io8 Bristol. — Life-history and Cytology of Chlorochytrium grande. 
Under these conditions the alga lived for several years, and increased 
very considerably in quantity. It is entirely submerged, resting upon 
the substratum, and consists of large unicells growing either singly or 
in loose globular clusters. 
Borzi described two species of Centrosphaera : C. Facciolae ) which 
occurs normally within bright green tubercles formed on the thalloid 
colonies of Lyngbya Phormidium , and C. minor , which is similarly situated 
among the filaments of Oscillatoria tenuis . He found that these forms were 
also capable of an entirely independent existence, floating freely upon the 
substratum, and he attributed their presence within the colonies of Lyngbya 
and Oscillatoria to the fact that the filaments of those algae, growing and ex- 
panding upon the substratum, surround and completely envelop the unicells, 
which have therefore acquired the power of living endophytically. Hence 
it is quite possible that the free floating condition of the alga under 
discussion is not the only one in which it exists, but that it may also grow 
endophytically. 
Experimental Cultures. 
From the material provided a number of cultures were prepared, with 
a view to finding out the effects of different nutrient solutions upon the 
alga. The vessels used for the cultures were small conical flasks and small 
wide-mouthed bottles, plugs of cotton-wool being used as stoppers. The 
whole apparatus was carefully sterilized three times at a temperature of 
130° C. before using, and sterilized culture media were used ; the material 
was transferred to the cultures by means of a sterilized pipette. 
The following culture media were used : 
1. Rain-water. 
2 . Mineral salt-solution consisting of 
Potassium dihydrogen phosphate (KH 2 P 0 4 ) 
Sodium nitrate (NaN 0 3 ) 
Magnesium sulphate (MgS 0 4 ) 
i*o grm. 
i*o grm. 
0.3 grm. 
o*i grm. 
o*i grm. 
o*oi grm. 
ioco c.c. 
Calcium chloride (CaCl 2 ) 
Sodium chloride (NaCl) 
Ferric chloride (FeCl 3 ) 
Distilled water 
3. Mineral salt solution of half the above strength. 
4. Distilled water. 
1. In rain-water rapid multiplication by aplanospores took place. 
The cells were relatively small owing to frequency of multiplication, and 
the cell-walls were thin. 
2. In the stronger mineral salt- solution the alga multiplied to a certain 
extent by means of aplanospores, but not nearly so frequently as in 
