394 JT'LIA ELEANOR MOODY 



stance swej3t into the pharynx, food-particles were passed into 

 the endoplasm while all foreign substances were rejected by a 

 reversal of ciliary motion. This question was again taken up 

 by Verworn in 1889 who, after experimenting on Vorticella 

 with chalk crystals, carmine and indigo concluded ''wenn man 

 die Bezeichnung Auswahl fiir einzelne dieser Erscheinungen 

 beibehalten will, sich klar machen mtissen, dass darunter keine 

 bewiisste Auswahl in einer bestimmten Absicht zu verstehen 

 ist, sondern ein vollig unbewiisster Vorgang, ahnlich der natiir- 

 lichen Auswahl, der Selection, die der Kampf um's Dasein hervor- 

 bringt." 



Hodge and Aiken in 1893 pubhshed a paper on the "Dailj' 

 Life of a Protozoan" with the significant sub- title ''A Study 

 in Comparative Psycho-Physiology." Here again Vorticella 

 was the subject of the experiment, chosen because it is easily 

 kept in the microscopic field during long periods of time. The 

 fact that the same animal subjected to similar conditions of 

 experiment shows different reactions at the hands of two skill- 

 ful observers, leading to diametrically opposed conclusions is 

 of interest. Hodge classed the action of the cilia under psycho- 

 reflex movements, assigning to them a sorting or discriminating 

 function, dependent apparently upon a touch sensation and 

 concluded that this process indicated a no less conscious action 

 on the part of Vorticella than the seeking of prey and the feed- 

 ing of animals in general. 



Schaeffer, in 1910, published the results of some exceedingly 

 interesting feeding experiments on Stentor. Every test was most 

 carefully controlled in order that the exact kind and quantity 

 of food might be accurately recorded. Without going into the 

 details of the experiments I will simply quote his results which 

 are of interest and importance in the light of other experimental 

 work on the feeding habits of Protozoa. Schaeffer found that, 

 as food, Stentor preferred Euglena to Phacus; that it could 

 discriminate between Phacus triqueter and Phacus longicaudus, 

 also between Trachelomonas hispida and Trachelomonas volvo- 

 cina; that it manifested no choice between living organisms 

 and those killed in chemicals, as for example osmic acid, iodine 



