. It is, however, 
yet more striking. 

t See Proceed, of Zool. Soc. (1833), p. 115. 

X The above statements are on the authority of De F^russac's Introduction 
to his recently published Monograph on the Cephalopoda. I have not seen 
Burmeister's work myself, which is said to be entitled Beitrage »ur Naturge- 
schichte der Rankenfiisser. 4to, Berlin, 1834. 

§ See L'Institut, No. 27. p. 226, and No. 62. p. 231. 



REPORT ON ZOOLOGY. 



227 



The classification of the Cirripeda was greatly advanced by 
the labours of Dr. Leach, who made a particular study of this 
class, and instituted several new genera in it. His arrangement 
is founded upon characters derived from the shelly covering of 
these animals, which he submitted to a more minute and rigor- 
ous analysis than any previous observer had done before him *. 

Mr. Gray has also attended to this subject. In the Ann. of 
Phil, for 1825 f, he has published a synopsis of the genera 
arranged in natural families. 

IV. Radiata, Cuv. 

As we descend the scale of organization we find the groups 
defined with less and less certainty. In the present division, 
our knowledge of their exact limits, we may even say of the 
number of primary types of form which this division comprises, 
is so imperfect, that it would be to little purpose to detail all 
the different arrangements which have been proposed for these 
animals, the classification of which is probably still destined to 
undergo great and important revolutions. After all, it is doubt- 
ful whether we must not admit with MacLeay that they form two 
groups, each of equal value with that of the Vertebrate, Annu- 
lose, and Molluscous divisions, instead of one only as Cuvier 
supposes. In this state of uncertainty, I shall merely take 
Cuvier's classes in the order in which they stand in the B^gne 
Animal, and under each state some of the principal additions 
which have been made of late years to our general knowledge of 
these animals. This will naturally lead to the mention of several 
impoijtant steps which have been gained towards an improved 
classification of them. 

The following are the classes into which Cuvier divides the 
Radiata : Echinodermes, Intestinaux {Entozoa, Rudolp.), 
AcaUphes, Polypes, and Infusoires. 

1. Echinodermuta. — To our knowledge of this class I am not 
aware of many important additions that have been made recently. 
Since the publication of Tiedemann's work on the anatomy of 
these animals, which gained the prize from the French Institute 
in 1812, and which served to clear up many points in the details 
of their organization, no one appears to have studied their struc- 
ture more deeply than Delle Chiaje. Several memoirs have 
appeared by this last author J treating of the genera Echimis, 

* See the article Cirripedes in the Sitppl. to the Encycl. Brit. Also Zool. 
Journ. (1825), vol. ii. p. 208. 

t vol. xxvi. p. 97. 

X Memorie sulla Storia e Notomi^ degli Animali senza Fertebre. 4to, Nap. 
1823, &c. 

q2 



228 FOURTH KEPORT — 1834. 

^sterias, Holothuria, and Siphunculus, sill which he has sub- 
mitted to a close investigation. His researches on the genus 
Siphuncuhis lead him to think that this group has been wrongly 
placed by Cuvier in the present class, and that it belongs more 
properly to the Annelida. 

In 1827, Mr. Thompson published an account of a newly dis- 
covei-ed recent species of Pentacrhnis*, a genus well known in 
a fossil state, but one of which the true situation in the system 
was before rather doubtful. From an examination of this spe- 
cies, the structure of which in its several stages of development 
he has given in full detail, Mr. Thompson fully proved that the 
Crinuidea (so ably illustrated by the late Mr. Millerf) are closely 
allied to the Asterice, and especially to the genus Comatula of 
Lamarck. The only previously known recent species of this 
tribe, the P. Caput Medusts, found in the West Indies, had not 
been brought to Europe in a fit state to allow of any investiga- 
tion of its structure. 

Mr. Gray has lately submitted to the Zoological Society:}: speci- 
mens of the shelly covering of a new genus, which is interesting 
as forming a distinct family, if not order, intermediate to the 
Echinidce and Asteriidce. It is allied to the latter in having 
only a single opening to the digestive canal ; while it agrees 
with the former in form and consistence, differing however from 
it in not being composed of many plates. For this genus, which 
Mr. Gray thinks bears a near affinity to the fossil Glenotremites 
paradoxus of Goldfuss, he proposes the name of Ganymeda. 

In XheAnn. of Phil, for 1825 §, Mr. Gray has published a 
natural arrangement of the families of the EchinidcB\\. 

2. Entozoa. — In this group, as it stands in the R^gne Animal, 
we find an assemblage of animals which, though not much studied 
in this country, have received great attention from several Ger- 
man and French naturalists, from whose combined researches 
it seexns now quite certain that they can no longer be arranged 
all in the same class, Cuvier divides the Entozoa into two 

* Memoir on the Pentacrinus Europaus, Sfc. 4to, Cork, 1827. 

f Nat. Hist, of the Crinoidea, or Lily-shaped Anmah,8fc. 4to, Bristol, 1821. 

J Proceedings of the Zool.Soc. (1834), p. 15. § vol. xxvi. p. 423. 

II Since tliis Rejiort was read, a short but important communication on the 
external structure of the Echinodermata and their mode of growth has been 
published by M. Agassiz. His cliief object is to show that the Echinodermata, 
although usually considered as partaking of a radiated structure in which all 
the parts of the body are similar, nevertheless exhibit a bilateral symmetry ; 
furthermore, that the addition of new plates, as the animal increases in size, 
takes place in a spiral anA not in a vertical succession, as would appear at first 
sit'ht to be the case. M. Agassiz announces it to be his intention to publish a 
monograph on these animals. See Load, and Edinb. Phil. Mag. and Journ. oj 
4'd. forNov. 1834, p. 3G9. 



REPORT ON ZOOLOGY. 229 

Dfders, which he calls Intestinaux Cavitaires and Intest. Paren- 
chymateux, the former answering to the Nematoidea of Rudol- 
phi, the latter comprising the last four orders of this author. 
Cuvier admits, however, that there is a great difference in the 
respective organizations of these two groups. In fact, the Ne- 
matoidea, raised so much above the other Entozoa by their di- 
stinct nervous system, are now generally allowed to approach 
closely the Annvdose structure, if not to belong to that division 
of the animal kingdom. Mr. MacLeay long since referred them 
to that type, observing, that in a natural arrangement it seems 
hardly possible to separate them far from Lumhricus and Gor- 
dius*. With Blainville they also form a portion of his Entn- 
mozoaires Apodes\. In a more recent publication J this last 
author has gone further into detail with respect to the arrange- 
ment of the Entozoa in general. He thinks they constitute 
two classes at least ; the greater portion forming the last class 
in his type Entomozoaires (in which class he includes the Ui- 
rudinidce) ; the remainder (comprising the third and fourth 
families of Cuvier's Intest. Pareiichymateiix) forming a sub- 
tjrpe intermediate to the Entomozoaires and Actinozoaires (or 
Zoophytes), though on the whole approaching nearest to the 
former. Blainville does not admit that in the classification of 
the Entozoa M'e should be at all more influenced by their pecu- 
liar habitat than in that of other animals. He looks only to the 
organization, which leads him to place in the same order ( Oxy - 
c4phaUs, Blain.) Filaria, Gordius, and Vibrio, genera certainly 
not very dissimilar in structure, though residing in very differ- 
ent situations. His other orders in the class Entomozoaires 
Apodes include in like manner both external and internal worms. 
There can be no doubt that this principle is just to a certain 
extent. Indeed it is supported by the opinions and researches 
of others. Lamarck and Bory-St.-Vincent both suspected an 
affinity between the Vibriones and the true Vermes. Duges, in 
the Ann. des Sci. for 1826§, has instituted a close comparison 
between the Vibriones and the Oxyures of Rudolphi, and from 
an examination of their digestive and reproductive systems, 
seems decidedly to think that they belong to the same group. 
Professor Baer of Konigsberg, whose researches have tended 
greatly to elucidate the structure and affinities of the Entozoa, 
has in a memoir (or rather one of a series of memoirs) on the 
lower animals, published in the 13th volume of the Nov. Act. 
Sfc. Nat. Cur., endeavoured to show that neither the jK?2^osoa nor 

* Hor. Ent., p. 224. f Principes d'jinat. Comp., tab. 7. 

\ Art. Vers in the 57th vohime of the Dic^ des Sci. Nat, published in 1828. 
This treatise also appeared separately under the title of Manuel d'Helmin' 
tholo(jie. § torn. ix. p. 225. 



230 FOURTH REPORT — 1834. 

Infusoria can be preserved as distinct classes. It should be 
Slated, however, that he has embraced some peculiar vievps re- 
specting the systematic distribution of animals, of which it is 
impossible to give any detailed account here. I may also allude 
to a curious memoir by Duges in the Ann. des Set. for 1832*, 
as affording fresh suspicion that the Entozoa do not form a 
natural class of themselves to the exclusion of other animals. 
He describes a new and veiy singular genus found free in water 
amongst duckweed, which appears to be closely allied to the 
ToEuicB and Bntliriocephali. It is small, but has its body di- 
vided into segments like those animals, these segments being of 
a similar form, and varying in number from four to eight. Duges 
thinks it not improbable that this may have been the supposed 
Tcenia which Linnaeus is said to have met with free in water. 
He gives it the name of Catenula Lemnce. 

The PlanaricE, again, present us witli a group of animals not 
parasitic, which are now universally admitted amongst the Paren- 
chymatous Worms, and considered as belonging to the Tremadota 
of Rudolphi. Cuvier iuf^ecd (as Lamarck and others had already 
done) assigned them this place in the first editi(m of the R^gne 
Animal, but it was not without doubts as to their true situation. 
These doubts are now quite removed by the researches of Dr. 
Baer and M. Duges, both of whom have investigated the struc- 
ture of these animals, the former in the memoirs before alluded 
to, the latter in the Ann. des Sci. for 1828 and 1830f . The 
result is, that neither of these observers has been able to detect 
any muscular, or ganglionic nervous system ; and the latter thinks 
that it is the absence of these systems principally which serves 
to separate them from the HirudinidcE, with Avhich they have 
been so often classed. At the same time, Duges points out seve- 
ral respects in which they clearly approach the group just men- 
tioned. It may be added, that Duges has proposed in his me- 
moir to raise the Planaria; to the rank of a family, in M^hich 
he particularizes three distinct genera. These he has charac- 
terized from the structure of the digestive organs, and the situa- 
tion as well as number of the orifices. 

As there are some groups which, though«o# parasitic, require to 
be associated with the Entozoa, there are others which are para- 
sitic, and which many have arranged with these animals, but of 
which the true situation is extremely doubtful. Such are the Ler- 
?««<:e,presentingsuch evident affinities to the Siphonostomous En- 

* torn. xxvi. p. 198. 

t I may also allude to two papers by Dr. Rawlins Johnson in the Phil. 
Trans, for 1822 and 182.5, containing the result of some inquiries into the power 
of reproduction possessed by these animals. This subject, however, had been 
previously investigated by Mr. Dalyell in his interesting memoir on the Plajia- 
riiE, published at Edinburgh in 1814. 



REPORT ON ZOOLOGY. 231 

tomostraca, to which they are referred by Blain ville, Straus-Durck- 
heim, Edwards, and others, although placed by Cuvier at the end 
of his Intestinaux Cavitaires. Blainville has made a particular 
study of this family, in which he has characterized eight distinct 
genera*. Nevertheless, we stand much in need of further informa- 
tion respectingtheir structure andoeconomyf. On tlie other hand, 
the Acephalocysti, and the Hydatids in general, appear so low in 
the scale of organization, that it may be questioned whether 
they can be placed in the same class with all the other groups 
included in Cuvier's second order. Nitzsch and Leuckart, as 
well as Dugez, think that the Acephalocysti are allied to 
the F'olvoces diwd other vesicular /«/M5or?'a J. M. Kuhn, in a me- 
moir lately published §, does not consider them as true animals, 
but thinks that they should have a place assigned them amongst 
those ambiguous beings which hold a middle rank between the 
animal and vegetable kingdoms, and to which Bory St. Vincent 
has given the name of Psychodiaires. 

From the above observations it will be seen how much re- 
mains yet to be done towards a natural arrangement of these 
animals. Those who would enter into the details of their history, 
will do well to consult, — besides the memoirs already alluded to, 
and the works of Rudolphi, which are well known, — the works 
of Bremser||, Cloquet^, Creplin**, and Leuckartft- Bremser, in 

* SeeJourn. dePhys. (1822), torn. xcv. pp. 372 and 437; also the 26tli vol. 
of the Diet, des Set. Nat., art. Lerne'e. 

f According to the observations of Dr. Surrirey of Havre, the LerncecB un- 
dergo a metamorphosis, and are very diflei'ent in their young state from what 
they are in their adult. (See Blainville ml)ict. des Sci. Nat., torn. xxvi. p. 115.) 
Since this Report was read, I have learned that the above fact has been recently 
confirmed by M. Nordmann, who is said to have published several very inter- 
esting researches connected with the gradual development of these animals, and 
8uch as leave no doubt of their forming part of the same group with the Sipho- 
nostomous Crustacea. These observations are contained in a work entitled, 
" Mikrographische Beitrage zur Naiurgeschichte der Wirhellosen Thiere," Ber- 
lin, 1832. Not having seen it, I can make no further allusion to it in reference 
to this subject. % Ann. des Sci. Nat. 1832. 

§ Mem. de la Soc. d'Hist. Nat. de Strasbourgh, torn. i. part 2. 

II Bremser published at Vienna, in 1819, a work on the human Entozoa, 
which in 1824 was translated into French by Grundler and Blainville, and en- 
riched with many valuable observations from this last author. 

^ \\xt\iox oi Anatomie des Vers Intestinaux. Par. 1824, 4to. ^ 

** Creplin has published two ti-eatises on the Intestinal Worms, one in 1825 
under the name of Ohservationes de Entozois ; another, entitled Nova Observa- 
tiones, ^-c. at Berlin in 1829. These works, which I have not seen, are said to 
contain descriptions of a great many new species, along with many detached 
observations on these animals. 

■ff Leuckart is the author of a natural classification of Intestinal Worms, in 
German, published at Heidelberg in 1827. This work has been before alluded 
to as containing an arrangement in conformity with the principles of Oken. 



232 FOURTH REPORT 1834. 

addition to his treatise on the Entozoa of the human species, has 
published a series of plates intended to illustrate Rudolphi's ge- 
nera, in which, by engraving on a dark ground, the white and 
transparent parts of these animals are brought out in an admirable 
manner. Van Lidth de Jeude has also published more recently 
(1829) a collection of lithographed plates of these animals*. 

3. Acalepha. — Our knowledge of this class must be considered 
as very imperfect, notwithstanding it has engaged the attention of 
many excellent observers. This is in a great measure to be at- 
tributed to several difficulties connected with the study of these 
animals, particularly those arising from their very delicate struc- 
ture, which renders the preservation of specimens in many cases 
almost impossible. Peron and Lesueur published some valuable 
memoirs on the Medusa: (taking this term in its full extent) in 
the 14th and 15th volumes of the Ann. du Mus., which contained 
a far more detailed history of this tribe than any that had ap- 
peared before, and contributed greatly towards an improved clas- 
sification of it. These authors are, however, generally allowed to 
have overmultiplied the species, and to have established several 
genera upon insufficient observation. Many additions to this 
class, and to our knowledge of its structure, were made subse- 
quently by Chamisso and Eisenhardt m the 10th volume of the 
Nova Acta Sfc. A^at. Ctir., and a few in the 11th volume of the 
same Transactions by Otto. Quoy and Gaimard also collected 
much information with respect to the habits and organization of 
these animals during their voyage with Freycinet. Some of their 
observations were published in the An7i. des Set. for 1824t and 
1825J. In this last volume, their remarks, so far as the Aca- 
lepha are concerned, relate only to the genus Beroe. In the 
BicU. de la Soc. Phil, for 1824§, M. De Freminville has pub- 
lished some observations on the Physaliajjelagica, to which are 
annexed descriptions of three new species belonging to that ge- 
nus. Some researches on the structure of the Physalice were 
published about the same time in the 9th volume of the Peters- 
burgh Memoirs by Eichwald. In 1825, Rosenthal published 
some collections towards the anatomy of the Medicsce\\, the spe- 
cies principally examined being the M. aurita, Linn. In 1827, 
another memoir was published by Quoy and Gaimard in the 
Ann. des Sci.%, containing an account of a vast number of new 

• Besides the above works, I may mention that of Nordmann, already alluded 
to, from which some valuable extracts will be found in the Ann, des Sci. Nat. 
for 1833, torn. xxx. 

t tom. i. p. 2 15 X torn. vi. p. 28. § p. 42. 

II Bull, des Sci. Nat. (1826), tom. ix. p. 253. ^ tom. x. 



REPORT ON ZOOLOGY. 233 

marine animals discovered by them the year before in the Straits 
of Gibraltar, where they were detained some days by a calm 
soon affeer the commencement of a second voyage with Captain 
D'Urville. Amongst these are several new genera belonging to 
the group of Diphyes, Cuv., which the authors consider as en- 
titled to rank as a family. This memoir contains by far the 
most valuable details respecting the organization of these re- 
markable animals which had appeared up to that time. In 1828, 
Rang published in the M4m. de la Soc. d'Hist. Nat. de Paris* 
a memoir on the genus Beroe, which he considers as forming 
another distinct family amongst the free Acalepha, in which he 
describes two new genera. Rang thinks that the free Aca- 
lepha may be divided into three families, having for their re- 
spective types Beroe, Medusa, and Diphya. The characters of 
these he proposes to take from the organs of locomotion. In 
the first {Beroides, Rang,) they consist of a number (always an 
even number) of longitudinal ribs formed by very numerous se- 
ries of small ciliae ; in the second (Medusaires), these organs 
are membranes, sometimes entire, sometimes fringed or cut into 
leaflets, and ranged in a circle round an umbrella ; in the third 
{Dip hides), these organs are found only in the margin of the 
principal opening, and sometimes also in a membrane bordering 
the circumference of it. 

By far the most valuable work which has yet appeared in this 
department of zoology is said to be the System der Acalephen, 
8^-c. of Dr. Eschsholtz, published at Berlin in 1829t. Its author 
is well known as the naturalist who accompanied Captain Kotze- 
bue in his voyage of discovery, and as having some time back 
published valuable observations on the Physalice, Porpitce, aiid 
Velella;, made by himself during that voyage^. In the present 
work he has given a detailed account of the structure of the 
Acalepha in general, as well as presented a new arrangement of 
these animals. Their organization, according to his researches, 
would seem to be of a more complex nature than was formerly 
supposed. He has discovered a very perfect vascular system in 
the Beroe tribe, which has led him to place this group at the 
head of the series. In his classification he adopts three orders, 
Ctenophora, Discophora, and Siphonophora, the characters of 
which are taken from the presence or absence of a central diges- 
tive cavity, and from the form and structure of the organs of lo- 
comotion. 

* torn. iv. p. 166. 

t I have not seen this work myself. The above notice of it is from the Bull, 
des Set. Nat. (1831), tom. xxiv. 

t See Kotzebue's Voyage, vol. iii. Append. 



234 FOURTH REPORT — 1834. 

Since the appearance of Eschsholtz's work, three or four valu- 
able memoirs have been published bydifferent observers in further 
illustration of the Acalepha. One of these is a monograph on 
the genus Diphya by Lesson*, containing several new remarks 
on these animals. He thinks that many of the genera instituted 
by Quoy and Gaimard are only separate pieces, or articulations, 
detached from the aggregate mass of the animal which forms his 
genus Plethosoma. A second is a memoir by Tilesius, published 
in 1831f , in which are descriptions and figures of many species of 
Meduscs, more particularly belonging to the genus Cassiopea, 
accompanied by general remarks on this group. A third is a 
paper byMilne Edwards on the structure of Carybda marsupialis, 
in the Jinn, des Sci. for 1833 J ; and a fourth, one by Dr. Grant 
on that of the Beroe P'deit^, published the same year§. These 
last two memoirs, although treating only of single species, are 
of importance as tending to raise our notions still further with 
respect to the organization of these animals. The Carybda 
marsupialis is a species belonging to that portion of the JHe- 
dnsce which have been hitherto considered as having no stomach, 
and in this and other respects, as possessing a structure even far 
more simple than the rest of this family. Edwards has found 
this to be erroneous, by tracing the existence not only of a sto- 
mach and mouth, but of biliary ducts, as well as ovaries. He 
shows that its structure is quite as complicated as that of anjf 
other oi the Jledusce. Dr. Grant, in dissecting Beroe Pileus, has 
discovered an arrangement of filaments and ganglia which, from 
their general appearance and mode of distribution, he considers 
as constituting a nervous system. This is a great step gained 
in our knowledge of the structure of the Acalepha. Rosenthal 
sought in vain for traces of a nervous system. Quoy and Gai- 
mard, as well as many others, seem satisfied with respect to its 
entire absence. Dr. Grant however observes, that although 
nerves have not hitherto been shown in the Acalepha, he thinks 
they will be found even in the simpler forms of Medusce, which 
he has shown elsewhere to be afl:ected by light, as well as 
Actinice, HydrcB, and Furcocercce, 

An important work was published by Blainville in 1830, in 
which he has embodied a vast deal of information relating to the 
structure, history, and classification, not only of the present 
tribes, but of all the other animals belonging to Cuvier's divi- 

• Published in his Centurie Zoolog. Nov. 1830. 

f Nov. Act. ^-c. Nat. Cur., torn. xv. p. 247. X toni. xxviii. p. 249. 

§ Zool. Trans., vol. i. p. 9. 



REPORT ON ZOOLOGY. -ggg 

sion of Mudiata, with the exception of the Entozoa. I speak 
of the 60th volume of the Diet, des Scien. Nat., the greater part 
of which is taken up with the article Zoophytes by the above 
author*. Blainville, however, has exposed some peculiar views 
respecting the affinities of certain families hitherto considered 
as belonging to the Acalepha, to which it is necessary to make 
some allusionf . These relate particularly to the PhysalicB, which, 
he observes, are of a very anomalous character, and in some mea- 
sure seem to depart from every known type. He has, however, 
ventiu'ed an opinion, grounded on an examination of specimens 
of Physsophora and Stephanomia communicated to him by 
Quoy and Gairaard, that the Phi/salice ought to be removed 
from the place usually assigned them, and made to constitute a 
distinct order among the 3IoUusca, near the orders called in his 
system Polyhranches and NucUohranches. Blain\ ille appears 
to have been led to this idea more from observing the arrange- 
ment of the external parts of these animals, than from any close 
investigation of their internal oi-ganization. On this ground, 
Cuvier expresses himself as decidedly opposed to \t%. He ob- 
serves, that before we can admit them to a place in that division, 
it ought to be shown that they possess a nervous, as well as 
vascular system, a heart, and liver, as well as male and female 
organs of generation, all which he (Cuvier) has in vain sought 
for. Blainville in like manner differs from other naturalists 
with respect to the affinities of the Diphyce, which he thinks 
constitute a group intermediate to the Salpce and Pkyssophurae. 
Also the genus Beroe he thinks should be removed from the 
great family oi Medusce {Arachnodermaires, Blainv.), with which 
it is so constantly associated. It must be obvious that many 
speculations will arise with respect to the situation and affinities, 
not of these groups only, but of several others amongst the lower 
animals, until we are made better acquainted with their organi- 
zation and habits. These oiler to us the only sure grounds upon 
which we can proceed in the endeavour to determine their place 
in the natural system ; and very many researches relating to 
these points remain yet to be made amongst the Acalepha. The 
Diphycs in particular astonish us by the singulai-ity of their 
form and structure. Composed of two polygonal, subcartilagi- 

• The Entozoa are treated of in a former volume under the art. Vers, which 
indudes also the Annelida. To this article allusion has been already made in 
a former part of this Report. 

\ A second edition of the above work has been published during the present 
year (1834) under the title oi Manuel d'Actinologie. The views of its author 
remain, however, unchanged with respect to the above aflinities. 

I Analyse des Trav., 1828. 



H'SG FOURTH REPORT — 1834. 

nous, transparent parts, found constantly in a state of union, 
naturalists seem hardly to be agreed, whether these parts belong 
to the same animal, or wliether they constitute two distinct in- 
dividuals, although in form always more or less dissimilar. 
Blainville embraces the former opinion ; Q.uoy and Gaimard, as 
well as Cuvier, seem inclined to the latter. It would not be 
difficult to point out other instances in which we want further 
information with respect to the Acalepha, The limits of this 
Report forbid, however, our dwelling any longer upon this class. 
It is one especially in which every new observation will have its 
value ; and it is only to be regretted that so few persons have it 
in their power to study these animals in a recent state, in which 
alone they admit of such an examination as is likely to conduct 
to any important discoveries. 

4. Polypi. — It is not advancing too much to affirm that natu- 
ralists are only just beginning to get an insight into the natural 
arrangement of that immense assemblage of beings which con- 
stitutes Cuvier's fourth class of Zoophytes, and that even this in- 
sight extends but as yet to comparatively few families. Their 
researches, however, are sufficiently advanced to prove clearly, 
that the true situation and affinities of these animals are in many 
cases very different from those which have been assigned to them 
in the It^gne Animal. Some have been shown to possess a struc- 
ture entitling them to a higher place in the scale of organization ; 
while in others the animal powers seem so reduced, the struc- 
ture at the same time offering such peculiarities, that they appear 
to constitute a distinct class, far below the generality of other 
Zoophytes. One great drawback to our better knowledge of 
these groups has arisen from the circumstance, that until lately, 
naturalists, with some few exceptions, scarcely paid any attention 
to the animals of the Incrusted Polyjn*, which constitute so 
large a portion of them. They looked only to the characters of 
the calcareous covering ; and it is not surprising that with this 
lialf-knowledge they should fall into many erroneous notions 
with respect to affinities, in their attempts to arrange the species 
systematically. It is this which at the present day detracts 
somewhat from the value of the works of Lamourouxf, notwith- 
standing their great merit in other respects, and the powerful in- 
fluence which they undoubtedly had over the progress of Zoophy- 
tology at the time when they appeared. He has made us ac-- 

• The Polypes a Polypier of the French, for which we have no adequate 
expression in our language. 

+ Hisloire des Polypiers Corallines Flexihles, S(c. Caen, 1816, 8vo. And 
Exposition MHhodiquc des Genres de I'Ordre des Polypiers, Paris, 1821, 4to. 



REPORT ON ZOOLOGY. 237 

qiiainted with a vast number of new species, as well as established 
several distinct genera which had not been before indicated, but 
his classification is decidedly artificial. Adopting from the first 
the artificial distinctions ol Polypier flexible, Poly pier pierreiix, 
and Polypier sarcoide, he has been necessarily led, as Blainville 
observes, to a similarly artificial arrangement of all his subordi- 
nate groups. A better prospect has, however, opened upon us 
in this respect. Naturalists are now guided in this department 
of zoology by the same principles which have for some time 
back directed their researches in the other branches of the sci- 
ence. They see the importance of studying the entire organiza- 
tion. And while this has led them to a close investigation of 
the Polypi themselves in those zoophytes in which they are 
really present, it has also led them to distinguish, and to sepa- 
rate from these last, others, in which it is now clearly ascertained 
that no Polypi ever exist. 

I can only make a brief allusion to a few important steps which 
have been gained of late years in our knowledge of these animals. 
One of these relates to the Madrepores, the animals of which have 
been proved, by the researches of Lesueur*, Eysenhardt, and Cha- 
misso, and more recently, as well as more decidedly, by those of 
Quoy and Gaimard, to hold a much nearer affinity to the Actinice 
than to the Hydrce. Blainville, who has attempted to characterize 
the generaf from a consideration of the hard and soft parts con- 
jointly, considers them as true Actinice, in the parenchyma of 
which is deposited a considerable quantity of calcareous matter, 
producing what the French call the Polypier. He observes, 
that we may even find a gradual transition in this respect from 
the softest of the Actinice to the most solid and most calcareous 
of the Madreporce. He accordingly throws them both together 
in one class {Zomitharia, Blainv.), in which however they form 
two distinct orders. Quoy and Gaimard paid particular atten- 
tion to the Polypiferous Zoophytes during their voyage with 
Freycinet;}:, and ascertained the nature of the animals in several 
genera in which they had not been described before, or only in 
an imperfect manner. Amongst others may be mentioned the 
Tubipora of Linnteus, which had been supposed by some to 

• Mem. du Mus., torn. vi. p. 271. 

\ Diet, des Scien. Nat., art. Zoophytes. 

X See the volume of Zoology annexed to that voyage ; also A?in. des Scien. 
Nat., torn. vi. p. 273, and torn. xiv. p. 236. The former of the two memoirs 
just cited contains some remarks on the supposed rapid growth of Coral Islands, 
and the power possessed by the Polypi of raising perpendicular walls from the 
bottom of the ocean. According to their observations, the labours which have 
been ascribed to these animals have been very much exaggerated, and the ac- 
counts which have been sometimes given of them altogether erroneous. 



