328 



wood to collect over a period of 10 days and estimated it b>' means of sedimentation 

 tubes. The results are shown graphically in figure 134. The amount of wood discharged 

 at a salinity of 30 parts per 1000 was regarded as representing 100% activity, and the 

 activity for the different salinities estimated accordingly. It will be noted that the 

 activity at a salinity of 16 is 45% and at 10 is about 10%, of the normal. That the 

 organisms can survive salinities as low as 10 parts per 1000 for a period of two weeks 

 has been shown by the experiments on the lethal salinity. But it seems very doubtful 

 that an organism which is exhibiting only 45%, of the normal in a fundamental activity 

 will continue to live and reproduce in that environment. 



This view is further supported by the distribution of Limnoria. The committee 

 report of the Danish Engineering Association (1921) shows the limiting salinity for 

 this organism in Scandina\ian harbors to be 16 parts per 1000. They point out that 



10(1 



9(1 



8(1 



7(1 



6(1 



40 



20 



2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 

 Salinity in Parts per Thousand 



Fig. 134. Graph of the activity of Limnoria Ugnorum in water of various salinities. 



