44S GEORGES BOHN 



memory, as a criterion of consciousness. Romanes and Morgan 

 hesitate to conclude that there is no consciousness where there 

 is no associative memory. According to Holmes, it is probable 

 that all animals which learn are conscious, but such is not 

 necessarily the case; moreover, we must not deny conscious- 

 ness to animals that cannot learn. But are there such animals? 

 I think not: there are, as Margaret F. Washburn has well shown 

 in her fine book, "The Animal Mind," various ways of learning. 

 Among these ways, one of the most perfect is "associative 

 memory." Now my researches on actinians and the very recent 

 ones of Metalnikow on infusoria show that associative memory 

 functions even in the lower organisms, and is consequently a 

 general property of living matter. We should thus be led to 

 admit that a sort of consciousness accompanies all organic 

 processes, a conclusion calculated to satisfy those who allow no 

 breach of continuity in the sequence of vital manifestations. 



Holmes devotes two chapters (II and III) to Reflexes and 

 Tropisms. According to him, the writings of Jacques Loeb, and 

 in particular Loeb's book on heliotropism in animals, by the 

 interesting facts which they have made known, the ingenious 

 experiments which they have suggested, and the general theory 

 to which they have led, have had a considerable and stimulating 

 influence. We must not rest contented with describing the 

 facts of behavior; we must seek to explain them. Holmes then 

 examines the criticism of Jennings to the effect that in certain 

 alleged tropisms there is no definite orientation. He next 

 passes to an examination of the variations in phototropism, and 

 speaks in particular (p. 50) of some unpublished experiments 

 by Michener, according to which chemicals cannot make a 

 reaction negative which was primitively positive. But Anna 

 Drzewina has recently succeeded in producing this result by 

 using a substance, potassium cyanide, which inhibits oxidations ; 

 and acids act in the same way when their action is prolonged. 



The next chapter (IV) treats of the " Behavior of the Proto- 

 zoa." The reader has already had an opportunity, in the Bio- 

 logical Bulletin for 1907, to become acquainted with the author's 

 very interesting considerations on the rhythmic activity of 

 certain infusoria (Loxophyllum) . Holmes thus treats this ques- 

 tion with especial competence. He recalls at the outset the 

 memory of our regretted Binet, and discusses at length the 