288 FOURTH REPORT — 1834. 

be inhabited by an annelidoiis animal. MM. Quoy and Gai- 
mard have shown it to be a true Polype. Delle Chiaje is said 
also to have described the animals of certain species which had 
previously been unnoticed. Dr. Fleming in our own country 
has made many interesting researches connected with the genera 
and species found on the British shores*. More important con- 
tributions, however, to our knowledge of this class of animals 
were made in 1825, and the two succeeding years by another of 
our countrymen, A-ihose labours in this department have acquired 
for him the highest reputation. I allude to Dr. Grant, whose 
series of papers on the Sponges and other zoophytes are replete 
with new and valuable observations. Those on the Sponges es- 
pecially, published in the Edinb. Phil. Journ. for the above 
yearsf, contain the results of a far closer investigation than had 
been before made into the nature of these anomalous productions. 
Indeed he was the first to discover their true organization and 
functions. He clearly ascertained that they do not possess any 
folypi, nor even the power of contracting and dilating their 
orifices, as had been formerly supposed. He was the first to 
draw the exact distinction between the faecal orifices and the 
pores ; as well as to point out the nature and directions of the 
currents which are constantly passing out from the former. He 
also succeeded in determining the origin and mode of develop- 
ment of the ova. The memoirs just alluded to relate to the 
Marine Sponges. In a sej^arate communication^, he gave the 
results of a similar investigation into the nature of the Spottgilla 
friabilis of Lamarck, found in fresh water, M'hich he showed to 
bear a close resemblance to the above in all essential respects, 
although more simple in its structure, and occupying a still lower 
place in the scale of organization. In 1827 Dr. Grant extended 
his researches to tlie FlustrtE, and published a detailed account 
of the structure and oeconomy of this tribe of Polypi, which were 
before but imperfectly understood. Several other equally valu- 
able papers relating to the zoophytes appeared from him about 
the same time, to which however I can only just allude. In one 
of these§, he has described a new and highlj' interesting genus, 
forming a connecting link between Alcyonium and Spongia ; 
" allied to the former by its contractile fleshy texture, and by 
its distinct though microscopic Polypi; to the latter, by its 

• See Edin. Phil. Journ., vol. ii. p. 82 ; and JVern. Mem., vol. iv. p. 485 ; also 
h\& British Animals, published in 1828. 

f vols. xiii. and xiv. ; also vols. i. and ii. of the New Series. 
X Edinb. Phil. Journ., vol. xiv. p. 270. 
§ Edinb. Phil. Journ., N.S., vol. i. p. 78. 



REPORT ON ZOOLOGY, 239 

siliceous tubular spicula, ramified internal canals, tubular papillae, 
regular currents, and the distribution of its ova." In another, 
published the same year in the same journal, he has detailed 
some observations on the spontaneous motions of the ova of 
several species of zoophytes, a motion which, though long since 
observed by Ellis in the case of the Campanidaria dichotoma. 
Lam., scarcely seems to have attracted notice afterwards, not- 
withstanding its importance as connected with the mode of 
generation in tiiese animals. In 1827, Dr- Grant also published 
two papers in iheEdinb. Journ. of Science, one* on the structure 
and mode of generation of the Virgularia mirahilis and Penna- 
tula phosphorea, the otherf on the generation of the Lohidaria 
digitata. A supplement to his first memoir appeared in the 
same joui-nalj in 1829. 

About the same time as that when Dr. Grant was engaged 
with these researches, two or three observers in France were 
busied in a similar investigation, as well of the Sponges as of 
some of the freshwater gelatinous Polypi of Cuvier's second 
order. Raspail and Robineau-Desvoidy first read a memoir to the 
Royal Academy of Sciences in 1827 § on the ^/cyo?ieZ/a of Lamarck. 
Their object was to elucidate the structure of this ill-understood 
zoophyte, and more especially to show that the supposed Po/5//9^ 
seen in it by Lamarck were only parasites, probably belonging 
to the genus Nais, the tubes of the Polypier being naturally im- 
perforate. This opinion was, however, retracted by Raspail in 
a second and very elaborate memoir on this zoophyte read the 
same year||, in which he acknowledged the existence of the Po- 
lypi, but sought to prove by a course of detailed observations that 
this genus was not distinct from Cristatella or Plumatella ; that 
in fact these three genera, as well as Difflugia of Lamarck, were 
one and the same animal in different stages of development^. Ras- 
pail also made several observations on the structure of Sponges, 
in some respects analogous to those by Dr. Grant. In a me- 
moir, likewise read in 1827 and published the year following**, 
he gave the results of a microscopic examination into the struc- 
ture of the Spongilla friahilis, many of which results, however, 
differed very materially from those arrived at by our own coun- 
tryman. Part of his object was to point out an analogy be- 

* vol. vii. p. 332. f vol. viii. p. 104. J vol. x. p. 350. 

§ Cuv., Anal, den Trav., 1827. 

II This second memoir was subsequently published in the Mem. de la Soc. 
d Hist. Nat. de Paris (torn. iv. p. 75). 

^ Further researches seem necessary in order to establish beyond doubt the 
identity of the above genera. The opinion of Raspail on this point has not 
been universally adopted. 

*• Mem. de la Soc. d'llist. Nat. de Par., torn. iv. p. 201. 



240 FOURTH REPORT — 1834. 

tween the Biliceous spicule found in this genus and in the other 
Sponges, and the spiculae of oxalate of lime met with in certain 
plants. In 1828, the Sjiongilla was again made the subject 
of a memoir, by Dutrochet*. He confirmed Dr. Grant's obser- 
vations, particularly those relating to the existence of currents 
(which Dutrochet attributed to endosmose) and the entire ab- 
sence of Polypi. Dutrochet, however, considered the SpoiigiUa 
as a vegetable. 

A series of valuable observations relating to the zoophytes 
were also published in 1828 by Audouin and Edwards f? being 
a portion of the researches of these indefatigable naturalists at 
the Chausey Islands. They afford fresh confirmation of the 
accuracy of Dr. Grant's views respecting the Sponges and Flus- 
trcE. They also seem to lead to the important discovery that 
many of the species in this last group possess an organization 
more complex than has been hitherto supposed, and such as 
brings them into near affinity with some of the compound As- 
ciditeX. The same complexity of structure is stated to have 
been seen by them to a certain extent in many Vorticella;. 
These observers indeed have found such great differences in the 
organization of the class of Polypi in general, so far as they 
have had an opportunity of examining them, that they propose 
a fresh division of this class into four sections, each of which 
will constitute a natural family characterized by a peculiar type 
of structure. ^\iQ first of these groups will embrace the Sponges ; 
the second, the fixed Polypi, whether naked or incrusted, in 
which the digestive cavity is in the form of a cul de sachoWovftd 
out in the very substance of the body {Hydrce, Sertularice, 
many Vorticellce) ; the third will include those Polypi having 
a cavity in the body, in the middle of which is suspended a 
membranaceous digestive canal, communicating outwards by a 
single opening, and bearing at its lower extremity appendices 
in the form of small intestines, which appear to perform the 
office of ovaries {Lohularice, Gorgonicp, PennatulcB, Veretillce, 
CornularicB, &c.) ; the fourth will include the Flustrcs and 
other Polypi, in which the digestive canal commvmicates out- 
wards by two distinct openings, and the organization of which 
approaches that of the compound ^*c/rf?<^. 

♦ Ann. des Sci. Nat., torn. xv. p. 205. t ^f^t torn. xv. p. 5. 

X Cuvier states that similar observations had been made by Spallanzani, and 
also more recently by Blainville. He adds, however, that according to Quoy 
and Gaimard, there are certainly other species in which the animals are true 
Polypi; and that hence it would be very desirable to ascertain which belong to 
one type of structure, and which to the other. See Regne Animal, torn. ill. 
p. ."^OS. note (5). 



RKPORT ON ZOOLOGY. ^4-1 

It is probably to this last group of zoophytes, containing the 
more perfectly organized genera, that the animal belongs which 
Mr. Thompson has described mider the name of Polyzoa in the 
fourth number of his Zoological Researches. This name he 
has applied as a general title for the animal inhabitants of seve- 
ral zoophytes, which in their organization he considers as be- 
longing to the Acephalous Mollusca, being possessed of a di- 
stinct guUet, stomach, intestine, and ovarium. Such a structure 
he has noticed in Sertularia imhricata, S. Cuscuta, S. spinosa, 
and S. pitstulosa, and he thinks that it will probably be found 
in all the other species of Sertularia "not furnished with ovi- 
ferous receptacles, distinct in size, shape, and situation from the 
cells occupied by the animals, and consequently in all the Sein- 
alaria of Lamarck." Mr. Thompson has also observed the 
same organization in the Flustrce, thus confirming the observa- 
tions of Audouin and Edwards, with which, however, he does 
not appear to be acquainted*. 

The memoirs which have been noticed above relate for the 
most part to particular groups in the class under consideration. 
The only work that has appeared of late years treating of this 
entire department of zoology (I except Blainville's, which is of a 
more general nature,) is one published by Rapp in 1829t' This 
work is divided into two parts. The first treats of the classifi- 
cation of the Polypi in general, presenting an arrangement in 
which due consideration is had to the form of the animal. The 

• 1 may take this opportunity of stating, that at the same meeting of the 
British Association at which this Report was read, Mr. Graham Dalyell brought 
forward a memoir containing some highly interesting observations connected 
with the mode of propagation and development of the SertularicB, as well as of 
some other zoophytes found on the coast of Scotland. An abstract of this 
memoir will be found in the Edinb. New Philos. Journ. for October last, 
p. 411. 

I may also observe, that since then an important memoir " On the Stioieture 
and Functions of tubular and cellular Po/?/pj" has been published by Mr. Jack- 
son Lister in the second part oi the Philosophical Transactions for 1834. The 
principal feature in this memoir is the discovery of the existence of currents 
within the stems of the Tubularia indivisa and of all the species of Sertularia 
which were examined by the author. The circulating fluid, which appears to 
be in some respects analogous to that observed in Ckarce, Mr. Lister is disposed 
to regard as an important agent in the absorption and growth of the parts. 

t Ueher die Polypen im allgemeinen, und die Actinien ins hesondere. Wei- 
mar, 1829, 4to. I should state that a work appeared in 1819 by Schweigger, 
entitled Anatomisch-physiologische Beobachtungen ilber Corallen, which is said 
to contain a great many valuable observations on the structure and ceconomy of 
zoophytes : 1 have not, however, seen it myself. Some of his researches went 
far to prove that the CorallincB are only calcified plants. See an analysis of 
his experiments on this subject by Dr. Grant in the Edinb. New Phil. Journ. ^ 
vol. i. p. 220. 

1834. R 



~42 FOURTH REPORT — 1834. 

primary division is grounded on the position of the ovaries or 
germs, which are either external or internal, and give rise to two 
groups accordingly. The former includes the genera Hydra, 
Coryne, Sertularia, and Tuhularia, united to form a small 
family ; and the genus 3Iillepora. The latter comprises the 
Alcyonia, or Polypi tubiferi of Lamarck ; the TubiporcB ; the 
Corals ( Corallium, Gorgonia, Isis, and Antipathes) ; the Pen- 
tiatulfs ; the genera Zoanthus and Cornularia ; and the Ma- 
drepores. The second part of Rapp's work is confined to the 
ActiniiB, and may he regarded as a kind of monograph on that 
difficult tribe, the species of which have been in general so ill- 
determined. 

The same year as that in which Rapp published the above 
work, he also published a paper, in the fourteenth volume of the 
Nov. Act. 3)'c., Nat. Cur., on the structure of some species of 
Polypi from the Mediterranean. 

It is not pretended, in what has gone before, to point out all 
the discoveries which have been made in this class of late years ; 
and possibly there may be some of more importance than any 
mentioned which I have omitted, through ignorance, to notice. 
But whatever our knowledge may amount to, we may safely say 
that it bears but a small proportion to what remains to be ac- 
quired. This is indeed true with respect to every department of 
zoologj^, but it is most especially so with regard to the present. 
As a proof, it is only necessary to mention that in Blainville's 
work (I speak of tlie second edition, which appeared during the 
present year,) there are upwards of fifty genera (without includ- 
ing those which have been hitherto only found fossil) the cha- 
racters of which commence vf'iXh animaux inconmis* . I need 
scarcely add what a field is here open to the naturalist, or how 
far we must be removed from imderstanding the structure and 
the true natural affinities of all the above groups. 

5. Infusoria. — So complete a revolution has been effected in 
this group by the recent brilliant discoveries of Professor Ehren- 
berg, as entirely to sink the value of every arrangement that 
had been previously brought forward of the animals which it in- 
cludes. It is not, however, a department of zoology which had 
before been much cultivated. Since the time of Miiller, to 
whom we are indebted for the first accurate researches into the 
history of these minute beings, but little progress has been made 
in our knowledge respecting them, till the period we are about 
to speak of. The most important contributions were those of 

* One of these geneva is Antipalhes, the animals of which, however, have 
heen discovered h)' Mr. Gray, who read a short notice respecting them to the 
Zoological Society in 1832. See Proceed, of Zool. Soc. for that year, p. 41. 



REPORT ON ZOOLOGV. 243 

Nitzsch in 1816, who illustrated the structure of the Cercarice 
and Bacillarice, and with whom rests the merit of having first 
ascertained the existence of eyes in several species belonging to 
the former of these groups. Many other observers have pub- 
lished descriptions of new species, as well as instituted new ge- 
nera ; but not having had a sufficiently correct idea of the real 
organization of these animals, they have in too many instances 
estahlished their characters upon considerations which are found 
at the present day to be of no importance whatever. This is 
particularly the case with many new groups instituted by Bory 
St. Vincent in the DicL Class, d' Hist. Nat., in 1826. In this 
work, under the Art. MrcROscopxQUES (which name he substi- 
tutes for that of Infusoria), he has given a new systematic ar- 
rangement of all the animals belonging to this class ; but being 
unfortunately based on the external forms, not only are his 
genera and species greatly overmultiplied*, but his classifica- 
tion is entirely artificial, and since the researches of Ehrenberg, 
become perfectly useless. More important views on this sub- 
ject were entertained by Professor Baer in a paper published in 
the 13th volume of the Nov. Act. S^c, Nat. Cur., to which al- 
lusion has been already made in a former part of this Report. 
He particularly noticed the great differences which appear in 
the organization of these animals. Carried away, however, by 
peculiar notions, which led him to consider them as only the 
imperfect prototypes of other classes, he was for placing them 
respectively in these classes, and suppressing that of Ii^usoria 
altogether. 

Ehrenberg's researches, which form quite an epoch in this 
department of zoology, were first made known in a memoir read 
to the Berlin Academy in 1830, and published in the Transac- 
tions of that body for that year. So many excellent analyses of 
them have already appeared f, that it is not necessary, neither 
\^ould it be consistent with the length of this Report, to enter 
here into any detailed account of them. I shall simply mention 
some of the chief results at which he has arrived with respect to 
the structure of these animals, and which he has made the basis 
of an improved classification of them. The principal feature is 
the discovery that the Infusoria possess a much more complex 
organization than naturalists before had any idea of. By sup- 

* The extent to which this has been carried, not only by Bory St. Vincent but 
by other writers on these animals, may be judged of from a statement by 
lihrenberg, who observes that Miiller has made of the Vorticella Convallaria 
twelve species, which form with Lamarck, Schrank, and Bory St. Vincent six 
genera. 

t See the Edinh. New Phil.Journ. for 1831 and 1833. Also the ^nn. des 
Set. Nat. for March, &c., of the present year. 

B 2 



244 FOURTH REPORT — 1834. 

plying them with organic colouring matter as nutriment, he has 
clearly ascertained that they are not mere homogeneous gela- 
tinous masses supported by cutaneous absorption, as was for- 
merly supposed, but organized bodies, provided in all cases with 
at least a mouth and digestive system. This last indeed he 
has found subject to great variation of structure, being some- 
times simply a round sac in the centre of the body, at other 
times a long canal, often very much convoluted, and furnished 
with a great number of caecal appendages, which he considers 
as so many distinct stomachs. The mouth also varies in its 
structure, and presents good characters for distinguishing the 
subordinate groups. In the simpler Infusoria, it is a mere 
xmarmed opening, surrounded with a greater or less number of 
ciliae. In those of a higher order, however, it is much more 
complicated, and in some cases even provided with a distinct 
pair of serrated mandibles. Besides a digestive apparatus, Ehren- 
berg has discovered a generative, and often a muscular system, 
and has even in one or two instances observed traces of what 
he considers as vascular and nervous systems. The existence 
of these last, however, is at present somewhat problematical. 

These striking discoveries have naturally led Ehrenberg to 
reject entirely the principles upon which all former classifica- 
tions of these animals had been grounded, and to construct a 
new one after the internal organization. His arrangement is 
based upon the structure of the digestive system, which gives 
rise to the two natural classes of Polygastrica and Rotatoria ; 
the former consisting of sucli as are provided with several sto- 
machs or internal cavities ; the latter of such as have only one, 
the moutli at the same time being surrounded by a peculiar 
rotatory apparatus. Of these two classes the last is much more 
complex in its structure than the former. It would even seem 
to be more highly organized than some other classes in the 
system, to which the animals included in it have been hitherto 
always thought subordinate. With respect to the inferior groups, 
those of the Polygastrica are characterized from the presence 
or absence of an excretory orifice, the relative positions of the 
mouth and anus when this last is present, and from the presence 
and situation of the cilise and other processes : in the Rotatoria, 
the families are characterized from the mode of arrangement of 
thecili{fi which form the rotatory organ. In each class the ge- 
nera form two parallel series, one consisting of the naked Infu- 
soria {Niida, Ehrenb.), the other of such as are protected by a 
crustaceous or horny covering {Loricata, Ehrenb.), these two 
series appearing to be intimately allied, and often presenting no 
other difference beyond that which has been just alluded to. 



REPORT OX ZOOLOGY. 



245 



Ehrenberg has rejected from the Infusoria several genera 
which were formerly classed with these animals ; amongst others 
the genus Vibrio, before spoken of as having been thought by 
Duges and Blainville to show an affinity to some of the Entozoa. 
It also appears probable from some of his observations, that 
the genus Monas and several allied genera are not distinct ani- 
mal forms, but only the young state of some Kolpodcs, Para- 
mcpcia, &c. This idea has been subsequently adopted by 
others*. 

Ehrenberg has since published a second memoirf, in which 
he has extended his researches to several points of great intei'est 
in the history of these animals. He has endeavoured to ascer- 
tain the duration of Iheir existence, as well as the mode of their 
development. He has also made some further discoveries with 
respect to their structure. He has detected eyes (which before 
he had only observed in some of the Rotatoria) in many of the 
Polygastrica, and he has found them to furnish distinctive cha- 
racters of great value in classification. He has fixed a nomen- 
clature for all the principal external organs and appendages, 
which he describes at much length. He has also made some 
further remarks on the modifications of the alimentary canal, as 
well as on those of the dental system. Since the date of his 
first memoir he has found the teeth existing under several di- 
stinct forms, and even ascertained their presence in some of the 
Polygastrica. These discoveries have suggested some new 
principles of arrangement. 

The above is a condensed abstract of the striking researches 
made by this acute obsei'ver. We may judge what important 
views they open to us, not only in respect to the structure of 
these animals, but in respect to what may be the structure of 
some other groups, in which also the organization has been con- 
sidered hitherto as of the most simple kind. It is moreover not 
improbable that they may ultimately help us in determining the 
true limits of the animal and vegetable kingdoms, if between 
them any fixed limits really exist. A complexity of structure, 
of such a nature as is found in no vegetables, has been shovm by 
Ehrenberg to exist in those forms which were formerly regarded 
as very near the boundary; and although we now know of some 
groups of a much more anomalous character than the Infusoria, 
it is only extending our researches a little further, and we may 
possibly be able to detect their real nature. There is one in- 

* See a paper entitled " Observations upon the Structure and Development of 
the Infusoria," by Dr. Rudolph Wagner of Erlangen, in i\iG Edinb. New Phil, 
Journ. for October 1832. 

+ Berlin Memoirs for 1831. 



^46 FOURTH REPORT — 1834. 

quiry in particular which forcibly suggests itself. Is there any 
similar complexity of structure, anything approaching to an 
alimentary sac or stomach, in those monads, which, it is asserted 
by so many observers, become fixed after a time, and transformed 
into Confervce ? The determination of this point will go far 
towards determining the true situation of a host of ambiguous 
genera at present hovering between the two kingdoms, and hav- 
ing almost equal claims upon the notice of the zoologist and 
botanist*. 

IV. Concltcsion. 

In the preceding pages I have endeavoured, though I fear 
very imperfectly, to give a condensed view of the principal re- 
searches which have been made of late years in Zoology, at least 
such as have tended to throw light upon the affinities of animals, 
and thereby to advance our knowledge of the natural system. It 
was my original intention to have proceeded here to the con- 
sideration of some other parts of the subject, such as the state 
of our knowledge with respect to the actual number of species 
in the several classes, and also with respect to the zoology of 
particular coimtries. The former, however, is rendered un- 
necessary from the appearance of an article in the Edinh. New 
Philos. Journ. of last year f, expressly devoted to this branch 
of inquiry. The latter would afford an opportunity of alluding 
to several valuable works which have been recently published in 
this and other countries, some containing many new and inter- 
esting forms of importance to the science in general. But the 
length to which this Repoi't has already been extended precludes 
mj' entering upon this subject. Considered also in connexion 
with that of the geographical distribution of animals, it would 
furnish ample materials for a separate communication. I shall 
therefore, in conclusion, merelj'^ offer a few remarks connected 
with the further progress of zoology, and its advancement in 
this country in particular. 

(1.) Its general progress, viewing the natural system as the 
true object of the science, and considering the very imperfect 
knowledge we have of this system at present, must clearly de- 
pend upon the discovery of new forms, and a more thorough in- 
vestigation of those already known to us. If the former be ne- 
cessary in order to supply some of the numerous links that are 
yet wanting to complete the chain of afl&nities, the latter is not 

• For further information respecting these anomalous productions, the reader 
is referred to the article Arthroidees in the Diet. Class. d'Hist. Nat., and to the 
articles Nemazoaires and Zoophytes in the Diet, des Sei. Nut. 

t No. 30, for July 1838, p. 221. 



REPORT ON ZOOLOGY. 247 

less SO to determine the parts of the system to which these links 
belong. But of these two, there can be no doubt the latter is 
what we stand most in need of. I question whether we shall not 
be rendering more service to zoology by paying closer attention 
to the species we are already acquainted with, than by further 
augmenting the immense collection of uninvestigated forms 
which exists now in our cabinets. We have, perhaps, sufficient 
materials on our hands, though not for discovering the whole 
natural system, at least for solving many important problems in 
zoology, were we only better instructed in the natiu-e of these 
materials. It has been shown in the course of this Report, that 
there are large groups, even whole classes, of which the true 
situation and affinities are either not determined at all, or in- 
volved in much uncertainty, from the impei-fect knowledge we 
have of their structure and oeconomy ; and in the details of the 
system, there is not one class which does not present many 
genera, and a vast many more species in this predicament. 
Here then is where the researches of naturalists should be di- 
rected. Until we shall have more closely analyzed the charac- 
ters of these groups, and learnt both the method of variation and 
relative importance of all the organs, until we shall come to 
understand their whole structure as compared with those struc- 
tures we are already acquainted with, we can neither determine 
the affinities of these groups, nor of any others allied to them 
which we may hereafter discover. 

Researches of the above nature are, perhaps, best embodied 
in monographs. The value of such works has been every day 
more and more appreciated since the science has become so 
extensive, and since its legitimate object has been better under- 
stood, especially when they refer to every point in the history 
of the group treated of, and when due care is taken first to 
ascertain what others have written on the same subject *. Many 
excellent monographs fulfilling these conditions already exist, 
some of which have been alluded to, and others might have 
been had it been allowable to enter so much into the details of 
the subject. Nevertheless it would be extremely desirable to 
have them multiplied. By the help of such works we may 
arrive step by step towards a more complete generalization of 
the large number of facts embraced by zoology, at the same time 
that we greatly facilitate the researches of other naturalists. But 
all inquiries into the structure and oeconomy of animals presup- 
pose an exact discrimination of species. Without this the most 
detailed observations are rendered of little use, and it is the 

t Seethe article Monographie, by Dccandolle, in the Diet, des Set. Nat. 



~48 FOURTH REPORT 1834. 

want of it which detracts from the value of much that has been 
recorded by those who have not sufficiently attended to this 
matter. Hence it should be one object of a monograph to in- 
vestigate species with a view to their exact differences, and to 
elaborate the synonyms of those which have been noticed by other 
authors. This is especially necessary in some groups, in which 
great confusion exists on this head. Cuvier was particularly 
sensible of the importance of this step. In his Histoire Naturelle 
dcs Foissons it is impossible not to be struck with the care 
which he has shown in endeavouring to trace every species to its 
first describer, and to disentangle its synonymy, before proceeding 
to other points in its history. No researches have been spared 
which could throw any light on this part of his subject. Every 
author has been consulted ; even the most ancient writers on 
this branch of zoology he has had recourse to, under the hope of 
being able to identify the species they have noticed. And he 
has more than once observed in some other of his works, that 
there is greater service done to natural history in thus extri- 
cating from error and confusion the history of old species, than 
in publishing and describing new ones. 

But not all have it in their power, from the want of requisite 
materials, to furnish a complete monograph of any entire group. 
Such persons may, notwithstanding, still contribute greatly to 
the advance of zoology by restricting their monograph to the 
species in their own neighbourhood : only let such works be 
conducted with the same care, the same original observation 
and research, which are thought necessary in the productions 
just alluded to. Faulty catalogues, or even works of a more 
elaborate kind, if merely compiled from other authors, are 
utterly worthless. Whereas good local Faunas, or portions of 
a Fauna, however limited the district, may be rendered of the 
greatest possible value. By studying with scrupulous exactness 
the structure and habits, although only of a few species, we 
may be able to throw much light upon their natural affinities *, 
we may accumulate enough facts to make some approaches 
to generalization ourselves; at any rate we are amassing the 
best materials for enabling others to do so. 

(2.) With reference to the further advancement of zoology 
in this country in particular, I cannot forbear observing, that 
while there are some branches of the science which are most 
.sedulously cultivated by us, there are others, and those too such 
as, from our insular position, it might be thought would be 
aniong the first to attract our notice, which have for a long 

* Witness the researches of Thompson with respect to the Clrripedu. 



REPORT ON ZOOLOGY. 249 

time lain comparatively neglected. I allude to Ichthyology 
and the study of the marine Tnvertebrata. I need scarcely say 
how small is the number of individuals who have added any- 
thing recently to our knowledge of the fish even of our own seas, 
notwithstanding the opportunities for so doing which daily 
present themselves to naturalists resident on the coast. The 
fact has been repeatedly noticed. With regard to marine In- 
vertebrata, I refer more particularly to the Radiata of Cuvier, 
although there is reason to believe that our knowledge of the 
Mollusca is far below what it might become by a more diligent 
inquiry into these tribes. Excepting the important researches 
of Dr. Grant and Mr. Thompson, excepting also a few detached 
papers by Drs. Fleming and Coldstream, and more recently by 
Dr. Johnston *, we have hardly any original observations with 
respect to the radiated animals since the time of Montagu f- 
In the several classes of Echinodermata, Acalepha^ and Polypi, 
it is impossible to say what and how many species are to be 
found on our own shores, or what important additions might 
not be made to our general knowledge of these groups, as parts 
of the natural system, by those whose situation and opportuni- 
ties afford the means of studying them. As a striking illustra- 
tion of what might be done, it is only necessary to look to the 
results obtained by two French naturalists % (whose example 
deserves to be imitated) during a series of annual excursions 
to different parts of their own coast. There is no occasion to 
specify these results in detail. Many, of the greatest possible 
interest and importance to zoology, have been already alluded 
to in former parts of this Report. I may, however, just state 
the fact, that on their return from the Chausey Islands, which 
were selected one season as the scene of their researches, they 
enriched the Paris museum Math upwards of 600 species of 
marine Invertebrata, of which at least 400 were considered by 
them as either entirely new, or before imperfectly understood §. 
While it is thus in our power to do much for this science as 
individuals, I conceive it is also in our power to do something 
as a nation ; and in no respect more than by encouraging and 
promoting expeditions to foreign countries, deputing naturalists 

* This gentleman has hately published a useful paper on the recent Zoo- 
phytes found on the coast of North Durham, in the Trans, of the Newcastle 
Natural History Society. 

t I should also make an exception of Mr. Graham Dalyell, whose researches 
on Scottish Zoophytes were brought forwards at the same meeting as when this 
Report was read. These, however, have not yet been published in detail. 

X M.M. Audouiii and Edwards. 

§ Cuvier's Anal, dts Travaitx, 1828. 



250 FOURTH REPORT — 1834. 

to those parts of the globe which have been least explored, and 
aflFording the means of making known to the public the fruits of 
their researches. France has long since set us an example in 
undertakings of this nature. In the splendid volumes of zoology 
annexed to the voyages of Captains Freycinet and Duperrey; in 
the appropriation of a yearly sum for the sxipport of travelling 
naturalists for the benefit of the Royal Museum, which mainly 
to this circumstance owes its unrivalled celebrity * ; we see 
marks of an anxious endeavour on the part of that nation to up- 
hold the interests of this science. I will not say that in no in- 
stance has anything of the kind been done here. Within these 
few years we have seen a woi-k emanate from the British press, 
the Fauna Boreali-Americana, under the immediate sanction 
and patronage of our own government. I believe, however, it 
is the first, wholly devoted to zoology, which ever appeared 
under such auspices. And with respect to researches in foreign 
lands, whatever may have been done for other sciences, or for 
this science by private individuals, I apprehend we have effected 
very little as a nation which will bear to stand in competition 
with what has been done in this way by France, and some other 
nations on the Continent which might be mentioned ■\. 

