The number on any one panel never exceeded a trace rating, except in 

 one panel removed early in 19^7 after 10 months' aulmergence, where 

 a peak low in the moderate rating was attained. 



b. Pier Ho. 1 (Fuel Oil Pier ). Limnoria occurred in 19 

 of the 58 control panels, but no forms were recorded after June 2h, 

 1947. The largest number on any one panel was 75 forms. They also 

 occ\H'red on k^ of the k^ test panels. "-During 19^5 and 19^6 the attack 

 was merely low in the slight rating, but in 19^7 i"t attained a peak 

 rating of moderate. 



c. Pier No. 8 . Limnoria occurred in 22 of the 56 control 

 panels. The largest number on any one panel was 115 forms. They occurred 

 on all except one of the hk test panels. The attack rated slight in 

 19^5^ attained a peak rating of moderate in 19^6, and lapsed to low in 

 the slight rating In 19^7. 



It is of interest to note that panels made of a number of 

 different kinds of wood were used on all 3 test boards in 19^^. 

 The woods used included Douglas fir, western hemlock, western white 

 pine, and cedar. In addition, panels of Douglas fir with heartwood 

 and sapwood also were used. Unfortunately, the use of the different 

 kinds of wood did not always coincide with the incidence of the Teredo 

 attack. It was perfectly clear from an analysis of the results, however, 

 that one kind of wood was filled or riddled by Bankia aetacea as readily 

 as another, and it made no difference whether the Douglas fir panels were 

 of heartwood or sapwood. It is also relevant to note that western hemlock 

 has been recommended for piling by some engineers because of its alleged 

 resistance to attack by marine borers. Tlie results of these tests' clearly 

 show that this kind of wood was riddled by Bankia setacea and attacked 

 by Limnoria Just the same as were the other kinds of wood. 



AJY.Oll- Foxaing Agents 



1. Silt . Silt occurred on all the panels at all three locations, 

 except on 2 control panels at each location and on single test panels 



at Pier No. 1 (Fuel Oil Pier) and Pier No. 8. The deposits mostly ranged 

 from traces to light on the panels of the control series and from light 

 to moderate on those of the test series. 



2. Algae . A trace of a green alga occurred on a single test 

 panel at Pier No. 1 (Fuel Oil Pier). - 



5. Invertebrate animal phyla . 



a. Porifera (sponges ). Two 'small sponges occurred on a 

 single test panel at the Receiving Station Pier. 



165 



