Natural History of the Vortlcellse. 385 



seeing that the anus also opens into it. The mouth therefore 

 only commences at the end of the vestibulum, near the anus, 

 which is situated in the same cavity. From the mouth, a short 

 tube (the oesophagus) leads to the somewhat spindle-shaped 

 terminal part of the nutritive tube, which is characterized as 

 the pharynx. The nutritive particles attracted and carried 

 into the above-described canal by the ciliary cun*ent collect in 

 the first place in the pharynx into a morsel, which, when it 

 lias attained a certain size, is forced into the interior of the 

 body, and here driven about with the soft gelatinous contents 

 until it is either entirely digested or removed again to the ex- 

 terior through the anus. 



Lachmann made a particularly careful investigation of the 

 question whether the pharynx is really the terminal part of 

 the nutritive tube, or whether there issues from it a wider 

 canal which receives the morsels from the pharynx, carries 

 them forward for a certain distance in a curved direction (as 

 appearances would seem to indicate), and only then passes 

 tliem into the interior of the body ; but he finally decides in 

 favour of the entire absence of any furtlier canaliform structure. 



Lachmann, then, regards the whole inner space enclosed by 

 the cuticula and the cortical layer as a great digestive cavity or 

 stomach, and the mass of contents rotating in it as chyme. 

 This is of great importance for the view which we have here- 

 after to expound. 



With regard to the behaviour of the ciliary spiral above de- 

 scribed and its relation to the vestibulum, as also with regard 

 to the further course and mode of termination of the nutritive 

 canal. Stein has completely accepted Lachmann's views. On 

 the other hand, however, he, and with him many otliers, has 

 expressed himself most decidedly in opposition to the concep- 

 tion of the interior space of the body as a digestive cavity and 

 of its contents as chyme, inasmuch as he denies the existence 

 of both the body-cavity and of the chyme filling it. He en- 

 deavours rather to reestablish the opinion that the whole con- 

 tents are to be regarded as contractile sarcode, supporting him- 

 self chiefly upon the supposition that the limits of the body- 

 cavity are not determinable, as the outer (cortical) parenchyma 

 passes quite gradually into the interior parenchyma, and is 

 intimately united with it at all points. 



If we first of all take up what is certainly the most impor- 

 tant question, namely that of the existence of a digestive 

 body-cavity, which has been answered so differently by the 

 two investigators, I will declare at once that my investigations 

 have led me quite unavoidably to Lachmann's opinion, and 

 that I cannot admit the arguments brought against it by Stein. 



