28 COLEMAN R. GRIFFITH 



induced either under normal living conditions or at times when 

 the rats are feeding, mating, mothering or sleeping. The dem- 

 onstrated unlearnedness of the behavior would indicate that 

 it is probably instinctive. 



animals" by Preyer (Preyer, W., Die Kataplexie und der thierische Hypnotismus, 

 1878), and (Verworn, M., Beitrage zur Physiologie des Centralnervensystems, 

 Erster Theil. Die sogenannte Hypnose den Thiere, 1898, Jena, pp. 1-92), much 

 work has been done on the somewhat similar attitudes known as death-feigning. 

 (See Severin, H. H. P., and Severin, H. C., Behavior Monog., 1911, 1, No. 3, pp. 

 43-44, for a bibliography of these studies) . Some of our rats, however, in spite 

 of an apparent rigidity were quite limp and inert when taken in the hand. 



