JuLy 17, 1902] 
NATURE 
267 
writes Mr. Millais, as the results of close observation, 
“between June 15 and October 10, undergo @ double 
moult, that is to say, the feathers are actually shed twice, 
whilst one-third (viz. the long scapulars, wings, tail 
and back feathers) are renewed only once, and during 
all the time, both in the shedding of the old feathers and 
the assumption of the new, there is a process of constant 
sympathetic change of colour.” 
Mr. Millais has something even more strange to tell. 
““T am convinced,” he writes, “that a bird has full 
power to command the moult as it will, and also”— 
stranger still—to infuse or withhold colouring matter as 
it thinks necessary.” 
The Lord of creation “‘ cannot make one hair black or 
white.” 
His conclusions, startling as they may be, are those of 
a thoughtful and observant man who has conscientiously 
devoted many years to a close study of a fascinating 
subject. 
It is not, as a rule, until the drake has completely 
assumed the duck’s brown dress, harmonising as it does 
with the colour of the dying reeds, that the quills are 
shed. The operation is got through without an hour’s 
waste of time. “I have known them” (Mr. Millais must 
speak for himself again) “all come out together in one 
day, the new flush starting at once.” 
The duck has others to think of besides herself. If 
she, like her mate, were to be deprived of flight-power, it 
would often be at the risk of her brood, and so her wing 
feathers are shed, like those of most birds, gradually, and 
she seldom, if ever, quite loses the use of her wings. If 
she hasa second brood to look after, and is thus occupied 
later than usual with family cares, even this compara- 
tively harmless wing moult is postponed for a more 
convenient season—as Mr. Millais believes, if we read 
him rightly—by a direct action of will on her part. 
It is a wonderful story, but nothing in Nature is 
incredible merely because incomprehensible. 
Mr. Millais has a very simple answer to a question 
which has puzzled many others than scientific naturalists. 
When ducks and other birds which usually nest on the 
ground change their habits, as they often do, and lay in 
trees, how do the young ones—wdifugae who leave the 
nest as soon as they are hatched—manage to get down? 
At the mother’s call, he says, they throw themselves 
down and alight unhurt. The explanation is good so far 
as it goes, and may, not improbably, be in most cases 
true. But it would be rash to accept it as of universal 
application. 
Three young birds found dead at the foot of a tree in 
a park in Sussex led this spring to the discovery of a 
moorhen’s nest at a very considerable height from the 
ground. The young birds were all well nourished and 
had been apparently killed by the fall. 
Woodcocks have been more than once seen by trust- 
worthy witnesses in the act of carrying their young, and 
’ there is no reason to suppose that ducks and other birds 
cannot on occasion as easily do the same. 
There are many other directions in which, if space 
permitted, it would be pleasant to follow Mr. Millais’s 
lead. But enough has, perhaps, been said already to 
show that his book is original and very interesting. The 
pictures are all excellent. 
NO. 1707, VOL. 66] 
{ 
is the pencil sketch by the author, facing p. 60, of the 
beak of a shoveller, with its strange spoonbill tip and the 
hanging bristles, in which—as in a sieve, or in the great 
mouth-fringes of the whalebone whale, to compare small 
things with large—dainty morsels are trapped as the 
bird skims the water as he paddles about with extended 
neck. 
“Here” (the quotation is from the note attached to 
the sketch) ‘“‘we see a wonderful provision of Nature. 
The comb-like teeth or /aminae of the surface-feeding 
ducks are developed in proportion to the extent to which 
the particular species feed on the surface or otherwise. 
An omnivorous and somewhat coarse feeder like the 
mallard only possesses them in a very rudimentary form, 
whereas the shoveller, which is constantly skimming the 
surface for fine substances, has them greatly developed in 
both upper and lower mandibles.” 
Mr. Thorburn contributes eight full-sized coloured 
plates. He is still, among English bird-artists, an easy 
first. But in some of his pictures, notably Plates xxx. 
and xxxvii., garganeys chasing water-beetles, and the 
pintails, Mr. Millais has run him close. 
The only fault to be found with a beautiful book is 
that in choosing his subjects for illustration the author 
has, perhaps, ridden his- hobby “Eclipse” a little too 
hard. 
The best work, excepting in the case of the few rare 
visitors figured, which are, strictly speaking, scarcely 
British, is confined almost entirely to birds in immature 
or transitional plumage. In a book of natural history, 
destined to take a well-earned place for some years to 
come as the standard work on our surface-feeding ducks, 
a few plates might with advantage have been spared, if 
only as a sop to unscientific bird-lovers, for ducks and 
drakes at their best. T. DicBy PIGOTT. 
A FRENCH TEXT-BOOK OF ZOOLOGY. 
Traité de Zoologie Concréte. Par Yves Delage et 
Edgard Hérouard. Tome 1i., 2° Partie, Les Coelen- 
térés. Pp. x + 848. (Paris: Libraire C. Reinwald, 
1901.) 
HE volumes of the “Traité de Zoologie Concréte ” 
already published are so well known and have 
been so acceptable to zoologists that the present volume, 
dealing with the Coelenterata, scarcely requires any re- 
commendation. While it leaves little to be desired in 
such important matters as abundance and excellence of 
illustrations, bibliography, index and glossary, the chief 
merit of the “ Traité de Zoologie Concréte” must be attri- 
buted to the logical and systematic method of exposition 
adopted by its authors. The majority of zoological text- 
books, following the German model, give a brief and 
insufficient definition of each class or order of the animal 
kingdom, and this is succeeded by a discussion of the 
organology and embryology of the class or order that is 
generally so diffuse as to leave the student in a state of 
hopeless uncertainty as to what are the characteristic 
structural features of the group in question. Recognising 
the importance of fixing clear and definite ideas of struc- 
tural relations in the student’s mind, MM. Yves Delage 
and Hérouard have adopted the time-honoured plan of 
illustrating the anatomy of each important group of 
Among the most interesting | animals by a description of a morphological type, which 
