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; 



(b) when budding takes place upward, in an ascending cumulate 

 series, more or less cylindrical stems are formed, as in the Oculinae, 

 branching Echinopores, and also the branch-like processes on the 

 Merulinse. 



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 to a 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 periodical 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 (i), when a polyp on the 

 side of a branch receives budding functions and becomes a parent- 

 polyp; — or (k), when a cluster of polyps, on the side of a branch or 

 stem, become gemmating. 



In segregate species, without acrogenous growth, when (I) 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), 



