366 



BIOLOGY OF THE PROTOZOA 



of Halteria grandineUa upon coming in contact with a tentacle of 

 Adinoholus is interpreted as due to the toxic action of the minute 

 trichocyst at the extremity of the tentacle (Calkins, Moody). In 

 D id i Ilium nasutum there is a zone of rods quite independent of the 

 pharyngeal trichites and interpreted as trichocysts near the extrem- 

 ity of the seizing organ of this voracious animal (F'ig. 89, p. 180). 

 A Paramecium jabbed by this proboscis in one of the vigorous 

 darts of Didinium is immediatel\' paralyzed and the poisoning is 

 attributed to the trichocyst material. While this interpretation is 

 plausible it cannot be regarded as proved, and it must be admitted 

 that the protoplasm itself may carry the toxic substance. Thus 



'm mm 



A 



B 







1^' 



'^^MiM 



C D 



Fig. 158. — Nassula aurca (C) and details of basket (.4, B, after Biitschli); 

 D, Chilodon sp. (Original.) 



in the Suctoria a ciliate or other small organism, is similarly par- 

 alyzed upon coming in contact with an outstretched tentacle in 

 which no trichocysts can be demonstrated. 



Pharyngeal baskets are characteristic of the Chlamydodontidse 

 where they form conspicuous oral armatures (Fig. 158). The 

 elements forming the basket are much larger than trichites and 

 are frequently combined in such a manner as to justify the term 

 basket. The rods are usually constant in number in a species and 

 may be united to form a tube at the posterior end of the basket, 

 or in some cases may be united throughout. In Chilodon the 

 basket is protrusible and serves a useful purpose in food-getting. 



