110 A.OKA. 



The inodinn side of the wall ends abruptly on the anal side of 

 the o;anglioii ; below this point cross sections show only one conti- 

 nuous body-cavity. Thus, the body cavity is divided into three 

 brandies on the upper part of the polypide. The middle one (fig. 26, 

 (■r>i>ilom. cav.), passing along the anal side of the ganglion, extends into 

 the epistonie, while the lateral ones are prolonged into the lophophoral 

 cavity. The inner walls of these lateral branches pass gradually 

 into the ciliated tubes. 



If we now trace the tubes upwards, they are found gradually to 

 approach each other, and their walls soon coalesce. A little higher 

 the cavities of both open into each other, and there is seen a single 

 flattened tube (figs. 23, Ncplir. & 23 A). The whole inner surface of 

 this part as well as that of the two deviating tubes below, show distinct 

 ciliation in sections, the cilia being always directed toward the 

 perigastric opening. If we trace this flat tube still further upwards, it 

 again becomes divided in most individuals into two, in some into three 

 tiil)es (tigs 22 t' & 22 A), each of which is continous with tentacu- 

 lar lumen. In this part, the ciliation is no longer visible, but 

 compared with the inner layer of the tentacles, there are more nuclei. 

 But, further upwards, the nuclei are fewer in number and the lining 

 epithelium presents similar appearance as that of ordinary tentacles 

 (figs. 21 ^' & 21 A). What can be the function of these ciliated tubes ? 

 The fact that they open int(^ the perigastric cavity by ciliated funnel- 

 shaped openings naturally reminds us of the segmental organs of 

 certain worms. And thus many observers have been induced to 

 regard the function of these tubes as being of an excretory nature. If 

 such is re:dl V th(î case, there should be some orifice by which they open 

 outwards, for the high degree of development they attain prove that 

 they are not useless remnants. This makes me venture to assume the 

 existence of minute apertures, at least on the two or three innermost 



