416 Prof. H. James-Clark on the Anatomy and 
§ 6. Tur Dicrstive System.—This infusorian takes so 
readily to an indigo diet that the process of collecting food and 
forming it into pellets at the bottom of the cesophagus and its 
passage into the general cavity of the body may be seen at any 
time, and without any particular preparation. On this account 
it is no difficult task to ascertain the position of the mouth and 
the trend of the vestibule and cesophagus, as well as the pos- 
terior termination of the latter. 
The vestibule (v) is as distinct from the cesophagus (0) as in 
most of the Vorticellide. Its aperture (m) is very broad, and 
diverges almost insensibly into the peristome (d). It passes 
into the body in a direction which is in strict continuation 
(fig. 13) of the spiral trend of the border (d) of the disk ; 
that is to say, it winds posteriorly, dorsally, and toward the 
Stein (Infusionsthiere, 1854, p. 176) controverts the assertion of Siebold, 
and insists that the “undulating membrane” of the latter is a crown of 
cilia; but yet, as in Siebold’s case, the velum has entirely escaped his no- 
tice. He writes as follows :—‘‘ The posterior cilia-crown . . . on account 
of the very closely set cilia, does certainly readily produce the impres- 
sion of an undulating membrane margining the rear-body, which, not only 
in T. mitra, but also in T. pediculus, appears to be denticulately notched ; 
but let one kill the animal with diluted acetic acid or alcohol, and he 
will separate each single cilium sharply. That the posterior cilia-crown is 
connected neither with the toothed horn-ring nor with the annuliform 
membrane, let one convince himself thereof by crushing the animal, by 
which one easily separates the entire adherent apparatus, in all its inte- 
grity, from the body.” 
Next Busch (Mill. Archiv, 1855, p. 358) appears in the field of contro- 
versy, and, commenting upon the observations of the two foregoing authors, 
makes a compromise between their views by uniting the vibratile cilia to the 
edge of the undulating membrane. This idea is set forth in the following 
words :—‘“‘ On the so-called hind body is found the (by Stein first very 
correctly described) saucer-shaped rim, on whose base is fastened the ring 
of the rigid-baton crown, from which the hooks arise. On the foundation 
of, and exterior to, the saucer-shaped membrane is implanted the chief 
locomotive organ of the animal, the posterior cilia-crown. Siebold has 
explaimed this as an undulating membrane, whilst Stein has evidently re- 
cognized the separate cilia of the same, and only speaks of a cilia-crown. 
The truth seems to me to lie intermediate ; for though I clearly observed 
the single cilia, especially im dying animals, yet I could never follow them 
to the margin of the saucer, unless a fissure was present. This organ 
consists, then, of a membranous undulating border, on whose free edge 
vibratile cilia are inserted. One may convince himself best of this on 
dying animals, where one sees the gentle pulsations of the border and the 
cilia.” Although it is certain that Busch did not see the velum, as such, 
and in its proper relations, yet it is not equally clear that he did not have 
it in view, but confounded it with the row of vibratile cilia which under- 
lie it. ; 
Finally, as the latest investigator, Claparéde (Etudes sur les Infusoires et 
les Rhizopodes, Mémoires de l'Institut Geneévois, 1858-59, p. 130) sus- 
tains the view of Stein, demurs to the opinions of Siebold and Busch, and 
says nothing about the true velum. 
