200 CILIATE FIBRILLAR SYSTEMS 



this system made before we can hope to have a complete understanding 

 of the parts that are, or are not, structurally integrated. 



In recent publications Chatton and Lwoff (1935, 1936) have de- 

 scribed a fibrillar complex in several ciliates, which has long been known 

 (Chatton and Lwoif, 1936) but has not been clearly distinguished from 

 Klein's silverline system. The fibrils are visible in vivo and may be clearly 

 difi^erentiated in preparations fixed in Bouin's or Champy's solution and 

 stained in iron-haematoxylin. 



Each fibril [cinetodesjne) has connected, always along its left side, 

 the basal granules {cinetosomes) of a longitudinal row of cilia. The 

 fibrils, together with their adjoined basal granules (the so-called infra- 

 ciliature), are each essentially an independent entity. They are never 

 united by anastomosis or otherwise at either body pole, and so include 

 no transverse or other fibrillar connectives throughout their course. 



The fibrils of this injraciliature are entirely superficial and adhere 

 to the pellicle as rectilinear (never sinuous) threads. Other granules, as 

 well as the ciliary basal granules, appear likewise attached, and these 

 represent successive stages of the multiplication of the basal granules. 

 Fibrils and granules stain alike, but in some species the fibrils cannot 

 be impregnated with silver by the usual techniques. After fixation (osmic 

 acid. Da Fano, Champy) and covering with gelatin or gelose, the fibrils 

 may show, upon silver-nitrate treatment, the basal granules connected 

 to a sinuous thread which, with its various connectives, represents Klein's 

 silverline "plexus." This plexus, according to Chatton and Lwoff 

 (1935), is acid labile and cannot be stained. 



The selective staining properties and relations of the infraciliature 

 show that it is quite distinct from the silverline fibrils, and is comparable 

 with the flagellar ridges of the Hypermastigidae, marking the place of 

 formation and of the insertion of the cilia. 



It would appear that Chatton and Lwoff 's infyaciliature may be identi- 

 fied with the longitudinal fibrils and basal granules of the inner fibrillar 

 complex reviewed above. The left lateral attachments of the cinetosomes 

 to the cinetodesmes is evidently a new finding. 



2. Stentor. — In his search for organs that would account for the 

 well-known contractile behavior of Stentor, Ehrenberg (1838) saw in 

 its conspicuous longitudinal bands the seat of that contractility. This 

 interpretation of its contractile mechanism was accepted by several later 



