Dicranochsele reniformis Hieron. i 13 
in fresh material stained with iodine the pyrenoid always gave a 
very distinct starch reaction so that a starch-sheath appears to be 
present. In one case when some of the material had stood for some 
weeks in water many of the cells were found to have lost their 
pyrenoid and were filled with minute angular starch-grains, but such 
starch-grains were never observed in the fresh material, although 
according to Hieronymus, scattered starch-grains are frequently 
present in old cells. For an elaborate description of the pyrenoid 
and its reactions to various stains, reference should be made to the 
above-quoted paper. The cell cavity below the chloroplast is filled 
with cytoplasm and a single nucleus, which may be demonstrated 
in alcohol material by staining with Delafield’s haematoxylin, is 
present, usually lying close against the flat basal wall (Fig. 1, C). 
As already stated, the organism is propagated by zoogonidia, 
every individual sooner or later becoming a zoogonidangium. The 
number of swarm-spores produced in each cell varies from 4 to 
about 30 (? 32), the most frequent numbers being 4, 8 and 16; in 
the larger individuals the number does not appear to be always a 
multiple of four; in one case 30 (? 32) were counted by me, this 
being the largest number observed. Hieronymus states that the 
contents of a cell about to form zoogonidia, divides by successive 
divisions, of which the directions of the first three are shown 
diagrammatically in Fig. 1, H, the later divisions being quite 
irregular. This appears to be true of the smaller cells which form 
4 or 8 zoogonidia (see Fig. 1, D, E), but in the case of larger 
individuals, numerous cleavages were seen to appear more or less 
simultaneously at the periphery of the protoplast, gradually extend 
inwards, meeting internal cleavages and finally dividing the contents 
into a variable number (not more than 32) of polygonal masses, 
which do not all lie in the same plane. Hieronymus noted the 
presence of 2, 4 or 8 nuclei in cells, the chloroplasts of which showed 
no evidence of division, so that the cleavages of the chloroplast do 
not appear to proceed along with the division of the nucleus. A few 
hours before the zoogonidangium dehisces, the swarm-spores round 
themselves off and each develops a small bright red pigment-spot 
(see Pig. 1, D, E, F). The zoogonidia are enclosed in a hyaline 
gelatinous vesicle, a similar but less conspicuous investment being 
round each individual swarm-spore ; owing to the swelling of this 
vesicle pressure is exerted on the dorsal cellulose “cap” and eventually 
this is slowly pushed on one side, the vesicle with its contents 
emerging gradually until it finally lies free in the surrounding 
