294 FRESH-WATEK ALG^J OF THE UNITED STATES. 



plasni into two or three series of cells, and scattered by the 

 diffluence of the sheath ; the latter formed in single series in the 

 filaments and ejected. 



CRENOTHRIX POLYSPORA, Colin. 



Filaments slightly increased in thickness towards the 

 apices; colorless, or sometimes changed to reddish or 

 ochraceous as the result of incrustation by solutions of iron. 

 Attached, or floating in small mats. 



The only plant of this genus hitherto recognized is near, 

 if not identical with Hypheothrix Kuehniana, Bab. It re- 

 ceived prominence through Prof. Colin, 1870, who was inter- 

 ested in the examination of the water-supply of the city of 

 Breslau, Silesia, and wrote a detailed history of the mode of 

 its development. Later, 1879, Dr. Zopf, searching into the 

 causes of complaints of impurities in the water furnished 

 by the city of Berlin, Prussia, took special pains to cultivate 

 this plant, and added more facts relating to its life-history 

 and rapid growth. It was found to prevail to an alarming 

 extent, developing in dark places, in deep wells, in water- 

 mains and in smaller pipes. The peculiar colorlessness, and 

 the gelatinous consistency of the plants, suggest a relation- 

 ship with some of the forms of filamentous fungi. Cohn 

 and Zopf retain it as an Algae. 



We are not aware that the plant was recognized in this 

 country until recently, 1886. It was found in somewhat 

 limited quantity, near the inlet to Lake Chautauqua, N. Y., 

 whence part of the water-supply to the city of Jamestown 

 is taken. 



Plate CCIX, figs. 1-3, a part of a filament with cytioplasm 

 divided longitudinally, turning into microgonidia, and de- 

 veloping in part, from the gonidia before separation from 

 the filament, two groups or clusters of young typical plants 5 

 figs. 4-9, niacrospores, or resting spores, single, or dividing 

 into two, and these in turn each dividing, and so on, 

 doubling the length of the filament at each division, indicat- 

 ing the process of growth ; fig. 10, part of filament under 

 higher magnification showing the arrangement of the cells ; 

 figs. 11, 12, cells, niacrospores, sliding out of the sheath ; 

 fig. 13, microgonidia gather in masses, imbedded in gelatin- 

 ous mucus, PaZwe7ta-like ; fig. 14, a small Palmetto, mass, 

 gonidia developing into plants ; figs. 15-17, three parts of 

 filaments with cytioplasm dividing longitudinally, magni- 

 fied about 600 diameters ; fig. 18, a caespitose cluster as of 

 common occurrence. 



