152 



PHYSIOLOGY. 



was present in any of the sj)ecinicns collected, its exact systematic position cannot now be more 

 than provisionally assigned to it.' 



Besides the ramuli which here, as in the hydroids generally, support the hydranths, others 

 are developed in abundance from all parts of the hydrocaulus. These (a, a) commence just like 



Fig. 01. 



Schizocladimn ramosum, showiug reproduction by spontaneous fission. 



A. Part of an adult colony magnified about six diameters, rz, One of the fissiparous ramuli, still entirely 

 invested by tbe chitinous perisare ; b, a fissiparous ramulus, in \\ hicb the contained L-ceuosarc has extended 

 itself beyond the distal extremity through the ruptured perisare ; a constriction (the commencement of 

 fission) has begun to show itself in the ccenosarc of the ramulus where still covered by the peri:*arc ; c, the 

 fission is completed, and the separated portion is escaping from the distal extremity of therauniUis ; rf, the 

 separated portion has entirely disengaged itself, and has become a free frustule in the surrounding water. 



B. Gemmation of the bydroid from tbe free fission frustule. _/", The free frustule, after having excreted 

 a mucous tube, from which it has partly withdrawn itself; g, a bud has begun to be emitted from the side 

 of the frustule ; e, the bud has become developed into a hydJrantb with its hydrotbeca and hydrocaulus, and 

 the young trophosome has bcguu to complicate itself by the emission of a branch. 



the ordinary ramuli as o£Fslioots from the hydrocaulus, and consist, as usual, of a continuation of 

 the ccenosarc invested by a chitinous perisare. Unlike the ordinary branchlets, however, they 

 never carry a hydranth, but are destined for the multiplication of the colony by a process of 

 spontaneous fission. 



After the entire ramulus has attained some length, the contained ccenosarc continues to 



It is quite possible that ia Schizocladhim ramosum spontaneous fission never occurs simulta- 

 neously with true sexual geueratiou. 



