EXTRACTS FROM FOREIGN PERIODICALS. 
157 
and the largest about two inehes, which led me to suppose that they were one or two 
months old. There were three or four layers superimposed one upon the other; 
tJie horses’ feet and the carriage-wheels crushed many thousands. We travelled 
upon the road, thus covered, at least a quarter of an hour, at the usual pace.”^— 
|[What would Mr. M’Adam have said to such a road! We hope there were no 
ladies in the diligence !— Ed.] 
4. Remarkable Instance op Intelligence in a Dog. —Mons. Alphonse De 
Candolle has communicated the following observations on the instinct of ani-- 
mals:—Being last October in the neighbourhood of Aiguesmortes, I had occasion 
to observe a remarkable instance of intelligence in a Dog. The day was hot, and 
the season unfavourable, by reason of the trade winds so troublesome on the 
shores of the Mediterranean. After walking several hours in the desert which 
separates the town of Aiguesmortes from Carmagne, we arrived at a plain where 
we found, in the midst of a whirlwind, some remains of a shipwreck. Out of 
three Dogs which had followed our guide, only two had accompanied us to this 
spot. Their black hair attracted the rays of the sun, and the poor creatures, like 
ourselves, seemed to find the sand somewhat too warm to be pleasant, I sat 
down on a mat half buried in the sand. One of the Dogs quickly conceived the 
idea of establishing itself near me. It nestled close to a horizontal plank, by 
way of procuring a little shade, but finding this insufficient, it hollowed the sand' 
until it came to the part moistened by the sea. It then stretched itself with 
delight in this fresh and shady bed. There, said I, is an undoubted instance of 
reason. Had it been instinct, every animal of the same species, placed in similar 
circumstances, would have acted alike. But the other Dog, though of the same 
race, and also weary, knew not what to do; it writhed in the hot sand. One of 
these Dogs evidently remembered that by hollowing the sand-hillocks, a cool and' 
moist part is arrived at, and it applied the reminiscence to this particular case. 
It may perhaps be said, that the Dog which made no burrow had never been on 
the plain, and had therefore had no opportunity of ascertaining the coolness of 
the sand underneath. But this is not probable, since both Dogs had been accus¬ 
tomed to the sea-shore. This, again, is another difference between instinct and 
reason; instinct acts without previous experience: The Dog of Peccai, the less 
sagacious of the two, might perhaps one day have learnt to burrow to the cool 
part of the sand hills .—Bibliotheque Universelle de Geneve. 
5. On the Structure of Teeth. —M. Retzius, in a letter dated September 
5, 1836, informs us, that he and M. Purkinje had been occupied nearly at the 
same time, but unknown to each other, with microscopic investigations on the 
structure of teeth. The observations of the latter anatomist have been promul¬ 
gated in the inaugural theses of two of his pupils, MM. Pranckel and Ras- 
CHOW ; M. Retzius has published his own in the last volume of the Transac- 
