58 THE ZOOLOGIST. 
varied, by which marine animals bore for the present, a glance 
may now be taken at the methods of protecting timber from 
their ravages. Very many suggestions and experiments have 
been made with this view. Even so early as the days of Sellius 
several hundred preparations were known, most of which, how- 
ever, were useless. At the present time the means for defending 
submerged timber from a scourge so serious group themselves 
under two heads, viz. (1) in regard to the kind of wood employed, 
and (2) the treatment of the wood before immersion. 
In the first category, it is stated that T’eredo will not touch the 
Pyengadu or Ironwood Tree, a species of Acacia from the Burmese 
forests. It contains a thick gelatinous oily substance. The same 
is said of Huon or Macquarie Harbour Pine, Tasmania, and the 
Kaurie or Cowdie Pine (Dammara australis) from New Zealand. 
The Jarrah Tree (Hucalyptus marginatus) defies Teredo and the 
white ants, so that copper-sheathing is unnecessary, a state 
probably due to its odour or taste, as no specially distasteful 
chemical substance, acid or otherwise, has been found. The 
Heartwood Tree (Nectandra Rhodiei) of Guiana, which furnishes 
Beberia, is considered by some to be proof against Teredo, 
though this is doubtful. It pertains to the natural order 
Lauracee, which comprehends sweet-bay, camphor, sassafras, 
and other well-known forms. Other woods, such as sneeze- 
wood from the Cape; teak, hemlock-tree with its bark, Cay-don 
from Cochin China; and various hard and close-grained woods 
have been recommended, though, so far as known, with com- 
paratively little success on a large scale. 
Under the second head fall all the chemical and other sub- 
stances which have been applied to the exterior of the wood, or 
forced into its tissue under great pressure. Many preparations 
of tar and varnish would suffice to keep out the young T'eredo, if 
such would remain intact, but unfortunately friction soon inter- 
feres with their continuity, and then a lodgment is effected. 
Soluble bitumen (composed in all probability of pitch and wax), 
silicate of lime, and various patent compositions have each in 
turn been tried externally; while the silicate of lime, creosote, 
and other fluids have been driven under great pressure into the 
tissue of the wood. 
The Dutch Commissioners experimented with metallic sub- 
