BORING LIFE 



141 



when they are able to infect new timber. It has been shown 

 by experiments that these larval Shipworms are attracted 

 by wood or by an extract of wood made in alcohol or 

 ether, and, as a result of this attraction, they remain on 

 its surface should they chance to drift there, whereas they 

 do not remain on any other hard surface such as stone. 



Very soon after it has alighted on the surface of the wood, 

 the larval Shipworm begins to change ; first of all it loses 

 the crown of tiny hairs whereby it swims, developing in 

 its stead a long, tongue-shaped organ or foot by means 

 of which it moves about on the wood until it finds a suitable 

 place to begin boring. This having been found, it com- 

 mences operations, first, it is said, covering itself with 

 fragments of wood or other particles. 

 Both shell and foot are quickly con- 

 verted into those of an adult Ship- 

 worm and the animal begins to bore 

 its way quickly into the wood, the 

 pallets and the siphons are formed and 

 remain attached to the burrow near 

 its opening while, as the burrow 

 grows longer and longer, the naked 

 body elongates until the long, worm- 

 like appearance of the adult is gained. Larva of Shipworm (Teredo) 



It is usual for them to enter the wood ^^^^ ^ ^° ^^^^ ' 



at right angles to the grain but they soon turn in the 

 direction in which this runs and excavate a long burrow. 

 However many animals there may be in a piece of wood, 

 the burrows never run into one another, to avoid this 

 they will twist and turn and interlace with one another in 

 the most intricate manner, as an X-ray photograph of a 

 piece of heavily infected timber shows extremely clearly 

 , (Plate 54). Owing to the. small size of the openings of the 

 ^burrows the wood may be heavily infected and show no in- 



