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NATURE 
| dugust 6, 1885 
during 1828, engaged on some hydrographical work off 
this coast, and good-naturedly assisted the littoral zone 
workers, enabling them to use the dredge in somewhat 
deeper water than they could reach from a row-boat. The 
results of these investigations were laid before the 
Academy of Sciences in July and November, 1829, and 
formed the subject of an elaborate report presented to the 
Academy in November, 1830, by Cuvier, Dumerit, and 
Latreille, Baron Cuvier being the writer of thereport. In 
this memoir, for the first time so far as we know, the idea 
of zones of marine life is promulgated ; these were four 
in number. A considerable portion of the memoir is 
devoted to the subject of the bristles in Annelids and to a 
description and classification of the Annelids of the coast 
of France. The reporters did not hesitate to express 
their satisfaction with the work the two friends had done, 
calling the special attention of the Academy to the 
“efforts heureux par lesquels ces deux habiles naturalistes 
sont parvenus a enrichir la Faune francaise d’espéces si 
nouvelles et si curieuses, et la zoologie en général d’observa- 
tions si intéressantes.” These happy efforts were but the 
forerunners of others carried on, in the case of Milne- 
Edwards, throughout a lengthened life. 
In 1841 Milne-Edwards was appointed to the Professor- 
ship of Natural History in the Collége Royal de Henri IV., 
and about the same time we find him holding the Chair 
of Zoology and Comparative Physiology at the Faculty of 
Sciences, of which Faculty he was afterwards the Dean. 
On his friend Audouin’s death, he was made Professor of 
Entomology at the Museum, Jardin des Plantes. 
A considerable number of original memoirs, the titles of 
which it is here unnecessary to detail, were published 
about this period by Milne-Edwards in the Annales des 
Sciences Naturelles. This famous periodical first 
appeared in 1824, under the editorship of Audouin, 
Brogniart and Dumas. In 1834 the second series, from 
which geology and mineralogy were excluded, com- 
menced under the joint editorship, for the zoological 
portion, of Audouin and Milne-Edwards, so that for now 
fifty years the zoological department has been under his 
management. 
While labours as important as they were numerous 
secured for H. Milne-Edwards a high position among 
men of science, his name was also universally well- 
known and made popular by his elementary works on 
zoology. His “ Eléments de Zoologie” were published in 
1834 and were reissued in 1851 as a “ Cours élémentaire 
de Zoologie.” This work had an enormous circulation in 
France, and has not only been translated into several 
other languages, but also, until almost the other day, it 
formed the stock-in-trade, either as to its text or its 
illustrations, of most of the many small elementary works 
on natural history published in Europe. 
In 1838 Milne-Edwards was elected a member of the 
Academy of Sciences in the section of anatomy and 
zoology. He was made an officer of the Legion of Honour 
in 1847,and a commander of this Order in 1861. In 
1862 he succeeded Isidore Geoffroy Saint-Hilaire as Pro- 
fessor of Zoology at the Jardin des Plantes, and in a 
year or two afterwards was made assistant director of the 
museum. 
Of his more important works as distinct from his 
memoirs may be mentioned his “ Histoire naturelle des | 
Crustacés,” 1834-40. In this he was assisted by his friend 
Audouin, and it long remained as a standard authority on 
this group. 
The “ Histoire naturelle des Coralliares,” 1857-60, was 
commenced after Milne-Edwards’s return, in 1834, from 
a collectingtour on the coast of Algeria ; but in 1847, in 
order to satisfy the calls of his publishers, he associated 
Jules Haime, so well known for his memoirs on the 
Polyps in the Palxontographical Society of London 
and in the Annales des Sciences Naturelles, with him in 
this work; but the death of Haime in 1856 compelled 
Milne-Edwards to complete the work himself. It is in 
a few tender words dedicated to the memory of Jules 
Haime. 
“Lecons sur la Physiologie et Anatomie comparée de 
!’Homme et des Animaux” were published between 1857 
and 1881, in fourteen volumes. The series is dedicated 
to his friend, M. J. Dumas, to whom he had dedicated 
the first work of his early pen. These lectures will always 
possess an importance to the student, from the immense 
mass of details, accompanied with copious references to 
the labours of others, that are brought within a limited 
compass. 
“ Recherches anatomiques et zoologiques faites pendant 
un Voyage sur les Cétes dela Sicile, &c.,” forms a splen- 
did quarto volume of over 850 pages, which are illus- 
trated with nearly 100 coloured plates. This work is, for 
the most part, a corrected report of a series of memoirs 
contributed to the Azmales des Sciences Naturelles by 
Milne-Edwards, A. de Quatrefages, and Emile Blanchard. 
There can be little question that the name of H. Milne- 
Edwards will always rank high among the naturalists of 
the first half of the nineteenth century, and for years he 
was incontestibly one of the leaders of zoology. He was 
among the first who, not content with the study of the 
dead forms of animal life, made prolonged visits to the 
sea-coasts to study the living forms and to investigate 
their habits. These were days before biological stations 
were thought of and when the details of geographical dis- 
tribution were little known. That Milne-Edwards’s study 
of the geographical distribution of the lower forms of 
Invertebrates led him to the theory of there being centres 
of creation was what, from a purely zoological point of 
view, might have been expected ; and when larger and 
truer views burst upon the world through the genius of 
Darwin, Milne-Edwards’s mind, already preoccupied, was 
never altogether able to take them in. By the student of 
biology Milne-Edwards will be remembered by his theory 
of the division of physiological labour, one which threw 
an interesting light on many an intricate problem. 
H. Milne-Edwards was an excellent linguist. English he 
spoke like a native. In manner courteous, he was kindly 
and affable to all. His house at the Jardin des Plantes 
was for years the focus of attraction for all the men of 
science in or visiting Paris. He was the possessor of a 
splendid library, the treasures of which were most freely 
at the services of students. He was a member of most 
of the learned Academies of Europe and America, and 
the possessor of several orders of State. Full of years 
and service, he died in Paris on July 29 last. As Geoffroy 
Saint-Hilaire was on his death succeeded by his son 
Isidore, so, happily for zoology, Henry Milne-Edwards 
has, in his son Alphonse, handed down his name and 
place to one every way worthy of both. 
RADIANT LIGHT AND HEAT 
Preliminary Notions 
T has been known from time immemorial that a suffi- 
ciently hot body when left to itself gives out light and 
heat, and likewise grows cold. It has also been known 
that a body not sufficiently hot to give out light may yet 
be capable of giving out heat, cooling as it does so. 
If the above facts be studied scientifically they at once 
give rise to a series of important issues, all of which we 
are now ina position to reply to. These may be put in 
the form of the following questions : : 
(1) Is radiant light a substance or, if not, what is it ? 
(2) With what velocity does it move through space? 
(3) Is radiant heat physically similar to radiant light ? 
(4) What is meant by a hot body? . 
(5) In what manner is the issue of radiant light and 
heat related to the cooling of the body ? 
Of these five questions the second was the first to 
