54 MR. A. W. BENNETT ON THE 
The third series, or CHLOROPHYLLOPHYCEA, is the one which 
alone has developed into the higher forms of vegetable life. 
It is characterized, from the outset, by the cells possessing a 
nucleus, starch-grains, pure chlorophyll of precisely the same 
composition and properties as that of the higher plants, and, in 
certain states, a true cell-wall of cellulose. In the lowest family, 
the Protococcacee, the individuals are unicellular, and motile 
by means of vibratile cilia, or collected into motionless palmel- 
loid or zooglmoid colonies. Although, as must almost necessarily 
be the case, the tendency to a higher development in the Proto- 
coccace® manifests itself in lines parallel to those in the Chroo- 
eoccacez, I cannot but agree with Schaarschmidt that there is, 
in all probability, no genetic connection between the individual 
members of the two series. Thus a tendency to develop into a 
plate of cells similar to that in Merismopedia is displayed also in 
Tetraspora; and the botryoid association of cells, only rudi- 
mentary in Colospherium, is carried out much more fully in 
Botryococcus. 
The further development of the Chlorophyllophyceew took 
place in two directions—the perfection and differentiation of the 
individual cells, and the association of cells into colonies or 
ceenobes. The latter course may be supposed to start from such 
forms as Botryococcus; and its first stage is represented by 
colonies like those of Sorastrum, Coelastrum, and Selenastrum, 
constituting the small family of Sorastree, in which the mode of 
reproduction is still but little known. In tbe Sorastree the 
colony moves slowly through the water without being impelled 
by vibratile cilia. In the next family, the Pandorinee, includ- 
ing Pandorina, Gonium, and Stephanosphera, we find active 
motion of the colony by means of cilia, and reproduction by the 
conjugation of zoogametes. Simpler organisms, like Chlamydo- 
monas and Chlamydococcus, consisting of nothing but conjugating 
zoogametes, ought possibly to be regarded as retrogressions from 
the higher forms, though they may also be stages in a direct 
ascent from Protococcus. Closely allied to the Pandorinee, and 
representing another stage in the ascending series, are the 
Volvocinee. The lowest member of this family, Eudorina, with 
a rudimentary differentiation of male antherozoids and female 
oospheres, unquestionably represents the line of development of 
Volvox, in which this differentiation is more strongly manifested. 
The Sorastrez, Pandorinez, and Volvocinee are, beyond doubt, 
