172 CTENOPIIORiE. Part II. 



The motions of the chymiferous j^y.stem are of two kinds. The tnl^e.s them- 

 yelves are distontlod by the influx of the fluid elaborated in the digestive cavity, 

 and their diameter Is reduced In- the contractions of the cells forming the .sphero- 

 some. The alternate currents from one half of the 1)ody to the other and vice 

 versa are also the result of the alternate contraction of the opposite halves of 

 the splierosome ; but the slower flow of the fluid through the chymiferous tubes, 

 and especially its undulating motions, now in one direction and then in the oppo- 

 site direction, -within comparatively short tracks of the tubes, are imquestionably 

 determined by the vibratile cilia which line their inner surface. 



For the same reasons, I am not inclined to consider the colored cells lining in 

 vertical rows the walls of the aljactinal portion of the digestive cavity as homolo- 

 gous to liver cells. No doubt they are analogous to a liver ; but, to be homolo- 

 gous with such a complicated glandular organ, the}- should derive the fluid they 

 contain from Ijloodvessels, and not from chymiferous tuljcs. As pigment cells do 

 not occur at the surfiice of all Ctenophora", but only in some of their representa- 

 tives, I shall describe them in their proper place. 



In our temperate latitudes the Ctenophora^ are annual animals, la3ing their 

 eggs in the autumn and then dying, and the young brood making its appearance 

 in the spring. I have watched the species of the coast of Massachusetts during 

 twelve successive 3-ears, and invariably found that in the earlier part of the sum- 

 mer the majority of sjiecimens observed were small and destitute of sexual organs, 

 or, at least, not yet filled with eggs and spermatic cells, as they are later in the 

 season. The largest specimens are always seen during the last sununer montlis, 

 and all disappear after the autumnal gales. The sexual organs of the Ctenophora? 

 are described by some anatomists as sexual glands, and called ovaries and testes, 

 according to the sexes. While I retain the name of ovaries for the female, and 

 propose that of spermaries for the male organs, I must record my objection to 

 the use of the word (jlaml to designate these organs. A glandular sexual organ 

 can only exist in animals which have a distinct vascular system, through which 

 blood is circulated ; and this is not the case in the Acalephs. Here again the 

 reproductive organs are only analogous, and not homologous, with the organs per- 

 forming the same functions- in the higher animals. In Ctenophora) they are simple 

 pouches or lateral sacs of the chymiferous tubes, and have no special walls dis- 

 tinct from those of the tubes with which they communicate. The actinal disposi- 

 tion of the sexual organs is another peculiarity of the Radiates, which distinguishes 

 them strikingly from similar organs in other types of the animal kingdom. It 

 should also be remembered, that hermaphroditism is not very uncommon among 

 these animals, in which case the male alternate with the female organs in their 

 radiated arrangement. Among Polj-ps, we have such a combination in Cerianthus : 



