ORGANIC DEVELOPEMENT. 87 



which these half-covered polyps receive ; while at the extremity, in 

 the purer waters, with a large supply of nutriment and more active 

 vitality, the intervals are short. 



This principle is not limited to zoophytes : there is evidence that 

 it prevails throughout the animal kingdom ; and most decidedly and 

 beautifully is it exhibited in the vegetable kingdom. 



85. In the vegetable kingdom, we have, in general, compound 

 individuals, analogous to those among zoophytes. The plant com- 

 mences with a single bud — a simple individual rises from the ground, 

 the germ of the tree which is in time developed. This parent- 

 individual enlarges and lengthens, and, after a while, buds shoot out 

 from its sides, which become new lateral individuals. Some of these 

 lateral buds, as the stem lengthens, begin themselves to bud and 

 form branchlets, and, at still longer intervals, now and then one con- 

 tinues budding and growing, till a large branch is formed. There is 

 thus a perfect parallelism with the mode of growth in the zoophyte; 

 the same law, with regard to interval, holds, and the same general 

 principle with reference to a gemmating injtuence. The terminal bud 

 is analogous to the apical polyp, and the lateral buds to the lateral 

 polyps; moreover, the branchlets and branches are formed by the 

 continued gemmation of certain of the lateral buds, the particular 

 bud, which becomes a parent-individual, depending, in each case, on 

 its distance from other parent-individuals; for, only within such 

 certain distances, is sufficient vital force and nutriment concentrated 

 on any centre or budding point.* 



The distinction in plants of budding and ova-bearing individuals, 

 should be here remembered, as it leads us to still closer analogies 

 between plants and zoophytes. The former produce leaves, and 

 lengthen out the extremity of the branch, as the summit polyp of the 

 growing Madrepore or Oculina. The latter take the form of a flower, 

 and develope ovules or seeds. 



It is altogether probable that buds alone proceed from the bud- 

 ding polyps at the extremity of a branch in zoophytes. It is defi- 

 nitely stated, by Milne Edwards, with regard to an Alcyonium 

 (§ 54), that the side of a polyp, which gave out buds, produced no 

 ovules; and, as all sides of an apical or parent-polyp in a Madrepore 



* The other modes of branching among zoophytes are illustrated among plants ; but 

 it is sufficient for our present purpose to refer particularly to the above. Branching, by 

 periodical budding at apex (§ 82, h), is exemplified in some species, and the same prin- 

 ciple, depending on intervals, holds, as has been explained. 