Such are the hints which, with much diffidence, I would ven- 

* M. D'Orbigny, who has been for these few years past exploring South Ame- 
rica in the above capacity, has recently returned to Paris with rich and valuable 
collections in all departments. He is said to have acquired no less than forty-six 
new species of Mammalia alone, a surprising addition when we reflect that the 
whole number before known scarcely exceeded 1200. (See L'lnsdt., No. 50.) 
It was observed eight years ago, that " in the present advanced stage of informa- 
tion, it cannot be expected that many new recent species oi Mammalia should 
be discovered. > " M. D'Orbigny, however, has shown that even in this class 
novelties are far from at an end to reward those who will go in quest of them. 

f Perhaps it may not be without its use, to call the attention of the members 
of the British Association to the following proposition which was made and 
adopted at the congress of French sawan* held at Caen, July 1833. It was resolved 
" to encourage travels of discovery ; to recommend naturalists and all persons 
interesting themselves in the progress of natural history, to organize these 
kinds of travels by means of subscriptions, and to direct them towards those parts 
of the globe which have been least explored." See Congres Scientif. de France, 
1833, p. 261. I will not presume to say how far it would be practicable for 
the British Association to set on foot any such project in this country. 

Since this Report was read, Mr. Swainson has published his Preliminary 
Discourse on the Study of Natural History, in which he has treated, at some 
length, of the Present State of Zoological Science in Britain as compared with 
other countries. Without wishing it to be thought that I subscribe to every- 
thing stated in that volume, I may refer to Part 4. as containing more ample 
details in reference to this inquiry than it was possible for me to enter into. 

* Bicheno's Address (o the Zoolog. Club, 1826, p. 5. 



REPORT ON ZOOLOGY. 251 

ture to throw out for the further promotion of zoology. I have 
only to add, that with reference to the progress it is actually 
making in our own country, and the promise which is held out 
of uninterrupted advancement, comparing this country, not with 
others, but with itself at former periods, there is ground for 
much exultation. Looking to what has been effected of late 
years, however more striking in some departments than others, 
to the important works and memoirs which have appeared 
amongst us, and to the channels which have been opened for the 
more successful cultivation of this science, it is impossible not 
to anticipate the most valuable results. There is one institution 
in particular, of which I have hitherto not spoken, but which 
more than anything has contributed to this impulse. I allude 
to the Zoological Society, founded in 1826. The scale and plan 
upon which this Society is conducted are calculated to obtain 
for it the highest place amongst institutions of this nature. Its 
Museum and Gardens, the latter for the reception of living 
animals; its extensive correspondence with naturalists in foreign 
countries, by which it has been enabled to acquire some of the 
richest and most valuable collections ; are too well known to the 
members of this Association to require being dwelt upon more 
particularly. I may state, however, that it has recently com- 
menced the publication of Transactions, of which two parts are 
before the public, containing memoirs of the first importance to 
zoology, and such as will bear competition with any of those 
which have emanated from other quarters. 

But it is not merely in the institution of the Zoological 
Society that we trace a rising spirit of inquiry in this branch of 
science. We see it in the establishment of Natural History 
Societies in almost all the principal towns of England. It is 
unnecessary to specify these individually. It is enough to be 
able to record the fact of their existence. This circumstance 
alone speaks to a more generally diflFused taste for zoology, 
which is the first step towards the advancement of zoology it- 
self. It is only necessary to give a proper direction to the re- 
searches of these societies, to point out those departments which 
need most cultivation, and we may reasonably hope that the time 
is not far distant when England will no longer be considered 
behind her continental neighbours in this, any more than in 
other sciences. 



253 



Report on the Theory of Capillary Attraction. By the Rev. 
James CnAhLis, late Fellow of Trinity College, Cambridge. 

In the Report which I had the honour of drawing up last year, on 
the analytical theory of hydrostatics and hydrodynamics, a di- 
stinction was made between problems on the common theory of 
fluids, and those in which molecular attraction and the repulsion 
of heat are explicitly taken account of, and the former kind alone 
came under review. That distinction, it was said, depended on the 
different bases of calculation, which in the former class of pro- 
blems are observed facts ; in the other, certain hypotheses, which 
can be verified only by a comparison of the results of calculation 
with experience. The latter kind of questions are of the more 
comprehensive nature, because frequently it is proposed in them 
to account for the facts which serve for bases of calculation in 
the other class, and an explanation of every such fact must in- 
clude the explanation of all those that can be mathematically 
shovni to be dependent on it. The above distinction ought to 
be kept in mind when we regard the part which calculation has 
to perform in our inquiries into the nature and properties of 
matter. It is not sufficient to say that analysis serves to classify 
facts of observation, and to prove that several which are allied 
to each other are consequences of some one observed fact ; for 
we have been taught by the labours of Newton, that there are 
facts which are not phtsnomena, the existence of which can only 
be proved by calculation. It may now be considered an esta- 
blished fact that all bodies attract each other proportionally to 
their masses, with forces varying inversely as the square of the 
distances ; but the evidence for this truth is essentially mathe- 
matical. So, if the existing theories respecting the internal 
constitution of bodies, and the nature of the forces which ema- 
nate from their molecules, should be established by the progres- 
sive advance of science, the evidence on which they will rest 
must be mathematical. For these reasons, this, the highest de- 
partment of physical science, may be properly denominated 
Mathematical Physics*. The great problem of universal gra- 
vitation, which is the only one of this class that can be looked 
upon as satisfactorily solved, relates to the lai'ge masses of the 

• In the former Report I have inadvertently written Physical Mathematics. 
It might perhaps be questioned whether these terms be not equally proper ; 
but when, in addition to what is said above, the title of Newton's Principia is 
recollected, the other would seem to be preferable. 



254 FOURTH RKPORT 1834. 

universe, to the dependence of their forms on their proper gra- 
vitation, and the motions resulting from their actions on one 
another. The progress of science seems to tend towards the 
sohition of another of a more comprehensive nature, regarding 
the elementary constitution of bodies, and the forces by which 
their constituent elements are arranged and held together. Va- 
rious departments of science appear to be connected with each 
other by the relation they have to this problem. The theories 
of light, heat, electricitj-, chemistry, mineralogj^ crystallogra- 
phy, all bear upon it. A review, therefore, of the solutions that 
have been proposed of all such questions as cannot be handled 
without some hypotheses respecting the physical condition of 
the constituent elements of bodies, would probably conduce, by 
a comparison of the hypotheses, towards reaching that generali- 
zation to which the known connexion of the sciences seems to 
point. This end is kept in view m the following Report. It hap- 
pens that with respect to fluids two problems have especially en- 
gaged the attention of mathematicians, which in a very marked 
manner lead to the consideration of molecular forces and the 
repulsion of heat, viz. capillary attraction, and the propagation 
of motion as affected by the development of heat. The one 
refers to fluid in equilibrium, the latter to fluid in motion. It 
was my intention originally to embrace both these in one Re- 
port, but the time required for becoming acquainted with works 
on these subjects which have not been very long before the 
public, and contain new trains of thought and mathematical in- 
vestigation, did not allow of preparing the Report, such as it 
was intended to be, in time for the present meeting ; and the 
matter connected with capillary attraction alone \vill perhaps be 
thought sufiicient, and of sufficient mterest, to form the subject 
of a separate report. 

The distinction above stated as applicable to two sorts of 
hydromechanical questions, applies equally to statical and dyna- 
mical questions respecting solids. Some may be treated on the 
supposition of perfect rigidity, as is the case in most of the pro- 
blems that occur in the common elementary treatises on mecha- 
nics : in others the solids must be supposed to be elastic ; and 
if the elasticity he regarded not as a datum of observation, b\it 
as a result of molecular attraction and repulsion, then, to take 
account of it, certain hypotheses must be made respecting the 
nature of these forces and the molecular arrangement, plainly 
analogous and intimately related to the like hypotheses with re- 
spect to fluids. Questions of this kind have of late largely en- 
gaged the attention of some French mathematicians ; and the 
nature of tlieir theories, and the results of the calculations 



REPOUT ON CAPILLAHY ATTRACTION. !?5& 

founded on them, deserve to be brought as much as possible 
into notice. 

Capillary Attraction. — ^The theory of capillary phsenomena 
will be best exhibited by tracing historically the principal steps- 
by which it has arrived at its present state. 

Dr. Hooke is among the earliest speculators on the cause of 
capillary attraction. He attributed the risfe of the fluid to a di- 
minution of the pressure of the atmosphere within the tube, by 
reason of friction against its interior surface. This opinion was 
shown to be erroneous when the fluid was found to rise as high 
under the receiver of an air-pump as in the open air. 

Hauksbee*, whose experiments on the capillary action of 
tubes and glass plates have not even yet lost their value, made 
the beginning of a true theory of the phsenomena, by ascribing 
them to the attraction of the tube or plate. Having ascertained 
by experiment that the thickness of the matter of the tube made 
no difference as to the height to which the fluid ascended, he 
saw that the attractive force must emanate entirely from the 
particles of the tube situated at its interior surface. He does 
not, however, pronounce a decided opinion whether the sphere 
of their attraction extends mediately or immediately to the par- 
ticles of the fluid situated about the axis of the tube ; and he is 
in error in supposing that this attractive force, by pressing the 
fluid particles perpendicularly against the capillary surface at all 
the points with which the fluid is in contact, diminishes the 
weight of the suspended column. 

In this last particular the explanation of Hauksbee was 
shown to be untrue by Dr. Jui-inf, who found by experiment, 
that the height to which water would rise in a tube, of which 
the portion occupied by the fluid consisted of two cylinders of 
dififerent diameters, depended only on the diameter of the upper 
cylinder. If the lower cylinder was the larger of the two, as 
soon as it was completely filled, the water rose in the upper cy- 
linder to the same height above the external level as it would 
have done in a tube uniformly of the same bore as this latter. 
Hence he was led to ascribe the phsenomena to "^ the attrac- 
tion of the periphery or section of the surface of the tube to 
which the upper surface of the water is contiguous and coheres." 
On this hypothesis he easily showed that the heights of ascent 
in tubes of the same matter are inversely as their radii. For the 

• Physico-Mechanical ETperiments. London, 1709. pp. 139—169. Also va- 
rious papers in the Philosophical Transactions for the years 1711 and 1712. 

+ Philosophical Transactions 1718, No. 355, p. 739. An additional paper 
on the same subject, Phil. Trans. 1719, No. 363, p. 1083. 



256 FOURTH REPORT — 1834. 

quantity of fluid raised being proportional to the raising peri- 
phery, and consequently to the radius, and being proportional 
also to the product of the height and the square of the radius, 
it follows that the height is inversely proportional to the radius. 
This reasonhig is not incorrect, but defective, as we shall pre- 
sently see. In a postscript to his paper. Dr. Jurin intimates 
that the principle of his explanation was not unknown to New- 
ton and Machin, who, however, do not appear to have sup- 
ported their views by like experiments. He says also, that the 
same two mathematicians suggested to him that what he calls 
the periphery of the concave surface of the tube, is in reality 
** a small surface whose base is that periphery, and whose height 
is the distance to which the attractive power of the glass is 
extended." It is sufficiently evident that the theory of capil- 
lary attraction had engaged the attention of Newton, from 
the 31st query in the last edition of his Optics, which was pub- 
lished a short while previously to the reading of Jurin's paper. 

In this 31st query, Newton is speculating respecting the na- 
ture of molecular forces, to which he is of opinion that chemical 
combinations are owing. In proof of the existence of such 
forces, he appeals to several instances of attraction of the kind 
which it has been agreed to call capillary attraction or cohesion. 
One veiy singular instance is the suspension of a column of 
mercury in a barometer tube, to more than double the height at 
which it usually stands, by its adhesion to the top of the tube, 
which it leaves only by being considerably shaken. Of the 
same kind with this phaenomenon, Newton considers the rise of 
water between two parallel plates of glass held at a very small 
distance from each other and dipped in the fluid. The height 
to which the water rises, he says, " will be reciprocally propor- 
tional to the distance [between the plates] very nearly ; for the 
attractive force of the glasses is the same, whether the distance 
between them is greater or less, and the weight of the water 
drawn up is the same, if the height of it be reciprocally propor- 
tional to the distance of the glasses." This explanation, though 
true, does not prove that Newton had formed anj^ very distinct 
idea of the extent of action of the attractive force of the glass, 
and the mode in which the water is influenced by it. He asserts, 
moreover, that the height to which water rises in a slender glass 
pipe, will be reciprocally proportional to the diameter of the 
cavity of the pipe, and will equal the height to which it rises 
between two planes of glass, if the semidiameter of the cavity 
of the pipe be equal to the distance between the planes, or there- 
abouts." These are not, however, theoretical deductions, but 
the results of experiments made before the Royal Society. 



REPORT ON CAPILLARY ATTRACTION. S57 

Hauksbee records an experiment by wliich it appears that if 
a large tube of glass be closely filled with ashes, and one end be 
dipped in water, in the space of a week or fortnight the water 
will rise within the tube to 30 or 40 inches above the level of 
the water without. Newton, in noticing this experiment, says 
correctly, that the rise is owing " to the action only of those 
particles of the ashes which are upon the surface of the elevated 
water, the particles which are within the water attracting or re- 
pelling it as much downwards as upwards." 

Another experiment by Hauksbee shows that a drop of wa- 
ter inserted between two plates inclined to each other at a very 
small angle, and touching at their edges, is attracted to the junc- 
tion of the edges by a force varying inversely as the square of 
the distance from it. Newton attempts to account for this phae- 
nomenon, but unsuccessfully. The true explanation was reserved 
for Dr. Young and Laplace. 

When two planes inclined at a small angle are immersed in 
water, with the line of their junction vertical, the outliYie of the 
water that rises between them is on each plane nearly an hyper- 
bola, of which the asymptotes are the line of intersection of the 
plane with the horizontal surface of the fluid, and the line of 
junction of the two planes. Taylor first ascertained this by 
measurement*. It is a simple consequence of the law accounted 
for by Newton, of the rise of water between parallel planes to a 
height inversely proportional to the interval between them ; for 
the planes being inclined at a very small angle, opposite elements 
of them may be considered parallel. 

The early theories of capillary attraction were defective in two 
respects : they contained no calculation founded on the hypo- 
thesis of an attraction sensible only at insensible distances from 
the attracting centres, although the existence of such forces was 
already recognised, and Newton had given an example of calcu- 
lation made with reference to force of this nature in the instance 
of the passage of light through a dense medium ; and they took 
no account of the cohesive attraction of the parts of the fluid 
for each other. The necessity of considering the mutual at- 
traction of the particles of the fluid would seem to be very evi- 
dent when once the law of attraction, sensible only at insensible 
distances, was admitted; for supposing the capillary tube to 
attract only the fluid particles at insensible distances from its 
surface, a column of water of sensible breadth could not be 
suspended except by the intervention of a cohesive power resi- 

* Philosophical Transactions, 1712, No. 336, p. 538. 
1834. s 



258 FOURTH REPORT — 1834. 

dent in the fluid. Yet Clairaut was the first to see the ne- 
cessity of taking account of the action of the fluid on itself; 
and this addition to the tlieory of capillary attraction is the princi- 
pal feature of the propositions on this subject introduced, in rather 
a cursory manner and beside his main purpose, into his cele- 
brated treatise on the Figure of the Earth*. After stating the 
insufficiency of the method of Jurin, he proceeds to a careful 
consideration of all the forces concerned in raising the fluid, 
both those due to the tube and those due to the fluid, as well at 
the upper part of the column raised, as at the lower extremity 
of the tube. His method of considering the forces, which is 
stated clearly and illustrated by good diagrams, has been for 
the most part followed in succeeding treatises on the same sub- 
ject. But although Clairaut asserts that the forces concerned in 
this problem are sensible only at very small distances, he does 
not seem to be aware that the distances must be considered alto- 
gether insensible. This is not a necessary condition in his view 
of the mode in which the forces act ; respecting the law of the 
variation of which, as the distances increase, he makes no other 
hypothesis than that the function which expresses it is the same 
both for the tube and the fluid. He is consequently unable to 
prove that the height at which the fluid stands in a capillary 
tube is inversely proportional to the diameter. 

By reasoning on the hypothesis just named, Clairaut arrives 
at the following conclusion : " If the attraction of the capillary 
tube should be of less intensity than that of the water, provided 
it be not so small as half the other, the water will still rise." 
This he confirms in another method, the principle of which will 
be exhibited by showing as follows, that if the attraction of the 
fluid for itself were exactly double that of the tube for the fluid, 
the surface of the fluid within the tube would be horizontal, and 
consequently on a level with the surface without. Let us sup- 
pose the fluid surface to be everywhere horizontal, and consider 
the equilibrium of a particle in contact with the vertical surface 
of the solid, which we will suppose to be plane. Now as the 
resultant of the forces acting on the particle must be perpendi- 
cular to the fluid surface, and therefore vertical, the horizontal 
attractions destroy each other. Therefore the horizontal attrac- 
tion of the solid, which is its total action, is equal to the hori- 
zontal attraction of the fluid, which is only half what it would 
be if the fluid were continued above the particle as it is below, 
and consequently placed under the same circumstances of at- 

* T/ii'orie de la Figure de la Terre. Paris, 1808, pp. 105—128. 



REPORT ON CAPILLARY ATTRACTION. 259 

traction as the solid. Hence the truth of the proposition is 
manifest. We shall have occasion in a subsequent part of the 
Report to allude to this demonstration. 

In 1751, Segner*, aware that Clairaut had written some arti- 
cles {" articulos quasi epi^odicos") on capillary attraction, but 
not having seen his work, attempted to determine theoretically 
the form of the surface of a drop of water resting on a horizontal 
plane, on the hypothesis of the attraction of the parts of a fluid 
for each other. This is a problem of the same nature as that of 
determining the form of the upper surface of the column of fluid 
sustained in a capillary tube, neither of which had yet engaged 
the attention of mathematicians. Segner begins with admitting 
the tenacity of fluids, and ascribes it to the action of an attrac- 
tive force resident in their constituent molecules, the law of 
which he does not pretend to assign, but assumes only that the 
sphere of the activity of each particle is of insensible magnitudef. 
Setting out with these correct principles, he is led to refer the 
shape which the drop assumes to the action of its superficial 
particles, which form, as it were, a sheet encompassing it, and by 
their tenacity counteract the tendency of the drop to spread in 
obedience to the force of gravity. The sequel of this essay is 
not equally successfvil. In estimating the superficial tension 
considered as depending on the curvature at each point of the 
Surface of the drop, the author commits an error in taking ac- 
count only of the curvature of the sections made by vertical 
planes through its axis, and neglecting the effect of the curva- 
ture in planes perpendicular to these. He intimates in a note 
at the end of the essay that he became aware of some defect in 
his theory. 

A considerable time after the theory of Segner was published, 
Monge asserted, at the end of a memoir | on certain eftects of the 
apparent attraction and repulsion of small bodies floating on 
fluids, that " by supposing the adherence of the particles of a 
fluid to have a sensible effect only at the svirface itself, and in 
the direction of the surface, it would be easy to determine the 
curvature of the surfaces of fluids in the neighbourhood of the 
solid boundaries which contain them ; that these surfaces would 
be linteari<E, of which the tension, constant in all directions, 

* Comment. Soc. Reg. Gotting. torn. i. Ann. 1751, p. 301. 

t " Generatim autem spatium illud sphsericum, intra quod particulse activitas 
consistit, adeo exiguum est, ut nuUo adhuc sensu percipi potuerit." (p. 303.) 
Segner appears to have been the first to apply to capillary phfenomena mathe- 
matical calculation founded on this hypothesis. 

X Memoires de VAcad. des Sciences, An 1787, p. 506. 
S 2 



260 FOURTH REPORT 1834. 

would be everywhere equal to the adherence of two particles ; 
and the phaenomena of capillary tubes would then present no»- 
thing which could not be determined by analysis." The process 
here indicated Monge did not follow up by mathematical calcu- 
lations. The main purpose of the memoir, from which the above 
sentence is extracted, is to give an explanation of the apparent 
attraction and repulsion observed to take place between small 
substances when they float near each other on the surfaces of 
fluids. These phspuomena are of three kinds. (1.) If two float- 
ing bodies are each surrounded by a depression of the fluid sur- 
face, and are separated at first by a small interval, they will 
move towards each other as if mutually attracted. (2.) When 
the fluid rises up around them, they will in this case also appear 
to be attracted when brought near each other. (3.) When one 
is surrounded by an elevation of the fluid, and the other by a 
depression, they will appear to be mutually repelled. The motion 
of the bodies towards each other in the first case, is owing to the 
circumstance that the depression of the fluid about one is in- 
creased on their mutual approach by the depression about the 
other, at those parts of each that are neighbouring ; which occa- 
sions an unequal hydrostatic pressure against each of the bodies 
in the horizontal direction, the pressure being greatest where 
the depression is least. This explanation was first given by 
Mariotte. To explain the second phaenomenon, Monge reasons 
as follows. If a plate of any substance be dipped with its plane 
vertical in fluid, the fluid will rise by capillary attraction on 
each side of it. The surface of the raised water, being stretched 
like a chain, will draw the plate in a horizontal as well as verti- 
cal direction, but equally on both sides, so that it will remain in 
its vertical position. If now another plate of the same matter, 
and exactly alike circumstanced, be brought near the other, the 
fluid, it is well known, will rise between them. The total quan- 
tity of fluid raised above the ordinary level will remain the same 
as if the actions of the two plates did not interfere with each 
other, because the raising forces will be the same. But the 
weight of water raised between the plates, being suspended from 
a diminished quantity of fluid surface, the superficial tension 
within will become greater than that without, and will more 
than counterbalance the latter. The plates will consequently be 
drawn together. The third phaenomenon is explained by saying, 
that when a body, surrounded by an elevation of the fluid, is 
brought near one surrounded by a depression, there is occasioned 
a diminution of depression on the side of the latter nearest the 
other, and a consequent inequality of hydrostatic pressure, the 
excess being on the side where the depression is least. This 



RBPOHT ON CAPILLARY ATTRACTION. 26\ 

body will consequently be repelled from the other. More ex- 
act explanations of these phaenomena have since been given by 
Young, Laplace, and Poisson, but not materially differing in 
principle from the above. 

We ought now to notice the labours of Dr. Young in the theory 
of capillary attraction, as being next in order of time j but as his 
paper on this subject was published only a short interval (some- 
thing more than a year) before the " Treatise on Capillary Ac- 
tion" by Laplace, and as it contains an idea which is not in 
Laplace's theory, and which may be considered an additional 
step towards the complete explanation of the phsenomena, it 
will be convenient to deviate from the historical order for the 
purpose of exhibiting more clearly the progressive steps by which 
the theory of capillary attraction has arrived at its existing state. 
I will, therefore, now endeavour to give some notion of the prin- 
ciples of Laplace's theory, and of the extent to which they will 
explain phsenomena. 

This essay was pubUshed in 1806, as a supplement to the 
tenth book of the M^canique Celeste. It contains explanations 
more exact than had hitherto been given of the several facts we 
have had occasion to mention in the foregoing part of the Report, 
and of others in addition to these : and the explanations are sus- 
tained throughout by mathematical calculations. The hypotheses 
of the theory are, that the fluid is perfectly incompressible ; that 
there is as well an attraction of the particles of the fluid for each 
other, as a mutual attraction between the particles of the fluid 
and the particles of the tube, and that these forces are sensible 
only at insensible distances from the attractive centres. From 
these principles a fundamental equation relative to the upper 
surface of fluid raised by capillary action, is derived by a process 
of the following nature. 

Conceive an infinitely slender canal, of uniform transverse 
section, to be drawn from any point of the fluid surface, sup- 
posed to be concave by reason of the capillary action, to a point 
of the horizontal surface which is unafiiected by the same cause. 
Let the canal be everywhere beyond the sphere of the attraction 
of the solid from which the capillary action proceeds. Suppose 
its two ends to terminate perpendicularly to the surfaces, and to 
be rectilinear for a distance from each of them not less than a 
certain small quantity A, the extent of the sphere of activity of 
the fluid's attraction : it is proposed to determine the condition 
of equilibrium of this canal. It is plain that any point of it 
distant by more than A from its extremities will be attracted 
equally in all directions. The case is different with all points 
situated within the distance A from either of the extremities. 



26:3 FOURTH REPORT — 1834. 

The attraction of the sun-ounding fluid on the points of the 
canal so situated at the extremity which terminates in the hori- 
zontal surface, will produce a pressure, which Laplace calls K, 
on the canal doivmvards. If a tangent plane be drawn at the 
other extremity, the fluid below this plane will produce an equal 
pressure on the canal at this end, and similarly directed. These 
two pressures acting in opposite directions along the canal, will 
destroy each other by reason of the incompressibility of the 
fluid. There will remain the attraction of the fluid between the 
curve surface and the tangent plane. This produces a pressure 
directed to the centres of curvature of the point where the canal 
ends, and, as the calculation shows, proportional to the sum of 
the greatest and least curvatures at that point ; for, in fact, the 
quantity of matter between the curve surface and tangent plane, 
taken within the small distance X from the point of contact, 
varies in the same proportion, and to this quantity of matter 
the total attracting force is proportional. Opposed to the pres- 
sure thus arising is the effect of gravity on the whole canal in 
producing pressure in the direction of its length, which effect, 
it is known from the common principles of hydrostatics, is 
equal to the weight of a column of the fluid of the same trans- 
verse section as the canal, and whose height is the elevation of 
one end of the canal above the horizontal plane in which the 
other is situated. Calling this elevation 2, the greatest and least 
radii of curvature at the point of the curved surface under con- 
sideration R and R', and the density of the fluid g, we shall have 

H / 1 1\ 

y Vr + R7;=^^^- 

This is the fundamental equation spoken of above. It does 
not contain, as we perceive, the quantity K, which Laplace sup- 
poses to be expressive of the force that causes the suspension 
before mentioned (p. 256) of mercury in the tube of a barometer 
to a height two or three times greater than that due to the at- 
mospheric pressure. He thinks also that on this quantity de- 
pends the forces which produce cohesion and chemical affinities. 
The left side of the equation, expressing the pressure that arises 
from the action of the small quantity of matter situated between 
the curve surface and the tangent plane, and circumscribed by the 
surface of the sphere of activity whose centre is the point of con- 
tact and radius X, must be exceedingly small compared to K. 

The above equation cannot be generally integrated ; but in 
the case in which it belongs to a surface of revolution the axis 
of which is vertical, as, for instance, when the capillary tube is 
cylindrical with a circular base, an integral is obtained which 



REPORT ON CAPILLARV ATTRACTION. 263 

conducts to the inference, that the surface of the fluid approaches 
so much the nearer to that of a sphere as the diameter of the 
tube is smaller. Hence it immediately follows that the surfaces 
in tubes of different small diameters will be similar portions of 
spherical surfaces, if at their jimcture with the interior surfaces 
of the tubes they make with them the same angle. This angle 
will appear to be independent of the diameter of the tube, from 
the consideration that the extent of the sphere of activity of the 
attraction of the tube is altogether imperceptible ; so that even 
in a tube of very small bore, we may regard the action of the 
cylindrical surface on the superficial fluid elemejits contiguous 
to it, the same as if it were a plane*. Hence if Z» = the radius 
of the fluid sui-face, and h its mean altitude above the horizon- 

TJ 

tal level of the exterior fluid, then R = R' =■ h, and — ■=. g qh. 

But in different tubes the surfaces of the fluid being similar seg- 
ments of spherical surfaces, b evidently varies as the diameter 
of the tube. Therefore h varies inversely as this diameter. 
Such is the explanation according to Laplace's theory of what 
may be looked upon as the principal phsenomenon of capillary 
attraction. 

If the surface of the interior fluid were convex, as it is known 
to be when a capillary glass tube is dipped in mercury, then if 
we suppose for a moment all below the tangent plane at any 
point to be fluid, the effect of the attraction on a canal terminat- 
ing at this point perpendicularly to the surface, will only be 
just equal to the action of the fluid on the other extremity, 
where it terminates at the exterior horizontal level. If now we 
subtract the fluid between the tangent plane and the surface, 
which tends to draw the canal upwards, the resulting inequality 
of action must be counterbalanced by the hydrostatic pressure 
arising from a depression of the fluid in the tube. The mean 
depth to which the fluid will be depressed may be shown, as in 
the case of concavity, to vary inversely as the diameter of the 
tube. 

From all this reasoning Laplace concludes that the attraction 
of capillary tubes influences the elevation or depression of the 
fluids they inclose, only by determining the inclination of the 
fluid surface to the contiguous surface of the tube, on which in- 
cUnation the concavity or convexity of the fluid surface depends, 
as well as the magnitude of its radius. He consequently speaks 

* M. Gauss, wlio first remarked that the reason here assigned by Laplace 
for the constancy of the angle of contact is vague and insufficient, has given a 
more satisfactory demonstration, which we shall have occasion to speak of in a 
subsequent part of the Report. 



S64 FOURTH REPORT 1834. 

of the concavity or convexity as the principal cause of the phse- 
nomenon of elevation or depression, a mode of speaking to 
which some have objected apparently because it does not expli- 
citly point to the nature of the forces to which the observed ef- 
fects are due. This manner, however, of referring capillary ef- 
fects to the concavity or convexity of the fluid surface, is con- 
venient in the explanation of phaenomena ; for we may say in 
general, that wherever the fluid is bounded by a curve surface, 
it is acted upon at each point by a force tending from the surface 
towards the centres of the curvature at that point. 

