74 
NATURE 
[Mov. 18, 1869 
the names Alunda, Arungo, Acumbe, not Balunda, &c. 
They tell us that the Alunda never pronounce the letter r, 
and that in writing the names Arungo, Moiro, &c.,in which 
that letter occurs, they have adhered to the Maravi dialect. 
We thence conclude that for the names Rua, Moero, Lufira, 
&c., and perhaps for the initial Ba above alluded to, Dr. 
Livingstone is probably indebted to his Arab friends, who 
rest satisfied with a jargon, in some degree intelligible 
everywhere, and nowhere perfect. 
Dr. Livingstone seems to be elated with the discovery that 
“the chief sources of the Nile arise between 10° and 12° S, 
lat., or nearly in the position assigned to them by Ptolemy, 
whose river Rhapta (?) is probably the Rovuma.” Here 
two different problems are attempted to be solved at 
once—one touching the Sources of the White Nile, and 
the other, those of Ptolemy’s Nile. With respect to these 
latter, it will be enough to observe that Ptolemy’s Lakes 
of the Nile, two in number, 8 degrees asunder, are 
placed by him respectively in lats. 6° and 7° S., but his 
graduation being defective, through an imperfect estimate 
of the length of a degree, the positions thus assigned to 
the lakes fall under true graduation, to 11” N., and 40’S. 
of the equator. Ptolemy’s Lakes, therefore, have not been 
reached by the zealous traveller. 
With respect to the sources of the Bahr el Abyad, they 
may of course be traced to the head waters of the Luapula, 
provided that the results of Capt. Burton’s observations 
on the altitude of Nyanza and the character of its northern 
end are completely thrown aside. Witha greater eleva- 
tion, and an outlet through Speke’s Mountains of the 
Moon, the waters of the lake may reach Egypt. 
It is to be regretted that Dr. Livingstone missed the 
opportunity of viewing the highest mountain in this part 
of the world, now known only by a ridiculously exagge- 
rated description ; and also a most interesting point in 
the centre of Africa. The great town, Katanga, as de- 
scribed by the Arabs, is near the copper mines, where 
75 lbs. of copper may be bought for 4 cubits of American 
sheeting. The town is larger than Roonda (the Cazembe’s 
town), and has good bazaars ; it stands on the Rafira 
(Luvira) which joins the Ruapura (Luapula). The people 
are peaceable, and kind to strangers. The people from 
Zanzibar learned the language almost immediately. 
ERSG:S: 
[We give a map of the region recently traversed 
by Livingstone, showing its connection with the known 
points in this part of Africa. We owe this map to the 
courtesy of the officers of the Royal Geographical Society. 
—ED.] 
CUCKOWS’ EGGS 
CARCELY any bird has so much occupied the atten- 
tion, not merely of naturalists, but of people gene- 
rally, as the Common Cuckow of Europe, and (we might 
almost add, consequently) scarcely any bird has had so 
many idle tales connected with it. Setting aside several 
of its habits wherein it differs from the common run of 
birds, its strange, and, according to the experience of most 
persons, its singular mode of entrusting its offspring to 
foster-parents, is enough to account for much of the in- 
terest which has been so long felt in its history. Within 
the last twenty years a theory (which is, as I shall pre- 
sently show, by no means a new one) with respect to an 
important fact in its economy, has attracted a good deal 
of attention, first in Germany, and latterly in England ; 
and as this theory seems to be especially open to miscon- 
ception, and in some quarters to have been entirely mis- 
understood, I shall endeavour to give an account of it in 
a manner more distinct than has yet (I think) been done ; 
and to show that there is no good ground for believing it 
to be irrational, as some have supposed, and for scouting 
it as something beneath contempt. 
It has long been notorious to oologists that the eggs of 
the Cuckow are subject to very great variety in colour, and 
that a large number of birds laying eggs of very different 
colours enjoy the doubtful advantage of acting as foster- 
parents to the young Cuckow. Now the theory to which 
I refer is that “the egg of the Cuckow is approximately 
coloured and marked like those of the bird in whose nest 
it is deposited, that it may be the less easily recognised by 
the foster-parents as a substituted one.” 
This theory is old enough, for it was announced and 
criticised nearly a hundred years ago by Salerne,* who, 
after mentioning that he had seen two Stonechats’ nests, 
each containing eggs of that bird, as well as a Cuckow’s 
(which was as blue as the others, but twice [?] as large), 
goes on to say that he was assured by an inhabitant of 
Sologne (a district in France to the south of Orleans), 
that the Cuckow’s egg is always blue; and then comes this 
remarkable statement :—“As to the assertion of another 
Solognot who says that the hen Cuckow lays its eggs pre- 
cisely of the same colour as those in the nest of which she 
makes use, it is an incomprehensible thing.” Many of my 
readers will, I doubt not, be at once inclined to agree with 
Salerne. 
Little attention seems to have been paid to this passage 
by succeeding naturalists ;f but in 1853 the same theory 
was prominently and (I believe) independently brought 
forward by Dr. Baldamus, then editor of Waumannia, a 
German ornithological magazine, now defunct ; so far as 
I know, however, it was not until April, 1865, that an 
article in the English ornithological journal, the /ézs, by 
Mr. Dawson Rowley, gave anything like an idea of it to 
the public of this country. Some months later (14th Sep- 
tember) Mr. A. C. Smith introduced the subject to the 
Wiltshire Archeological and Natural History Society, and 
the paper he then read, having been since printed in the 
Wiltshire Magazine (vol. ix. p. 57), and elsewhere, has, 
with Mr. Rowley’s article, made the theory very generally 
known. Mr. Smith also published, subsequently, in the 
Zoologist for 1868, a translation of Dr. Baldamus’s ela- 
borate essay; but this translation being unaccompanied 
by the coloured plate which illustrated the original, unfor-. 
tunately fails to do justice to the Doctor’s theory, for with- 
out seeing the specimens on which this is founded, or good 
figures of them, the evidence in its fayour can scarcely be 
appreciated fully. 
Dr. Baldamus’s theory had been some time known to 
me, when in 1861 I had the pleasure of being shown by 
him his collection of Cuckows’ eggs, and I can declare 
* L'histoire naturelle, éclaircie dans une de ses parties principales, ]’orni- 
thologie, &c. Paris ; 1767, p. 42. 
+ Montbeillard (Hist. Nat. des Ois, vi. p. 309) mentions it, but I am not 
aware of any one else who has done so, until M. Vian in the Revue et 
Magasin de Zoologie for 1865 (p. 40), referred to it, and from this reference I 
became acquainted with it. 
