Cytology and Movements of the Cyanophycee. 303 
weeks after collection. The real spores will grow after a 
resting period of at least a year and a half, which is as long 
as I have had them under observation. 
The formation of spores is a much more profound pro- 
cess than the mere drying of the vegetative cells, and it is 
. probable that more than one cell, and possibly the whole 
plant, takes part in it. In Oscillaria, one to four cells will 
begin to enlarge to form a spore (Figs. 51 and 52). The 
adjoining cells to these gradually disintegrate and pass 
their chromatin elements into the forming spore, the turgor 
of which causes these cells to become concave (Fig. 52). 
The chromatin of the nuclei of the spore cells loses its 
vesicular appearance, and forms dense staining masses in 
the cytoplasm which gradually disappear owing to the dif- 
fusion of the chromatin throughout the whole cell. This 
diffused chromatin again aggregates towards the centre, 
forming there a granular chromatin body. If two or more 
cells are absorbed in the formation of the spore, as is usually 
the case, the original partition walls become absorbed and 
the protoplasts flow together, thus forming one spore with 
a large diffuse central body of chromatin. Whether this 
fusion should or should not be looked upon as a form of 
sexuality is problematical, however, for the reason that 
spores are sometimes formed in Oscillaria as in Cylindro- 
spermum and other Cyanophycez, by the transformation 
of only one cell, but even here we find the same passing of 
chromatin into the single spore cell from the adjoining, or as 
they might be termed, the nurse cells. In higher plants, 
where undoubted sexuality occurs, it is nothing more than 
the passing of the substance of one cell into another, usually 
in the form of a definite body. In the Cyanophycee we 
find similar passage of a substance into the reproductive 
spores, but the substance is not here differentiated into a 
definitely formed structure. This should then be looked 
upon as the sexual act rather than the fusion of the whole 
cells as mentioned above. After the spore has formed, the 