In this way Laplace explains the well known fact, that a drop 
of water put in a slender conical tube, having both ends open 
and its axis horizontal, will move towards the smaller end. The 
surface of the drop will be concave towards both ends of the 
tube, but with a greater curvature on the side directed to the 
smaller end than on the other. The drop will therefore be urged 
by two forces in opposite directions ; but the forces being pro- 
portional to the curvatures, the greater force will be that which 
urges it towards the vertex of the cone. If a drop of mercury 
were inserted, its surface would be convex towards both ends 
of the tube, and the greater curvature would again be at that 
part of the drop which is nearer the smaller end. Therefore, of 
the two forces directed from the curved surfaces to the centres 
of curvature, that will prevail which urges the drop towards the 
base of the cone. It follows from the constancy of the angle of 
contact, that the surfaces of the two ends of the drop, whether 
it be of mercury or water, are similar segments of spherical sur- 
faces. Their curvatures are therefore inversely as their distances 
from the vertex of the cone ; and the difference of the curvatures, 
to which the diiference of the forces which urges the drop is pro- 
portional, will vary inversely as the product of these distances, 
if the length of the column into which the drop is formed be 
given, that is, this length being small, nearly as the square of 
the distance inversely of the middle of the drop from the vertex 
of the cone. 

As the fundamental equation obtained above admits of being 
successfully treated whenever the surface of the fluid contained 
in a capillary space is one of revolution, it may be employed to 
determine the capillary action which takes place between two 
cylindrical surfaces having a common axis and distant from each 
other by a small interval ; for the surface of the inclosed fluid 
will evidently be in this case a surface of revolution. The re- 
sult of the analj'tical calculation is, that the fluid will be raised in 
this space to the same height as in a tube of which the radius is 
equal to the interval between the cylindrical surfaces. If the 



REPORT ON CAPILLARY ATTRACTION. 265 

radii of the two cylinders be supposed infinitely great, we have 
the case of fluid inclosed between two vertical and parallel planes 
very near each other. The same result still holds good ; and thus 
the experimental fact cited by Newton in his 31st query re- 
ceives a theoretical explanation. 

The case in which the fluid is raised or depressed between 
vertical parallel planes admits of being treated independently ; 
and this Laplace has also done. The upper surface of the raised 
or depressed fluid is that of a common cylinder when the interval 
between the planes is small, and the elevation or depression is 
directly proportional to the curvature. 

These propositions being proved with respect to the action of 
parallel planes, we may apply to the case of a drop inserted be- 
tween two planes inclined to each other at a very small angle, 
reasoning analogous to that applied to a drop inserted into a 
cone of small vertical angle. The force by which the drop is 
urged, is shown, as before, to be inversely proportional to the 
square of the distance from the juncture of the planes. We 
have already mentioned that this law was obtained experimen- 
tally by Hauksbee for the case in which a drop of water is in- 
serted between planes. He arrived at it by observing the incli- 
nation the planes must have to the horizon, that the effect of 
gravity may just counteract the capillary action by which the 
drop of water is drawn to the line of their junction. The sine 
of the inclination, to which the resolved part of gravity is pro- 
portional, was found to vary for the same drop when in equili- 
brium, inversely as the square of the distance of its middle point 
from the line of junction. Laplace's calculation, besides verify- 
ing this experimental result, further informs us, that if the two 
planes form with each other an angle equal to half the vertical 
angle of a cone which incloses a drop of the same fluid, the in- 
clination to the horizon of the plane which bisects the angle 
formed by the two planes ought to be the same as that of the 
axis of the cone, in order that the drop may remain in equili- 
brium ; and that " the sine of the inclination of the axis of the 
cone to the horizon, is nearly equal to a fraction whose deno- 
minator is the distance of the middle of the drop from the vertex 
of the cone, and numerator is the height to which the fluid is 
raised in a cylindrical tube, the diameter of which is equal to that 
of the cone at the middle of the drop." 

If fluid be raised by capillary action between two vertical and 
parallel planes, they will be drawn towards each other. The 
same thing will happen if the fluid be depressed between them. 
These two facts, known by experience, were in a great measure 
explained, as we have seen, by Monge. The theory of Laplace 



266 FOURTH REPORT — 1834. 

not only accounts for the attraction of the planes towards each 
other, but gives the measure also of the pressures which urge 
them. By an exact consideration of all the forces concerned in 
these phaenomena, he finds that when the fluid is raised between 
the planes, each plane experiences, from without to within, a 
pressure equal to that of a column of the contained fluid, of 
which the height is half the simi of the elevations above the or- 
dinary level, of the points of contact of the interior and exterior 
surfaces of the fluid witli the plane, and whose base is the part 
of the plane comprised between two horizontal lines drawn 
through these points. The value of the pressure is similarly 
stated when the fluid is depressed between the planes. Hence, 
neglecting the small exterior elevation or depression, the pres- 
sure varies as the square of the elevation or depression between 
the planes, and consequently inversely as the square of the in- 
terval between them. 

Laplace also enters into a consideration of the proposition 
first announced by Clairaut, viz. that if the law of the attraction 
of the matter of the tube upon the fluid, differs only by its in- 
tensity from the law of the attraction of the fluid on itself, the 
fluid will be raised so long as the intensity of the former of these 
attractions surpasses the half of the intensity of the other. He 
arrives at the following conclusions*. If the one intensity be 
exactly half the other, there is neither elevation nor depression. 
If the intensity of the attraction of the tube for the fluid be in- 
sensible, the fluid will be depressed, and the depressed surface 
will be convex and hemispherical. If the two intensities be 
equal, the surface of the elevated fluid will be concave and hemi- 
spherical. When the intensity of the attraction of the tube is 
the greater of the two, the fluid, by attaching itself to the tube, 
forms an interior tube to which alone the capillary elevation is 
due, and which being of the same matter as the raised fluid, acts 
with the same intensity, and causes the surface to be still con- 
cave and that of a hemisphere. This appears to be the case with 
water and oils in capillary glass tubes. M. Haiiy found by ex- 

* These conclusions appear to be correct, but the reasoning of Laplace in 
this part "of his theory is liable to a serious objection, first pointed out by 
Dr. Young. For in art. 12, he obtains the following equation, 

Q cos {■7r — d)=. (2 g' — ?) K sin 6, 
in which 5' and ^ are respectively proportional to the intensities of the attrac- 
tion of the solid for the fluid, and the fluid for itself; 2 j K is equal to the re- 
sultant of the molecular attractions on a superficial particle of all the fluid 
particles within the sphere of its activity ; but ^ the resultant of the attractions 
of only a portion included between a tangent plane and surface passing through 
the particle. This equation, therefore, could scarcely be true unless 2 j' = j . 
The source of the error that occurs here will be elucidated as we go on. 



REPORT ON CAPILLARY ATTRACTION. 267 

periment that the concave surface of these fluids differed little 
from that of a hemisphere*. It would seem from this theory that 
the intensity of the solid's attraction for the fluid must exceed 
that of the fluid for itself, in order that the fluid may ivet the 
solid. 

The preceding are the principal facts which Laplace explains 
in his first published Treatise on Capillary Action. The expla- 
nations of some few others are added by way of corollaries at the 
end of the Treatise. One of these, which serves to exhibit the 
effect of the convexity of the fluid surfaces, may be mentioned 
here. 

If a capillary tube be plunged to a small depth in water, and 
then, with its lower extremity closed by the finger, be taken out, 
on withdrawing the finger the fluid will be seen to sink in the 
tube, and to form a drop at the lower end. But when it has 
ceased to descend, the height at which it rests above the extre- 
mity of the tube is always greater than the elevation due to ca- 
pillary action when the tube is just dipped in the fluid. The 
reason of this excess is, that the effect of the convexity of the 
drop, which takes place in the upward direction, is added to the 
effect of the concave surface within the tube. 

Hence it follows that if a slender siphon with unequal arms 
be filled with water, when the fluid is just on the point of run- 
ning from the longer arm it has to overcome the capillary 
actions due to the concavity formed at the extremity of the 
shorter arm and the convexity at that of the longer arm ; and 
unless the difference of the,lengths of the arms be greater than 
the sum of the lengths of the fluid columns which these two 
actions will sustain at the respective extremities, the fluid will 
not run. 

The theory of Dr. Young respecting the phsenomena of capil- 
lary tubes is contained in an "Essay on the Cohesion of Fluidsf," 
read before the Royal Society, December 20, 1804, and inserted 
in the second volume of his Lectures on Natural Philosophy. 
His views resemble those advanced by Segner and Monge. 
Like these two mathematicians, he considers the phaenomena to 
be referable to the cohesive attraction of the superficial particles 
of the fluids, in so far as it gives rise to a uniform tension of 

* It would be difficult to decide by experiment whether the surface be nearly 
or exactly a hemisphere, because when the angle of contact is very small, the 
line of contact is not readily discernible. The method of determining the angle 
of contact by reflection, proposed by Dr. Young in his Lectures on Natural 
Philosophy, (vol. ii. p. 66G,) is preferable to measuring the sagitta of the sur- 
face, which was the method adopted bj' Haiiy. 

t Philosophical Transactions, 1805, p. 65. 



268 FOURTH REPORT — 1834. 

the surface. He shows, moreover, how this uniformity of ten- 
sion may be a consequence of ulterior principles. 

The course of reasoning Dr. Young pursues in his essay is as 
follows. He begins with making two assumptions : first, that 
the tension of the fluid surface is uniform ; secondly, that at the 
juncture of a fluid surface with the surface of a solid, there is an 
appropriate angle of contact between the two surfaces. *' This 
angle," he says, " for glass and water, and in all cases where a 
solid is perfectly wetted by a fluid, is evanescent : for glass and 
mercury, it is about 140° for common temperatures, and when 
the mercury is moderately clean." He shows next that a theory 
founded on these two hypotheses will explain various capillary 
phaenomena. And lastly, at the end of the essay, derives the hy- 
potheses from ulterior physical principles. It is in this last 
part that Dr. Young's theory contains views not to be found in 
any previous theory. Following the order which the author 
adopts, I will endeavour first to exhibit the way in which his 
theory accounts for phenomena. 

It is known from mechanical principles that if a curve line 
be uniformly stretched, the normal force it exerts at any point 
in a direction tending to the centre of curvature is directly as 
the curvature. The same will be the case with a surface, if it 
be cylindrical, and therefore curved only in one direction. If 
the surface be spherical or like that about the vertex of an ellip- 
tic paraboloid, the curvatures in directions at right angles to 
each other will have independent effects. Consequently the 
normal force in this case will vary as the sum of the curvatures : 
and as, from a known property of curve surfaces, this sum is the 
same for all perpendicular directions, the normal forcewill bepro- 
portional to the sum of the greatest and least curvatures. Hence 
because this force, applied at the surface, is employed in de- 
pressing the fluid when the surface is convex, and elevating it 
when concave, (for it is always directed to the centres of curva- 
ture,) it may be shown in the usual manner, that by reason of 
the action of gravity, the force at each point is proportional to 
the distance of that point from the ordinary level of the fluid. 
By reasoning of this kind. Dr. Young is conducted to the rela- 
tion between the vertical ordinate and curvature of the surface, 
which is expressed by the fundamental equation of Laplace's 
theory. As both theories also admit the constancy of the angle 
made by the fluid surface with that of a given solid at the junc- 
ture of the two, it is plain that the explanation of phaenomena 
must be virtually the same in both. In fact, before the publi- 
cation of Laplace's theory Dr. Young had accounted for most of 



REPORT ON CAPILLARY ATTRACTION. 269 

the facts whose explanations according to that theory have al- 
ready been exhibited, and his mode of accounting for them dif- 
fers not in any essential respect from that of Laplace, but chiefly 
in a scrupulous avoidance of the use of mathematical symbols. 
It will therefore be unnecessary to adduce the explanations of 
any of these facts given by Dr. Young ; we will only advert to 
some applications contained in his treatise which do not occur 
in the other. 

Having first considered the rise of water in capillary tubes, 
he proceeds to find the weight of water raised by the horizontal 
surface of a solid elevated from the horizontal surface of a fluid, 
and to determine the relation between the height of ascent in a 
given tube to the height of adhesion ; that is, the height of ele- 
vation above the ordinary level just when the fluid detaches it- 
self from the horizontal surface of the solid. The fluid is 
supposed to wet the solid. Hence as the fluid surface, being 
horizontal where it is in contact with the solid, has no tendency 
by its tension to depress, the weight of water raised is very 
nearly equal to the hydrostatic pressure of a column of water 
standing on the raising surface and equal in height to the height 
of adhesion. This pressure he finds to be 50^ grains on a square 
inch, agreeing very nearly with the result of experiments by 
Taylor. If the raising surface be small, for instance a disc of 
an inch in diameter, the curvature of the horizontal sections of 
the raised fluid, which are convex outwards, will have a con- 
trary effect to the curvature of the vertical sections which are 
concave, and will consequently diminish the weight of fluid 
raised. This also is confirmed by experiment. " The height 
of ascent in a tube of given bore varies in the duplicate ratio of 
the height of adhesion." 

The depression of mercury in capillary tubes is next considered, 
and the author does not confine himself to the case in which the 
surface of the mercury is spherical, which is true only when the 
diameter of the tube is very small. In tubes less than half an 
inch in diameter, the surface is very nearly that of an oblate 
spheroid. The depressions for different tubes calculated theo- 
retically, are compared with a table of experiments made by 
Lord Charles Cavendish to ascertain the depression of mercury 
in different barometer tubes. 

The height of adhesion of mercury to glass, and to substances 
which it is capable of wetting, such as gold, silver, tin, &c., as 
well as the thickness at which a portion of mercury will spread 
out on glass and on substances wholly incapable of attracting it, 
are quantities all determinable by this theory, and being cal- 



270 FOURTH REPORT — 1834. 

Ciliated are found to be sufficiently accordant with the same 
quantities determined experimentally. 

The theory conducts also to the following result : " The linear 
dimensions of similar drops of different fluids depending from 
a horizontal surface vary in the same ratio as the heights of 
ascent of the respective fluids against a vertical surface, or as 
the square roots of ascent in a given tube." 

In explaining the instances of apparent attractions and re- 
pulsions treated of by Monge, Dr. Young shows that in the two 
cases of attraction, the force which urges the planes towards 
each other varies inversely as the square of the interval between 
them, because it varies once inversely as the distance on account 
of the increase of curvature of the fluid surface as the interval 
diminishes, and again inversely as the distance by reason of the 
increase, proportional to the ascent of the fluid, of the surface on 
which the capillary action is exerted. With respect to the 
third case, that of repulsion, which is omitted in Laplace's 
treatise, he remarks, that " the repulsion of a wet and dry body 
does not appear to follow the same proportion, for it by no 
means approaches to infinity on the supposition of perfect con- 
tact : its maximum is measured by half the sum of the elevation 
and depression on the remote sides of the substances, and as the 
distance increases, this maximum is only diminished by a quan- 
tity which is initially as the square of the distance." 

The strong cohesion of two solids produced by the interposi- 
tion of a small quantity of a fluid, which wets them, between 
their plane surfaces, is sufficiently accounted for by the great 
curvature, arising from the proximity of the surfaces, of the 
outer boundary of the interposed fluid, which is everywhere con- 
cave like the rim of a pulley. This curvature corresponds to a 
force which would be capable of sustaining a great elevation of 
the fluid ; but in this instance the force is not exerted in sup- 
porting the fluid, but acts by reason of the mutual attraction 
between the solid and fluid, on the plane surfaces of the solids, 
drawing them together. If the solids were wholly immersed in 
the fluid, no such cohesion would take place. On the same prin- 
ciple, if fluid be interposed between two solids which it is quite 
incapable of wetting, so that its boundary is everywhere convex, 
the force due to the convexity, being directed inwards, would 
present a strong opposition to any force tending to make the 
planes approach each other. 

After showing, in the manner exhibited above, that a theory 
founded on the two assumptions of a uniform tension of curved 
fluid surfaces, and a constant angle of contact of the surface of 



REPORT ON CAPILLARY ATTRACTION. 271 

a given fluid with that of a given solid, will explain various ca- 
pillary phsenomena, Dr. Young proceeds to derive these laws 
from ulterior physical principles. To account for the first he 
reasons as follows. The repulsive force which appears to act 
uncontrolled in aeriform bodies, exists also in fluids and solids. 
In these it is counteracted by a cohesive force. These forces in 
fluids are so balanced, that they allow the particles to move freely 
in all directions. In solids the cohesion is accompanied by a 
force opposed in greater or less degree to all lateral motion, and 
independent, as he supposes, of the cohesive force. He considers 
it simplest to regard the cohesive force as nearly or perfectly con- 
stant in its magnitude throughout the minute distance to which 
it extends, and its apparent variation to be owing to the variation 
of the repulsive force, which diminishes with the increase of the 
distance. In the internal parts of a fluid, the two forces hold 
the particles in equilibrium ; but wherever the surface is curved 
or angular, it would be found by collecting the eff^ect produced 
on a given particle at the surface, by all the particles contiguous 
to it and lying within the sphere of its proper activity, that on 
the above hypothesis respecting the relative variation of these 
forces, the cohesion must necessarily prevail over the repulsion. 
The particle will consequently be urged in the normal direction 
towards the centres of curvature of the point at which it is situ- 
ated, whether the surface be concave or convex ; and reasons are 
adduced by the author for concluding that the force which urges 
it is proportional to the curvature, if single, or to the sum of 
the curvatures in i*ectangular directions, and consequently indi- 
cates, as is known from Mechanics, a uniform superficial ten- 
sion. The reasoning by which he shows this need not be in- 
troduced here. Suffice it to say, that this result might be obtained 
by an analysis precisely the same as that which Laplace has 
employed at the beginning of his capillary theory, in calculating 
the attraction experienced by a superficial particle on the suppo- 
sition of forces sensible only at insensible distances. Laplace 
makes no hypothesis respecting the law of force, excepting that 
it is wholly attractive. The mathematical calculation would 
remain the same, if the force were supposed partly attractive 
and partly repulsive, provided the attractive force decreased less 
rapidly with the increase of distance than the repulsive, and be- 
came the greater of the two before it ceased to be of sensible 
magnitude. With this alteration* in Laplace's theory, it would 

• This modification of the theory is pointed out by its author in a note at 
p. 122 of the Bulletin de la Socu'tePhilotnatique, An 1819. 



S72 FOURTH REPORT — 1834. 

differ in no essential respect from that of Dr. Young, as far as 
regards the principles on which the equation relative to the ca- 
pillary fluid surface is obtained; and neither possesses an advan- 
tage over the other in the explanation of pheenomena. But the 
way in which the latter mathematician accounts on physical 
principles for the constancy of the angle of contact, (which is 
the other hypothesis of his theory,) though incomplete, is more 
satisfactory than anything we meet with on the same subject 
in Laplace's treatise. The following is his reasoning on this 
point. 

When the surface of a fluid is free, or exposed to a gas, the 
superficial tension arising from the cohesive power of the par- 
ticles acts with full force to produce pressure directed inwards, 
from which, in fact, arises the tendency observable in small 
fluid masses to assume a globular form. This contractile power 
is altered by contact with a solid surface. For instance, if a 
cube of water had one of its halves congealed, its other proper- 
ties remaining the same, the other half would retain its form, 
because the tendency to contract at the edges contiguous to the 
solid, would be just counteracted by an equal and contrary action 
of the solid ; and at all other points of contact, the contractile 
force would vanish for the same reason as at any point in the 
interior of the fluid. If the solid were of smaller attractive 
power than the fluid, the tendency to contract, and consequently 
the tension of the surface in contact, would be proportional only 
to the difference of the attractive forces, or to the difference of 
the densities of the solid and fluid, if the law of the forces be the 
same for both*. The portion of the solid surface which is con- 
tiguous to, but not touched by, the fluid, will act on the fluid par- 
ticles situated at the angle of contact, just as the fluid superficies 
itself does, but in a different degree according to the difference 
of density. Hence, the conditions of equilibrium are to be sought 
of three forces acting on a particle at the angle of contact, one 
in the direction of the surface of the fluid only, another in that 
of the common surface of the fluid and solid, and the third in 
the opposite direction along the exposed surface of the solid. If 
q and g' be the densities respectively of the fluid and solid, and 
the first force be k g, the second will he k(§ — §'), and the third 
k §'. If then & be the angle of contact which the free surface of 
the fluid makes with its surface of contact, the first force re- 

• Dr. Young adduces some facts relating to the spreading of the drops of oil 
on water in support of the proportion here assigned. (Lectures on Nat. Phil., 
vol. ii. p. 659.) 



REPORT ON CAPILLiARY ATTRACTIOX. 273 

solved in the direction of the solid surface, will give k g cos i, 
which is counteracted hy k §' — k {§ — §'), the difference of the 
other two forces. Hence it follows that 

g' = f cos«— . 

When Q = 90°, 2 §' = §, as Clairaut found. The preceding 
theory is deficient in not informing us how the other resolved 
portion of the tension of the fluid, viz. k g sin 3, is counteracted. 

The essay of Dr. Young, as it appears in the second volume 
of his Natural Philosophy^ contains by way of appendix some 
remarks and strictures on Laplace's theory, the results of which 
are shown to be readily derivable from his own theory ; but an 
objection is raised against its principles on the ground that no 
account is taken of a repulsive molecular force. We have al- 
ready seen in what way this objection may be obviated without 
affecting the results of Laplace's theory, or materially altering 
the analysis. Another objection urged by him, to which allu.sion 
has been made before (p. 266), lies against the reasoning, and not 
the principles, of Laplace's theory. In determining the conditions 
of equilibrium of a fluid particle situated at the angle of contact, 
Laplace takes account only of the attractions of the solid and 
fluid upon it, omitting the consideration of the variation oi pres- 
sure occasioned by these forces as well near the free surface of 
the fluid as near that in contact with the solid. The error to 
which this omission leads will be understood by reverting to 
the reasoning by which it was shown (p. 258), according to Clai- 
raut's method, that when the attractive force of the fluid is double 
that of the solid, the capillary surface will be horizontal. The 
same kind of reasoning as that employed to show that the hori- 
zontal attractions in this case counterbalance each other, would 
also prove that the particle at the angle of contact is urged ver- 
tically downwards, by only half the force with which another 
particle at the fluid surface situated beyond the sphere of the 
attraction of the solid, is urged in the same direction. The 
horizontality of the fluid surface may nevertheless be maintained 
if we consider that the variation of pressure near the surface, 
due to the molecular attractions, will not be the same at the sur- 
face in contact with the soUd as at the free surface, by reason of 
the solid's attraction. Had Laplace taken account of this cir- 
cumstance, as the principles of his theory required him to do, 
notwithstanding the supposition of incompressibility, he would 
have obtained an equation equivalent to that which expresses 
above the relation between g' and g, instead of the faulty equation 
of art. 12 of his treatise. In fact, M. Gauss and M. Poisson, as 

1834. T 



274 FOURTH REPORT — 1834. 

we shall afterwards see, have obtained in different manners such 
an equation on the supposition of absolute incompressibility. 

The addition to Dr. Young's essay contains also a more care- 
ful investigation than he had given before of the depression of 
mercury by capillarity in barometer tubes of diameters not ex- 
ceeding half an inch. He obtains two formulaej one for the 
central depression, the other for the difference between the cen- 
tral and marginal depressions. The diameter in inches being rf, 

, , . . . -015 d 

and e being put for -j ^ , 

the first formula is — j e — 14 . 5 e^, 

« 4 

, ^, . 5 (/ + 100 d^ 

and the other, 



15 (5rf + 100 #) -f- 18" 
The next work that we have to notice is Laplace's Supple- 
ment to the Theory of Capillary Action, in which the object 
of the author is to perfect the theory and extend its applications, 
to confirm it by additional comparisons with experiments, and 
to present it under a new point of view. This work is prefaced 
by a discussion relative to the fundamental equation of the 
theoiy, which is shown to be derivable as well from the condi- 
tion of the perpendicularity of the resultant of the forces to the 
fluid surface as from that of the equilibrium of canals, the equa- 
tion obtained by the former method being the differential of 
that given by the other. Here also is deduced, from the funda- 
mental equation, an expression for the weight of fluid raised in 
a cylindrical tube, the transverse section of which is any con- 
tinuous and reentering curve. If c be the contour of the ho- 
rizontal section of the tube, H and q the same as in the fim- 
damental equation, and 6 the angle of contact as before, the 

weight of the fluid column is found to be — x— cos 6, It is to 

be observed that this result is obtained by assuming the angle 
of contact to be constant for the same solid and fluid, of which 
law Laplace has failed to give a satisfactory proof. 

After these preliminaries, the author proceeds to consider 
capillary action in a manner different from that of his former 
treatise *. It may be proper to remark that the subject admits 
of this other method of treatment for the same reason that in 

• In the observations with which the Supplement concludes, the author re- 
marks that this second method resembles that of Jurin, while the other may be 
classed witli the method of Segner and Young ; and that the reasoning by 
which Jurin proved the elevation in a capillary tube to be inversely as the dia- 
meter, is correct when the tube is completely wetted by the fluid, and when in 



REPORT ON CAPILLARY ATTRACTION. 275 

common statical problems there are two kinds of equations of 
equilibrium, those in which pressures and tensions are involved, 
and those which result when forces of this kind are eliminated. 
The force corresponding to the convexity or concavity of the 
fluid surface in capillary tubes is of the nature of a tension, and 
may be kept out of view in finding the conditions of the equi- 
librium of the forces which suspend or depress the fluid column. 
For this pm-pose it will be necessary to pay regard only to the 
action of the tube on the parts of the fluid contiguous to it, and 
to the action exerted on the raised or depressed column con- 
tained within the tube by the rest of the fluid. The former, as 
Laplace shows, resolves itself into the attraction of a ring of the 
tube immediately above the extreme upper edge of the fluid, 
and an equal attraction of a like ring at the lower extremity of 
the tube; and the latter, into the attraction of the upper ex- 
tremity of a tube of the fluid, supposed to be a continuation of 
the solid tube, and attracting with the proper action of the fluid 
on itself. The first two forces tend to raise the fluid, the other 
to depi-ess it. If the total upward force be called 2q'§c, and the 
downward force qgc, both being proportional to c the contour, 
it will hence appear that {2q' — q) §c := the weight of fluid raised. 
If 2q' = q, there is no elevation ; a result which, as we know, 
may be obtained in a very different manner. 

The preceding expression for the weight of the elevated 
column being equated to that previously obtained, gives 

XT 

2q' — q =. — cos $. 
Now it is shown satisfactorilyin the former treatise*, that when 

q' ■= q, & = : SO that q = — , This equality is also proved 

z 

by Laplace in an independent manner. It hence follows that 

o' 2 g 

— = cos-—, which equation, if 9' and q be assumed to be m 

the proportion of the densities of the sold and fluid, is the same 
as that first obtained by Dr. Young. 

consequence the elevated column may be conceived to be contained in an 
aqueous tube. Leslie, in a paper containing some original and ingenious views 
on Capillary Atti-action, {Phil. Mag., vol. xiv. 1802, p. 193,) objects to the 
principle of Jurin's explanation, and attributes the rise of the fluid solely to its 
perpendicular pressure against the surface of the tube occasioned by the tube's 
attraction. By this consideration he finds the height to be inversely as the dia- 
meter. No doubt, as Leslie appears to have first observed, the rise is depen- 
dent on a particular state of pressure at the surface of contact of the solid and 
fluid, and according as this is greater or less than a certain pressure, there will 
be a rise or depression. 
•Art. 12. p. 48. 

T 2 



276 FOURTH UEt'OUT 1S34. 

As it appears that the weight of the elevated column varies as 
the periphery of the transverse section of the tube ; and as, for 
tubes of like peripheries, the weights are as the products of the 
heights and the squares of homologous lines, it follows that the 
heights are inversely as homologous lines. This proportion, 
says Laplace, is true also if the contour be not continuous, but 
of the form, for instance, of a rectilinear polygon ; for the error 
that would be occasioned by the angles of the polygon would 
be of insensible magnitude, by reason of the small extent of 
the sphere of activity of the particles. Gellert has made some 
experiments on the elevation of water in glass prismatic tubes, 
with rectangular and triangular bases *. They confirm the law 
according to which the heights are inversely as the homologous 
lines of like bases. He thinks also that the elevation is the same 
for a rectangular as for an equal triangular base ; but the experi- 
ments do not appear to be decisive of this point. Laplace calcu- 
lates theoretically that the diiference would be one eighth be- 
tween the elevations in a prism Avith a square base, and in one 
whose base is an equilateral triangle of equal area. 

One of the most interesting of the questions considered by 
Laplace in the Supplement, relates to the capillary action 
which takes place when two or more fluids are contained in the 
same tube. Suppose a prismatic tube to be plunged vertically 
in a vessel containing any number of fluids lying horizontally 
one above another ; then " the excess of the weight of the 
fluids contained in the tube above the weight it would have con- 
tained without capillary action, is equal to the weight of fluid 
which would have been raised above the exterior level, in case 
the vessel contained only that fluid in which the loAver extremity 
of the tube is immersed." For, in fact, the action of the prism 
and of this fluid on the column of it in the tube, is plainly the 
same as in this case, the action of the tube on each of the other 
fluids being equal in opposite directions, and the mutual action 
of the fluids being destroyed just as if they were supposed to 
form a solid mass. The surface of the uppermost fluid is the 
same as if that alone were in the tube. 

