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THE POPULAR SCIENCE MONTHLY 



few years. We now know something 

 at least of the learning process, to 

 mention mammals alone, of several 

 of the monkeys (Thorndike, Kinne- 

 man, Watson. Haggerty) ; dogs and 

 cats (Thorndike, Hamilton) ; raccoons 

 (Davis and Cole) ; the rat (Small, 

 Watson, Berry, Richardson) ; the 

 dancing mouse (Yerkes) ; the guinea- 

 pig (Allen) and the grey squirrel 

 (Yoakum). Other forms have not 

 been neglected, and we have to-day as 

 a result of the ten years' work a fairly 

 respectable body of knowledge on the 

 learning methods and capacities of 

 animal forms ranging from the amoeba 

 to man. This work has shown that 

 even the lowest organisms possess 

 plasticity. Jennings has been chiefly 

 responsible for challenging the conti- 

 nental idea (Loeb, Bethe, Beer, Bohn 

 and others) that the behavior of the 

 invertebrates is of the fixed and non- 

 plastic type. 



The second problem, that of imita- 

 tion, has been largely studied. Unfor- 

 tunately the work in this direction has 

 been characterized by a marked differ- 

 ence in experimental results. Thorn- 

 dike (dogs, cats, monkeys) and Watson 

 (monkeys) have been convinced by 

 their results that learning by imita- 

 tion is not an important function in 

 animal adjustment. Haggerty (mon- 

 keys). Porter (birds) and Berry (rat, 

 and manx cat) reach opposite conclu- 

 sions. Haggerty's recent work on the 

 chimpanzee and ourang shows clearly 

 that imitation of a complex character 

 is present in the anthropoid apes. 

 There is still room for doubt in the 

 case of other animal forms. 



Careful work on the sensory equip- 

 ment of animals is only just beginning. 

 The American Psychological Associa- 

 tion has appointed a committee for the 

 determination of standard methods of 

 testing vision in animals. The appear- 

 ance of this report will probably lead 

 to renewed interest in this problem. 



It ought to have the effect of making 

 the work of the different investigators 

 directly comparable and to lead to safe 

 conclusions concerning the phylogenetic 

 development of sense organ processes. 

 In conclusion, the renewed interest 

 in field observation may be mentioned. 

 The establishment of laboratories for 

 the study of animal behavior at first 

 drew interest away from field work. 

 Recently animal psychologists have 

 been forced to admit partially the 

 truth of the claims of Wesley Mills, 

 John Burroughs, Hobhouse and Mor- 

 gan, viz., that animal experimentation 

 ought not to be carried out under too 

 rigorous and unnatural conditions. 

 Studies in the field in the last ten 

 years have been made by the Peckhams 

 (insects), Newman (amphibia) and 

 Watson (birds). Interesting possibili- 

 ties in field observation are offered in 

 studies of the beaver, the prairie dog 

 and lizards. 



SCIENTIFIC ITEMS 

 We regret to record the deaths of 

 Dr. Johann Gottfried Galle, the emi- 

 nent German astronomer, at the age 

 of ninety-eight years, and of the Rev. 

 Robert Harley, F.R.S., an English con- 

 gregational clergyman, known for his 

 contributions to mathematics and sym- 

 bolic logic, at the age of eighty-three 

 years. 



At a meeting of the Berlin Academy 

 of Sciences on June 30, commemorative 

 addresses were made on Friedrich 

 Kohlrausch, by Professor Rubens; on 

 Hans Landolt, by Professor van't Hoff, 

 and on Robert Koch, by Professor 

 Rubner. — On October 2 the unveiling of 

 the statue of Johann Gregor Mendel 

 will take place at Gregor-Mendel-Platze 

 in Altbriinn. — A tablet in memory of 

 Richard Hakluyt, the navigator, was 

 unveiled in Bristol Cathedral on July 

 7, the address being made by Sir 

 Clements Markham. 



