286 THE DEVELOPMENT 



that it stands, with many others of a similar kind, in direct 

 relation with those which I have just mentioned, not only by 

 its method of feeding, but also by its internal organization, it 

 would seem to be advisable to apply the name Suctoria to the 

 whole group, from Amoeba to Podophrya, merely for the sake of 

 having some single term by which we may distinguish it from 

 the other group, the Ciliata. 



The Ciliata is a group which comprises all those usually free 

 forms that are endowed with one or more vibratile cilia, and 

 includes, in an ascending series, Euglena, (p. 144, fig. 86,) 

 Chlamidomonas, (p. 145, fig. 87,) Heteromastix, (p. 146, fig. 88,) 

 Ceratium, (p. 148, fig. 89,) Pleuronema, (p. 148, fig. 90,) Para- 

 mecium, (p. 163, fig. 96,) Stentor, (p. 62, fig. 30,) and attains 

 its highest point in Epistylis (p. 161, figs. 94, 95). 



Suctoria. As a representative of the mode of development 

 of the first group, I shall bring forward one of its highest mem- 

 bers, Podophrya, (p. 51, fig. 25,) not only because it is best 

 known, but also for the reason that it presents the greatest range 

 of modifications in the process of development. All that has 

 been learned of its earliest stages is that the embryo appears as 

 a clear globular body within the parent. Next it is observed to 

 have a wreath of vibratile cilia about an oval, or broad, cylin- 

 drical body. In this condition it is born, and, when fully ex- 

 panded, (B,) its wreath of cilia is seen to be arranged in an 

 oblique circle about one end, and two contractile vesicles become 

 evident, one on each side of the body. In a short time the 

 vibratile cilia disappear, and four groups of globe-tipped feelers 

 (A) take their place. When the young has developed a stem, 

 which it does in a very few hours, it has all that is requisite 

 to constitute it a fully organized Podophrya, although, before it 

 arrives at a full adult state, the size of its body, as well as the 

 number of its feelers, increases considerably. 



Ciliata. There is no one of the members of this group whose 

 embryology has been so closely and frequently studied as that 

 of Paramecium (p. 163, fig. 96). It is a curious fact in its devel- 

 opmental history, that it passes through a course which appears 



