CONTENTS.

I.

ON THE ADVISABLENESS OF IMPROVING NATURAL KNowledge.

(A Lay Sermon delivered in St. Martin's Hall, on the evening

of Sunday, the 7th of January, 1866, and subsequently published

in the Fortnightly Review)

PAQE

1

II.

EMANCIPATION-BLACK AND WHITE. (The Reader, May 20th, 18C5) 20

III.

A LIBERAL EDUCATION AND WHERE TO FIND IT. (An Address
to the South London Working Men's College, delivered on the
4th of January, 1868, and subsequently published in Macmillan's
Magazine).

IV.

SCIENTIFIC EDUCATION: NOTES OF AN AFTER-DINNER SPEECH. (De-

livered before the Liverpool Philomathic Society in April 1869,

and subsequently published in Macmillan's Magazine).

V.

ON THE EDUCATIONAL VALUE OF THE NATURAL HISTORY SCIENCES.

(An Address delivered at St. Martin's Hall, on the 22d July, 1854,

27

54

VI.

ON THE STUDY OF ZOOLOGY. (A Lecture delivered at the South

Kensington Museum, in 1861, and subsequently published by the

Department of Science and Art)

PAGE

94

VII.

ON THE PHYSICAL BASIS OF LIFE. (A Lay Sermon delivered in

Edinburgh, on Sunday, the 8th of November, 1868, at the request

of the late Rev. James Cranbrook; subsequently published in the

Fortnightly Review)

120

VIII.

THE SCIENTIFIC ASPECTS OF POSITIVISM. (A Reply to Mr. Congreve's

Attack upon the preceding Paper. Published n the Fortnightly

Review, 1869)

IX.

ON A PIECE OF CHALK. (A Lecture delivered to the Working Men of
Norwich, during the Meeting of the British Association, in 1868.
Subsequently published in Macmillan's Magazine) .

X.

GEOLOGICAL CONTEMPORANEITY AND PERSISTENT TYPES OF LIFE. (The

Anniversary Address to the Geological Society for 1862)

147

174

202

228

THE ORIGIN OF SPECIES. (The Westminster Review, April 1860). 255

XIII.

CRITICISMS ON "THE ORIGIN OF SPECIES." (The Natural History

Review, 1864)

РАСБ

299

XIV.

ON DESCARTES' "DISCOURSE TOUCHING THE METHOD OF USING ONE'S

REASON RIGHTLY AND OF SEEKING SCIENTIFIC TRUTH." (An

Address to the Cambridge Young Men's Christian Society, delivered

on the 24th of March, 1870, and subsequently published in

Macmillan's Magazine).

320

XV.

SPONTANEOUS GENERATION. (An Address delivered before the British

Association for the Advancement of Science, at the Liverpool

meeting, September, 1870, and published in Nature)

345

ON THE ADVISABLENESS OF IMPROVING

NATURAL KNOWLEDGE.

THIS time two hundred years ago-in the beginning of January, 1666-those of our forefathers who inhabited this great and ancient city, took breath between the shocks of two fearful calamities: one not quite past, although its fury had abated; the other to come.

Within a few yards of the very spot on which we are assembled, so the tradition runs, that painful and deadly malady, the plague, appeared in the latter months of 1664; and, though no new visitor, smote the people of England, and especially of her capital, with a violence unknown before, in the course of the following year. The hand of a master has pictured what happened in those dismal months; and in that truest of fictions, "The History of the Plague Year," Defoe shows death, with every accompaniment of pain and terror, stalking through the narrow streets of old London, and changing their busy hum into a silence broken only by the wailing of the mourners of fifty thousand dead; by the woful denunciations and mad prayers of fanatics; and by the madder yells of despairing profligates.

But, about this time in 1666, the death-rate had sunk to nearly its ordinary amount; a case of plague occurred only here and there, and the richer citizens