few years. We now know something at least of the learning process, to mention mammals alone, of several of the monkeys (Thorndike, Kinneman, 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 continental idea (Loeb, Bethe, Beer, Bohn and others) that the behavior of the invertebrates is of the fixed and nonplastic type.
The second problem, that of imitation, has been largely studied. Unfortunately the work in this direction has been characterized by a marked difference in experimental results. Thorndike (dogs, cats, monkeys) and Watson (monkeys) have been convinced by their results that learning by imitation is not an important function in animal adjustment. Haggerty (monkeys). Porter (birds) and Berry (rat, and manx cat) reach opposite conclusions. 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 equipment of animals is only just beginning. The American Psychological Association has appointed a committee for the determination of standard methods of testing vision in animals. The appearance 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 Morgan, 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 possibilities 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 eminent German astronomer, at the age of ninety-eight years, and of the Rev. Robert Harley, F.R.S., an English congregational clergyman, known for his contributions to mathematics and symbolic 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 Altbrünn.—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.
