J 
740 
mates. * Professor Le Conte maintains not 
only that ‘‘ the fovea is necessary to the concen- 
tration of the attention on the thing looked at,’’ 
but also (p. 302) that ‘‘the existence’’ of the 
fovea is determined by ‘‘the habits of the 
animal, especially in looking attentively.”’ 
2. I regard it as either bad psychology or 
bad terminology to say: ‘‘ We do, indeed, see 
all objects double except under certain condi- 
tions.’’? We do not hear each of the overtones 
of a tone because most people can learn to dis- 
tinguish them, nor do we know the motives of 
‘our actions because we believe that motives 
exist. 
3. I am glad that Professor Le Conte here 
calls attention to the real psychological prob- 
lems involved in localization in the field of 
vision and in the coordination of visual and 
motor perceptions. The section in his book 
which I criticised is, however, headed ‘ Erect 
Vision,’ and he writes : ‘‘ How, then, with in- 
verted retinal images, do we see objects in their 
right position, 7. e., erect? This question has 
puzzled thinkers for many centuries,’’ etc. The 
question seems to me analogous to that of the 
child who asks how people in China with their 
heads down can hang on by their toes. It may 
be a popular paradox, but I donot admit that 
it is a question deserving serious scientific dis- 
cussion. J. McKEEN CATTELL. 
A SIMPLE METHOD OF COMBINING THE COLORS. 
THE following very simple method of illus- 
trating the recomposition of the spectral colors 
into white light has some obvious advantages 
in the way of ease of apprehension on the part 
of the beginning student. It also possesses an 
additional and not inconsiderable advantage in 
that it is striking. 
A rectangular refraction tank with glass ends 
is set up in front of the lantern, both being pref- 
erably upon a rotating stand. From a hori- 
zontal slit a beam is projected and the prism 
interposed in such a manner that there is sent 
down into the water the rays of the spectrum, 
* Por the most. recent work on the subject cf the 
thesis by Dr. Slonaker in the Journal of Morphology 
XIII., 3. Professor Le Conte himself in a later 
chapter refers to a more highly organized central area 
in the lower mammals. 
SCIENCE. 
[N. S. Von. VI. No. 150. 
their order from red to violet running length- 
wise of the tank. A few drops of milk are 
mixed with the water, and with care a mixture 
may be obtained which in a side view shows 
the separated rays clearly, while at the same 
time if viewed from the end of the tank it looks 
quite white. On cutting off either the violet 
or red end of the spectrum the end view be- 
comes colored. 
If a strong beam is available it is better to 
turn it back toward the lantern by a reflector 
before sending it through the prism. This 
brings the violet rays which are least intense 
nearest the end, where they have to traverse a 
thinner stratum of the mixture. 
F. W. McNarr. 
MICHIGAN COLLEGE OF MINEs. 
SCIENTIFIC LITERATURE. 
Report of Explorations in the Labrador Peninsula 
along the East Main, Koksoak, Hamilton, Man- 
icuagan and the Portions of Other Rivers in 
1892-938-94-95. By A. P. Low, B. Ap. Se.” 
Annual Report of Progress, Geological Sur- 
vey of Canada, Vol. VIII., pp. 385. 
One of the most interesting and valuable re- 
ports which has been issued by the Geological 
Survey of Canada in recent years has just ap- 
peared on the peninsula of Labrador, by Mr. 
A. P. Low. 
The report embodies the results of four years’ 
exploration, during which time Mr. Low has 
traversed Labrador from north to south and 
from east to west, and it presents in readable 
form a summary of our knowledge, not only of 
the geography and geology, but also of the 
climatology, botany, zoology and natural re- 
sources of this remotest part of the Dominion, 
the interior of which, prior to Mr. Low’s ex- 
ploration, was practically unknown. Mr. 
Low’s work, the results of portions of which 
have been previously published in preliminary 
reports to the Geological Survey, and in papers 
presented to various scientific societies, has at- 
tracted much attention and has recently been 
accorded an especial recognition by the Royal 
Geographical Society of England. The report 
is accompanied by a fine map of Labrador, in 
four sheets, on a scale of 25 miles to the inch, 
which is colored geologically along the lines 
