148 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



formed, reaching to the surface of the host plant ; through this 

 the zoospores escape. In fronds of Iridaca, Sarcophyllis, etc. 

 Greenland, Alaska to Cal. Northern Europe. 



4. RHODOCHYTRIUM Lagerheim, 1893, p. 43. 



Cell dark red in color, with rhizoidal branching prolongations 

 among the cells of the host plant ; developing numerous bicili- 

 ate gametes which escape through a narrow neck, and unite to 

 form a zvgote which penetrates between the epidermis cells of 

 the host, and develops a cell like the original one ; the gametes 

 may also develop to such a cell without copulation. Thick 

 walled resting cells also formed, whose development is unknown. 



The genus seems intermediate between algae and fungi ; 

 whether it possess chlorophyll is not certain ; the mycelium-like 

 prolongations appear to draw nourishment from the host. Only 

 one species is known. 



R. SPILANTHIDIS Lagerheim, 1893, p. 43, PI. II. Cell 

 spherical to ovoid, or irregularly rounded, 100-200 ^ diam., 

 with relatively thin wall, communicating with the exterior of 

 the host by a tube, the end of which opens to give passage to 

 the gametes ; branching prolongations abundant, diminishing 

 to about 4 /a in the final divisions ; gametes obconic to spherical 

 with two cilia attached to the red anterior end ; resting cells 

 100-200 /A diam., with thick, stratified wall. In stems and leaves 

 of Ambrosia artemisiifolia. Fig. 34. South Carolina. 



So. America. 



5. CHLOROCYSTIS Reinhard, 1885, p. 4. 



Cells as in Chlorochytrium, but asexual reproduction by 4-cil- 

 iate zoospores ; no sexual reproduction known. 



C. COHNII (Wright) Reinhard, 1885, p. 4, PI. I; Moore, 

 1900, p. 100, PI. X; P. B.-A., Nos. 565, 1121. Cells 16-26 /x 

 diam., spherical or nearly so, chromatophore bright green, 

 usually somewhat star-shaped and covering only part of the cell 

 wall, but sometimes covering the whole, with one large pyre- 

 noid ; zoospores of two sizes, one spherical, 6-7 //. diam., the 

 other pyriform, 2.5-3.5 ^ diam., both 4-ciliate, escaping through 

 an opening in the cell wall ; either kind of spore can germinate, 

 and no conjugation has been observed. Fig. 35. Greenland to 

 Mass. Europe. 



This species forms dense coatings on EntcroDiorpha, Schizo- 

 ncma and other marine plants, often penetrating into the tissue 

 of the host, but apparentlj 7 never entirely covered by the latter. 



