UNITED STATES DEPARTMENT OF AGRICULTURE 
BUREAU OF BIOLOGICAL SURVEY 
WASHINGTON, D. C. 
July 23,191^ 
Mr. Alex Viietmore 
San Juan, Forto Rico 
Dear Mr. Wetmore: 
The mailing tube containing two bottles of diatoma.ceous ma- 
terial from Porto Rican Yi^aters is at hand. Our expert has examined 
the contents so far as to be able to state that they contain ex- 
ceedingly few diatoms - a fact all the more surprising because, 
judging from the appearance of the muddy sand, it should have teen 
fairly swarmed with diatoms. You could not possibly have selected 
better looking material, and I am entirely at a loss to understand 
why Porto Rican waters contain diatoms in such comparatively 
small numbers - compared, for instance, with Florida marine de- 
posits. Should you have time and opportunity, you might make one 
more gathering, if possible, from the bottom of shallow water in 
some harbor or sheltered bay. It is evident that the brackish 
water, for some reason or other, is very deficient in these mi 
A 
croscopic plants. 
I should judge from the nevirspapers that the plague situation 
in Porto Rico is improving and that the disease is being controlled. 
Very truly yours, 
LL 
