418 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 5 



above, although the real cause was probably the exhaustion of oxy- 

 gen and the poisons given off by putrefactive bacteria during the 

 decay of the abundance of organic matter present. 



It is hard to believe that cattle can be killed in this manner. When 

 one is riding by train through the country in August and Septem- 

 ber, again and again flashes upon the vision scene after scene of 

 cattle peacefully resting beneath the trees and chewing their cuds 

 beside the still ponds covered with apple-green water bloom, or 

 frog spit, as the farmers call it. 



The common fresh-water alga Botryoooccus frequently forms wa- 

 ter bloom. The radially arranged green spherical cells are em- 

 bedded within a tough, sometimes orange-colored mucous envelope, 

 which is folded or wrinkled and frequently drawn out into irregular 

 lobes or spines. The deposits formed by this alga are distinguished 

 by a slow rate of decay and are sometimes responsible for consid- 

 erable sapropelic accumulations (the slimy sediment of organic 

 debris derived from aquatic plants and animals). Various author- 

 ities believe that the Paleozoic remains {Pila, Reinschia) found in 

 boghead coals are ancient allies of Botryoooccus and that such coals 

 were to a great extent formed by them. 



Odors of the algae may interfere with the lake as a recreational 

 center. Often they affect the taste of reservoir water. Not until the 

 middle of the past century was the practical significance of the study 

 of organisms in water realized. Dr. Hassall, of London, England, 

 was the first to call attention to the value of microscopic examinations 

 in the interpretation of drinking-water analyses. About the same 

 time, Ferdinand Cohn (1853), working on the Continent of Europe, 

 wrote his treatise entitled " Living Organisms in Drinking Water ", 

 in which he indicated the correlation between aquatic life and water 

 purity. To the Massachusetts State Board of Health belongs the 

 credit of having begun as early as 1887 a systematic examination 

 of all the water supplies of the State. 



MyHophyllum and a number of the filamentous algae possess a 

 natural odor that gives a strongly vegetable and at times almost 

 fishy taste to the water. The colonies of the alga Symura give a 

 strong cucumber taste to the water. Algal odors are sometimes strong 

 enough to be sensed in the vicinity of reservoirs. In some cases the 

 odors have been wafted by the wind for distances of a quarter of a 

 mile. The decay of littoral growths of filamentous algae may cause 

 objectionable odors along the shore. The odors derived from the 

 exposed bottoms of reservoirs when the water has been drawn off are 

 familiar to all of us, but it is not generally known that these odors 

 are largely due to algae. Sometimes algae are blown inshore by 

 the wind and stranded on beaches where they decay and produce 



