18 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



will resist their attacks. The pile from which the section exhibited 

 was cut was driven about fourteen months ago. Externally at first 

 glance the stick seemed to be as sound as when first put in place, but 

 on close examination minute pin holes were seen. Within a thin 

 outer shell the wood is honeycombed in all directions with holes up 

 to half an inch in diameter. Near the outer shell the holes are 

 smaller than towards the center ; all of which seems to indicate that 

 the embryo is deposited on the outside and develops in size and 

 rapacity as it works its way inward. The head is covered with a 

 shell open in front with cutting edges like a ship's auger ; but 

 instead of the cut wood being outside as with that implement, the 

 particles are drawn into the animal's mouth as it works its way 

 onward, and nearly all of it is assimilated, as but very little dust is 

 found in the passages in the stick. It secretes a thin layer of calcare- 

 ous matter with which it lines the chambers it eats out. The tail is 

 a most peculiar part of its structure, appearing like the vertebrae of 

 small fishes or two small feathers attached to either side of the 

 exti'emity, and which is probably used to propel the Teredo forward. 

 The rest of the body is a soft white mass. It is said to confine its 

 attacks to wood between high and low water marks, or a distance of 

 about 12 feet in Bui-rard Inlet. Creosoting has been tried as a 

 preventive, but in many instances with but indifierent success. A 

 stick of " gumwood" brought from Australia was driven some time 

 ago, as it is said to be impervious to them, but I have not learned 

 that it has been examined since. Copper sheathing has been adopted 

 on the piles of a small wharf which has stood for some years here. 

 This is, I believe, about the only complete way of excluding them. 

 Iron piles are largely used in the construction of tlie C.P.R. wharves. 



G. S. Ryerson, M.D., L.R.C.S., Edin., then read a paper on 

 " The Influence of Tobacco and Alcohol on Vision." 



He stated that Mr. Jonathan Hutchinson was the first to describe a 

 palsy of the optic nerve with certain general symptoms due to the 

 poisonous influence of tobacco and alcohol. He quoted a number of 

 medical authorities in support of his contention. The conditions which 

 render persons particularly subject to jioisonous efi'ect of tobacco are a 

 sedentary occupation, middle life, prolonged use of and rapid consump- 

 tion of Tobacco. The quantity necessary to produce ill eflects was on an 