When only two fluids are contained in a cylindrical tube, the 
theory determines the common surface of their junction to be 
spherical, and gives for the angle of contact f of this surface a 

* Memoirs of the Academy of Petershiirgh, vol. xii. p. 302. 

t It ought to be observed that the angle which is here and elsewhere called 
the angle of contact is, strictly speaking, not the angle which the fluid surface 
makes with the surface of the solid at the points of their junction, but the angle 
which a tangent plane to the surface of the fluid at the limit of the sphere of 
activity of the solid's attraction makes with the surface of the solid. 



RliPORT ON CAPILLARY ATTRACTION. 277 

formula involving the angles of contact proper to the fluids when 
separately contained in the tube. 

When water and mercury are put in the same cylindrical glass 
tube, and the water completely wets the tube, the mercury may 
be considered to be contained in an aqueous tube, the action of 
which on the mercury being small, the angle of contact is nearly 
180° instead of 136°'8, which, according to Laplace, is that be- 
tween glass and mercury. This result, which is also deduced 
from the above-mentioned formula, is confirmed by the observa- 
tions of Gay-Lvissac. Another deduction from the theory also 
receives confirmation from the same eminent experimenter, viz. 
that mercury is less depressed in a capillary tube when its upper 
surface is covered with a small portion of water, than when 
covered by alcohol. For the capillary action of water on itself 
exceeds that of alcohol on itself, and would therefore be likely 
to have a greater action than alcohol on mcrcur^^ 

Various other interesting results, which it would be long to 
enumerate here, are readily deduced by the method of consider- 
ing capillary effects exhibited by the author in his Supple- 
ment. This method, in some applications, leads to results 
more rapidly than that of the Treatise ; wliile at the same 
time the latter has advantages peculiar to itself in all questions 
relating to the surfaces of fluid inclosed in capillary spaces, or 
subject in any way to capillary action. Three such qviestions, 
which had been either omitted or partially treated in the first 
work, are handled at considerable length in the Supplement ; 
and it will be proper now to advert to their solutions. These 
problems, which for the most part had previously engaged the 
attention of Dr. Young, are : (1.) The apparent attraction and 
repulsion of small bodies swimming on the surfaces of fluids. 
(2.) The adhesion of discs to the surfaces of fluids. (3.) The 
figure of a large drop of mercury, and the depression of mercury 
in a glass tube of a large diameter. 

(1.) By considering generally the capillary action between 
two vertical and parallel planes of different matters plunged with 
the lower extremities in tlie same fluid, the following theorem 
is obtained : Whatever be the substances of which the planes 
are formed, the tendency of each towards the other is equal to 
the weight of a fluid prism whose height is the difi"erence of ele- 
vation of the extreme points of contact of the fluid on the oppo- 
site sides of the plane, whose depth is half the sum of these 
elevations, and breadth, that of the planes. The elevation is to 
be taken negatively when it changes into a depression ; and if 
the product of these three dimensions be negative, the apparent 
attraction of the planes becomes a repulsion. These tendencies 



278 FOURTH REPORT — 1834. 

ai*e shown to be the same for the two planes, and their actions 
on each other by the intervention of the fluid to be equal and 
opposite. The theory leads to the singular result that the re- 
pulsion will change into attraction by making the planes ap- 
proach very near each other, and experiments by M. Haiiy show 
that such is the fact. 

(2.) When a disc is applied to the surface of standing water, 
on being raised it draws, by capillary action, a portion of the 
fluid with it, which detaches itself when the disc is raised above 
a certain elevation. At this limit the suspending force must 
plainly be equal to the weight of the disc and of the portion of 
fluid raised above the horizontal level of the water. As this force 
may be accurately determined by experiment, we are furnished 
with means of putting the theory to a test, because the surface, 
and consequently the volume of the raised column, can be found 
from the fundamental equation of the theory. When the calcu- 
lation is made, the expression for the volume involves a quantity 

2 2 H 
which Laplace calls — , and which is, in fact, the same as 

a . 5" 

Now, as was said above, the weight of fluid raised in a capillary 

tube is — i- cos 9, or — ^ if the fluid perfectly wets the tube ; 

and this weight in a cylindrical tube is also equal to ^r c hg g,if r 
be the radius of the cylinder, and h the mean elevation of the fluid ; 

2H 

so that = 2r A = diameter of the tube x mean elevation of 

the fluid *. If, then, the diameter of a cylindrical capillary tube, 
and the elevation in it of a fluid which perfectly wets it, be ob- 

2 
served, the value of- for that fluid is found experimentally. The 

2 
following numerical values of — are deduced by Laplace from 

the experiments of Gay-Lussac, after correcting for the tempe- 
rature f, M'hich was 8°"5 of the centigrade thermometer, and for 
the difference of one sixth of the diameter between the mean 
elevation, and the observed elevation of the lowest point of the 

* This equality is also readily deduced from the fundamental equation. 

f " The elevation of a fluid which wets completely the sides of a capillary 
tube is, at different temperatures, in the direct ratio of the density of the fluid, 
and in the inverse ratio of the interior diameter of the tube." This is shown at 
p. 38 of the iiupplement. An increase of temperatui'e diminishes the elevation 
both by diminishing the density of the fluid and increasing the capacity of the 
tube. Admitting that H varies as q, it will be seen from the equation above 

thai h varies as — . 



REPORT ON CAPILLARY ATTRACTION. 



SJ79 



surface. The diameter of the tube was in each case l""' -29441.*, 
or in English measure, '05096 of an inch. 



2 



Mi.mi. 
30-2621 



Sq. Inch. 
= -0469 



= 12-1649 = -0188 



= 13-1606 = -0204 



For water, . . 

For alcohol, sp. gr.\_2 
•81961, ..../« 
For oil of turpentine,"! ^ 
sp. gr. -86946, . ./"^ 
By means of these values the weights of the columns of fluid 
raised by a disc of white glass, 118"''-366, or 4-66 inches 
in diameter, just when the fluid detaches itself from the disc, 
are determined by the theory to be respectively 

Grammes. Grammes. Grammes. 

59-5873 31-1435 34-350, 

and the experimental determinations t are. 

Grammes. Grammes. Grammes. 

59-40 31-08 34-104. 

The nearness of these to the theoretical results not only con- 
firms the theory, but shows also the correctness of the values 

2 
of — deduced from the experiments on capillary tubes. Dif- 
ferent experimenters | have determined differently the heights of 

• The '"'• attached stands for millimetre, and mi-mi- foj- square millimetre. 

f These weights expressed in English grains are respectively 917"14, 
479'87, and 526'56, which being divided by the number of square inches in 
the surface of the disc, give 53 J grains con-esponding to each square inch for 
water, 28 gi-ains for alcohol, and 31 grains for oil of turpentine. Achard obtains 
for water 39^ grains, for alcohol 23-4 grains: Dutour finds 44"1 grains, and 
25-6 grains. In the experiment of Taylor {Phil. Tram. 1721) on the attrac- 
tion of wood to water, the raising force was 50 grains to each square inch. 

X The following Table is given in the Art. Capillary Attraction of the Edinh. 
Encycl. : the heights are reduced to a tube whose diameter is -01 of an inch. 



Height of the 
water. 


Height X 
diameter. 


Observers. 


Inches. 


Sq. Inch. 




21 


0021 


Haiiy and Tremery. 


2-6 


0026 


Hallstrbm. 


3-27 


0-0327 


Dr. Brewster. 


3-92 


00392 


Musschenbi-oek. 


4-0 


004 


Average assumed by Dr. Young. 


4-2 


0042 


Monge. 


4-28 


0-0428 


Weitbrecht. 


4-6 


0-046 


From Morveau's experiments. 


4-8 


0-048 


Martin. 


5-3 


0-053 


Atwood. 



The experiments of Sir David Brewster were made with much care, and em- 



FOURTH REPORT — 1834. 

elevation in glass tubes, probably by reason of different degrees 
of humidity of the interior of the tubes. When the tubes were 
well wetted, Gay-Lussac found the elevations to be always very 
nearly the same in different experiments. As the weights re- 
quired to detach discs from fluid surfaces can be measured with 
considerable precision, the accordance of the preceding experi- 
mental and theoretical values serves to verify the experimental 

values of — . 
a. 

Equal discs of different substances perfectly wetted by a fluid, 
ought to raise columns of the same weight, because the resist- 
ance to the separation of the disc is, in each case, produced by 
the adhesion of the fluid to itself, that is, to the stratum of fluid 
that lines the inferior surface of the disc. 

As the angle of contact of mercury with glass under water is 
nearly 180°, a glass disc applied under water to the surface of 
mercury would not be capable of drawing up any portion of 
mercury on being raised from the surface. 

These two conclusions from the theory have been confirmed 
experimentally by Gay-Lussac. 

(3.) The analytical calculation for determining the form of a 
large drop of mercury serves also to find the depression of this 
fluid in a glass tube of large diameter. Gay-Lussac ascertained 
by experiment that the height at which a large drop of mercury 
stands on a horizontal plane of glass is 3™'"378 (= '133 of 
an inch), agreeing very nearly with the result of a like experi- 
ment by Segner, The drop was circular and one decimetre, or 
3*937 inches in diameter, and the temperature at 12°'8 of the 
centigrade thermometer. To calculate the height theoretically, 

. . ^ 2 

it is necessary to know the value of — for mercury in a glass 

tube, and its angle of contact with glass. Laplace takes for 
the former 13 mi-mi^ (_ -0201 square inch), and for the latter, 
152° ( = 136°*8). These values, he says, are mean results ob- 
tained by comparing several observed capillary phaenomena with 
the theory, and may be further rectified by more numerous ex- 
periments. The height of a large drop of mercury given by the 
theory by means of these data is 3"''-39664. 

brace a great variety of fluids ; but the tube does not appear to have been 
moistened in its whole extent. Tlie results are tabulated in the article above 
refeiTed to, as well as those from the experiments of Mr. B. Martin, which, for 
the same fluids, uniformly give a higher value of the constant. The values of 
the constant for alcohol and oil of tui-pentine, as found by Gay-Lussac, do not 
differ materially from the determinations of others. Sir David Brewster finds for 
alcohol -0178, for oil of turpentine -0187; Martin, for the same fluids, '018 
»nd '022; Musschenbroek for alcohol -021, 



REPORT ON CAPILLARY ATTRACTION. 2Sl 

Gay-Lussac also observed in a large glass vessel, containing 
mercury and having its sides vertical, the diflference between 
the extreme elevation of the fluid and the elevation at the points 
of contact vfith the sides of the vessel, and found it to be 
l™'-455 (= -057 in.). The theory gives l'"'-432. 

Laplace concludes his work with some general observations 
respecting the interior constitution of bodies, and the nature of 
molecular forces. The viscosity of fluids, he remarks, is a dis- 
turbing cause in capillary phaenomena, which can be strictly ex- 
plained by the theory only when the condition of perfect fluidity 
is fulfilled. To that cause and the friction against the sides of 
the tube, he considers the differences between the elevations of 
water in capillary tubes as determined by different obsei'vers, to 
be attributable. With respect to the variation of pressure from 
nothing to the quantity K, which according to the calculations of 
the theory ought to take place within- a space extending from 
the free surface of the fluid to a small depth below, Laplace 
observes that it may be attended with a sensible variation of 
density, and have a perceptible effect on capillary phaenomena. 
The modification that his theory must undergo if this circum- 
stance be taken into account, has been fully discussed, as we shall 
presently see, by M. Poisson. 

There is a good exposition of the leading propositions of 
Laplace's theory by M. Petit in the Journal of the Polytech- 
nic School*, 

The work of M. Gauss, entitled Principia generalia TheoricB 
Figiirae Fliddoriim in statu jEqnilibrii\, has for its main object 
the correction of the defect already pointed out in Laplace's 
theory, with regard to the proof of the constancy of the angle 
of contact. To form the equations of equilibrium, M. Gauss 
employs the principle of virtual velocities, which he applies to 
the whole mass of the fluid, and not, as Lagrange has done, to 
a differential element. This elegant method, which has the pe- 
culiar advantage of evolving at once the equation of the free 
surface of the flviid, and that relative to the contour, conducts 
to a sextuple integral, which extends to the whole mass, and 
is to be a minimum. By supposing the fluid to be homogeneous 
and incompressible, the integral becomes quadruple. Byfurther 
supposing the only forces that act to be gravity and the 
molecular attractions of the fluid and containing solid, and the 
sphere of activity of these attractions to be insensible, the 
quantity (W) to be a minimum, is found to be expressed by 

f^ds -\. «-2U + («2 - 2^3) T, 



/' 



torn. ix. eah. xvi. p. 1. f GottingGn, 1830. 



282 FOURTH REPORT — 1834. 

in which the first term is equivalent to the volume of the con- 
tained fluid multiplied by the vertical ordinate of its centre of 
gravity, U is the area of its free surface, and «'^ * a constant de- 
pending on the intensity of the attraction of the fluid particles 
for each other, T is the area of the solid surface mth which the 
fluid is in contact, and j3^ a constant depending on the intensity 
of the attraction to which the fluid is subject from the particles 
of the solid. By making S W =0, and in the variation suppos- 
ing U constant, it is readily found that the mean elevation in a 
capillary lube varies inversely as its diameter. By again put- 
ting S W = 0, and making the free surface subject to variation, 
M. Gauss ai-rives at two equations, one of which, relating to the 
free surface, is the fundamental equation of Laplace's theory, 
and the other, relative to the angle of contact, is equivalent to that 
which Dr. Young obtained. It is not the object of the author to 
trace the consequences to be derived from these equations in ex- 
plaining phsenomena, as this was satisfactorily done by Laplace. 

The first published ideas of M. Poisson on the theory of ca- 
pillary action are contained in a memoir on the Equilibrium of 
Fluids, read before the Paris Academy November 24, .1828 f. 
His object in this memoir is to form the equations of the equi- 
librium of fluids on physical principles, that is, by considering 
them as composed of distinct molecules, separated from one 
another by spaces void of ponderable matter. He commences 
with the following preliminary notions. 

The dimensions of the molecules and of the spaces between 
them are so small, that a line which may be supposed a great 
multiple of them is of insensible magnitude. The molecules at- 
tract each other ; at the same time they mutually repel by their 
proper heat. For each of these forces the action is equal to the 
reaction : both decrease with great rapidity as the distances in- 
crease, and are sensible only at insensible distances. The radii 
of activity of these forces are nevertheless supposed to be ex- 
tremely great compared with the intervals between the molecules, 
and the rapid decrease to commence only at distances which 
are great multiples of these small intervals. Without this sup- 
position, in bodies whose molecules are not regularly distributed, 
the resultant of the molecular forces, that is, the total force 
which acts on each molecule, might be very different in magni- 
tude and direction for two consecutive molecules, and conse- 
quently would not be subject to the law of continuity. It seems 
necessary therefore to make the above supposition. 

2 

• 4 5t* in M. Gauss's work is the same as tlie — of Laplace. 

cc 

t Memoires dc I'Academie des Sciences, torn. ix. Paris 1830. 



REPORT ON CAPILLARY ATTRACTION. 283 

By molecular action M. Poisson understands the excess of 
the repulsion above the attraction between the molecules. This 
force he supposes to be different for different points of the two 
molecules. Its mean value he c?iW.s \he principal iorce, and the 
variation from this normal value according as different points of 
the molecules are directed towards each other, the secondary 
force. This latter plays an important part in solids, giving rise 
to their rigidity and resistance to the lateral motion of their 
molecules. Its absence from fluids is the occasion of the per- 
fect mobility of their particles. The characteristic of fluids that 
distinguishes them from solids is thus stated : If a point be 
taken anywhere in the interior of a fluid mass, and a straight 
line of insensible length but a great multiple of the mean inter- 
val between the molecules, be drawn in any direction from that 
point, the mean interval between the molecules that lie on the 
line is constant, though the particles may be irregularly dis- 
posed along it. The constancy of this mean interval is consi- 
dered to be owing to the absence of the secondary force above 
mentioned, by reason of which the molecules can readily take 
positions that satisfy this condition*. 

Setting out with these principles M. Poisson arrives at equa- 
tions relative to the pressure in the interior of a fluid mass, 
which are the same as those usually obtained on the supposition 
of equality of pressure in all directions from any given point. 
The reasoning by which these equations are deduced is not 
immediately founded on any observed fact, and as it conducts to 
the same equations as those deducible from the known law of 
equal pressure, it may be said to account theoretically for the 
existence of this law. This is an instance of mathematics ap- 
plied in the manner spoken of at the commencement of the 
Report. The bases of the reasoning are hypotheses ; and it 
leads to the explanation of a known fact. It would not be right 
to conclude from this one explanation that the hypotheses must 
necessarily be true. They can be considered to be satisfactorily 
established, only when they have been successfully employed in 
accounting for all the facts that are known to depend on the in- 
timate constitution of fluids, and when they are found to require 
for this purpose no modification. 

After calculating, on the above-mentioned hypotheses, the 

• Dr. Young has also speculated on the interesting subject of the immediate 
cause oi fluidity. He remarks in his Lecture on Cohesion, {Lectures, vol. i. 
p. 620,) that "the apparent weakness of the cohesion of fluids is entirely owing 
to the mobility of their particles." It would be perhaps more correct to say, 
that a weak cohesive power is a condition necessary to the existence of a great 
degree of mobility. 



S84 FOURTH RKl'ORT — 1834. 

pressures in the interior of a fluid, M. Poisson finds equations 
of equilibrium relative to the surface of separation of two fluids 
incumbent one on the other, and thence, by supposing one of the 
fluids suppressed, the equation of the free surface of a single 
fluid. The principal conclusion arrived at in the memoir is 
thus stated in Art. 31 : " Capillary phagnomena are due to the 
molecular action resulting from the calorific repidsion and an 
attractive force, and modified not only by the form of the sur- 
faces as in Laplace's theory, but moreover by a particular state 
of compression* of the fluid at its supei-ficies." The variation 
of density near the surface, it is shown, must be extremely rapid. 
Also, " the molecular attraction in fluids as well as solids extends 
further than the calorific repulsion." (Art. 30.) 

The above conclusion is confirmed in various waj^s, and the 
consequences that flow from it with reference to capillary phae- 
nomena are fully discussed in the woi-k of M. Poisson entitled 
Nouvelle Theorie de V Action Capillairef. The object of this 
treatise is to bring the theory of capillary phaenomena to the 
greatest degree of perfection that the power of analysis and the 
existing knowledge of facts will permit. In the first chapter the 
author proves that if the rapid variation of density near the 
surface were neglected, the fluid within the tube would remain 
horizontal, and there would be neither elevation nor depression. 
He shows also the necessity of having regard to the variable 
compression experienced by the fluid near the surface of the 
tube, and i-eaching to the extent of the action dvie to the solid. 
Whence it follows that the principles of Laplace's theory are 
defective, notwithstanding it is so successful in the explanation 
of phaenomena. In Arts. 18 and 19, M. Poisson obtains, on the 
supposition of incompressibility, the equation of Dr. Young re- 
lative to the angle of contact, which, as we have seen, was also 

* It is not perhaps difficult to see, without the aid of analytical calculation, 
that if bodies be assumed to be composed of i«oZa<e(? atoms held in places of 
equilibrium by attractive and repulsive forces, the sphere of whose sensible in- 
fluence is very small, there must be a rapid change of density at their surfaces. 
If experiment should ever be able to detect such a change, this assumed con- 
stitution of bodies would be rendered extremely probable. 

t Paris 1831. Extracts from this work, with Remarks by H.F. Link, will be 
found in Poggendorif's Annalen der Physik und Chemie, bd. xxv. 1S;32, p. 270, 
and bd. xxvii. 1833, p. 193. 

M. Poisson states in the preamble of his forthcoming treatise on "The Ma- 
thematical Theory of Heat," which appeared recently in a Paris weekly scien- 
tific Journal {L'Insti/ut, No. for May 24, 1834,) that that theory forms the 
second i^art of a " Treatise on ]\Iathematical Physics," in which he proposes to 
treat, without restriction to any predetermined order, different physical ques- 
tions whicli admit of the application of analysis. The " New Theory of Capil- 
lary Action " is the first part. 



REPORT OX CAPILLARY ATTRACTIOX. 285 

found by M. Gauss without deviating from the principles of La- 
place's theory. But this equation is no longer true if it be ne- 
cessary to take account of the variation of density at the fluid 
surface ; nor in the same case can the argument hold good by 
which Clair ai\t showed that the fluid surface is horizontal when 
its attractive power is double that of the solid*. 

In the next chapter, the equation of the free surface of fluid in 
equilibrium in a capillary space is obtained by an analysis which 
takes into account any variation of density that may exist at the 
fluid surface, although the exact law of variation be unknown. 
This equation is of the same form as the fundamental equation 
of Laplace, and involves an analogous quantity H. As M. Poisson 
infers from it, by assuming an angle w, which is the supplement 
of that we have hitherto called the angle contact, to be. constant, 

that the weight of fluid raised in a capillary tube is — — ^ cos w, 

which is the expression for the same weight obtained by La- 
place, it follows that H in the two theories is the same in mag- 
nitude, though differently represented by the analytical for- 
mulae. 

The third chapter is employed in finding on the same princi- 
ples the equation relative to the contour of the capillary surface. 
The angle of contact, which is found as in preceding theoi'ies to 
be constant, is assigned by the equation 
F = H cos o). 

It may be useful to give some idea of the natiu-e and compo- 
sition of the constants F and H. The following formulae will 
serve to do this, when the significations of the letters they con- 
tain have been explained : 

H , F 

ir=? + y/' -77 = ? '^ 



8 »/o 



9i = - 



2 Jo ./o c/o >" 

:!Lr^ r rw'ldudsds' 



Conceive the fluid mass to be divided by a curve siu'face pass- 
ing through any point M into two parts A and B, and through 
the sides of a rectangular element of the surface at the point M, 
let normal planes be erected inclosing a pi'ismoidal element of 

• M. Poisson's theory cannot inform us how far that equation is erroneous, 
nor whether it is, or not, very approximately true. 



286 FOURTH UEPORf — 1834. 

the portion A. Let m and m' be two molecules of the fluid, 
one in the prismoid, the other in some part of A. Then r is the 
line joining them, u is its projection on the tangent plane at M, 
and * s' are the perpendiculars from the molecules on the same 
plane, so that r^ = ^<^ + (*—*')'-. R, R;, and R' are functions 
of r, which are insensible for every sensible value of this varia- 
ble, and express the mutual action referred to the units of volume 
of the fluid molecules at the distance r from each other. R re- 
lates to the interior of the fluid, R, to its superficial stratum, and 
R' to the stratum adjoining the side of the tube. With respect 
to R^ the surface through M is parallel to the free surface of the 
fluid at a distance I from it, and A answers to the fluid contained 
between these two surfaces. So with respect to R', the surface 
through M is parallel to the surface of the tube at a distance 
which may also be called /, and A answers to the fluid contained 
between this surface and the tube. Ry and R' vary very rapidly 
with A' and s', and confound theiiiselves with R so soon as 
these variables exceed the radius of the molecular activity. The 
quantity /, which is the limit of the integrals with respect to s 
and si , is greater than this radius, yet of insensible magnitude. 
It is shown that q, and •or do not change sensibly with the mag- 
nitude of I. 

As the forms of the functions R, R^, and R' are quite un- 
known, the values of q, qp and •cy cannot be calculated a jjriori. 
Neither are there any means known at present of determining 
them experimentally. But experiment can assign the numeri- 
cal values of H and w, and consequently that of F. Hence if 
the ratio of q^ to q should become known, the three quan- 
tities wovdd be determined. The knowledge of this ratio is the 
chief desideratum of the theory. M. Poisson has shown that if 
there be no variation of density near the surface of the tube, 
which will happen when the molecular action of the tube is the 
same as that of the solid, ct = 2 y. In this case cos «j = — 

— - — . He shows also, according to what might be expected 

from experience, that cosco = — 1, when the molecular attrac- 
tion of the tube exceeds that of the fluid, but assigns no limit- 
ing value of the excess at which this value of cosw begins. It 
seems, therefore, reasonable to conclude that when the forces 
are equal, cos w is nearly equal to — 1, and consequently that 
qi is a small quantity compared to q. Also, as the density in the 
thin superficial stratum of the fluid varies from to the density 
of the interior, the state of dilatation near the surface would 
naturally lead us, as M. Poisson observes, to make this inference 
with respect to the value of q^ . 



RKPORT ON CAPILLARY ATTRACTION. 287 

Enough has perhaps been said to give an idea of the physical 
part of M. Poisson's theory ; it remains to notice some of the 
mathematical deductions obtained from the two principal equa- 
tions in the succeeding chapters of the work. These equations 
being the same in form as in Laplace's theory lead to like results. 
In several instances M. Poisson has carried the mathematical 
calculation to a greater degree of approximation, and by this 
means obtained numerical results more nearly agreeing with 
experiment. Thus, the elevation of the lowest point of the ca- 
pillary surface in a tube I'^'-goSSl (= -075 in.) in diameter, by 
the experiments of Gay-Lussac is 15™'- 5861 ; by M. Poisson's 
calculations 15"''-5829, by those of Laplace 15'"'-5787. 

After extending the analysis to the case in which the interior 
surface of the tube instead of being cylindrical is any surface 
of revolution with its axis vertical and its diameter small in the 
whole extent, M. Poisson considers what will take place when 
the fluid rises to the upper extremity of the tube, and finds, con- 
trary to an opinion expressed by Laplace*, that the invariabi- 
lity of the angle of contact is still maintained under these cir- 
cumstances, because the radius of curvature of the edge which 
terminates the interior surface of the tube is always exceedingly 
greater than the radius of the molecular action. This circum- 
stance ought to be taken into account in determining the weight 
necessary to detach a solid disc from the surface of a fluid. 

The weight of a drop of water suspended at the lower extre- 
mity of a capillary tube and spreading to the exterior edge, is 
calculated by the theory for the case in which it is just ready to 
detach itself, and found to be something less than the mean 
weight of drops falling in succession from the same tube, as in- 
ferred from an experiment by Gay-Lussac. 

In considering the case of two fluids superincumbent one on 
the other in the same tube, M. Poisson obtains the same for- 
mulae as Laplace, and employs them to explain a singular phae- 
nomenon observed by Dr. Young, and supposed by him to pre- 
sent an objection to Laplace's theory. Into a capillary tube 
containing water. Dr. Young inserted a small drop of oil, and 
then saw the superior surface of the oil depress itself below the 
original height of the water. This depression, no doubt, refers 
to the centre of the capillary surface, where it cuts the axis of 
the tube. If it may be supposed that the oil in descending 
moistened the tube, and that the water did not wet it originally 
in its whole extent, the fact is accounted for by the theory. 

The pressure of fluids as modified by capillary action is treated 

* Supplement a la Theorie de l' Action Capillaire, p. 25. 



;?S8 FOURTH REPORT — 1S34. 

at considerable length : both the vertical and the horizontal 
pressures on a solid partly immersed in a fluid are determined, 
and from tlie calculation of the latter it appears, that if a plate, 
the two parallel faces of which are of different substances, be the 
solid immersed, the horizontal pressures on the opposite faces 
exactly counterbalance, and consequently the solid can have no 
motion of translation. It appears from a remark made by La- 
place at the beginning of page 43 of the Supplement to his Ca- 
pillary Theory, that his reasoning led him to suppose there would 
be some difference of pressure, but so small that it might be 
neglected. However small it might be, a motion of translation 
would be the consequence, and this it seems difficult to admit. 
Dr. Young advanced this objection to Laplace's theory in a 
letter to M. Poisson, against whose more exact theory, as we 
see, the same objection does not hold good. 

Various problems which had been handled by preceding 
mathematicians, receive solutions in chapter vi. more exact 
than had hitherto been given them, and more carefully com- 
pared with experiments. The following are some of the re- 
sults. 

When two plates are immersed with parallel faces in a fluid 
which rises against the surface of one and is depressed near that 
of the other, it is found that the fluid surface between them may 
assume two different forms when the plates are near each other. 
In one there is a point of inflection which is retained however 
near the plates be brought to each other, and in this case they 
constantly repel with a force independent of the interval between 
them ; the other is the form remarked by Laplace, which con- 
tains no inflection, and when it subsists the repulsion changes to 
an attraction on making the plates approximate. M. Poisson 
is of opinion, that the first of these forms obtains when the 
plates, being originally at a great distance, are gradually brought 
near each other, and the latter Avhen, one plate being previously 
immersed, the other is inserted into the curved portion of the 
fluid contiguous to it. 

The values of the two constants of the theory, viz. 2 «^, the 
product of the diameter of the capillary tube by the mean ele- 
vation of the fluid in it, and tt — w, the angle of contact, are found 
with reference to mercury and glass, by comparing the theory 
with the experiments of Gay-Lussac on the height of a large drop 
of mercury on a horizontal glass plane, to be as follows : 

2 «2 = 2 X 6-5262 sq. millimetres (=: '02023 sq.in.) 
the angle of contact = 154°-30' (= 138°-52'). 

In Art. 116 the weights of fluid raised by circular discs are 
calculated, and compared very satisfactorily with the experi- 



REPORT ON CAPILLARY ATTRACTION. 289 

inents of Gay-Lussac cited by Laplace for the same purpose. 
The heights of the disc above the horizontal level of the fluid, at 
the instants when the Meights of the elevated columns are at a 
maximum, are determined at the same time by the theory, but 
these were not measured in the experiments. 

Besides the usual problems in the capillary theory, M. Pois- 
son has solved two others, not previously attempted, one relat- 
ing to the form of fluid poured upon another fluid of greater 
specific gravity ; the other relative to the adhesion of the base of 
a capillary solid cylinder to a fluid from which it is raised with 
its axis vertical. This question is similar to that of the adhesion 
of a disc, but requires to be treated by a different analytical 
process. 

