144 A. OKA. 



such is iKjt tlie ca«e. On the contrary, we usually see in an actively 

 budding individual at the margin of a colony, not (jnly buds of the 

 iirst order but also tlKJse of second and third order already formed, 

 lîuds of the first order are present, as already stated, in a single 

 pair, while those of the second occur in two pairs, and the next 

 order, the most rudimentary, in four pairs. AVhen the buds of the 

 first order have grown sufiiciently to be regarded as new individuals, 

 those of the second and the third order occupy the grade of the first 

 and the second order, while those of the third order arise anew. A 

 comparis(3n of the lower series of diagrams in fig. 62. with the upper 

 series will help to make the matter clear. The blackened spots in 

 the lower diagrams slnnv the gemmiparous porti«jn of the endocyst. 

 This spot might appropriately be compared with the growing point 

 of plants. With the growth of the colony, it advances centrifugal ly, 

 splitting dichotomously at regular intervals. In this way, the colony 

 oTows as long: as the condition is favorable. 



It need scarcely be pointed (jut that the development of the first 

 polyzoiUd in a statoblast essentially agrees in process and conditicjn 

 with that of hiter polyzooids l)y means of budding. In fact the first 

 polvzoöid is similarlv budded oft" from the statoblastic contents, the 

 whtjle of which is to be seen in the light of a piimary cystid derived 

 (jf and containing all the essential elements of cystids of the previous 

 year. Whereas in marine forms the cystids winter as such, those of 

 fresh-water forms persist only in the form of statoblasts to germinate 

 in the following year as do the perennial cystids of the former. In 

 the budding of fresh- water Polyzoa, a cystid and a polypide are 

 formed simultaneously and an intrastatoblastic primary cystid is to 



