182 BIOLOGY OF THE PROTOZOA 



by "importation" finally occurs when a food body, without apparent 

 movement on the part of the Amoeba, merely sinks into the proto- 

 plasm of the captor as in Amceha dofleini according to Xeresheimer. 



In most of these types, which grade more or less into one another, 

 the process of food ingestion ma\' be interpreted as due to local 

 liquefaction in the more solid ectoplasm, and to special conditions 

 of capillarity in the more fluid endoplasm. Rhumbler has shown 

 that a filament of Oscillaria which enters Amwha verrucosa by 

 "importation" and is too long to be entirely engulfed, becomes coiled 

 up as a result of the ph\'sical properties of the protoplasmic mass. 

 In a similar way a filament of shellac may be drawn from water 

 into a chloroform drop in which, by ^-ariations in surface tension, it 

 becomes rolled up in a strikingly similar manner. 



Some of these methods of food-getting in holozoic types are sug- 

 gestive of "conscious" activities to a given end. Thus ingestion by 

 "circumfluence" suggests preliminary activities in anticipation of 

 a "square meal." Or traps formed b\' pseudopodia or by tentacles, 

 or the balloon sails of PJearoueina chriisaVis, etc., might be regarded 

 as "set" by Protozoa for the purpose of catching food. Such inter- 

 pretations, however, are more probably evidences of a tempera- 

 mental imagination on the part of the observer than of purposeful 

 activities on the part of these minute organisms. "Sensing" at a 

 distance has been described for Antceba (Schaeffer, 1912), and for 

 Spathidimn siKithida (Woodruff and Spencer, 1922), and until these 

 phenomena are explained they will continue to serve as a basis for 

 such speculations. 



The so-called "selective" activities of some Protozoa in their 

 apparent choice of food or of building materials for their shells are 

 likewise better interpreted as the outcome of physical conditions of 

 the protoplasm than as purposeful actions of the organisms. 

 Schaeft'er (1917) attributes the power of discrimination in food- 

 taking to Amceba, as does INIetalnikoff (1908), to Paramecium, a 

 conclusion \igoroush' opposed hy Wladimirsky (191(5), who inter- 

 prets negative reactions as a result of depression (fatigue?) of their 

 physiological condition. Actinoboliis radians apparently chooses, 

 from a great number of miscellaneous forms, one i)articular species 

 to harpoon, paralyze and swallow. "This remarkable organism 

 possesses a coating of cilia and protractile tentacles which may be 

 elongated to a length equal to three times the diameter of the 

 body, or withdrawn completely into the body. The ends of the 

 tentacles are loaded with trichocysts. When at rest the mouth is 

 directed downward and the tentacles are stretched out in all direc- 

 tions, forming a forest of plasmic processes among which smaller 

 ciliates, such as Urocentrum turbo, (iastrostyla steinii, etc., or 

 flagellates of all kinds may become entangled without injury to 

 themselves and without disturbing the Aciiuobolus or drawing out 



