MONSOON-DUST OF SOUTH ATLANTIC OCEAN. 
125 
stroyed, and therefore cannot be due to any peculiarity of the 
water itself. 
Hitherto it has been generally held in explanation of the phe¬ 
nomena that the monsoon wind at the time of this peculiar appear¬ 
ance, blowing over the long stretch of forest along the Brazilian 
coast becomes laden with pollen, especially that of the Abietineae. 
When the pollen-laden breezes blow over the ocean the pollen falls 
upon the surface. So, during the pollen season, the ocean surface 
would owe its strange color to floating pollen grains. 
This explanation has recently been shown to be quite erro¬ 
neous. Reinsch, from whose paper in Flora this note is in part 
a rather literal transcription, has examined samples of water taken 
off the coast of Brazil (Lat. 19.34 0 S., Long. 38.58° W.) from 
water that showed the peculiar color. These samples were found 
to contain quantities of one of the Oscillariaceae, belonging to the 
genus Trichodesmium, established by Ehrenberg. Three differ¬ 
ent species occur floating on the surface of different oceans. Ac¬ 
cumulating in endless mass they give rise to the phenomenon 
known as “ sea blossoms” ( Seeblute ). The color varies from 
purple-red to brownish yellow and yellowish green. The ma¬ 
terial examined by Reinsch was classified as Trichodesmium 
Hildebrantii Gom. forma Atlantica. 
Ehrenberg* in 1830 described a similar coloring of the sea in 
the Gulf of Sinai, and attributed the phenomenon to the presence 
of these algae. 
There is also recalled in this connection the “ flowering ” of 
some of the Adirondack lakes, described by Howe,f and due to 
the presence on the water surface of quantities of Gloiotrichia 
echinulata. 
The “ water bloom ” of some of the glacial lakes of Minnesota 
is also attributed by Nelsoni to the presence of algae. 
C. S. G. 
* Ehrenberg, Annalen der Phys, rind Chemie, 18:506. 1830. 
f Howe, Marshall A., A note on the “ flowering ” of the lakes in the 
Adirondacks. Torreya, 3 : 150. 1903. 
X Nelson, A. P. B., Observations upon some algae which cause “ water- 
bloom.” Minn. Bot. Studies, 3:51. 1903. 
