82 ZOOPHYTES. 
2. Aggregate, when the polyps of a compound zoophyte are united 
to one another by their sides. 
3. Segregate, when the buds are separate from the parent, except 
at base, each forming a distinct shoot or branch. 
Aggregate corals are covered with calicles when the polyps. secrete 
lime to their summits, but are united to one another laterally only by 
the lower part of the body. 
In aggregate zoophytes, without acrogenous growth in the polyps, 
when (a) budding takes place in a single extending plane, more or less 
oblique, explanate forms are produced, as in the Gemmipora and 
Echinopora, the former by inferior, the latter by superior budding ; 
(6) when budding takes place upward, in an ascending cumulate 
series, more or less cylindrical stems are formed, as in the Oculine, 
branching Echinopores, and also the branch-like processes on the 
Meruline. 
In aggregate zoophytes, with acrogenous growth in the polyps, when 
(c) budding is not limited to certain polyps, nor lost by age, glomerate 
forms are produced, often regularly hemispherical or globular ;—(d) 
when the polyps, after a certain age, lose the function of budding, and 
consequently this budding power is limited toa number of the younger 
polyps,—a budding-cluster,—ascending stems are formed, as in the 
cumulate process ;—(e) when the function of budding is limited to a 
particular polyp (parent-polyp), similar ascending stems are formed. 
Branching takes place by furcation (f), through the gradual accu- 
mulation of buds from a parent-cluster, which widens the cluster 
beyond its normal limits ;—or (g), through a pertodical developement 
of buds in a parent-cluster at apex, widening in the same manner the 
extremity, and, for the same reason, leading to a subdivision ;—or (h), 
where there is no proper parent-cluster, as is exemplified in the 
cumulate process, by a periodical budding at apex, each bud giving 
origin to a separate branch. The two last, are but varieties of the 
same process, and the first is closely allied to the second. 
Branching takes place by lateral shoots (7), when a polyp on the 
side of a branch receives budding functidns and becomes a parent- 
polyp ;—or (4), when a cluster of polyps, on the side of a branch or 
stem, become gemmating. 
In segregate species, without acrogenous growth, when (/) the 
buds proceed as shoots from the base of the polyps, the zoophyte 
forms single lines of individuals, which, by coalescence, often become 
reticulated, as in the Aulopora;—or, with acrogenous growth (m), 