The concluding chapter of the treatise contains notes and ad- 
ditions, in which some points of the theory are further developed, 
and new experiments compared. One section is devoted to a 
full exposition of the author's views respecting " the interior 
constitution of bodies, particularly of fluids, and the nature of 
molecular forces;" another treats of "the general equations 
of the equilibrium of fluids." It results from the complete 
equation of the free surface of a fluid, obtained on the hypothesis 
of disjoined molecules, held in equilibrium by attractive and re- 
pulsive forces, that the resultant of the extraneous forces acting 
on the fluid, is not exactly perpendicular to its surface, uijless it 
be perfectly plane. The views advanced in these sections are for 
the most part those we have had occasion to adduce in speaking 
of the Menioir on the Equilibrium of Fluids. Some of the 
other subjects of this chapter ought not to be passed over with- 
out notice. 

The depression of mercury in the barometer cannot be con- 
veniently calculated by the theory except the ratio of the radius 
of the tube to the constant a be either small or great. In 
other cases it is necessary to recur to the method of quadratures. 
A table of depressions calculated in this way by M. Bouvard, 
and inserted in the Connaissance des Tenis for 1812, is cited by 
M. Poisson, and placed in comparison with a like table from 
Lord Charles Cavendish's experiments, with which it is found 
to agree as nearly as could be expected from the nature of the 
observations. It is desirable, he remarks, that the calculations 
should be repeated with the more exact values of the constant a 
and the angle of contact determined by himself. 

Casbois, Professor of Physic at Metz, pointed out a method 
of constructing barometers with plane or even concave surfaces, 
having observed that by boiling mercury the convexity of its 
capillary surface is diminished, and by continuing the "boiling 

1834. u 



290 FOURTH REPORT — 1834. 

a sufficient length of time, might he changed to concavity. 
M.Poisson ad(hices a communication from M. Dulong containing 
the following satisfactory explanation of this phsenomenon. In 
the operation of boiling, a thin layer of the mercury in contact 
Avith the air is oxidized, and then mingling with the whole mass, 
changes its properties in such a manner, that the action of the 
mercury on its own particles and on those of the tube, or rather 
on the particles of a thin coating of water which is always in- 
terposed between the mercury and the tube, is not the same as 
before, the change being greater in proportion to the greater 
quantity of metal oxidized, that is, in proportion to the duration 
of the boiling. 

A formula obtained in a previous part of the work (Art. 53,) 
applicable to the rise in a capillary tube of a fluid consisting of 
two fluids mixed in given proportions, is here compared with 
expei-iments made a long time since by Gay-Lussac,butnotbefore 
published. This formula is founded on the supposition that the 
loss of heat Mhich takes place in mixing, has no influence, 
when the temperature has become the same as before, on the 
integral which determines the value of H, and on which the 
pliJEnomena of capillarity depend, an hj^othesis favoured by the 
fact, that in the case of a single fluid, the decrement of elevation 
at difi"erent temperatures is proportional to the augmentation of 
density. The theoretical heights agree much less exactly with 
the experimental for a mixture of water and alcohol, than for a 
mixture of water and nitric acid; which shows that the above 
hypothesis is more true for one mixture than the other. 

M. Poisson lastly applies his theory to the explanation of the 
remarkable phaenomenon of endosmose. He conceives that the 
two fluids meet without mi.ri)ig in the capillary tubes which 
permeate the membrane, and by the relation of the molecular 
forces at their common surface of separation, one prevails over 
the other, and so passes through to the opposite side of the 
membrane. It has been objected to this theory that it does 
not account for the phaenomenon of exosmose*. An abstract 
of Mr. Power's views on this subject having been inserted in 
the Tldrd Report of the British Associatioit, it will be only 
necessary to state that in the paper on Residuo-Capillary 
Attraction by the same author, subsequently published in the 

• Admitting, as suggested by Professor Henslow, that each fluid tends to 
spread into the other through the capillary communications, may not effects such 
as are observed, be expected to result merely from the state of compression of 
the fluid stratum in contact with the substance of the membrane? This will 
vary with the varying density of the fluid from one point to another of the 
surface of contact, being greatest where the density is least. 



REPORT ON CAPILLARY ATTRACTION. 2.01 

Transactions of the Cambridge Philosophical Society*, his 
theory has undergone some modification, the phaenomena both 
of endosmose and exosmose, and the variation of the maximum 
difference of the heights of the fluids according to the difference 
of their densities, being accounted for independently of any 
particular mode of communication of the fluids in the capillary 
spaces. 

I beg leave to close this Report with proposing a query sug- 
gested by the existing state of the theory of capillary attraction. 
How does it happen that the principles with which Laplace's 
theory sets out conduct to two fundamental equations the same 
in form as those of M. Poisson's theory ? Ought not the lat- 
ter, seeing that the law of the molecular forces is quite ar- 
bitrary, to embrace every possible method of arriving at these 
equations ; and should we not expect that the method of Laplace 
is not inconsistent with the other, but a particular case of it ? 
The most probable supposition respecting the molecular forces 
of fluids is, that the attractive force is comparatively small, de- 
creases much more slowly with the distance than the repulsive, 
and is sensible to a much greater distance from the centre to 
which it is directed. The hypothesis of incompressibility cor- 
responds to the limiting case, when the repulsive force being 
infinitely great at first, decreases by very large gradations as 
the distance from the centre increases, and within a very small 
space becomes less than the attractive force. As the above law 
of the forces as well as the limiting case of it are embraced by 
M. Poisson's theorjf, we may perhaps hence see why the sup- 
position of incompressibility conducts to the same form of 
the principal equations. In some objections that have been 
made to the principles of Laplace's theory, it does not appear 
to have been sufficiently considered that by supposing the fluid 
to be incompressible, he does in fact take account of a molecular 
repulsion. It remains to be determined whether the variation 
of density, which on the hypothesis of a disjoined molecular 
constitution of bodies must obtain at their surfaces, be such as 
to admit of the supposition of incompressibility as a near ap- 
proximation to the truth. But this there are at present no 
experimental means of determining. The experiments of Has- 
senfratzf, from which he inferred that glass by being pounded 
became specifically lighter, are not confirmed by those of Gay- 
Lussact- As no variation of density has been hitherto detected, 
we have a sort of negative evidence that the depth of the super- 

* vol. V. part ii. f Ann. Ch. Gilh. I. p. 515. 

X See Nouvelle Theorie de V Action CapUlaire, p. 6. 

u2 



■292 FOURTH REPORT — 1834. 

ficial stratum in which there is any sensible variation must be 
exceedingly minute. If that depth may be neglected in com- 
parison of the radius of sensible activity of the attractive force, 
Laplace's principles suffice for a theory of Capillary Attraction, 
without being inconsistent with those of M. Poisson. We may 
add as a theoretical reason for the supposition of a rapidly 
decreasing repulsive force united with a feeble and slowly de- 
creasing attractive force, that we may thus understand how the 
fluid particles will move readily among each other, retaining 
the same mean interval ; for there will be a small obstacle to any 
change of their relative positions by separation, but a great 
obstacle to any approach within a certain limit*. Perhaps 
experiments with light, which appears to be the most success- 
ful instrvmient for searching into the intimate constitution 
of bodies, offer the best chance of getting at something satis- 
factory on the delicate point we have been speaking of. In the 
mean time, while M. Poisson 's theory will engage the attention 
of the speculative philosopher, there appears no reason why the 
simpler theory of Laplace should not be made the vehicle for 
conveying" to the younger students of science, in an elementary 
form, the explanations of a numerous and interesting class of 
phjenomena. 

Various causes, which it would be useless to detail, prevented 
me having a sight of the Number of Poggendorff's Annalen 
containing the " New Experiments on Capillarity," by H. F. 
Linkf, (mentioned by Professor Moll at the Meeting of the 
Association,) till within a short interval before the revision of 
this Report for the press. I fear that, from want of time and 
sufficient acquaintance with the German language, the following 
notice of them will not be such as their importance demands. 

The object of M. Link is to ascertain the comparative ascents 
of different fluids bj'^ capillary attraction, in a manner that would 
be free from the sources of error to which the methods of former 
experiments had been liable. For this purpose he observes the 
ascent between two glass plates inclined at a small angle with 
the line of junction vertical, in which case, as we know, the 
suspended fluid takes the form of a rectangular hyperbola. The 
instrument he made use of provided for the adjustment of the 

* It will readily be seen, that under these circumstances the fluid would be 
susceptible of division by a thin plate by the application of a very small force, 
and we might thus account for a characteristic property of fluids, which, as was 
mentioned in my former Report (p. 1.33), has been employed as the basis of 
their mathematical treatment. I was in error in supposing that this method 
has only been recently proposed ; it appears to have been thought of by Pascal. 

f Annalen der Pliysik und Cheviie, bd. xxix. 1833, p. 401. 



REPORT ON CAPILLARY ATTRACTION. 293 

angle of inclination to any required magnitude, and was con- 
venient for dipping the plates very frequently in the fluids. 
The peculiar advantage of this method was, that the ascents 
of different fluids could be observed under exactly the same 
circumstances : for all the observations could be taken at 
the same parts of the plates and with the same interval of 
separation; and after experiments made with one fluid, the 
plates could be conveniently cleared of all remaining moistux'e, 
before experiments were made with another. When the same 
capillary tube is used, it is difiicult to get rid of the moisture 
adhering to the interior ; and when different tubes are used, 
the experiments cannot well be under like circumstances by 
reason of superficial inequalities in the glass surfaces, besides 
that the exact proportion of the diameters is not readily ascer- 
tained. The principal result that M. Link arrives at is, that all 
the fluids rose to the same height. The fluids employed were, 
distilled water, nitric acid, a solution of kali causti'jum (one oz. 
to six of water), spirit of wine (very rectified), sulphuric asther, 
and rectified sulphuric acid (sp. gr. 1*84). The ai.ther stood 
lower at first, but after repeated dippings rose to the same height 
as the water. The sulphuric acid was at first higher than the 
water, but afterwards sunk to the same level as the rest. Pre- 
vious experiments have uniformly assigned a less ascent to sether 
and spirit of wine than to water, and a greater ascent to sidpliu- 
ric acid. M. Link is of opinion, that the experiments were not 
carried far enough, and that the different results of his own ex- 
IJeriments are attributable to the repeated wetting of the plates 
by dipping them in the fluids. In another set of experiments 
the plates were of various substances ; viz. glass, copper, zinc, 
copper and zinc plates soldered together, first, with the zinc 
surface opposed to the copper, next, the zinc surfaces opposed 
to each other, and then the copper surfaces opposed ; lastly, 
wooden surfaces smeared over with tallow. The heights of as- 
cent were very nearly the same for all these, excepting that the 
tallow plates did not give quite so high a column. It would 
seem, then, that the heights of ascent under similar circumstances 
are alike independent of the fluids and solids. It is remarkable 
that this result miglit have been looked for from either Laplace's 
or Poisson's theory: for by either theory the height of ascent 
in a given capillary tube, or between parallel plates separated by 

a given small interval, varies as — , when the fluid completely 

wets the solid*; and as H, in this case, depends only on the 

• See p. 2G3. 



^4 FOURTH REPORT 1834. 

molecular action of the parts of the fluid on each other*, the 
simplest supposition respecting it is, that it varies as p ; whence 
it would follow that the height of ascent is the same for different 
fluids. 

In the applications of the theories of Laplace and Poisson to 
Gay-Lussac's experiments on the ascents of fluids in capillary 
tuhes, and the weights of the fluid columns raised by circular 

2 
discs, the values of the constant — for the different fluids, were 

a 

borrowed from the first class of experiments, and being em- 
ployed in the theoretical formulae, gave results according M'ith 
the other class. If those values were incorrectly determined by 
the experiments, this accordance can only be explained by sup- 
posing the cause of error to be of the same kind and to act in 
the same degree in the two classes of experiments. 

M. Link remarks that there is an essential difference between 
the ascent of fluids against solid surfaces not previously wetted, 
and the remaining height of suspension after the wetting. Tal- 
low, for instance, %rill scarcely allow water to ascend at all in the 
first instance ; but after being moistened, will sustain a suspended 
column, of nearly the same height, according to the experiment 
mentioned above, as when other substances are employed. The 
theory of the^tsf ascents, must be of a very complicated nature, 
on account of the difficulty of estimating the amount of various 
retarding causes, such as greasiness, and the inequalities of the 
solid surfaces. But the theory of the remaining suspensions 
that result fi-om wetting the surfaces, is of a more simple nature. 
M. Link adduces an explanation of this fact, founded on a theory 
of fluidity developed in the first part of his paper, in which, set- 
ting out with Newton's definition of a fluid, he is led to regard 
it as composed of solid particles in an extreme state of pulveriza- 
tion, and aggregated like the grains of a heap of sand. What- 
ever in other respects may be the comparative merits of this 
view of the nature of fluiditj', and that adopted by Young and 
Poisson, the latter has the advantage of being more readily made 
a basis of calculation. 

» pp. 275 and 285. 



295 



Report on the Progress and Present State of Physical, Optics. 
By the Rev. Humphrey Lloyd, A.M., M.R.I.A., Fellow 
of Trinity College, and Professor of JVattcral and Experi- 
mental Philosojjhy in the University of Dublin. 

In the Report which I have the honour to submit to the Associa- 
tion, I have attempted to consider in some detail the present 
state of our knovpledge with regard to the physical theory of 
light, and the successive advances which have, in late years, 
been made towards its establishment. The method which I 
have thought it expedient to adopt in this review has been to 
take, in the first instance, a rapid survey of the several leading 
classes of optical phenomena, which the labours of experimental 
philosophers have wrought out in such rich profusion, and after- 
wards to examine how far they are reducible to one or other of 
the two rival theories which have alone advanced any claim to 
our consideration. This is, in fact, the only way in which the 
truth of a physical theory can be established ; and the argument 
in its favour is essentially cumulative. 

But in making this comparison it is not enough to rest in 
vague explanations which may be moulded to suit any theory. 
Whatever be the apparent simplicity of an hypothesis, — whatever 
its analogy to known laws, — it is only when it admits of mathe- 
matical expression, and when its mathematical consequences 
can be numerically compared with established facts, that its 
truth can be fully and finally ascertained *. Considered in this 
point of view, the wave-theory of light seems now to have 
reached a point almost, if not entirely, as advanced as that to 
which the theory of universal gravitation was pushed by the 
single-handed efforts of Newton. Varied and comprehensive 
classes of phnomena have been embraced in its deductions; 
and where its progress has been arrested, it has beeii owing 
in a great degree to the imperfections of that intricate branch of 
analysis by which it was to be unfolded. The principles of the 
theory of emission, on the other hand, have, in comparativelj' 

• C'est en tirant des formules les consequences les plus subtiles et les plus 
eloign^es des principes, puis allant les verifier par I'experience, que Ton peut 
reellement s'assurer si une th6orie est vraie ou fausse, et si Ton doit s'y confier 
conime a uu guide fidele, ou la rejeter comme un syst^me trompeur. — Biol, 
Traile de Physique, torn. i. p. xiv. 



29G FOURTH REPORT 1834. 

few instances, been mathematically expressed and developed ; 
and accordingly this theory presents but rarely those points of 
contact with experimental truth by which alone it can be judged. 

This signal difference in the present state of the two theories 
has been by some ascribed to a difference in the intellectual 
poM'er by which they have been worked ; and it has been said 
that had the Newtonian theory been cultivated with the same 
zeal and talent as the Huygenian, it might have had equal 
triumphs to boast of. This position, I confess, appears to me 
altogether untenable. With respect to the implied fact, it may 
be enough to observe that Newton and Laplace were both en- 
gaged on one side of the question ; and I believe I may add that 
among the supporters of the wave-theory of light there are few 
who have not had to encounter early predilections in favour of 
the theory of emission. The nature and laws of projectile 
movement are far more familiar to every lover of mechanical 
philosophy than those of vibratory propagation ; and the tri- 
umphant career of the former branch of this science, in its appli- 
cation to the movements of the heavenly bodies, is in itself 
sufficient to induce every one to lean to a theory which proposes 
to account for the phenomena of light on similar principles. 
As to the opinion itself, it seems highly improbable, to say the 
least, that two theories so widely separated should run hand in 
hand in their explanation of phenomena. There is indeed one 
case, and that a striking one, of this kind : — The fundamental 
laws of reflexioji and refraction are exact and necessary conse- 
quences of each of these theories ; but I believe their history 
affords no parallel instance. 

An unfruitful theory may, however, be fertilized bjr the addi- 
tion of new hypotheses. By such subsidiary principles it may 
be brought up to the level of experimental science, and appear 
to meet the accumulating weight of evidence furnished by new 
phenomena. But a theory thus overloaded does not merit the 
name. It is a union of unconnected principles, Avhich can at 
best be considered but as supplying the materials for a higher 
generalization. Its very complexity furnishes a presumption 
against its truth ; for the higher we are permitted to ascend in 
the scale of physical induction, the more we perceive of that 
harmonjr, and unity, and order, which must reign in the works 
of One Supreme Author. The theory of emission, in its present 
state, exhibits all these symptoms of unsoundness ; but there is 
something stronger than mere presumption against it. It will 
appear, I think, upon a fair review, that in almost every in- 
stance in which it has been developed, its consequences are at 



REPORT ON PHYSICAL OPTICS. 297 

variance with facts ; and the proof of its insufficiency seems 
even stronger than tlie positive evidence in favour of the rival 
theory. 

In proceeding to the consideration of these arguments, I have 
foiindit necessary to deviate from tlie arrangement which a strictly 
theoretical view of the subject would naturally suggest. The 
relation of theory to phenomena, which I propose to consider, 
obliges me to examine the latter in the groups in which they 
have been usually brought together, and under which their laws 
have been investigated. I propose, therefore, to divide the fol- 
lowing Report into two parts ; of which the first will treat of 
nnpolarized, and the second oi polarized, light. In the former 
I shall consider separately, 

1 . The propagation of light, and the principle of interference ; 

2. The reflexion and refraction of light; 

3. Diffraction; 

4. The colours of thin and thick plates. 

The second part will comprise, 

1. The polarization of light, and the principle of transversal 

vibrations ; 

2. The reflexion and refraction of polarized light ; 

3. Double refraction ; 

4. The colours of crystallized plates. 

Many subjects of high interest are omitted in this arrangement, 
as being but remotely connected with the leading object of the 
present Report. I have left wholly untouched, for this reason, 
that branch of optical science which is sometimes denominated 
" mathematical optics," or the development of the fundamental 
laws of reflexion and refraction. The phenomena of vision 
have been in like manner omitted, as involving also the science 
of physiology ; and the relations of light to other agents, as 
heat, electricity, and magnetism, because these relations are as 
yet little understood, and in the present state of the kindred 
sciences, the science of light can hope to derive little aid from 
their examination. These interesting subjects would, each of 
them, well merit a separate consideration. 



Part I. Unpolarized Light. 

I. Propagation of Light. Principle of Interference. 

The first property of light which claims our notice is its pro- 
gressive movement. Light, we know, travels from one point 



298 FOURTH RKl'ORT — 1834. 

of space to another in time, with a velocity of about 195,000 
miles in a second. The inquiry concerning the mode of this 
propagation involves that respecting the nature of light itself. 

There are tMO distinct and intelligible ways of conceiving such 
a motion. Either it is the self-same body which is found at 
different times in distant points of space ; or there are a mul- 
titude of moving bodies, occupying the entire interval, each of 
which vibrates continually within certain limits, while the vi- 
bratoiy motion is communicated from one to another, and so 
advances uniformly. Nature affords numerous examples of each 
of these modes of propagated movement ; and in adopting one or 
other to account for the phenomena of light, we fall upon one 
or other of the two rival systems, — the theories of Newton and of 
Huygens. 

The Newtonian theory, in the shape in which it is usually 
presented, is undoubtedly simpler in conception than its rival ; 
but this simplicity is only apparent. Newton himself was 
far too clear-sighted to suppose that the forces of attraction 
and repulsion, by which the molecules of light were supposed to 
be refracted and reflected, were adequate to account for all the 
phenomena ; and it is remarkable that, Avhen he proceeds to 
speculate on the physical theory of light, he has fomid it neces- 
sary to admit all the apparatus required in the theory of waves. 
In fact, Newton felt, and distinctly stated, that the vibrations 
of an ethereal medium were necessary in his hypothesis *, al- 
though he denied that these vibrations constituted light. He 
has even gone further, and asserted that they were the chief 
and essential parts of that hypothesis, the molecules emitted 
from luminous bodies only performing the office of exciting these 
vibrations, as stones flung into water produce waves f. On the 
other hand, the molecules themselves are supposed to be emitted 
by a vibratory motion of the parts of the luminous body J ; — the 
same vibratory movement, though acting with a different energy, 
in which he supposes heat to consist. It would appear, then, 
that Newton assumed too much, and that he erred against his 
own valuable rule: " Caiisas rerumnaturaliumnonjilures ad- 
mitti dehere," &c. Had he simply left out the molecular part of 
his hypothesis, and supposed that the vibrations of his ethereal 

• Phil. Trans. 1672. 

f " Were I to assume an hypothesis, it should he this, if propounded more 
generally, — so as not to determine what light is, further than that it is something 
or other capable of exciting vibrations in the ether ; for thus it will become so 
general, and comprehensive of other hypotheses, as to leave little room for new 
ones to be invented." — Birch's History of the Royal Society, vol. iii. p. 249. 

J Optics, Query 8. 



REORT ON PHYSICAL OPTICS. 299 

medium were directly excited by those of the luminous body, 
his theory would have resolved itself into that of Huygens and 
of Hooke. It may be observed, in connexion with this subject, 
that Newton seems actually to have admitted the wave-theory 
with respect to radiant heat; and that he supposed it to be pro- 
pagated, not by the translation of material particles, but by the 
vibrations of an ethereal medium *. 

The peculiar part of the theory of emission — the supposition 
that the rays of light are bodies projected with a great velocity — 
would seem to offer an easy criterion of its truth. If the weight 
of a molecule of light amounted to one grain, its momentum 
would equal that of a cannon ball 150 pounds in weight, and 
moving with the velocity of 1000 feet in a second. The weight of 
a single molecule maybe supposed many millions of times less than 
this ; but, on the other hand, millions of such molecules maybe 
made to act together, by concentrating them in the foci of lenses 
or mirrors, and the effects of their impulse might, it was ex- 
pected, be thus rendered sensible. This easy test of the materi- 
ality of light was long since appealed to. The experiments of 
Homberg seemed to have established the existence of a sensible 
impulsive effect ; but when these experiments were repeated 
with more caution by Mairan and Dufay, they conducted to the 
opposite conclusion. The results obtained by Michell at a later 
period, and with the aid of a more sensible apparatus than any 
before employed, seemed to be decisive in favour of the materi- 
ality of light f -. The effects observed in these experiments, 
however^ have been with much probability referred to aerial 
currents, produced by unequal temperature, or even to a differ- 
ence in the elastic force of the air in contact with the opposite 
surfaces of the body acted on J, The subsequent experiments 
of Mr. Bennet were made under circumstances far more favour- 
able ; and in particular, having been repeated in vacuum, they 
ax*e independent of the sources of error now alluded to. Their 
result was conclusive as to the non-existence of a sensible 
effect §. 

The objection to the materiality of light, arising from its want 
of sensible momentum, was first urged by Franklin. Horsley 
attempted to remove the difficulty || ; but his laborious arithme- 
tical calculations only go to prove that the particles of light, if 
material, must be of extreme minuteness. It must at the same 
time be confessed that objections of this nature are entitled to 

* Optics, Query 18. 

t ¥riest\ey'» Hisiuri/ of Oplics, p. 387. 

X Young " On the Theory of Light aad Colours, " Phil. Trans. ISOL 

§ Phil. Tram. 1792. ' || lb. 1770. L 



300 PouuTii REPOur — 1834. 

little weight. It is easy to attribute to the molecules of light a 
minuteness sufficient to evade any means that we possess of 
detecting their inertia by their effects upon otiier bodies', and 
in whatever point of view we regard tlie phenomena of optics, 
we are forced to contemplate quantities immeasurably smaller 
than any to which the imagination has been accustomed. 

The aberration of the light of the fixed stars, resulting from the 
motion of tlie earth and that of light, is an easy consequence 
of the theory of emission, in which these motions are con- 
ceived to subsist independently. In order to account for the 
phenomenon in the theory of waves, it seems necessary to assume 
that the ether which encompasses our globe does not participate 
in its motion ; s-o that the ethereal current produced by this re- 
lative motion must be supposed to have a free passage through 
the solid mass of the earth ; or that, in the words of Young, " the 
luminiferous ether pervades the substance of all material bodies 
with little or no resistance, as freely perhaps as the wind passes 
through a gi-ove of trees*. Fresnel has maintained the same opi- 
nion, and, startling as tlie position seems at first, he has very 
clearly shown that no fair argument can be advanced against it, 
founded on the opacity of the mass which the ether is supposed 
to permeate f. 

The discoveries of Bradley and Roemer, when compared to- 
gether, have led to a further and most important conclusion re- 
specting light, — namely, that its velocity is one and the same, 
whatever be the luminous origin ; the light of the sun, the fixed 
stars, the planets and their satellites, being all propagated with 
the same swiftness. This conclusion must be allowed to present 
a formidable difficulty in the theory of emission. Laplace has 
shown that if the diameter of a fixed star were 250 times as great 
as that of our sun, its density being the same, its attraction 
would be sufficient to desti'oy the whole momentum of the 
emitted molecules, and the star would be invisible at great di- 
stances %. With a smaller mass there will be a corresponding 
retardation ; so that the final velocities will be different, what- 
ever be the initial. The suggestion of M. Arago seems to 
offer the only means of avoiding this difficvilty. It may be sup- 
posed that the molecules of light are originally projected with 
very diflerent velocities ; but that among these velocities there 
is but one which is adapted to our organs of vision, and which 

* " Experiments and Calculations relative to Physical Optics," Phil. Trans. 
J 803. 

t " Sur rinfluence du Mouvument terrestrc dans quelques Phenomenes 
d'Optique," Annales de C/iimie, torn. ix. 

t Zach, Ephem., iv. 1. 



REPORT ON PHYSrCAL OPTICS. 301 

produces the sensation of liglit. This supposition seents to be 
supported by the discoveries of Herschel, Wollaston, and Ritter, 
respecting tlie invisible rays of the spectrum ; but it does not 
appear to be easily reconciled with any h3rpothesis which we are 
able to frame respecting the nature of vision. This uniformity 
of velocity, on the other hand, is a necessary consequence of 
the principles of the wave-theory. Tlie velocity with which 
vibratory movement is propagated in an elastic medium depends 
solely on the elasticity of that medium and on its density ; and 
if these be uniform in the vast spaces which intervene between 
the material bodies of the universe, (and it is not easy to sup- 
pose it otherwise,) the velocity must be the same, whatever be 
the originating source. 

The rectilinear motion of light has long been ui'ged in favour 
of the theory of emission, and against the theory of waves. If 
light consists in the undulations of an elastic fluid, (it has been 
said,) it should be propagated in all directions fi'om every new 
centre, and so bend round interposed obstacles. Thus luminous 
objects should be visible, even when an opake body is between 
them and the eye, just as sounding bodies are heard, though a 
dense body intervene between them and the ear. To this ob- 
jection, which was first insisted on by Newton*, a full answer 
has been given. The phenomena of diff'raction, and especially 
the interior fringes in the shadow of narrow opake bodies, prove 
that light does bend round obstacles, and deviate perceptibly 
from the rectilinear course. When the obstacle is of consider- 
able dimensions, the intensity of the light decreases, indeed, 
very rapidly within the edge of the geometric shadow ; so that 
at a very small distance from that edge, it is no longer percep- 
tible. But the darkness does not arise from the absence of 
luminiferous waves, but from the mutual destruction of those 
sent there. In fact, if the surface of the wave when it reaches 
the obstacle be divided into any number of small portions, the 
motion of the ether at any point behind it is, by the principle of 
Huygens, the sura of all the motions produced there by 
these several portions, considered as separate centres of dis- 
turbance ; and it is easy to show, that, when the distance of 
the point in question from the obstacle is a large multiple 
of the length of a wave, the magnitude of this resultant must 
diminish rapidly within the shadow, and the light become 
insensible when the line drawn from that point to the edge of 
the screen is inclined at a small angle to the normal to the front 
of the wave. The accurate calculation of the intensity, in this 

* Optics, Query 28. 



302 FOURTH REPORT — 1834. 

and other similai" cases, has been made by Fresnel by the aid 
of the principle of interference, and the result is found to agree 
in the most complete manner with observation *. 

The same principles apply to the aerial waves which consti- 
tute sound, and these too should present analogous phenomena. 
But the scale is widely different. The length of an aerial wave 
is more than 10,000 times greater than that of an ethereal un- 
dulation ; and the distance of the ear from the obstacle must be 
augmented in the same proportion, in order that the same con- 
clusions may be applicable to the two cases. 

