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plainly seen : and it is scarcely necessary to remind the reader of the 
zoospores of a confervoid Alga, or of the similar mode of reproduc- 
tion of an Ulva. It may he objected that here only two stages of 
the cycle are present ; hut a third, the amoeboid, not uncommonly 
occurs, for that the brief quiescent state of the zoospore before 
re-encystment may fairly he considered amoeboid, is demonstrated by 
such observations as those of Keinke,* who has lately figured a true 
amoeboid stage in the settling zoospore of Bangia. 
In Fucus, again, the ovum- cell has rejuvenesced, in other words 
has gone through an amoeboid stage, while other cells rejuvenesce 
as antherozoids into the ciliated phase. In the terrestrial Arche- 
goniata, too, we have the same phenomena; even in the Phanerogams, 
condemned as all their cells seem to perpetual incarceration, there 
remains one fleeting and imperfect recapitulation of the cellular life- 
cycle in the embryonic rejuvenescence of the pollen grain and ovum 
cell (see fig. 15). 
7. Relation of Protozoa to Higher Animals . — If transverse 
division occur in the ciliated state, the new cells must necessarily 
almost invariably separate, must row apart, and thus it is natural 
that only comparatively few and transitory cases of ciliated aggre- 
gates are known. In the amoeboid state, however, the aggregate 
produced by division remains much more readily in continuity, and 
it would thus seem much more probable that the Metazoa should 
originate from Protista in which the amoeboid stage was somewhat 
more permanent and more subject to division, than from the ciliated 
forms, as has sometimes been suggested, particularly for the sponges. 
8. Common or separate Descent and Affinities of Animalia and 
Vegetahilia . — If the preceding facts and deductions he accepted, it 
need only he briefly pointed out, that the affinities of plants and 
animals are far closer than botanists and zoologists are generally 
accustomed to assume, since both are descended from a Protomyxoid 
ancestor, and may, in fact, from our present point of view, be 
described not merely, as the common phrase goes, as amoeboid or 
encysted cell-aggregates, but as aggregates of Protomyxomycetes, 
variously grouped and arranged indeed, hut never so highly spe- 
cialised as to lose all traces of their individual ancestral life-cycle. 
The notion of three kingdoms of nature — animal, vegetable, and 
* Op. cit. 
