CK we Oe eS eee E TSAS CST S 
T ee Sen C TD» Cu eee eS 
MALAY FORM OF CHLOROCOCCUM HUMICOLA. 479 
chiefly in cells from 10 to 20 w in diameter ; cells larger than this multiply 
either by zoogonidia or by the formation of numerous aplanospores. 
VI. Curonococcva HUMICOLA IN ẸNGLISH BOILS. 
Of the samples of soil taken from fifty-one localities in this country, all 
but two yielded C. humicola in greater or less quantity, showing the wideness 
of its distribution and the constancy with which it ocenrs in soil. Of the 
two in which it did not occur, one was taken from the Broadbalk plot at the 
Rothamsted Experimental Station in the year 1846, and had been kept in a 
dry state for nearly eighty years before being put into the culture. A 
similar sample of soil collected from the same plot in 1856 yielded the alga 
in considerable quantity, hence its absence from the cultures of the 1846 soil 
indicates that the limit of resistance against desiccation and of retention of 
vitality for C. humicola lies somewhere between seventy and eighty years. 
In no essential features did the Chlorococewm humicola found in the Malay 
soil differ from that found in the English soils. The spores germinated far 
more slowly and the cells are on the whole larger than the English ones, but, 
even in a single culture, the variation in size of the cells is so great that 
no importance is to be attached to such distinctions. For the rest, the 
cytology and the life-history are the same, the dominant stage depending 
on the surrounding nutrient medium. 
VII. AMENDED DIAGNOSIS. 
Rabenhorst distinguished the species C. humicola by the following 
diagnosis :—“ Ch.strato effuso, obseure viridi pulverulento ; cellulis globosis, 
magnitudine variis, plerumque numerosis in familias consociatis, tegumento 
communi hyalino achroo circumvelatis ; eytiodermate tenui, state provecta 
suberasso ; cytioplasmate initio dilute vel luteolo-viridi, homogeneo, demum 
saturate viridi, granuloso. 
* Diam. cell ad 1/126" —0:0007". 
“ Propagatio fit gonidiis cytioplasmatis divisione succedanea ex ultima 
generationis serie transitoria ortis, e cytiodermatis abaviwm (intellige 
tegumentum extremum) rupturis excedentibus et examinantibus." 
To this must now be added the following characters :— 
“ Zoogonidia aut quiescunt statimque in cellulas vegetativas angescunt 
aut copulatione duorum facta zygota efformant. 
* Propagatio fit quoque aplanosporis plurimis (zoogonidiis redactis) in 
mueilagine ex solutione cytiodermatis cellule matricalis orta inclusis. 
Fieri potest ut aplanospore divisiones plures subeant ; postea aplanosporze 
aut cilia extrudunt et se velut zoogonidia normalia prebent, aut tardissime 
in cellulas vegetativas augescunt. 
« Contentus cellularum vegeiativarum majorum sepissime pigmento rubro 
obscuratur,” 
