Journal 



OF THE 



NEW-YORK MICROSCOPICAL SOCIETY. 



Vol. II. JANUARY, 1886. No. 1. 



PROTOCOCCUS VIRIDIS. 



BY E. E. SOUTHWICK. 

 {Read Dec. iWi, 1885.) 



The microscopic plant to which your attention is called 

 this evening is classed among the Protophyta, the sub-kingdom 

 containing certain imperfectly known genera which are in all 

 probability but degraded forms of Algte, such as the families 

 RivulariecB, Oscillariece, Nostochinex, Palmellece, and Volvocineoe. 



They are gelatinous organisms found on damp stones, 

 trunks of trees, and the earth, in fresh water either cold or 

 thermal, rarely in the sea, and are composed either of globules 

 or of simple or branched filaments continuous or chambered, 

 and nearly always enveloped in mucilage. 



Protococcus, the genus under consideration this evening, in- 

 cludes various unicellular Falmellacece. They increase by 

 division into two or four parts, which separate, but are connected 

 by a semi-gelatinous layer. Sometimes its cells give rise to four 

 ciliated zoospores of two sizes, the larger of which settle down 

 and develop a cellulose coat, while of the farther development 

 of the smaller, nothing is known. The famous Red Snow of the 

 Arctic regions and the Alps, which is also found on stones in 

 fresh-water streams, belongs to this genus, and is* known as Pro- 

 tococcus nivalis. 



Protococcus viridis grows on the trunks of trees, on stones, on 

 patches of mortar, and apparently in most places sufificiently 

 moist and shaded to induce its growth. 



As observed in Central Park, New York city, it is chiefly on 

 the northern and the northwestern exposures, being most abund- 

 ant on many trees near the ground. On those favorable for the 

 retention of moisture and sufficiently shaded, the Protococcus is 



