Structure and Origin of “ Cladophora Balls.” 7 
some point on the inner wall of the spore. It is probably at this 
point that the outer coat is broken. This thickening increases 
until a distinct peg-like process, sometimes reaching a length of 20//, 
is formed. This process eventually develops into a “ rhizoid ” and 
part of the protoplast passes into it (Fig. 5, F). It was not possible 
to trace the development of the spore beyond this stage. It has 
been mentioned before that the material had been in the laboratory 
for eight years and the balls were slowly dying owing to being 
completely covered by a layer of minute diatoms which come from 
the tap water. Examination of the balls introduced various fungus 
spores and the rapid development of these hastened the decay of the 
alga. 
Fig. 5. A, group of small resting spores : B, spores shewing oil drops ; 
C, spore which has remained attached to the old cell wall; D, germinating 
spore throwing off outer coat. E and F, germinating spores. A, C, E and 
F, X 150. 13 and D, X 370. 
Resting spores could not be found in balls which had been fixed 
in formalin as soon as they were collected. Possibly they are only 
formed under very adverse conditions and in balls which are about 
to break up. Balls which have been partially destroyed by the action 
of too strong light at the surface of the water may sink to the 
