412 S. J. HOLMES 



particles impregnated with various chemicals. There is a selec- 

 tive elimination of the contents of food vacuoles, as indigestible 

 substances that have been taken in are soon gotten rid of. 



Mast (25) has made an extended reply to a paper on Euglena 

 by Bancroft, which was reviewed in this journal last year. The 

 question at issue concerns the method of orientation, Mast up- 

 holding the previous contention of Jenning's and himself that 

 it is brought about through a more or less modified form of 

 the ' motor reaction." It is impossible to give an adequate 

 presentation of the arguments of Mast in a short space, and 

 reference must be made to the original paper. 



Metalnikov (26) finds that Paramecia that had injected 

 Sudan powder so that they contained an average of 20 food 

 vacuoles enclosing this substance, almost completely failed to 

 take in Sudan on the following day, although they had been 

 kept in the meantime in a fresh hay infusion. They took in 

 other substances, such as carmin, sepia and egg albumen in 

 abundance. If a mixture of nutritive and non-nutritive sub- 

 stances be given the Paramecium takes both at first, but later 

 rejects the non-nutritive and continues to take nutritive material. 



Orton (27) gives an account of the feeding mechanism and 

 feeding reactions in brachiopods and certain polychaetes and 

 discusses the evolution of similar food-taking mechanisms and 

 their reactions in unrelated groups of animals. 



Echinus miliaris were found by Orton (28) to aggregate into 

 groups in the period of sexual maturity. Males and females 

 were most frequently associated, but groups were not infre- 

 quently found containing but one sex. 



In an extensive review of work on actinians Pax (29) has 

 given a very useful resume of investigations on the reactions 

 and natural history of these animals. 



The Smithsonian Institution has reprinted a paper by Pearse 

 (30) on the habits of fiddler crabs, which was reviewed in an 

 account of the literature for 1912 published in this journal 

 last year. 



Powers (31) has experimented on the reactions of four species 

 of crayfish (Cambarus) to C0 2 , HC1 and acetic acid. In C0 2 

 the species die in the following order: virilis, propinquus, diog- 

 enes, immunis. All four species react more strongly to HC1 

 than to acetic, and more strongly to acetic acid than to C0 2 . 



