Cytology and Movements of the CyanophycecB. 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- 

 spermiim and other Cyanophyceae, 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 Cyanophycese 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 



