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nearly the whole Island conditions prevailing which favored the 
development of rusts and other parasitic fungi: heavy dews which 
completely covered leaf surfaces with a solid film of moisture, 
cool nights and hot days. Fortunately for us, we largely missed 
the rainy season on this part of the Island, so that during the 
month and more which we spent in and about Mayagtiez, we 
were deterred only a few times by rain. 
Making Mayagitez headquarters, we made rich collections in 
the vicinity and surrounding districts, including the mountainous 
region around Maricao, north to Anasco, and south to the south- 
east corner of the Island, around Boqueron, Guanica, Yauco and 
San German. Returning to the north shore on April 5, we spent 
several days again in Barceloneta, testing the effects of sulphur 
and other dust mixtures, as mentioned above, on certain plant 
diseases, and collecting in the vicinity. We then made head- 
quarters for the remainder of our stay of two weeks and a halt 
in an American boarding house at Martin Pefia, a suburb of San 
Juan. Here we had at hand the facilities so freely tendered us 
at the insular Exeriment Station at Rio Piedras, and to Director 
Tower and Mr. J. A. Stevenson, plant pathologist of the station, 
we are under especial obligations. Our trips from this locality 
included excursions to El Yunque, the high mountain on the 
eastern end of the island, to Naguabo and the near-by mountains, 
to Manati and other points in the grape-fruit district, and, finally 
a hasty trip to points near the middle of the Island and to Coamo 
on the south slope. 
It will thus be seen that in the comparatively short time at our 
disposal, we almost circumnavigated the island which is, roughly, 
about 100 miles long by about 40 miles wide, ascending from the 
coastal plain into the interior at about five points. We were thus 
able fully to appreciate the wonderful diversity in vegetation, due 
perhaps largely to the great differences in rainfall, which ranges 
from 123 inches annually near El Yunque at the east end, to 
practically desert conditions at many points on the south and 
southwest. This remarkable diversity of host plants was nat- 
urally accompanied by great diversity of fungous parasites. 
While it is true that quite a goodly number of parasitic fungi 
were found to be very generally distributed over the island, a 
