450 Unwersity of California Publications in Botany L v ol. 8 



This species, like Streblonema my rionemat aides and S. scabiosum, 

 has the larger part outside of the host. It penetrates to a considerable 

 depth among the cells of the uninjured host, later apparently mechanic- 

 ally causing the death of a few surface cells and an abnormal growth 

 of others, giving to the surface a rugose appearance. The plants 

 seem to associate in small groups of indefinite shape and size, often 

 confluent and although small, can readily be detected by the peculiar 

 appearance they give to the host. 



13. Streblonema scabiosum S. and G. 



Fronds forming circular to elliptical pustules of indefinite size 

 on the host ; penetrating portion profusely branched, at first pushing 

 between the cells causing their death, later taking possession of the 

 lumen of the cell, causing complete disintegration ; erect filaments 

 extending beyond the surface of the host, unbranched or more or less 

 f asciculately branched at the base, 50-80/* high ; cells of the creeping 

 filaments very irregular in shape and size ; cells of the erect filaments 

 cylindrical, 4.5-5.5/* diam., 1-2.5 times as long; chromatophores band- 

 shaped; zoosporangia unknown; gametangia cylindrical, sessile or 

 short-pedicellate, extending beyond the surface of the host, 40-60,u. 

 long. 4.5-6/* broad. 



Growing on the stipe of Nereocystis Luetkeana. Cast ashore near 

 the "Cliff House," San Francisco, California. 



Setchell and Gardner, Phyc. Cont. V, 1922, p. 389, pi. 44, fig. 5. 



Streblonema scabiosum forms marked scrofulous-like areas on the 

 lower part of the stipe of the host. It has a disastrous effect upon 

 the host, destroying its cells as far as it penetrates, and seems con- 

 stantly to spread by new infections around the margin of the affected 

 area. The cause of the death of the cells of the host has not been 

 investigated. In habit of growth and general form the species seems 

 related to 8. myrionematoicles and to 8. penetrate. 



14. Streblonema aecidioides f. pacificum S. and G. 



Fronds microscopic, showing on the surface of the host as small 

 elevations, 75-150/* diam., the vegetative part forming a more or 

 less parenchymatous layer just beneath the surface layer of cells of 

 the host and giving rise below to a few rhizoidal filaments penetrating 

 deeper into the host ; all erect filaments fructiferous except a few 

 short hair filaments arising in the center of the frond; cells of the 

 hair filaments 4-5.5/* diam., quadrate below, 5-8 times as long above, 



