384 S. J. HOLMES 



" may be accompanied by motor reactions to either sudden 

 shading or sudden illumination," and ' the ability to react to 

 sudden changes in illumination by means of motor reactions 

 is possessed by Euglenae which are not heliotropic. Conversely, 

 there are heliotropic Euglenae that cannot be made to respond 

 to changes in illumination." The orientation to light and the 

 ability to react to sudden changes of light intensity being to a 

 large extent independent variables, it is concluded that the two 

 types of reaction depend upon different mechanisms. Orienta- 

 tion is not the outcome of trial and error, but "is as direct as 

 the locomotor mechanism of the organism will allow." 



Baunacke (5) gives a general discussion of the function of the 

 statocyst in various invertebrates and describes several experi- 

 ments showing the relation of the statocysts to the preservation 

 of the normal position in various mollusks. 



Bohn (6) has given a discussion of modifiability of behavior 

 in lower organisms and its relation to certain physical and 

 chemical processes. That he is correct in ascribing associative 

 memory to protozoans and coelenterates may be questioned by 

 many comparative psychologists, but all will find his treatment 

 of the topic suggestive. 



The experiments of Miss Brundin (7) on some terrestrial am- 

 phipods from California showed that the more terrestrial of the 

 two species studied, Orchestia pugettensis, is the more strongly 

 positive to light. This species commonly lives in holes in the 

 sand above high tide mark, while Orchestia iraskiana lives in 

 cooler and moister conditions under sea weeds and rubbish 

 nearer the water's edge. It was found that both dryness and 

 heat tend to make negative Orchestias positive. Enforced 

 activity also produces the same effect. Orchestias compelled 

 to lie on one side by being compressed between two glass plates 

 would nevertheless manage to go toward the light. Specimens 

 with one eye blackened over would at first perform circus move- 

 ments toward the normal side, but after a time they would go to 

 the light in a more direct course. There is a discussion of the 

 relation of the behavior of the two species to the choice of their 

 respective habitats. 



Brunelli (8) has given a resume of the behavior of hermit 

 crabs and adds a detailed description of how Pagurits auosor 

 detaches the anemone Adamsia and then places it, base down- 



