UNITED STATES DEPARTMENT OF AGRICULTURE 
BUREAU OF BIOLOGICAL SURVEY 
WASHINGTON, D. C. 
» 
Uarch 22,1912 
I'-ir. Alex 'Wetmore 
Box 626 
San Juan, Porto Rico 
Dear tlr. Wetmore: 
The Dox containing the two vials of ooze reached rne safely. 
One of them contained very few Diatoms, and the other a good 
nany and of interesting kinds; but why did you not gather some 
when you were about it? In order to separate the Diatoms from 
the sand, mud, and organic matter it is necessary to boil the 
whole for hours in. strong acids and alkalis, and to do this and 
be sure of results a moderate amount of ooze is essential,- say 
irom a half a cup to a cupful. 
V/ith this I am sending two tubes each containing one bottle. 
One of these will answer very well for a single gathering. As 
I stated above, to insure that fermentation does not take place 
and dIov/ out the cork, it is only necessary to add a little 
formalin or alcohol and then it will come througli without any 
difficulty. 
I iiaay add that if out of three gatherings you secure a 
gooaly quantity of Diatoms in one, you may consider yourself 
fortunate. VAien you get another chance please take a rather 
more liberal quantity of the mud. 
Very truly yours, 
LL 
Chief p Biological durvey 
