GROWTH OF THE CORAL COLONY 71 



the stage in which its upper surface is flattened and dead, the 

 varying circumference of the growth represents practically the 

 entire increase, and where possible such colonies were taken. 



Put briefly, and in the form in which they are most readily 

 comparable, the results were as follows: In 100 days the 

 averaofe growth of branching forms was 2"74 centimetres ; that 

 is to say, the distance of the copper band from the tip of the 

 branch was, on an average, 12"74 centimetres after it had 

 been in place for 100 days. 



In English equivalents the growth is 1 ' 9 inches in 100 days, 

 or roughly 3"7 inches in a year. 



In 100 days the massive forms of growth had increased 

 on an average to the extent of adding -^-j of their original 

 circumference to their growth. 



That is to say, a massive coral 37 inches in circumference ivill 

 have increased its circumference hy 1 inch in 100 days. 



This increase in the size of the colony is entirely effected 

 by the multiplication of the number of the individual zooids 

 composing the colony, and the multiplication is carried out by 

 the division and budding of the already existing zooids. The 

 various methods by which this division is effected differ from 

 each other considerably ; and it is necessary to touch briefly 

 upon the chief methods by which a zooid reproduces itself. 



It is as well to state at the outset, and thus avoid much 

 further explanation, that the different methods of division, 

 though highly characteristic of certain well-marked types of 

 growth, are not definitely and unalterably fixed ; and I think 

 it is justifiable to dogmatise, and state that any form, of coral 

 may upon occasion exhibit any form of division. Since the 

 resulting form of vegetative growth is purely the outcome of 

 the type of division adopted by the zooid, then it follows that 

 coral colonies may grow in many vegetative forms ; and, 

 again, these vegetative forms are not definitely fixed, for as 

 any form of coral may exhibit any form of division, it follows 

 that any form of coral may also, under different circumstances, 

 exhibit any form of vegetative growth. 



Speaking quite broadly, a colony may grow according to 



