Growth Integration 97 



TABLE 



Series Tube-feet Ambulacral plates Adambulacral plates 



number Length Length Width Thickness Length Width Thickness 



5 3.9 6.4 3.1 1.2 3.8 S.Q 1.0 



10 3.7 3.9 2.7 1.3 S.5 2.4 1.2 



15 S.5 3.5 2.4 1.3 2.8 2.2 1.4 



20 3.1 2.6 2.0 1.2 2.4 2.0 1.2 



25 2.2 2.3 2.0 1.0 2.1 1.9 1.1 



30 2.1 2.1 1.9 0.9 1.9 1.7 1.2 



35 2.3 1.8 1.6 1.0 1.7 1.3 1.1 



40 1.7 1.2 1.1 0.9 1.4 1.0 1.0 



45 1.8 0.8 1.0 0.6 1.0 0.8 0.9 



50 1.3 0.7 0.7 0.5 0.7 0.7 0.6 



55 0.9 



60 0.8 



65 0.7 



68 0.5 



Not only do these graded meristic series appear in the 

 individual makeup of a great range of animal species, hut 

 they occur in the colonies of many species in which aggrega- 

 tions are produced by budding. Sometimes, as in many al- 

 cyonaria, the size gradations are very obvious, wliile in otlier 

 groups the distinctions are so small as to be discoverable 

 only by close quantitative study. An example of this latter is 

 furnished by the plumularian hydroids. A typical colony of 

 the genus here studied, Torrey writes, "closely resembles a 

 feather, of which the shaft is represented by the stem and the 

 veins by the two ranks of alternating branchlets, or hydro- 

 cladia, corresponding to barbs. Each hydrocladiuni is 

 divided by more or less definite nodes into internodes and 

 bears on one aspect — the same in all hydrocladia — a compact 

 series of hydranths, one to each internode." ^ 



Without entering into the tabular and graphic details 

 contained in this study, the author's summarized statement 

 concerning one of the tables will suffice: "It will be seen from 

 the table that, as the tip of the colony is approached, not 



