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 Cyanophycez 
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 Cyanophyceze from other alge has been 
entirely removed, and they are shown to be merely a more 
lowly organized form of true alge, 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 : 
