1899-1900. The Broch of Torwoodlee. 117 
attracted to these places. After a pond has been fed in 
this way for about a fortnight the fish collect very quickly, 
and can be fed in a few minutes. 
_ The varieties of trout which are reared are the Salmo 
levenensis or Loch Leven trout, S. fario or common trout, 
_ §. fontinalis, and S. irideus or rainbow trout. Of these last 
a number were netted and taken out of one of the ponds for 
our inspection, but at the time of our visit the characteristic 
iridescence had not developed itself. 
_ That the hatchery is not a mere experimental station but a 
commercial enterprise is evidenced by the large number of ova 
-packing-cases and fish travelling-tanks and railway vans built 
specially for the live-fish traffic. That the enterprise is suc- 
cessful is evidenced by the demand being greatly in excess of 
the supply, necessitating the construction of new ponds cap- 
able of rearing 50,000 more yearlings. Ova are sent to all 
| parts of the world, packed in trays with perforated zinc 
bottoms. To supply the oxygen necessary to the life of the 
ova, they are packed between layers of fresh sphagnum moss. 
Fry and older fish are conveyed in specially constructed tanks 
of galvanised iron. Considerable attention has to be given 
to the aération and temperature of the water; and before 
‘despatching, the fish have to undergo a course of treatment to 
fit them for the journey. 
: | > 
THE BROCH OF TORWOODLEE. 
By Dr STEVENSON MACADAM. 
TuE doings of our ancestors or predecessors in prehistoric 
times are chronicled, not in writings or even in folk-lore, but 
in the remains of their places of abode and the fragments of 
their contents. The earliest places of shelter appear to have 
been cave dwellings, where the natural cavities in the rocks 
were taken advantage of, and such were gradually developed 
into earth dwellings, which were scooped out of the ground 
and often mounded over, forming chambered cairns or eirde 
