146 



SIDNEY F. HARMEB. 



situated on the side on which the last branch is developed, 

 thus causing the position of the basal zooecium of the next 

 internode, and consequently of the first branch of that inter- 

 node, to be on the opposite side. 



Just as C. eburnea is, on the whole, characterised by 

 branching from z^, so this species may be said to branch nor- 

 mally from z^, or to produce branches on the type {r„+„+2r), 

 where n usually represents Zc^ or z-^^. 



The extent to which this must be taken as a general rule 

 may be understood by the following analysis of the complete 

 formula of a well-developed colony : 



(1) Internodes with one branch, originating from Z2 



(2) Branches arranged on the type {r^+^r) . 



(3) „ » ,, {ri+iV) or {r^+,r) 



(4) „ » >, ('•2+2»-) 



(5) » „ ,, (^2 + 3'') 



(6) „ „ „ (ri+^r) 



(7) „ » » (^3+4'-) 



(8) One branch only, originating from z, 

 ("J J) >j » ^i 



(10) ,, ,, ,, 1^4 



(11) .. » » ^5 



Number of Cases. 

 24 

 5 

 5 

 1 

 5 

 1 

 2 

 2 

 8 

 7 

 3 



Total number of internodes which had developed branches 63 

 Only eight of the completely developed internodes were 

 branchless. Thus in this particular colony, in which no ovi- 

 cells were present, and in which no internode possessed more 

 than two branches — 

 30 p. c. of the branching internodes bore two branches ; 

 38 p. c. „ „ „ one branch, originating from Zj. 



32 p. 0. „ „ „ „ „ from other 



zooecia. 



100 p. c. 



Or, adding together Nos. 1 to 4, the cases in which the branches 

 come off from z^^, or in which the second branch is two zooecia 

 higher than the first, we find that these cases amount to 55"5 

 per cent, of the total number of branching internodes, and this 

 may be taken as a case which does not exaggerate this feature 

 of the branching. 