According to this account, then, the right-lined propagation 
of the rays of light is a consequence of the principle of inter- 
ference, combined with the principle of Huygens. A very 
different view of the subject, however, has been presented by 
M. Poisson, in a memoir on the propagation of motion in elastic 
fluids, read before the French Academy in the year 1823 f- The 
elasticity of the fluid being supposed the same in all directions, 
the velocity of propagation will be also the same, and conse- 
quently the waves spherical. The absolute velocities of the mo- 
lecules themselves, however, will be very different. M. Poisson 
finds that when the original disturbance takes place only in one 
direction, the velocity of the molecules will be indefinitely small 
in all directions inclined to it at finite angles, so that the motion 
will not be sensibly propagated except in that direction. This 
diminution of intensity, he finds, will be greater the moi'e rapid 
the velocity of propagation ; and it is in this manner only, he 
concludes, that we can account for the rectilinear motion of 
light in the wave-theory. This conclusion however, M. Fresnel 
has shown, is contradicted by the ordinary plienomena of dif- 
fraction ; and he has adduced theoretical reasons, drawn from the 
principle of the coexistence of small motions, to prove that it 
cannot hold in any fluid whatever, but that the molecules are in 
all cases disturbed in a sensible manner, in directions very much 
inclined to that of the original vibrations |. 

The principle of the superjiosition of small motions, which has 
been more than once adverted to, is an immediate consequence of 
the linearity of the original equation of partial differences which 
determines the law of vibration of an ethereal particle. The 
complete integral of this equation will contain, in general, a term 
for every distinct original disturbance ; and the total disturbance 
will be the sum of all the partial disturbances due to each cause 
acting separately. The partial disturbances may, however, con- 

* " Memoire sur la Diffraction," Mhnoircs de rinslHut, torn. v. 
\ Annales de Cliimie, toni. xxii. t Ibid., torn, xxiii. 



REPORT ON PHYSICAL OPTICS. 303 

spire, or be opposed ; so that in the case of two such disturb- 
ances, for example, the second may have the effect either of aug- 
menting or diminishing the first, and the absolute velocity of the 
ethereal molecules may be increased, or lessened, or even wholly 
destroyed by the union. In fact, if the form of the function 
which expresses the wave-disturbance, be assumed to be that 
by which the law of vibration of the cycloidal pendulum is re- 
presented, the sum of two coexisting disturbances will be a sin- 
gle disturbance of the same form, provided the component un- 
dulations have the same length ; and the effect of two such co- 
existing undulations will be a single undulation of the same 
length, but differing in the position and magnitude of the space 
of greatest vibration from either of the components. The mag- 
nitude of the resulting vibration may be the sum, or difference 
of those of the component vibrations, or it may have any value 
intermediate to these limits. When the component vibrations 
are equal, the resultant may even vanish altogether ; and two 
lights of equal intensity when added together will produce 
darkness, provided that the interval of retardation of one wave 
on the other is an odd multiple of the length of half a wave. 

This important con sequence of the theory of waves — the princi- 
ple of interference of the rays of light — was first distinctly stated 
and established by Dr. Thomas Young, although some of the 
facts bj'^ which its truth is experimentally confirmed were known 
to Gi'imaldi*. The genei-al calculation of the intensity of the 
resulting light, for any relative position of the interfering waves, 
is due to Fresnel ; and has been followed out and developed by 
Sir John Herschel in his valuable Essay on Light. When a 
beam of homogeneous light is transmitted through two small 
apertures in a card, or plate of metal, the light will diverge from 
each as from a new centre. If the two apertures are close toge- 
ther, and the diverging pencils received on a reflecting surface, 
a series of parallel straight bands is observed, perpendicular to 
the line connecting the apertures, and separated by intervals 
absolutely dark. That these alternations of light and darkness 
are produced by the mutual action of the two pencils. Young 
proved by the fact, that when one of the beams is intercepted, 
the whole system of fringes instantly disappears, and the dark 
intervals recover their former brightness. 

The experiment of Fresnel is still more satisfactory. In this 
important and instructive experiment, the fact of interference is 
placed beyond all question. The two pencils proceed from one 

• This ingenious philosopher even stated explicitly that an illuminated body 
may be rendered darker by the addition of light, and adduced a simple experi- 
ment in proof of it. Physico-Mathesis de Liimine. Bologna, 1663. 



SOI FOURTH REPORT — 1834. 

common origin, and are separated simply by reflexion at plane 
surfaces, without any attending circumstance which can, by 
possibility, be supposed to influence the result. The pheno- 
menon is thus divested of everything nonessential, and it 
becomes impossible to hesitate about its nature. But the ac- 
cordance of theory and experiuient is maintained, not only in 
the general features of the phenomenon, but even in its minu- 
test details. The distances of the points of each fringe from the 
two foci of reflected rays should, according to theory, differ by 
a constant quantity, — that constant being an odd multiple of the 
length of half a wave for the dark fringes, and an even multiple 
of the same quantity for the bright ones. Hence the fringes 
should be propagated in hyperbolic lines, whose foci are the 
foci of the reflected pencils ; — and the most accurate measure- 
ments have shown that it is so. The constant diffei-ences jus; 
alluded to are far too minute to be directly measured ; but they 
can be calculated with great accuracy, when the distances of the 
successive bands from the central one have been obtained. The 
latter distances have been determined by Fresnel with much 
nicety by micrometrical measurements ; and the lengths of the 
waves of each species of simple light, thence computed, agree 
in the most satisfactory manner with the values of the same quan- 
tities as deduced from the observation of Newton's rings. 

The central fringe is formed at those points in arriving at 
which the two pencils have traversed equal paths ; and as its 
position is therefore independent of the length of a wave, the 
rays of all colours will be united there, and the fringe itself will 
be white, or colourless. Such is the fact, as described by Fresnel 
himself, and by most observers who have repeated the experi- 
ment. Mr. Potter states, however, as the result of his obser- 
vations, that the central fringe may be seen both black and white, 
although more frequently the former ; and he urges the fact in 
opposition to the wave- theory*. But it seems premature to 
draw any inference from such experiments, until the circum- 
stances which have occasioned the variation in the results have 
been fully investigated and understood. 

The interference of the rays of light has, since the decisive 
experiment of Fresnel, been admitted on all hands ; and the 
phenomena which were previously explained on the Newtonian 
hypothesis of the " fits of easy reflexion and transmission," are 
now, by most of the advocates of the Newtonian theory, referi'ed 
to this simpler and more fertile principle. This principle is, 
it has been stated, an immediate and necessary consequence of 
the wave-theory, and its experimental establishment must be 
* Phil. Mag.. (3rd Series,) vol. ii. p. 280. 



REPORT ON PHYSICAL OPTICS. 305 

regarded as a weighty argument in favour of that theory. It now 
remains to inquire whether any account can be given of it in the 
theory of emission. 

The molecules of light cannot be supposed to exert any 
mutual influence; for the regularity of the laws of reflexion 
and refraction compels us to consider them as independent, 
and each, separately, the subject of those forces from which, 
in the theory of emission, these laws are derived. The phe- 
nomenon of interference may, however, be plausibly accounted 
for by the vibrations of the optic nerve, produced by the 
impulse of the rays of light upon the retina; and by the 
accordance or discordance of these vibrations when caused by 
two interfering pencils. On this supposition, which was sug- 
gested by Dr. Young himself, the intensity of the light will de- 
pend on the relation between the time of vibration of the optic 
nerve, and the interval of the impulses of the succeeding parti- 
cles. If this interval be equal to the time of vibration, or to any 
multiple of it, the second impulse will add its effect to that of 
the first, and the motion be accumulated. It will, on the other 
hand, be destroyed, if the second impulse follows the first at an 
interval equal to half that time. 

It is here assumed that the emitted particles succeed one 
another at equal intervals, as will be the case if their emission 
be owing (as Newton supposed it to be) to a vibratory motion of 
the parts of the luminous body. But we must assume further 
that the intervals of emission vary with the nature of the par- 
ticles, in the light of different colours; or that all the red- 
making particles (to use an expression of Newton) are emitted 
at one certain interval, all the blue-making at another; and so for 
each different species of simple light. Hence the vibrations of 
the parts of the luminous body must be of different periods for 
the light of different colours. This is, in truth, a part, and a 
necessary part, of the theory of waves ; but it has no connexion 
whatever with the principles of the rival theory. 

II. Reflexion and Refraction of Light. 
^ To account for the phenomena of reflexion and refraction it 
IS supposed, in the Newtonian theory, that the particles of bodies 
and those of light exert a mutual action ;— that, when they are 
nearly in contact, this action is attractive,— that, at a distance 
a little greater, the attractive force is changed into a repulsive 
one,— and that these attractive and repulsive forces succeed one 
another probably for many alternations. The absolute values, 
or intensities, of these forces are different in different bodies : 
1834. X 



306 FOURTH REPORT 1834. 

but the form of the law, or the function of the distance by which 
they are expressed, is assumed to be the same for all*. From 
these postulates Newton has rigorously deduced the laws of re- 
flexion and refraction. The problem is the first in which the 
efl'ects of that important class of forces acting only at insensible 
distances have been submitted to calculation ; and the solution 
is regarded by M. Poisson as forming an era in the history of 
science. 

The reflexion of light at the exterior surface of dense media 
is ascribed to the repulsive force ; refraction and internal re- 
flexion, to that inner attractive force which extends up to actual 
contact. The outermost sphere of action of every body, in this 
theory, is necessarily attractive, as well as the inmost ; for, were 
it otherwise, no ray could enter, or emerge from, the medium at 
an extreme incidence. Sir David Brewster has made an inge- 
nious use of this principle to explain the remarkable fact noticed 
by Bouguer, that water is more reflective than glass at oblique 
incidences. 

But though the theory of emission is perfectly successful in 
explaining the laws of reflexion and refraction, considered as 
distinct phenomena, yet it is by no means equally so in account- 
ing for their connexion and mvitual dependence. When a beam 
of light is incident on the surface of any transparent medium, 
part is, in all cases, transmitted, and part reflected. The in- 
tensity of the reflexion is in general less, the less the difterence 
of the refractive indices of the two media ; and accordingly the 
reflective and refractive forces (if such be the cause of the phe- 
nomena,) are related to one another in all media, so that one 
increases or diminishes along with the otherf. But how is it 
that some of the molecules obey the influence of the repulsive 
force, and are reflected ; while others yield to the attractive force, 
and are refracted ? To account for this, Newton was obliged 
to have recourse to a new hypothesis. The molecules of light are 
supposed to pass through certain periodical states, called " fits 
of easy reflexion and transmission," which modify the effects of 
the attractive and repulsive forces, and in which they are dis- 

* This assumption is tacitly made by Newton, when he takes the function 

u'' — 1 

— as th^ measure of the i-efractive power. See Herschel's " Essay on 



Light," Encyc. Met. 

^ The reader will find much novel and interesting matter connected with 
this subject in a paper by Sir David Brewster, " On the Reflexion and Decom- 
position of Light at the separating surface of media of the same and of differ- 
ent refractive powers," Phil. Trans. 1829. 



REPOKT ON PHYSICAL OPTFCS. 307 

posed to yield alternately to one or the other. The actual deter- 
mination of the particle \vill depend, partly on the phase of the 
fit, and partly on the obliquity under which it meets the bound- 
ing surface. Now the molecules composing a beam of light are 
supposed to be in every possible phase of their fits, when they 
reach the surface : some of them consequently will be reflected, 
and others refracted ; and the proportion of the former to the 
latter wiU depend on the incidence. 

As to the fits themselves, Newton thought they must be re- 
ferred to a vibratory motion in the ether, excited by the rays 
themselves ; just as a stone flung into water raises waves on its 
surface. This vibratory motion is supposed to be propagated 
faster than light itself, and thus to overtake the molecules, and 
impress upon them the disposition in question by conspiring 
with or opposing their progressive motion. In one of his 
queries Newton has even calculated the lesser limit of the elas- 
ticity of the ether, as compared with that of air, in order that 
it should have so great a velocity of propagation*. The hypo- 
thesis of Mr. Melville and M. Biot is more in accordance with 
the spirit of the theory of emission. The molecules of light are 
supposed, in this hypothesis, to have a rotatory motion round 
their centres of gravity which continues along with the progres- 
sive motion, and in virtue of which they present attracting and 
repelling poles alternately during their progress in space f. 
Boscovich imagined a vibratory motion in the parts of the ray 
itself, which it received at the moment of emission, and retained 
in its progress J. 

The theory of the fits has now lost much of its credit, since 
the phenomena of the colours of thin plates, phenomena which 
first suggested it to the mind of Newton, have been shown to be 
irreconcileable with it. The explanation which it gives of the 
facts now under consideration is, as was observed by Young and 
Fresnel, inconsistent with the regularity of refraction. In fact, 
the molecules which are transmitted, are not all in the maxi- 
mum of the fit of transmission, but are supposed to reach the 
surface in very different phases of this, which may be denomi- 
nated the positive fit. Now as a change of the fit from positive 
to negative is, in general, sufficient to overcome altogether the 
effect of the attractive force, and subject the molecule to the 
repulsive, it is obvious that the phase of the fit must modify the 
effects of these forces in every intermediate degree ; and that the 
molecules which do obey the attractive force must have their 
velocities augmented in different degrees, depending on the 

* Optics, Query 21. f Phil. Trans. 1753. Traite He Physique, iv. p. 245. 

+ PhilosophitB Naturalis Theoria. 

X2 



•"^OS FOURTH REPORT — 1834. 

phase. Consequently, as the direction of the refracted ray de- 
pends on its velocity, the transmitted beam will consist of rays 
refracted in widely different angles, and will be scattered and 
irregular. 

In some of his writings Newton attributes the reflexion and 
refraction of light to a difference in the density of the ether 
within and without bodies ; or rather he refers the attractive 
and repulsive forces to this, as to a more general principle. The 
ether is supposed to be rarer within dense bodies than without, 
and the rays of light, in crossing the bounding surface, are 
pushed from the side of the denser ether ; so that their motion 
is accelerated if they pass from the rarer to the denser body, 
and retarded in the opposite case. Reflexion at the surface of 
the rarer medium is explained on the same suppositions ; but, 
to account for the ordinary reflexion by a denser medium, 
Newton Avas obliged to introduce new and gratuitous hypotheses 
respecting the constitution of the ether at the confines of two 
media in which its density is different*. 

The velocity of propagation, in the wave-theory of light, de- 
pends solely on the elasticity of the vibrating medium as com- 
pared with its density. If, then, • a plane wave be incident ob- 
liquely on the bounding surface of two media, it is obvious that 
its several portions will reach that surface at different moments 
of time ; and each of these portions will become the centime of two 
spherical waves, one of which will be propagated in the first me- 
dium with the original velocity, while the other will be propa- 
gated in the new medium, and with the velocity which belongs 
to it. But, by the principle of the coexistence of small motions, 
the agitation of any particle of either medium is the sum of the 
agitations sent there at the same instant from these several cen- 
tres of distui'bance ; and the surfaces on which they are accumu- 
lated at any instant will be the reflected and refracted waves. 
These surfaces are those which touch all the small spherical 
waves at any instant. It is easy to see that they are both plane ; 
and that the reflected wave is inclined to the surface at the same 
angle as the incident wave, while the sine of the angle of incli- 
nation of the refracted wave is to that of the incident in the con- 
stant ratio of the velocities of propagation in the two media. 

Such is the demonstration of the laws of reflexion and re- 
fraction given by Huygens f . The composition of the grand, or 
primary wave, by the union of the several secondary or partial 
waves, in this demonstration, has been denominated the princi- 
ple of Hnt/getis ; and it is obviously a case of the more general 

* Birch's Hintori/ of the lioyal Sociefi/, vol. iii. p. 247. Optics, Query 19. 

I Tni'itl; lie la Litmiire. 



REPORT ON PHYSICAL OPTICS. 309 

principle of the coexistence of small motions. It easily follows 
from this mode of composition, tliat the sm'face of the primary 
wave must mark the extreme limits to which the vibratory move- 
ment is propagated in any direction, in any given time ; so that 
light, according to this theory, is propagated from any one point 
to another in the least possible time. This is the well-known 
law of Fermat, the law ofstviftest propagation, and it Avill rea- 
dily appear that it holds, whatever be the number of modifica- 
tions which the course of the light may undergo by reflexion or 
refraction ; as, likewise, whatever be the form of the elemen- 
tary wave. 

The demonstration of Huygens has been thrown into an 
analytical form by Lagrange*, but he has added nothing to its 
rigour or perspicuity. An important supplement to the demon- 
stration was however given by Fresnel. From the reasoning of 
Huygens it did not appear what became of those portions of 
the secondary waves which did not conspire in the formation of 
the grand wave. The crossing of these in all directions ought 
to give rise to a weak diffused light, filling the entire space be- 
tween the grand wave and the reflecting or refracting surface ; 
and, in fact, Huygens supposed that such a light did actually 
exist, but was too feeble to affect the eye. Fresnel has shown, 
however, that all those portions which do not conspire in the 
formation of the grand wave, are destroyed by interference f ; 
so that the formation of one grand wave, by the union of an in- 
definite number of lesser waves, becomes a precise and definite 
effect. 

The total reflexion of light at the surface of a rarer medium 
has been urged by Newton against the wave-theory, and the 
apparent difficulty seems to have had much weight in inducing 
him to reject that theory. It is, in fact, not easy to perceive at 
first view wl y the disturbance of the ether within the denser 
medium shoi d not be communicated to the external ether, and 
a wave be thus propagated to the eye, whatever be the obliquity 
of the incident wave. To this it may be enough to reply, that 
the law of refraction itself, in all its generality, is a necessary 
consequence of the wave- theory ; and therefore that the phe- 
nomenon of total reflexion, which is a particular case of that 
law, is likewise accounted for. But the principle of interfer- 
ence furnishes a direct answer to the difficulty. It can be 
shown that the elementary waves, which are propagated into the 
rarer medium from the several points of the bounding surface, 

* " Sur la Theovie dc la Lumiere d'Huygens," Annales de Chim., torn, xxi, 
t 'I Explication de la Ilefractlon dans la Systeniu dcs Ondcs," Annates de 
Chimie, torn. xxi. 



310 FOURTH REPORT 1834. 

destroy one another by interference, when the sine of the angle 
of incidence is greater than the ratio of the velocities of propa- 
gation in the two media, or the angle itself greater than the li- 
miting angle of total reflexion *. It is here supposed that 
the distance from the refracting surface is a large multiple 
of the length of a wave. The conclusion does not apply 
to points very near that surface ; and for such points, there 
is reason to think, the law of refraction is more complicated. 
Experience shows, in fact, that light may issue from the 
denser medium, to an appreciable distance, when the incidence 
exceeds the limiting angle of total reflexion. If two prisms, 
whose bases are slightly convex, be put together, and the 
inclination of these bases gradually changed while we look 
through them, it will be observed that, beyond the limiting 
angle, the light will still be transmitted in the neighbourhood 
of the parts in contact. By measuring the breadth of this space, 
and comparing it to the diameters of the coloured rings, Fresnel 
found that the interval of the glasses, through which this devia- 
tion from the ordinary law of refraction occurred, exceeded the 
length of a wavef . The analysis of M. Poisson points also to 
the same result, and it is proved that the second medium will 
be agitated in the part immediately in contact with the first, this 
agitation decreasing rapidly and becoming insensible at a very 
minute distance from the surface. 

The laws of reflexion and refraction, then, follow from the 
theory of waves, whether we suppose the vibrating medium, in 
dense bodies, to be the body itself, the ether within it, or both 
conjointly. Euler maintained the first of these opinions, and 
believed that light was propagated through the gross particles 
alone, in the same manner as sound. But this hypothesis is 
contradicted by the most obvious facts ; and according to it, as 
Dr. Young has observed, the refraction of the rays of light in 
our atmosphere should be a million times greater than it is. Of 
the other two opinions, Yoimg seems to have held the latter, 
and to have thought that the molecules of the body formed, to- 
gether with those of the ether within it, a compound vibrating 
medium, which was denser than the ether alone, but not more 
elastic. Others, lastly, attribute the propagation of light in 
transparent bodies to the vibrations of the ether alone, that fluid 
being retained bj^ the attraction of the body in a state of greater 
density within it than in free space. 

A very diiferent view of this subject has been recently main- 

* Sec Fresnel " Stir le Systeme dcs Vibrations lumineuses," Bibiwtluquc 
Universelle, torn. xxii. 
t JbiJ. 



REPORT ON PHYSICAL OPTICS. 311 

tained by Mr. Challis. Assuming that the density of the ether 
is the same in solid media as in free space, (an assumption 
which he seems to think required by the phenomenon of aberra- 
tion,) this mathematician conceives that the reflexion of light, 
and its retardation in the denser medium, may be both accounted 
for by the reflexions which the ethereal waves undergo from 
the solid particles of the medium which they encounter in their 
progress *. He shows, in fact, that the absolute velocities 
impressed upon the ethereal particles by such reflexion may be 
resolved into two parts, one of which is propagated uniformly, 
and is accompanied by a change of density ; while the other is 
propagated instantaneously, without change of density f. The 
former of these, he thinks, will account for the reflexion of light, 
the latter for the diminished velocity of transmission J. This 
ingenious theory has the advantage of connecting the velocity of 
propagation in dense bodies directly with their constitution, and 
so of advancing a step in the process of physical induction. On 
the other hand, it requires us to admit that the particles of ether 
and those of gross bodies exert no mutual action of any kind. 
We know too little of the ether, or of its properties, to deny this, 
simply because it is unsupported by any of the properties of 
matter hitherto revealed ; but it must at the same time be ad- 
mitted that the violation of such analogies furnishes an argument 
of some weight against the theory which demands them. 

Whatever supposition we may frame respecting the constitu- 
tion of bodies, or of the ether within them, in the wave-theory, 
it must be such that the velocity of propagation is less in the 
denser medium. In the theory of emission, on the other hand, 
it is the reverse ; so that although it conducts to the same result, 
it does so by an opposite route. Here, then, the rival theories are 
at issue upon a matter of fact • and we have only to ascertain 

• This manner of conceiving the reflexion of light, in the wave-theory, was 
that originally entertained by Fresnel, and was put forward in a memoir read 
to the French Academy in 1819. 

t P/iii- Mag., New Series, vol. xi. 

X The mean effect of these reflexions, Mr. Challis shows, is equivalent to 
that of a retarding force ; and, by a certain supposition respecting its value, 
he has arrived at the following simple formula for the determination of the ratio 
of the velocities of propagation in free space and in the medium 

^2 — 1 = ^SH; 
in which S denotes the density of the medium, and H a constant proportional 
to the mean retarding effect of a given number of its molecules. For the gases, 

then, the quantity — t is nearly constant, whatever be the compression. 

This result is a very simple consequence of the theory of emission ; its ex- 
perimental truth has been established by MM. Biot and Arago. Phil Mug., New 
Series, vol. vii. 



S\2 FOURTH UKPORT — 1834. 

this fact, in order to be able to decide between them. This 
seemed to be accomplished by the reasonings of Young. From 
the laws of interference it appears that homogeneous light, 
in its progress in space, passes through certain periodically re- 
turning states, the intervals of which are constant in the same 
medium ; while in different media they are proportional to the 
velocities of propagation, since the number of such intervals in 
a given quantity of light cannot be supposed to vary. Now it 
followed from the experiments of Newton that the intervals, 
by which he explained the phenomena of thin plates, were di- 
miiiished in the denser medium ; and as these intervals have 
been shown by Young to be identical Mith those deduced from 
the law of interference, it followed that the velocity of light was 
slower in the denser medium *. Newtpn had even found the 
ratio of the magnitudes of the intervals to be the same with that 
of the sines of incidence and refraction ; and this is precisely as 
it should be on the principles of the wave-theory. 

But the retardation of light in the denser medium has been 
directly established by M. Arago. If two pencils be made to 
interfere and produce fringes, as in the experiment of Fresnel, 
and if a thin plate of a denser medium be intei-posed in the 
path of one of them, the whole system of fringes will be shifted 
to one side or the other, according as the light has been accele- 
rated or retarded within the plate. The result of this import- 
ant and decisive experiment was in favour of the theory of 
waves f. 

The refractive index being equal to the ratio of the velocities 
of light in the two media, direct or inverse, it follows, which- 
ever theory we adopt, that any change in the velocity of the in- 
cident ray must cause a variation in the amount of refraction, 
unless the velocity of the refracted ray be altered propoi-tionally. 
Now the relative velocity of the light of a star is altered by the 
earth's motion ; and the amount of the change is obviously the 
resolved part of the earth's velocity in the direction of the star. 
It w^as therefore a matter of much interest to determine how, 
and in what degree, this change affected the refraction. By the 
observation of this effect, it was hoped, we should have an easy 
and accurate method of determining the constant of aberration ; 
Ave should be enabled to compare the light of different stars, 
and detect any difference which might exist in their velocities ; 
and lastly, we might compare these velocities with that of light 

* " Experiments and Calculations relative to Physical Optics," Phil. Trans. 
1803. 

t Amuiles de Cliimie, lorn. i. See also the account of Mr. Potter's rcfcti- 
tion of this experiment, Phil. Mag., vol. iii. p. 333. 



REPORT ON PHYSICAL OPTICS. 313 

emanating from other sources. The experiment was undertaken 
by M. Arago, at the request of Laplace*. An achromatic 
prism was attached in front of the object-glass of the telescope 
of a repeating circle, so as to cover only a portion of the lens. 
The star being then observed directly through the uncovered 
part of the lens, and afterwards in the direction in which its 
light was deviated by the prism, the difference of the angles 
read off gave the deviation. The stars selected for observation 
were those in the ecliptic, which passed the meridian nearly at 
6 A.M. and 6 p.m., the velocity of the earth being added to 
that of the star in the former case, and subtracted from it in 
the latter. No difference whatever was observed in the devia- 
tions ; and the result was the same whatever was the origin of 
light f . Fraunhofer has likewise compared the light of several 
of the fixed stars with respect to its refrangibility. No differ- 
ence whatever was observed, although the method employed 
was adequate to the detection of a difference so small as the 
10,000th part of the whole refraction nearly J. 

This remarkable and unexpected result can be reconciled to 
the theory of emission §, as M. Arago has observed, only by 
the hypothesis already adverted to, namely, that the molecules 
are emitted from the luminous body with various velocities ; but 
that among these velocities there is but one which is adapted to 
our organs of vision, and which produces the sensation of light. 
The wave-theory has been more successful in its explanation. If 
the ether which encompasses our globe were like its atmosphere, 
and partook of its motion, the refraction would be precisely the 
same as if the whole were at rest. This however, we have seen, 
cannot be the case ; and the phenomena of aberration compel 
us to admit that the ethereal medium which encompasses the 
earth is not displaced by its motion. This being assumed, it 
follows that the ether which is carried along by the refracting 
medium, is that which constitutes the excess of its density above 

* The idea of detecting a difference in the velocity of the light of the fixed 
stars, by its effect upon the amount of refraction, seems to have first occurred 
to Mr. Michell. Such a difference of velocity, he conceived, must necessarily 
arise from the different attractions of the stars upon the emitted molecules; and 
he has computed the diminution of the original velocity of emission arising 
from this cause. Phil. Trans. 1784. 

t Biot, Astronomie Physique, vol. iii. 

X Edinh. Journ. of Science, viii. p. 7. 

§ M. Prevost has endeavoured to reconcile the experimental result of M. 
Arago with the ordinary suppositions of the theory of emission, and to show that 
a change in the relative velocity of the light of the stars, caused by the motion 
of the refracting plane, does not affect the refraction in the same manner as an 
equal change of the absolute velocity, — " Dc I'Effet du Mouvcment d'un plan 
refiingent sur la Refraction, "Ge/iei»a Memoirs, vol. i. His reasonings do not 
appear to be conclusive. 



814 FOURTH RKPORT — 1834. 

tliat of the surrounding ether. On this supposition Fresnel has 
calcuhited the length of a wave in the moving medium, and 
thence also the actual change in the direction of the refracted 
ray produced by the earth's motion *. This change is found to 
be opposite, and exactly equal to that produced by the same 
cause in the apparent direction of the ray ; so that the ray is 
actually seen in the same direction as if the earth were at rest, 
and the apparent refraction is unaltered by the earth's motion. 
These results, it may be observed, are precisely the same for 
terrestrial objects, the velocity of wave-propagation being inde- 
pendent of the motion of the luminous body. 

Newton tliought that the different refrangibility of the rays of 
light could be explained by supposing simply that they were 
bodies of different sizes, the red being greatest and the violet 
least. It is obvious, however, that this supposition can have no 
reference to the simple projectile hypothesis held by his followers, 
or to the demonstration of the law of refraction given in the 
Prmcijiia. It is connected with that more complex theory, in 
which the molecules of light are supposed to excite the vibrations 
of the ether in the bodies which they meet. 

M. de Courtivron and Mr. Melville proposed to account 
for the dispersion of light by a difference in the initial velocity 
of the molecules, the red being swiftest and the violet slowest. 
But were such the cause of the phenomenon, the dispersion 
should be proportionate to the mean refraction. Indeed the 
hypothesis was abandoned almost as soon as proposed. Its 
authors had foreseen the consequence that, in the eclipses of 
Jupiter's satellites, the colour of the light should var}' just before 
immersion, and after emersion ; and the existence of such an 
effect, in the degree indicated by theory f, was completely dis- 
proved by the observations of Mr. Short J. Another conse- 
quence of such a difference in the initial velocities of the light of 
different colours is, that the aberration of the fixed stars should 
also vary with the nature of the light, and each star appear as a 

* The sine of the change is to the sine of the total deviation of the ray in the 
ratio of the velocity of the earth to that of light. Fresnel's result is much more 
complicated, but it will be easily seen to reduce itself to this. — " Sur I'lnfluence 
du Mouvement terrestre dans quelques Phenomenes d'Optique," Annales de 
Chimie, torn. ix. 

f The duration of this change, according to Mr. Melville, should amoiuit 
to thirty-two seconds, the velocity of the light of different colours being in- 
versely as their refractive indices. — {Phil. Trans. 1753.) This principle, how- 
ever, as M. Clairaut has shown {Phil. Trans. 1754), is obviously incorrect. 
It will easily appear that the initial velocities must vary inversely as 
the quantity /^(^^ — 1, in order to account for dispersion ; and that the dura- 
tion of the expected phenomenon must be even greater than that assigned 
by Mr. Melville. 

