324 Phillips on a Comparative Study of the 



characteristics: (a) absence of sexual reproduction; (b) 

 absence of a chromatophore, and (c) absence of a nucleus. 

 Inasmuch as many higher plants having undoubted cell 

 nuclei are devoid of sexual reproduction, it seems that this is 

 scarcely a proper characteristic upon which to base a dis- 

 tinction. But even this is represented in the Cyanophycese 

 by the flowing of what may be hereditary material through 

 the intercellular protoplasmic threads in the formation of 

 spores. Sexuality, after all, is merely the passing of certain 

 reproductive or hereditary substances from one cell into, and 

 its fusion with, those of another. This is certainly accom- 

 plished by these plants, and probably only during the forma- 

 tion of the spores or reproductive bodies. On the other hand, 

 the chromatophore and nucleus are undoubtedly present. 

 The nucleus has begun to differentiate the karyokinetic divi- 

 sion as is found in higher plants, but has not reached the 

 same degree of evolution. The chromatophore is also primi- 

 tive, and combines the function of a color-bearing organ with 

 that of the cytoplasm. Thus the boundary which has seemed 

 to separate the Cyanophyceas from other algas has been 

 entirely removed, and they are shown to be merely a more 

 lowly organized form of true algje, having many character- 

 istics in common with them. 



There can be no doubt, however, that these plants are 

 much higher in their organization than has been supposed. 

 Their evident correlation of movement, their intercellular 

 protoplasmic continuity, their sexually formed spores, and 

 many other activities, place them much higher in the scale 

 of classification than we have supposed, though they still, in 

 various points, exhibit the beginnings of the activities which 

 we find in the higher plants. These facts have been shown 

 by the present investigation and have been reported fully 

 above. They are briefly reviewed in the following sum- 

 mary: 



