of the Polygastric Infusoria. 441 



in Paramecium stomioptycha * is worth notice. It is surrounded 

 by three to four annular fibres a, which are of a tougher and 

 more solid structure than the rest of the body ; in it occurs a 

 peculiar appendage z (rudiment of a tongue ?) . 



We must now minutely examine another remark of Siebold. 

 This philosopher divides the Protozoa (by which term he desig- 

 nates Ehrenberg's Polygastrica) into Astoma and Stomatoda, 

 referring to the former the Astasia, Peridinaa and Opalina, and 

 to the latter the remaining families of the Polygastrica. Inde- 

 pendently of the question whether this division is natural, some 

 parts must be corrected. As regards the Astasia, the mouth has 

 certainly not been distinctly recognised, but may be imagined to 

 exist in several. All the Peridincea cannot possibly be referred 

 to the Astoma, because P. pulvisculus f and cinctum % are by 

 no means destitute of mouth. Among the Opalina, Sie- 

 bold has evidently taken Op. ranarum, Val., Bursaria ranarum, 

 Ehrenb., as his type, as is shown elsewhere. Whether the author 

 refers the remaining components of the genus Bursaria to the 

 family of the Opalina or not, in no case can they be referred to 

 the Astoma ; for I have seen a distinct mouth in Bursaria 

 truncatella, flava, and when young, ranarum. That the latter 

 has not hitherto been found to take up particles of colouring 

 matter or other nutriment internally does not appear very strange 

 to me ; for these animals live inside others, the fluids of which 

 are so delicate that solid substances are not fit for their nutrition. 

 Even if the oral fissure could not be pointed out, I should still 

 hesitate to place so much value upon this distinction ; for in 

 taking such nutritive substances as the Opalina feed upon, a 

 simple mere oral spot, a part of the body of more delicate struc- 

 ture than the other parts, especially adapted to the passage of 

 animal juices as nutriment, would be sufficient. We have similar 

 instances in the intestinal worms. Their proboscis has no mouth, 

 still pouch-like organs proceed from the anterior part of it which 

 cannot well be considered as anything else than alimentary 

 canals. 



2) Intestinal Canal. — The nutritive matters which have been 

 taken by the mouth next arrive at a cavity which runs through 

 the body in a direction varying in different genera (fig. 5 s). The 

 gastric cells z are appended to this by means of hollow pedun- 

 cles i. We might be easily led to consider the cavity m — a as 

 an intestine ; its function however does not admit of this suppo- 

 sition, as it merely serves for the transmission of the nutriment, 



* Ehrenberg found this new species in the summer of 1845 on Ectosperma 

 clavata, and had the kindness to give me some specimens of it for examina- 

 tion. (See contractile vesicle.) 



t Ehrenberg, tab. 22. fig. 14. % lb. tab. 22. fig. 22. 



