Fz 
few years, 
at least of the learning process, to 
mention mammals alone. 
of the monkeys 
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 ameba_ 
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 conelu- 
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. | 
of several | 
(Thorndike, Kinne- | 
THE POPULAR SCIENCE MONTHLY 
We now know something 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 Rey. 
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—aA tablet in memory of 
Richard Hakluyt, the navigator, was 
unveiled in Bristol Cathedral on July 
7, the address being made by Sir 
Clements Markham. 

. 
