444 M. Ecldiard on the Organisation 



above, have also been disputed by Siebold. His views of them, 

 according to § 12> are essentially these : — The Polygastrica swal- 

 low nutritive matter (coloured particles) with the water. So long 

 as this remains at the lower extremity of the oesophagus*, it ap- 

 pears as a pedunculated vesicle. It is loosened by the contrac- 

 tion of the oesophagus and then appears without a peduncle, and 

 containing the bodies which have been swallowed, perfectly in- 

 closed within it. The swallowed masses in the form of vesicles 

 mutually press upon one another in the body when the animals 

 have eaten too much, the earlier yielding before the subsequent 

 ones. It sometimes happens that these drops when filled with 

 solid food run into one another, which shows that they are not 

 surrounded by a distinct (gastric) membrane. Against this in- 

 genious supposition we have the following objections : — 



a. No oesophagus has been proved to exist by observation, 

 which continues for a certain distance within the body and then 

 stops; the above phenomena rather indicate that an uninterrupted 

 canal runs through the body from the mouth to the anus. 



b. Hence the entire theory of the vesicles is untenable; this 

 is confirmed by various observations and considerations. 



In Vorticella microstoma^ I often perceived how the nutri- 

 tious matter about to be swallowed was formed into a minute 

 ball in the anterior part of the oral aperture — I cannot better de- 

 signate it than as a morsel. After this was effected, it was swal- 

 lowed by the animal in such a manner that the separate particles 

 remained united, as they had become in the oral aperture. The 

 morsel then passed through the intestine for a considerable di- 

 stance in the body, and appeared of the same form in a gastric 

 cell. . Certainly no drop inclosing the nutritive matter had formed 

 at the lower extremity of the supposed oesophagus, for the for- 

 mation of the morsel occurred in the oral aperture ; but to admit 

 that the morsel had become inclosed in a vesicle of water at the 

 end of the oesophagus, or any such attempts at explaining this 

 fact, would be opposed to physical laws. In other instances, and 

 this may be observed with distinctness, especially in Epistylis 

 grandis, when colouring matters are present in great quantity, 

 the entire cavity is sometimes filled as far as a cell. On exa- 

 mining a mass of colouring matter, as z> fig. 6, without a drop of 

 water in which it might be inclosed, and the continued filling of 

 this cavity with solid particles, every appearance of the vesicle, as 

 described by Siebold, vanishes. I have observed the running 

 together of these aqueous vesicles inclosing solid matters but 



* Siebold denies the existence of an alimentary canal, and supposes the 

 presence of an oesophagus which only enters the body to a limited extent, 

 and then terminates. 



