The Pharyngeal Protein Fibres of the Ciliates 



217 



9 



Fig. 2. Nassiihi iiiirea. Cross section of a part of the pha- 

 ryngeal basket. A, proteic rods; B, peripheral sheath with 

 (C) aliform crests, and (D) attempts at cristallisation. 

 Magnification 31,000. 



a nearly cylindrical bundle of protein rods — or 

 trichites — quite distinct from the trichocysts wfiich 

 may coexist with them. 



The transverse section on the level of the buccal 

 depression of the Coleps hirtiis (fig. 1) shows the 

 order of these trichites. They are themselves built up 

 from a bundle of long parallel homogeneous fibrils. 

 To return to transverse sections one may see that 

 these fibrils are regularly arranged on a series of 

 longitudinal parallel planes and so evenly spaced 

 that the structure has a cristalline appearance. 



Comparable micrographs have been obtained 

 from two species of Prorodon, but in one of these, 

 P. nucleolatus, the arrangement of the fibrils is less 

 regular, due to the presence, near the buccal extre- 

 mity of the trichites, of an amorphous interstitial 

 substance. 



In the hypostomal Gymnostomata (called Cyrto- 

 phorina) the pharyngeal framework appears as a 

 much more clearly defined organite, the basket, whose 

 protein rods, in general thicker than the trichites, 

 are united, near the mouth at least, by a peripheral 

 sheath. This structure is shown by the different 

 species of the genus Nassiila. In Nassiila aiirea 



Fig. 3. Nassiila ornata. Paracristallinc strLictiire of a pliaryn- 

 geal proteic rod. Magnification 68,000. 



Fig. 4. Frontonia niari/ia. Cross section of tlie pharyngeal 

 proteic fibres (F). M, mitocliondria. Magnification 30,000. 



(fig. 2) the twenty-five rods of the basket have an 

 elliptical transverse section, and one of their side 

 surfaces is extended into the pharyngeal cytoplasm 

 by a fibrillar lamella. Their ultrastructure shows a 

 dense and remarkably regular packing of longitu- 

 dinal and parallel fibrillar planes. The peripheral 

 sheath which unites the rods extends its outer surface 

 with aliform crests. It is eqiiallN built up from an en- 

 semble of longitudinal fibrils but these are loosely 

 arranged, although there may be observed, from 

 place to place, some attempts at cristallisation. 

 Nassiila ornata (fig. 3) shows the same structure 

 with thicker rods of triangular cross sections. 



The basket becomes more complicated in Chla- 

 niydoclon where at the same time there may be ob- 

 served a pharyngeal tube of lamellar structure which 

 runs from the buccal epiplasm to the endoplasm. The 

 protein rods include an axial mass which is appar- 

 ently amorphous and around which the fibrils are 

 assembled in a random manner. Their buccal extre- 

 mity is dilTerentiated and capped by a dense protein 

 sheath conical in form, resembling a tooth. All these 

 teeth form a maxillary crown. 



This type of difTerentiation is accentuated in 



