162 TEREDINID^E. 



But is anything learnt now-a-days, save only the arts of 

 money-making and pleasure-seeking ? 



In all probability the constitution of a shipworm is 

 poison-proof. Most of the remedies proposed in the 

 last century were of this nature, and they signally failed. 

 Quatrefages, indeed, has suggested that the production of 

 the Teredo might be checked by dissolving in the water 

 at the proper season a trifling quantity of corrosive 

 sublimate or acetate of lead, so as to destroy the sper- 

 matozoa or fertilizing agent. He tried some experi- 

 ments of this kind on a small scale in the harbour of 

 St. Sebastian. Quatrefages is an excellent naturalist, 

 and especially conversant with the natural history of 

 the Teredo ; but I fear his plan is not a practical one. 

 The Teredo attacks wood in the open sea, or in harbours 

 which the tide enters twice a day, and never in floating 

 harbours or wet docks, to which the tide has only 

 occasional access. Now, in order to prevent the birth 

 of the Teredo, which is always going on during the 

 summer months, it would be necessary that the tidal 

 harbour should be enclosed ; otherwise the poison must 

 be continually applied in prodigious quantities, and at 

 an enormous expense, or else it would be diluted to such 

 an extent by the action of the tide and waves (to say 

 nothing of the river which is generally indispensable as 

 a scouring power, and therefore flows through nearly 

 all such harbours), that it would become too weak to 

 produce the desired effect. An eminent civil engineer, 

 Mr. Hartley, of Liverpool, recommended green-heart 

 timber to be used in harbours ; the costliness, however, 

 of that kind of wood is a serious objection to this re- 

 medy. Copper-sheathing and scupper-nailing are often 

 and successfully employed to protect piles in exposed 

 situations. The former is also expensive; and the crust 



