DESTROYERS OF SQBMERGED WOOD — MURPHY. 219 



into the territory of the other. The reason that these destruc- 

 tive creatures cannot thrive on the same ground is quite apparent. 

 The Teredo enters the wood in the embryonic stage tlirough an 

 aperture having- a diameter of one-quarter to half a millimetre 

 only, which enlarges little by little until it reaches a diameter of 

 five millimetres or more. This diminutive entrance protects it 

 from its enemies the Annelides. If the opening is enlarged by 

 the exterior burrowing of the Limnoria, the Teredo becomes 

 a prey to its enemies and cannot exist. Both borers may be 

 found on the same pile at work at the same time, but such are 

 not the fittest conditions provided by nature for their growth 

 and development. 



Since the researches of Quatrefages and Kater and the report 

 of the Dutch commission on the Teredo and its depredations, 

 nothing more reliable as to fecundation of eggs, development and 

 •expulsion of young, has been added. Quatrefages tells us that 

 the eggs pass through a series of modifications, such as is met 

 with in the examination of all animals, that in the third phase 

 of development the bivalve shell is formed, the foot appear- 

 ing on the outside, that the embryo possesses the faculty of 

 locomotion, and that the development is very rapid, four days 

 on\y being required for the acquisition of full equipment 

 for living in wood. Kater observed them in large num- 

 bers on the surface of wood towards the end of June and by 

 the loth of July he found them in the interior, in the form of 

 perfectly developed Teredos. 



They enter the wood thus in small openings which, as we ha^'e 

 before remarked, are necessary for their protection as well as, 

 probably, for their growth and manner of sustenance. With such 

 information before us and with the knowledge, from my own 

 •observations, that they seldom, if ever, pass from one piece of 

 timber to another, I was led to think that a pile made of 

 l>oards wutli a thick coating of tar, or white lead, between them, 

 to protect the inner leaves from the attachment of larvae or 

 the penetration of the full}^ developed teredo itself, might arrest 

 their depredations, or perhaps, prevent them fi-om entering fur- 

 ther than the outer coverinp'. 



