THE BEHAVIOR OF THE LOWER INVERTEBRATES 397 



etc., to this rhythmic pulsation. The same author (9) gives a 

 note on the behavior of the barnacle Conchodermata virgotum 

 and another (10) on the immunity coloration in the nudibranch, 

 Chromodoris zebra. 



In studying the feeding habits of certain pelagic copepods, 

 Esterly (11) finds that the head and appendages of Calanus 

 finmarchicus produce water currents which carry floating parti- 

 cles toward the mouth. These currents are directed chiefly by 

 a trough-like arrangement of the bristles of the anterior maxil- 

 liped. The particles are formed into a pellet which is held behind 

 the mouth and from where it is passed into the oesophagus. 

 The author then takes up a study of the various food forms 

 found in the digestive tracts of various copepods. 



Grave (12) takes exception to Kellogg (Jour, of Morph., 26, 

 625-701), who is working on the feeding of Lamellibranchs 

 comes to the conclusions that " Volume alone determines whether 

 the collected foreign matter that reaches the palps shall pro- 

 ceed to the mouth or shall be sent from the body on outgoing 

 tracts." Also, as corollaries to this conclusion, that a Lamelli- 

 branch can feed only in comparatively clear water, can make no 

 separation or selection of food particles, and has no mechanism 

 for the reversal of the effective beat of the cilia. Grave gives 

 some experiments on Ostrea which tend to show that they 

 can feed in water which contains a large quantity of sediment, 

 etc. He then collects certain evidence on other animals which 

 shows that they can make a selection of food by a control of the 

 beat of the cilia and suggests that the same may hold in the 

 case of Ostrea. Kellogg (16) answers this criticism in a polemic 

 entitled " Opinions on Some Ciliary Activities." 



Jordan (13), in a study of the irritability of the muscles and 

 the influence of the nervous system on the musculature of cer- 

 tain holothurians, gives a description of certain reactions of 

 these animals. 



Kanda (14) finds that the marine snail Littorina littorea is 

 negative in its reaction to gravity, but that this reaction is 

 influenced by the fact that the animal is also negative to light. 

 The author finds that in sea water the angle of inclination (to 

 the horizontal) of the surface on which the snails move, has a 

 marked influence on the percentage of positive and negative 

 animals, — the larger the angle, the larger the number of nega- 



