1892.) Bacterial Investigation of the Sea. 315 
possible chance for contamination is from diffusion which 
might take place from the sides and lower end of the iron 
tube. The material is ‘within this for so short a time how- 
ever, that in so solid and dense a mass as the mud core, this 
element of error has, I believe, little or no effect. 
Attention may now be directed to some of the problems 
which arise in connection with the investigation of marine 
bacterial life. Space will only permit a reference to one or 
two phases of the work, and I can only briefly recapitulate 
some of the results which have already been obtained. 
First, in regard to the presence of bacterial forms in the 
sea. o determine the bacterial content of the sea, it is nec- 
essary for one to secure material outside of the contamination 
limit from the land. This is of course a varying distance, 
depending upon the configuration of the shore and other con- 
itions. Fresh water or sewage germs discharged into the 
sea soon perish on account of the change in their nutritive 
medium. Of course any quantitative determination of the 
bacterial contents of the sea must exclude all samples taken 
within this limit. To my knowledge, the surface water of the 
sea has not been analyzed bacteriologically at any great dis- 
tance from land, but samples taken from the coastal line out- 
side of land contamination show that micro-organi invari 
ably present in the water. The number per unit of volume 
varies naturally within certain limits, yet there is on the 
Whole quite a constant average number per unit of measure 
in these surface waters. 
taken at different depths from the surface down to a depth of 
“a feet Showed that bacteria were present in all weet 
th Zonary distribution was to be observed in any case an 
© Intermediate depths as well as the water immediately 
“ag me Sea floor were found to contain germs in about the 
© Proportion as at the surface. 