: Phil. Trans. 1753. 



REPORT ON PHYSICAL OPTICS. 315 

coloured spectrum, whose length is parallel to the direction of 
the earth's motion. 

According to the modern advocates of the theory of emission, 
the molecules of light are heterogeneous ; and the attractions 
exerted on them by bodies vary with their nature, and are, in 
this respect, analogous to chemical affinities. This supposition, 
however, as Dr. Young has justly observed, is but veiling our 
inability to assign a mechanical cause for the phenomenon. 

It is remarkable that Newton himself was the first to suggest 
that part of the wave-theory, in which the colour of the light is 
supposed to be determined by the frequency of the ethereal vibra- 
tions, or by the length of the wave * ; and the addition has been 
received by all its supporters. But observation proves that the 
refractive index, or the ratio of the velocities of propagation, 
in the two media, is different for the light of different colours. 
The advocates of the wave-theory, therefore, are forced to con- 
clude that the velocity of propagation in refracting media varies 
toith the length of the wave. Here, then, we encounter a diffi- 
culty in this theory, which has been regarded as the most for- 
midable obstacle to its reception. Theory indicates that the 
velocity of wave-propagation is constant in the same medium, 
depending solely on the elasticity of the medium as compared 
with its density. That velocity, therefore, should be the same 
for light of all colours, as it is found to be for sound of all notes. 

Various attempts have been made to solve this difficulty f. 
Euler thought that the successive waves underwent an increase 
of velocity arising from their mutual action ; and this increase 
he supposed to vary with their length, the waves of greatest 
length undergoing the least augmentation of velocity, and 
being therefore most refracted |. But the phenomena of coloured 
rings, as Euler perceived, compel us, on the contrary, to sup- 
pose that the lengths of the waves dimmish as the refrangibility 
increases ; and he seems himself to have abandoned his first 
conjecture. 

Dr. Young accounted for dispersion by the supposition that 
the solid particles of the refracting substance vibrate, as well as 
the particles of the ether within it ; and that the former vibra- 
tions affect the latter, and affect them differently according to 

« P/iil. Trans. 1672. 

t It is scarcely necessary to advert here to the law proposed by M. Rudberg, 
to connect the lengths of an undulation, or the velocities of propagation, in 
different media ; — for this law is purely hypothetical, and its apparent consist- 
ency with observation has arisen solely from the adaptation of tlie arbitrary 
constants which enter the expression. — ^finales de Chimie, tom. xxxvi. xxxvii. 

J Opuscula varii Jrgumenti, tom. i. p. 217. 



316 FOURTH REPORT— 1834. 

their frequency. Mr. Challis has adopted and developed this 
hypothesis. According to this author, it has been ah-eady ob- 
served, the diminished velocity of transmission in the denser 
medium may be explained by the obstacle which the solid 
particles of the medium offer to the free movement of the 
ethereal particles. If the former be supposed to be immoveable, 
the ratio of the velocities of propagation, in free space and in 
the medium, will be a simple function of the density of the 
latter, and in a given medium its value will be constant ; but 
when the particles of the medium vibrate, the value of this 
ratio will depend also on the length of the wave, and will there- 
fore vary with the colour of the light *. 

The solution suggested by Professor Airy is more closely 
connected with received principles. It is now generally admitted 
that part of the velocity of sound depends on a change of elas- 
ticity, which the air undergoes during its vibrations, in conse- 
quence of the development of latent heat by compression. If 
this heat required time for its development, the quantity de- 
veloped, and therefore the elastic force, must vary with the time 
of vibration. Consequently the velocity of propagation should 
also vary with the time, and be diiferent for waves of different 
lengths. Professor Airy imagines something similar to this 
in the case of light ; and conceives that the elasticity of the 
ether, in refracting media, may consequently undergo a change, 
whose amount depends on the time of vibration. 

But the explanation offered by Fresnel seems to be the 
simplest and most natural. The conclusion of analysis — that 
the velocity of wave-propagation is constant in the same homo- 
geneous medium, — is deduced on the particular supposition that 
the sphere of action of the molecules of the medium is inde- 
finitely small compared with the length of a wave. If this re- 
striction be removed, we have no longer any ground for con-^ 
eluding that waves of different lengths will be propagated with 
the same velocity. Fresnel states that he has demonstrated, 
that when the mutual action of the ethereal molecules extends 
to a sensible distance as compared with the length of a wave, the 
waves of different lengths will be propagated with different 
velocities ; the elasticity of the medium, and therefore also the 
velocity, increasing with the length of the wavef. Here then 

• " An Attempt to explain theoretically the different Refrangibility of the 
Rays of Light, according to the hypothesis of Undulations," Phil. Mag., New 
Series, vol. viii. 

t This demonstration is more than once referred.to hy the author, as con- 
tained in a note appended to his memoir on double refraction. The note how- 
ever, probably by some oversight, has never been printed. 



REPORT ON PHYSICAL OPTICS. 317 

the constancy of the velocity of wave- propagation is regarded 
but as the approximate result of an incomplete analysis. The 
problem presented itself to M. Cauchy in a similar point of 
view. In the profound researches of this matheinatician relating 
to light, the ether is considered as a system of particles solicited 
by mutual attractions or repulsions ; and from the partial diffe- 
rential equations which represent their movement, he had de- 
duced the laws of propagation in crystallized as well as homo- 
geneous media. These equations however were but approximate, 
and derived from others of greater generality by the omission of 
the terms containing the higher powers of the displacements, 
and of their derivatives with respect to the coordinates. Re- 
suming the problem of the propagation of a plane wave, with 
the aid of the more general equations, he has finally demon- 
strated the existence of a relation between the velocity of pro- 
pagation and the length of the wave *. 

The opacity of bodies is ascribed by Newton to the discon- 
tinuity of their parts, and to the multitude of internal reflexions 
which the rays of light undei-go within themf . We have many 
reasons for believing this to be the case; but as yet we are far 
from a complete account of the phenomenon. If the reflexions 
and refractions, which thus arise at each new bounding surface, 
be similar to those which take place at the outer surfaces of 
bodies, the molecules of light will indeed be scattered in every 
direction, but they should undergo no diminution of velocity. 
How, then, is it that they do not emerge finally from the body as 
readily as they entered it, and thus render it visible in all di- 
rections, — not by a superficial reflexion, but by a secondary 
emission ? To account for the extinction of light, in the theory 
of emission, we must suppose it united to the body which it 
enters ; and the simplest mode in which we can conceive this 
union to be brought about, is by the direct impact of the mole- 
cules of light on those of bodies, whereby they are brought within 
the sphere of those interior attractive forces to which chemical 
combinations are referred. This appears to have been the opinion 
of Newton. " Are not gross bodies and light," says he, " con- 
vertible into one another, and may not bodies receive much of 
their activity from the particles of light which enter their com- 
position ? For all fixed bodies being heated emit light, so long 
as they continue sufficiently hot, and light mutually stops in 
bodies as often as its rays strike upon their partsj ." 

* Memoire siir la Dispersion de la Lumiere. — The attention of the Mathe- 
matical Section of the British Association was drawn to this theory by Professor 
Powell, at the last meeting, chiefly in reference to a limitation which seemed 
to be required in the physical hypothesis. — See Report of Prnceedinf/!i. 

t Oplic.1, book 2, part 3. I Optics, Query 30. 



318 FOURTH REPORT — 1834. 

When from the simple fact of absorption we proceed to con- 
sider its law, as depending on the nature of the light, the diffi- 
culties increase at every step. The intensity of the transmitted 
light considered as a function of its refrangibility appears to be 
subject to no law, or to a law so complicated as completely to 
baffle all attempts to embrace it in an empirical rule. The max- 
ima and minima are often actually numberless ; and the vari- 
able does not reach them gradually, but by what seems to be an 
abrupt violation of the law of continuity. These apparently ca- 
pricious changes were observed long since by Dr. Young, in the 
light transmitted through the common smalt-blue glass. Sir 
David Brewster has recently directed his attention to the same 
subject, and examined a great number of coloured bodies with 
reference to their absorptive properties. He has found, in par- 
ticular, that a very remarkable definite action is exercised upon 
the rays of the spectrum by the green liquids obtained by extract- 
ing the colouring-matter of the leaves of plants in alcohol; and 
this action does not cease altogether even when the liquid has 
become perfectly colourless *. But the absorbing properties of 
nitrous acid gas, observed by the same author, are by far the 
most remarkable ever noticed. When the light transmitted 
through this gas is analysed by a prism, it is found that about 
two thousand portions of the beam are stopped, and two 
thousand dark spaces, or abrupt deficiencies of light, appear in 
the spectrum. These increase in number and magnitude with 
the temperature of the gas, until, by a sufficient elevation of 
temperature, this rare body becomes perfectly opaque, and re- 
fuses to transmit a single ray of the brightest sunshine f. 
Prof. Miller and Prof. Daniell have found some analogous pro- 
perties in other gases. In the spectrum produced by the light 
transmitted through the vapours of bromine and iodine, more 
than one hundred dark lines are visible, disposed at equal di- 
stances J. 

To account for the selection of certain classes of rays by 
coloured media, in the theory of emission, it seems necessary 
to suppose that an attractive force is exerted at a distance be- 
tween the molecules of the body and those of light, and that 
the absolute value of this force varies with the colour. It does 
not seem easy to reconcile these suppositions to the Newtonian 
account of refraction ; and the difficulty is still further increased 
when we proceed to apply the same considerations to the ab- 
sorption of definite rays ; and introduce the hypothesis of 

• " On the Colours of Natural Bodies," Edin. Trans., vol. xii. 

f " On the Lines of the Solar Spectrum," &'c., Edin. Tran.t., vol. xii. 

J French transkttion of Herschel's Essay on Light, Supplement, p. 45.'). 



REPORT ON PHYSICAL OPTICS. 319 

Specific actions, varying in the most abrupt and irregular man- 
ner with the refrangibility of the ray *. 

The absorption of light, and the opacity of bodies, were long 
since urged by Halley as difficulties in the wave-theory. The 
ether is supposed to penetrate all bodies freely, and why not 
also the undulatory motion in which light consists ? To this 
difficulty we find a full and complete solution in the principle of 
interference. When a wave enters a discontinuous substance, 
it will be broken up, and its parts undergo continued subdivision 
by internal reflexions ; so that when these parts reach the 
second surface of the body, they are found in every possible 
phase, and must destroy one another by interference. The 
phenomenon, as has been observed by Sir John Herschel, is 
analogous to the impeded propagation of sound in a mixture of 
gases differing much in elasticity as compared with their density. 

The same writer has given an ingenious and natural account 
of the absorption of specific rays on the principles of the wave- 
theory, in a paper read before the Association last year f . He 
considers the molecules of the body and those of the ether as 
forming, conjointly, compound vibrating systems, which are 
more disposed to transmit vibrations of some determinate period 
than others. Other vibrations, however, not in unison with 
these systems, may be propagated through them. These/orcerf 
vibrations, as he calls them, will be obstructed in their pi-ogress, 
and their amplitudes diminished by the mutual influence of the 
motions of the parts of the systems ; and he shows that it is 
possible to conceive systems, which will be wholly impervious 
to a vibration of a particular period, while they freely transmit 
others not differing from them materially in their frequency |. 
But these important and interesting speculations, it must be 
remembered, are advanced by their author solely with the view 
of removing an imagined inconsistency between the phenomena 
of absorption and the mechanical laws of vibratory movement. 

* See Sir David Brewster's Report on Optics. 

f " On the Absorption of Light by coloured Media, viewed in connexion with 
the Undulatory Theory," Phil. Mag., Third Series, vol. iii. 

t An interesting interference experiment, similar in some respects to that 
indicated by Sir John Herschel in this paper, has been recently made by Mr. 
Kane. A compound tube, whose branches of 9 and 13| inches united at the 
two extremities, was made to sound by the languette of an organ pipe. Each 
of the tubes, separately, gave its own fundamental note, and all its harmonics; 
and when a free communication was opened between them, the system gave all 
the notes of the two series, with the exception of those whose waves were in 
complete discordance. Thus the fundamental note of the short tube was stopped 
altogether, while its octave was given with remarkable clearness ; the two 
waves being in complete discordance in the former case, and in complete ac- 
cordance in the latter. 



820 FOURTH REPORT — 1834. 

We are still far from a precise theory of absorption. When 
such a theory shall have been established, there seems reason to 
believe that it vrill bring with it also an insight into the internal 
constitution of bodies even yet more close than that afforded by 
the affections of polarized light ; and that the laws of molecular 
action may perhaps, at some future day, be studied in the phe- 
nomena of transmitted light. 

The properties of solar phosphori, which attracted so much 
of the attention of experimental philosophers of the last century, 
seem at first view to favour the account of absorption suggested 
by the theory of emission, and to arise from the disengagement 
of the light which had become united to the body. Canton ob- 
served that light may remain in these bodies, as it were in a 
latent state, for several months, until its re-emission is deter- 
mined by the action of heat. But it must be observed, in the 
first place, that the feeble light emitted from the phosphori 
bears a very small proportion to that which they are supposed 
to receive by absorption. Dessaignes has remarked that most 
of these substances emit the same kind of light, whatever be 
the species of light to which they have been exposed*. The 
same fact has been observed by M. Grotthouss f and other sub- 
sequent inquirers ; and in some of the diamonds possessing 
the property of phosphorescence, the most efficacious exciting 
light is of a different colour from that excited. These facts 
seem to be inexplicable in the theory of emission. In the wave- 
theory, on the other hand, the phenomenon is easily compre- 
hended. As the vibrations of the air excite those of sounding 
bodies, and communicate to them a motion which continues for 
some time after the exciting cause has ceased to act ; so it must 
also be with the undulations of the ether. When the body is 
in unison with the incident light, their vibrations will continue 
isochronous, and the undulations of the ether excited by the 
body vpill be of the same length as those by which it is itself 
excited. In the other case, the period of vibration, and conse- 
quently the length of the wave, will be altered, and the excited 
and exciting lights will be of different colours. The fact ob- 
served by Canton is indeed not so easily explained. Young 
supposed that the vibrations of the body may be abruptly sus- 
pended by cold, and may proceed anew when released from this 

* Mem. Inst. torn. xi. 

t Schweigger's Journal, 1815. — The same observer discovered the curious 
fact, that the electric current restored the property of phosphorescence, in 
many cases where it appeared to have been destroyed by tlie action of violent 
heat. 



RRPORT ON PHYSICAL OPTICS. 3,^1 

restraint, like a string which has been stopped and detained in 
any part of its vibration on either side of the centre. 

The fixed lines in the solar spectrum first noticed by Wollaston, 
and afterwards more minutely traced by Fraunhofer, have lately 
been examined with great care, and with his usual success, by 
Sir David Brewster ; and he has observed a remarkable coinci- 
dence between these lines and the dark bands of the spectrum of 
the nitrous acid gas *. Sir David Brewster has also studied, in 
connexion with the same subject, the definite absorbing effects 
of the earth's atmosphere. This has been effected by examining 
the solar spectrum, when the sun was near the horizon ; and it 
has been found that most of the dark bands thus developed be- 
longed to the fixed lines of Fraunhofer, which were thus, as it 
were, widened, and brought out, by the absorptive action of the 
atmosphere. A similar result has been arrived at in other cases, 
and it has been found that the points of the spectrum on which 
absorbing bodies exert the strongest specific actions are gene- 
rally coincident with the deficient rays of solar light f. This 
singular connexion gives considerable weight to the speculations 
of Sir David Brewster respecting the latter phenomena |. 

The observation of the fixed lines in the solar spectrum led 
Fraunhofer to examine the optical characters of the lights ema- 
nating from other sources. He thus arrived at the interesting 
discovery, that the system of bands in the different species of 
light which he examined, varied with the source ; while it was 
constantly the same m the number of the bands, and their 
relation to the coloured spaces, in the light of the same 
source, however modified. In the light of Sirius there are three 
broad bands which have no resemblance to those of solar light. 
The light of the electric spark, on the other hand, when ana- 
lysed by the prism is found to have several bright lines, of 
which that in the green is remarkably brilliant. Similar plie- 
nomena were observed in the light of artificial flames, — the flame 
of an oil lamp, for example, exhibiting a well-defined bright 
band between the red and yellow, and another not so distinct 
in the green §. This however is not universally the case. In 
the red flame of strontia, as was observed by Dr. Faraday and 
Mr. Talbot, there are a number of red rays separated from each 
other by dark bands ; and in the flame of cyanogen, when 
similarly analysed, the violet is found to be divided into three 
distinct portions with broad dark intervals §. 

* " On the Lines of the Solar Spectrum," EJin. Trans., vol. xii. 
t " On the Colours of Natural Bodies," Ed'm. Trans., vol. xii. 
X Report on Optics. § Munich Memoirs. 

II Phil. Mag., Third Series, vol. iv. p. 114. 
1834. Y 



322 FOURTH REPORT — 1834. 

It is easy to account for the general fact of the deficiency of 
certain classes of rat/s in certain lights. When a body violently 
heated begins to shine, the phenomenon is simply accounted 
for, in the wave-theory, by an increase in the frequency of its 
vibrations. In the same manner it seems natural to suppose, 
generally, that the mechanical agencies at work during com- 
bustion accelerate or retard, in various ways, the rate of vibra- 
tion, and so alter the character of the emitted lights. The 
light emitted in weak or incipient combustion is generally blue. 
Sir John Herschel observed that when sulphur burns with a 
feeble flame, its light contains all the rays of the spectrum, 
and particularly the blue and violet ; while, in vivid combustion, 
these disappear entirely, and the light is a yellow of almost 
perfect homogeneity *. The various shades of colour in the 
flame of a common candle, — from the deep blue of the lower 
part (which is found by prismatic analysis to consist of five 
distinct portions,) to the yellowish white in the centre, and 
thence to the dusky red at the apex of the flame, — seem to be 
referrible to the same principle. Fraunhofer and Sir David 
Brewster have both remarked that the flame of oil, urged by 
the blowpipe, consists chiehy or wholly of yellow rays. The 
same fact was long since observed by Mr. Melville with respect 
to the flame of alcohol, into which nitre, muriate of soda and 
other salts had been introduced f ; and Sir David Brewster has 
found that the quantity of yellow light given out by burning 
bodies increases with their humidity, the flame of alcohol diluted 
with water being nearly a homogeneous yellow;}:. It is more im- 
portant to remark however, in illustration of the undulatory 
view of the phenomenon of emission, that the colour of flames is 
often found to depend on the presence of something which is it- 
self unaltered in the process of combustion. Thus Mr. Talbot 
has remarked that when a smaU quantity of muriate of lime was 
placed on the wick of a spirit lamp, it gave out red and green 
rays during an entire evening, though the salt was not sensibly 
diminished §. The absence of definite rays in certain lights, 
and the fixed lines of the solar spectrum, have been referred 
by Sir John Herschel to the same principle by which he has 
explained the absorption of specific rays || . 

In what has preceded we have assumed the truth of the re- 
ceived theory with respect to the composition of solar light, 
and the connexion between the colour of a ray and its refrangi- 
bility. This theory however has been recently opposed by Sir 

* " On Absorption of Light in coloured Media," Edin. Trans., vol. ix. 
i Ed'nib. Essays. J On a Monochromatic Lamp. Ihid. 

§ Ediub. Jaitni. of Science, v. 77. || Phil, il/rti/., Third Series, vol. iii. p. 407. 



REPORT ON PHYSICAL OPTICS. 32S 

David Brewster. According to this philosopher, white light 
consists of but three simple colours, — red, yellow, and blue ; 
and the solar spectruni is composed of three overlapping spectra 
of these colours, the intensity of each of which is greatest at 
the point where that colour is strongest in the compound spec- 
trum. According to this view, then, all the colours in the solar 
spectrum are compound, and consist of red, yellow, and blue 
light, in different proportions. These compound colours can- 
not be analysed by the prism, in as much as the rays of which 
they consist at any point of the spectrum have the same refran- 
gibility ; and it is only by the different action of absorbing 
media on their constituent elements that their compound nature 
can be detected. Each of them may be conceived to consist of 
a certain quantity of white light, and of an excess of the light of 
two of the simple colours ; and if this excess be absorbed, a 
white light will be the result, which will be indecomposable by 
the prism. This result of his hypothesis has been experimentally 
confirmed by Sir David Brewster *. 

These views, if finally established, sever the connexion be- 
tween the colour of a ray and its refrangibility, laid down by 
Newton ; and the former must be supposed to depend, — not on 
the length of the wave, — but on some other element of the vi- 
bratory movement. 

III. Diffraction. 

It has been already stated that Newton considered the undu- 
lations of an ethereal medium to be a necessary part of his the- 
ory, and that that theory as maintained by its author differed 
from the theory of Huygens and of Hooke, only by the addition 
of a new hypothesis. The necessity of something extraneous to 
the undulations of the ether seems to have been admitted by 
Newton mainly to account for the right-lined propagation of 
the rays of light ; and a careful consideration of his optical 
writings leaves the impression, that had the wave-theory alone 
appeared to explain this fact, Newton would not have hesitated 
to embrace it. This explanation has been spoken of in another 
place, and it has been shown to follow from that theory, that 
the light which encounters an obstacle must diminish rapidly 
in intensity within the edge of the geometric shadow. It now 
remains to consider the other phenomena which arise under these 
circumstances ; and it will be found that the same theory affords 
the most complete account, not only of their general characters, 
but even of their numerical details. 

In order to understand the theory of shadoius, it is necessary 

* " On a New Analysis of Solar Light," Ed'm. Trans. 1831. 
Y 2 



3j?4 FOURTH REPORT — 1S34. 

to investigate their laws in the simple case in which the mag- 
nitude of tlie hnniiious body is reduced to a point. The eflects 
thus presented were first observed bj^ Grimaldi, and they have 
been since studied, as a separate branch of optical science, under 
the title of diffraction or injiexioii. Grimaldi found that when 
a small opaque body was placed in the cone of light, admitted 
into a dark chamber through a very small aperture, its shadow 
was much larger than its geometric projection, so that the light 
suftered some deviation from its rectilinear course in passing by 
the edge. Observing these shadows more attentively, he found 
that they were bordered with three iris-coloured fringes, which 
decreased in breadth and intensity in the order of their distances 
from the edge of the shadow, preserving the same distance from 
the edge throughout its entire extent, unless where the body 
terminated in a sharp angle. Similar fringes were observed 
under favourable circumstances within the shadows of narrow 
bodies*. 

The phenomena of diffraction were subsequently examined 
by Hooke and by Newton. The first observations of Newton 
were but repetitions of those of Grimaldi ; and it is remarkable 
that he altogether overlooked the important phenomenon of the 
interior fringes noticed by the Italian philosopher. But to 
Newton we owe the analysis of the phenomena, so far as they 
depended on the nature of the light. When the different species 
of simple light into which the sun's rays were divided by a prism 
were cast in succession on the diffracting body, Newton observed 
that the fringes formed were broadest in red light, narrowest in 
the violet, and of intermediate magnitude in the light of mean 
refrangibility, so that the iris-coloured fringes which are formed 
in white light are but the fringes of different colours superposed. 
But the observations of Newton most closely connected with his 
physical theory are those in which the light is made to pass be- 
tween two near knife-edges, whether parallel or inclined. From 
these observations Newton concluded that the light of the first 
fringe passed by the edge, at a distance greater than the 800th 
of an inch, that of the second and third fringes passing at still 
greater distances. These distances, however, were not the same 
wherever the fringes were formed ; and it appeared to follow 
from the experiment, that the light of the same fringe was not 
the same light at all distances, but that each fringe was, as it were, 
a caustic formed by the intersection of the rays passing at dif- 
ferent distances from the edge ; the portion of the fringe near 
the knives being formed of light which passed nearest to the 
edge and was most bentf. 

* P/ij/sicO'Mathesh de Ltwiine, Bologna, 1G65. 
t Optics, Book iii. 



REPORT ON PHYSICAL, OPTICS. 325 

To account for these phenomena Newton sujjposed the ravs 
of light to be inflected in passing bj^ the edges of bodies, by the 
operation of the attractive and repulsive forces which the mole- 
cules of bodies were conceived to exert on those of light at sen- 
sible distances. Thus, the rays passing by the edges of a nar- 
row opaque body are supposed to be turned aside by its repul- 
sion ; and as this force decreases rapidly as the distance increases, 
the rays which pass at a distance from the body will be less de- 
flected than those which pass close to it. The caustic formed 
by the intersection of these deflected rays will be concave in- 
wards 5 and as none of the rays pass within it, it will form the 
boundary of the visible shadow. To explain the alternations of 
darkness and light beyond this, Newton appears to have sup- 
posed that the attractive and repulsive forces succeed one another 
for some alternations ; and that the molecules composing each 
ray, in their passage by the body, are bent to and fro by these 
forces " with a motion like that of an eel," and are finally thrown 
off at one or other of the points of contrary flexure. The sepa- 
ration of white light into its elements is explained, by supposing 
that the rays which diflfer in refrangibility differ also in injiexihi- 
lity ; the body acting alike upon the less refrangible rays at a 
greater distance, and upon the more refrangible at a less di- 
stance*. In one of his letters to Oldenburgh f, Newton advances 
a more refined theory of diffraction. The bending of the ray 
near the edge of the obstacle he conceived to arise from a varia- 
tion hi the density of the ether in the neighbourhood of the body ; 
and, following the analogy of thin plates, he endeavoured to ac- 
count for the coloured fringes by the vibrations of the ether 
which are propagated faster than the rays themselves, and over- 
take them at the middle of the curved portion of the trajectory 
they describe. 

It is needless to comment upon the vagueness of these expla- 
nations. Newton himself was dissatisfied with them, and the 
subject fell from his hands unfinished. Still, however, the mere 
guesses of such a mind as that of Newton must possess a high 
interest, and we are not to wonder that among his followers more 
weight should be attached to these explanations than he himself 
ever gave them. It seems necessary therefore to advert to some 
of the circumstances of these phenomena, which are not only 
unexplained by this theory, but which seem moreover irrecon 
cileably at variance with it. 

If the phenomena of inflexion be the effects of attractive and 
repulsive forces emanating from the interposed body, and if 
these forces are the same, or even analogous to those to which 

• Optics, Book iii. Queries 1, 2, 3, 4. 

t December 21, 1675.— Birch's History of Royal Society, vol. iii. 



32G FOURTH REPORT — 1834. 

the reflexion and refraction of light are ascribed in the theory of 
emission, it will follow that they must exist in difterent bodies 
in very different degrees ; so that the amount of bending of the 
rays, and therefore the position of the diffracted fringes, should 
vary with the mass, the nature and Xheform of the inflecting 
body. Now it is clearly ascertained, on the contrary, that alC 
bodies, whatever be their nature or the form of their edge, pro- 
duce under the same circumstances fringes identically the same; 
and in fact the partial interception of light, caused by the inter- 
position of an obstacle of any kind, seems to be the only condi- 
tion on which the character of the phenomenon depends. 
Gravesende seems to have first observed that the nature or den- 
sity of the body had no effect upon the magnitude of the diffracted 
fringes ; and the fact has since been confirmed in the fullest 
manner by almost every inquirer in this branch of experimental 
science. Oneof the ablest supporters of the theory of emission 
has admitted that the inflecting forces, if such exist, must be inde- 
pendent of the chemical nature of the inflecting body, and altoge- 
ther difterent in their nature from those to which, in the same 
theory, the phenomena of reflexion and refraction are ascribed*. 
To ascertain whether the form of the edge had any effect upon 
the fringes, Fresnel took two plates of steel, the edge of each 
of which was rounded in one half of its length and sharp in the 
remaining half, and placed the rounded portion of one edge op- 
posite the angular part of the other, and vice versa. If, then, the 
position of the fringes depended on the form of the surface, the 
effect would thus be doubled, and the fringes appear broken in 
the middle. They were found, on the contrary, to be perfectly 
straight throughout their entire lengthf . 

Again, the inflecting forces (though they must be supposed 
to vary in intensity, with the form and mass of the bod}', and 
with the distance of the luminous molecule from the edge) can- 
not be conceived to depend in any way upon the distance pre- 
viously traversed by the molecule before it arrives in the neigh- 
bourhood of that edge ; so that the magnitude and position of 

* Biot, Precis elementaire, vol. ii. p. 473, 3""^ Edit. 

•f Memoire sur la Diffraction, p. 370. The Bulletin Z7w»»e««/ for February 
1828 contains some animadversions on this part of Fresnel's optical labours, in 
a paper signed by the secretary of the Academy of Sciences of St. Petersburgh, 
and purporting to be an official reply to some remarks in a former number of 
the Bulletin on the programme of the prize questions proposed by the Academy. 
The writers have confounded two experiments of Fresnel which were instituted 
with different views, and differently reasoned upon. Fresnel's object in this 
experiment was simply to show that the form of the edge produced no eftect 
upon the fringes, as it ought to do if diffraction arose from attractive or repul- 
sive forces extending tosensible distances from bodies. Most of the objections 
urged in the same paper agaiubt the wave-theory