ae 
a ages ged Shi ergs S5- 
We te “e 
a 8 Phan 
418 
NATURE Bs 
[April 3, 1873 
soothed ; and then they recover. Itis well-known that cer- 
tain lesions of the br iin, or internal parasites, cause animals 
to turnincessantly round and round, either to the right or 
left, sometimes accompanied by a Dawn movement : 
and I have just read, through the kindness of Dr, Brunton, 
the account given by Mr. W. J. Moore (/udian Medical | 
Gazette, Jan. and Feb 1873) of the somewhat analogous 
result which followed from pricking the base of the brain 
of a pigeon with a needle. Birds thus treated roll over 
backwards in convulsions, in exactly the same manner as 
do the ground-tumblers ; and the same effect is produced 
by giving them hydrocyanic acid with strychnine. One 
pigeon which had its brain thus pricked recovered per- 
fectly, but continued ever afterwards to perform summer- 
saults like a tumbler, though not belonging to any 
tumbling breed. The movement appears to be of the 
nature of a recurrent spasm or convulsion which throws 
the bird backwards, as in tetanus; it then recovers its 
balance, and is again thrown backwards. Whether this 
tendency originated from some accidental injury, or, as 
seems more probable, from some morbid affection of the 
brain, cannot be told ; but at the present time the affec- 
tion can hardly be called morbid in the case of common 
tumblers, as these birds are perfectly healthy and seem to 
enjoy performing their feats, or, as an old writer expresses 
it, “showing like footballs in the air”? The habit appa- 
rently can be controlled to a certain extent by the will. 
But what more particularly concerns us is that it is strictly 
inherited. Young birds reared in an aviary which have 
never seen a pigeon tumble, take to it when first let 
free. The habit also varies much in degree in different 
individuals and in different sub-breeds; and it can be 
greatly augmented by continued selection, as seen in the 
house-tumblers, which can hardly rise more than a foot 
or two above the ground without going head over heels in 
the air. Fuller details on tumbler-pigeons, may be found 
in my “Variation of Animals under Domestication,” 
vol. i. pp. 150, 209. 
In conclusion, from the case of neuter insects, of cer- 
tain reflex actions, and of movements such as those of the 
tumbler-pigeon, it seems to me in the highest degree 
probable that many instincts have originated ‘rom modi- 
fications or variations in the brain, which we in our 
ignorance most improperly call spontaneous or acci- 
dental ; such variations having led, independently of ex- 
perience and of habit, to changes in pre-existing instincts, 
or to quite new instincts, and these proving of service to 
the species, have been preserved and fixed, being, how- 
ever, often strengthened or improved by subsequent 
habit. 
With regard to the question of the means by which 
animals find their way home from a long distance, a striking 
account, in relation to mah, will be found in the English 
translation of the Expedition to North Siberia; by Von 
Wrangel: He there describes the wonderful manner in 
which the natives kept a true course towards a particular 
spot; whilst passing for a long distance through hum- 
motky ice; with incessant changes of direction; and with 
no guide in the heavens or on the frozen sea: He states 
(but I quote only from mémory of many years standing) 
that he, an experienced surveyor; arid using 2 compass, 
failed to do that which these savages easily effected. 
Yet no one will suppose that they possessed any special 
sense which is quite absent in us. We must bear in 
mind that neither a compass, nor the north star, nor any 
other such sign, suffices to guide a man to a particular 
spot through an intricate country, or throuzh hummocky 
ice, when many deviations from. a straight course are 
inevitable, unless the deviations are allowed for, or a sort 
of “dead reckoning” is kept. All men are able to do this 
in a greater or less degree, and the natives of Siberia 
apparently to a wonderful extent, though probably in an 
unconscious manner. This is effected chiefly, no doubt, 
by eyesight, but partly, perhaps, by the sense of muscular 
movement, in the same manner as a man with his eyes 
blinded can proceed (and some men much better than 
others) for a short distance in a nearly straight line, or 
turn at right angles, or back again. The manner in 
which the sense of direction is sometimes suddenly dis- 
arranged in very old and feeble persons, and the feeling of | 
strong distress which, as I know, has been experienced by i 
persons when they bave suddenly found out that they have 
been proceeding in a wholly unexpected and wrong direc- | 
tion, leads to the suspicion that some part of the brainis 
specialised for the function of direction. Whether animals 
may not possess the faculty of keeping a dead reckoning 
of their course in a much more perfect degree than can 
man ; or whether this faculty may not come into play on 
the commencement of a journey when an animal is shut 
up in a basket, I will not attempt to discuss, as I have on 
sufficient data. 
I am tempted to add one other case, but here again I 
am forced to quote from memory, as I have not my books 
at hand. Audubon kept a pinioned wild goose in confine- 
ment, and when the period of migration arrived, it became 
extremely restless, like all other migratory birds under 
similar circumstances ; and at last it escaped. The poor 
creature then immediately began its long journey on 
foot, but its sense of direction seemed to have been per- 
verted, for instead of travelling due southward, it proceeded 
in exactly the wrong direction, dite northward. 
CHARLES DARWIN 
j 
UNIVERSITY OARS 
IL. 
Ver resume our remarks at the point at which we left 
off last week, zz. the uncomfortable one of the 
killed and wounded in the great annual battles on the 
Thames. 
Of the 294 men who rowed in the 26 races taking place 
between the years 1829 and 1869 (both inclusive), 39 men 
have died, or rather we should say 40, for one other 
death has occurred, apparently since the introductory 
portion of the work was written, and the tables inthe 
appendix were compiled, and we are assured on the 
authority of elaborate statistics and the logic of averages, 
that, in comparison with other portions of the civil com- 
munity, this is a very moderate death-rate. Of the dis- 
eases which have carried off in youth or early manhood * 
these 40 men, we will only instance one kind, as being thé 
only one with which boat-racing ¢an presumably be con 
hecied, nainely constimption, “ and other diseases of thé 
chest :” to thesé perhaps may be added “Heart affee- 
tions.” Of the former there are 9, of the latter 3, in all i2. 
We are assured, again, that this percentage is a mode- 
