PEBBLE-SWALLOWING ANIMALS. 
27 
stones found were foreign to the locality and not such as would be 
picked up in the Gardens. They must have been in the stomach for 
years. All were beautifully rounded and polished. (At the reading of 
this paper one of these stomachs from the Cape tilled with pebbles was 
exhibited, being kindly lent by Dr. Harrison, and formed a most 
interesting and convincing piece of evidence. The whole length is 14 
inches, and largest circumference 9 ^ inches ; in its dried state it weighs 
2 lbs. 2 ozs., and as the viscus is probably only 2 ozs. or less, there 
must be quite 2 lbs. of stones — all of these, which can be seen through 
the small incisions made, are of white or pale quartz, well rounded, and 
of a silky smoothness, very different in the latter respect from the 
ordinary beach pebble. Judging from the average weight of those 
which can be removed, it is estimated the number of the pebbles in this 
stomach would be from 90 to 100). 
Some years afterwards, in 1894, the same writer, in his Presidential 
Address to the “Bristol Medico-Chirugical Society,” again refers to the 
subject as follows : “It is not at all an uncommon thing to find in the 
stomachs of Seals quantities, even large quantities, of stones, gravel, 
and pieces of rocks, rounded off, which have evidently been in the 
stomach a very long time. This condition is found in the Sea-lions, 
or Cape Seals, to a more marked extent than in ordinary Seals. I 
have the notes of a case where ten pints of stones, weighing twenty- 
two pounds, were found. The explanation of the reason does not seem 
very clear. The stones are doubtless swallowed, but for what purpose ? 
The tradition amongst the Seal hunters is this, that when the Seals get 
very fat they cannot sink themselves in the deeper water with the same 
facility as when they were thinner, and so they take in the stones as 
ballast, and the stomachs, with their strange contents, are locally 
known as ‘ Ballast Bags.’ 
The theory is a pretty one, almost romantic, but I don’t think we 
can accept it. I collected a good deal of information about this 
subject some years ago, and embodied the results in a paper I had the 
honour of reading before the ‘Bristol Naturalists’ Society.’ I think 
that probably there is a physiological reason.” (These notes by Dr. 
Harrison will be further referred to later on). 
Some observations by two French geologists appear in the “ Bulletin 
Soc. Geologique de France,” C. Janet (1891), and Vaillant (1892), both 
of whom give numerous instances of pebbles found in fishes, proving 
the possibility^ of their being transported from their original to other 
localities by such means. 
Frank T. Bullen (the well-known author of man}^ excellent works on 
Marine Life) writes (1904), “ All Seals and Penguins (which are a sort 
of connecting link between seal and bird) have a habit of swallowing 
large quantities of stones, most probably for digestive purposes, since 
they do not masticate their food. These stones, after some ,tinie, 
naturally have their angles rubbed off and become pebbles, like the 
smaller fragments in a bird’s gizzard.” 
In his entertaining work, “Creatures of the Sea” (1905), he refers 
to the Penguin in the following quaint passage, “ A ballasted bird . . . 
Like most of the Seals, and for probably the same hidden digestive 
