72 



ZOOPHYTES. 



functions. This actually takes place. A polyp from those of the 

 lateral surface commences to enlarge, and then to bud and lengthen, 

 till tinally a branch is formed, the new budding polyp being the 

 parent-polyp of the branch. 



c. This change occurs at certain intervals upon the branch, though 

 j-jg 30. with considerable irregu- 



larity, depending on expo- 

 sure, position, food, and 

 other circumstances. The 

 uniformity is, however, so 

 general that a particular 

 mode of branching is cha- 

 racteristic of each species, 

 and is readily distinguished. 

 In some Madrepores, the 

 branches are distant and 

 long, and often between the 

 large branches, are others, 

 short and rudimentary, at 

 nearly regular intervals. 

 The gemmating powers of 

 the apical polyp in these 

 smaller branchlets are soon 

 exhausted, and only at con- 

 siderable distances can one 

 of them continue to bud 

 and become one of the 

 larger branches. The late- 

 ral polyps sometimes as- 

 sume budding functions 

 very early, and then the 

 branchlets are numerous, 

 and crowded. 



d. In certain species, the 

 gemmating polyps are de- 

 veloped only on a particu- 

 lar side of a branch. In 

 the horizontally growing 

 Madrepores,* the new budding polyps on the main branches are con- 



* See plates 32, 33, and 34. 



^li,:^ 



