80 BULLETIN OF THE 



ally replace a Ndhrthier, and tlie latter seems never to produce secondary 

 individuals. The formula of the stock might be \vz"itteu : — 



* 

 b 

 a 

 (10) -$-F — E — I — D — C — B — I — A 



In Bowerhankia pustulosa we have two rows of individuals produced 

 side by side fi'om near the end of the stolon. This condition would be 

 represented by 



(11) 



pi'ovided the individuals of this primary series possess the power of giv- 

 ing rise occasionally to secondary buds, as seems certainlj^ to be the case 

 in some members of this genus which I have seen. The spiral arrange- 

 ment of some colonies is striking ; it is of evident advantage to the stock, 

 but its cause in these cases is wholly unknown. 



In every one of these cases, and, in foot, in all of those figured by 

 Hincks, which belong to the Stolonifera, there is no trace of dichotomy. 

 Throughout we have to do with linear series, which give rise to lateral 

 branches. 



Turning now from the Stolonifera to the other grand division of 

 Ctenostomata, the Alri/nniidce, we find the same prevalence of a law in 

 budding. In its typical expression it may be written as follows : — 



(12) 



Although secondaiy median individuals are not habitually formed, 

 3'^et, owing to the capacity of regeneration possessed by individuals 

 A, B, C, etc., an asterisk is affixed in parentheses to show the probable 

 persistence of embryonic tissue. Of the lateral series one or both may 

 fail to be developed. 



