se) 
Or 
5 
G. H. PARKER 
Summary 
From what has been stated in the preceding sections it appears 
that in a normally quiescent Renilla sea-water is entering the 
colony almost exclusively through the pores of the lateral si- 
phonozodids. A small amount may enter through the mouths 
of the autozodids, but this at most must be very insignificant. 
There is no reason to suppose that water enters the colony 
through any other openings. In a quiescent colony water from 
time to time passes out through the pore of the axial siphonozo6id, 
and this is apparently the only method of exit under ordinary 
circumstances. Possibly an insignificant amount of water may 
pass out by the mouths of the autozodids. If for any reason the 
fluid pressure within the colony becomes high, the currents of 
the lateral siphonozodids may reverse and a small amount of 
water may escape through the pores of these zodids. If the 
pressure increases still more, the terminal peduncle pore may 
eventually open and discharge. Such, however, would probably 
occur only under extreme pressure. In ordinary conditions the 
whole inflow of water is through the lateral siphonozoéids and 
the whole outflow through the axial siphonozodid—a view long 
ago Clearly set forth by Wilson (’83). 
THE COURSE OF THE WATER WITHIN THE BODY OF RENILLA 
The course of the water within the Renilla colony is dependent 
upon the system of canals within this animal. Agassiz (’50, p. 
208) noted that both the peduncle and rachis of Renilla were 
more or less hollow and that their cavities communicated, and 
Verrill (64, b, p. 12) was the first to recognize that the peduncle 
contained two canals each of which opened into extensive spaces 
in the rachis. Kolliker (’72, p. 85) showed that of these two 
canals one was superior in position and the other inferior and that 
the two communicated with each other near the distal end of the 
peduncle. Eisen (’76) confirmed these various statements and 
demonstrated further that the superior canal led directly to the 
pore of the axial siphonozodid. He also claimed (’76, p. 12) that 
in the region of the rachis the peduncle of Renilla possessed four 
