— B22 
added by himself in a footnote, that the “solar 
spectrum does produce the complementary colors in 
the after-image.’’ For if the so confidently pro- 
claimed law did not turn out true for saturated col- 
ors, the simplest of all perceptions of color, why did 
not our author suspect*that he was on dangerous 
ground? As for the rest of his article, it is really no 
contribution to science, but contains an effort to re- 
fute the doctrine of fatigue in favor of some quite 
unintelligible explanation of after-pictures, and to 
edify the reader by general reflections. 
We are far from being fully persuaded of the truth 
of the common theory, and have nothing ourselves 
to add to the discussion of the subject, save the 
present note of warning to solitary observers of men- 
tal phenomena. Let us all observe, by all means, 
and independently; but let us know what other peo- 
ple have said, or at least what the greatest men have 
said. Mr. Hodges is actually capable of believing 
and saying, at the outset of his article, such words as 
these: ‘‘I should add, that brief references to after- 
images with closed eyes may be found in Helmholtz’s 
great work on Physiological optics, in Dr. Foster’s 
Text-book of physiology, and in a few other works; 
but the fact that neither of them contains any de- 
tailed experiments (?) such as I am about to describe, 
induces me to hope,’ etc. And this Mr. Hodges 
could write, presumably with Helmholtz’s book, § 23 
and all, before him. What he is about to describe 
we have indicated. He looked at a window, and 
then covered his eyes; afterwards he tried the sun, 
colored cards, ete.; then he asked two or three people 
to try similar experiments; and then he wrote his 
article. And now who shall say that every intelli- 
gent man understands how to use even the best- 
known and best-arranged books? And why should 
the pages of the Nineteenth century be thus occu- 
pied ? JOSIAH ROYCE. 
LAKES OF THE GREAT BASIN. 
As the geological observations given in a recent 
paper by Prof. E. D. Cope! relate to a region some- 
what familiar to me, I venture to offer the following 
comments. 
Under the heading of ‘Preliminary observations’ 
it is stated that the geologists of the Fortieth-parallel 
survey have shown that Lake Bonneville existed 
during tertiary time. It must be known to every 
one, however, who has read vol. i. of the reports of 
the survey mentioned, that this lake is there classed 
as quaternary: it has been so regarded by all geolo- 
gists who have made any considerable study of the 
surface geology of Utah. Lake Lahontan is sup- 
posed, with good reason, to have been contempora- 
neous with Lake Bonneville, and therefore also of 
quaternary age. Recent observations tend to prove 
that the last great rise of these lakes was later than 
the greatest extension of the Sierra-Nevada glaciers, 
1 On the fishes of the recent and pliocene lakes of the western 
part of the Great Basin, and of the Idaho pliocene lake (Proc. 
acad. nat. sc. Philad., June, 1883). 
SCIENCE. 
[Vo. III., No. 58. 
and perhaps synchronous with the Champlain epoch 
of the Atlantic coast. 
Lake Bonneville was not named by the geologists 
of the Fortieth-parallel survey, as stated by Professor 
Cope, but was first so designated by Mr. Gilbert. 
The list of lakes given as now existing in the 
Lahontan basin should also include Honey Lake, 
California, as the valley in which it occurs formed a 
bay of the old lake with over three hundred feet of 
water. A map, showing the outline of Lake Lahon- 
tan as recently determined, will appear in the third 
annual report of the U.S. geological survey. 
The prediction ‘‘ that it will be shown that a third 
lake existed in Oregon, north of the supposed north- 
ern boundary of Lake Lahontan,’’ has proved correct _ 
only in part. A geological reconnoissance conducted 
by myself in this region in the spring of 1882 has 
shown that the Great Basin, north of the hydrographic 
rim of Lake Lahontan, was divided during quater- 
nary time into not less than ten independent hydro- 
graphic areas, each of which held a lake of small 
size, as compared with Bonneville and Lahontan. 
The statement that ‘“‘the lakes of the Great Basin 
in Nevada and Oregon diminish in alkalinity as we 
approach the Sierra Nevada Mountains,”’ meets with 
a notable exception in Moro Lake, California, which 
lies at the immediate base of the highest portion of 
the mountains, but is yet, according to an analysis of 
its water made for me by Dr. F. W. Taylor, far more 
alkaline than any of the lakes of the Lahontan basin, 
excepting the soda-ponds at Ragtown, Nev. 
Professor Cope also says, that ‘‘ the lakes most re- 
mote from the mountains are not inhabited by fish, 
their only animal population being crustacea and the 
larvae of insects.’’ That this conclusion is too broad 
is illustrated by the life of Humboldt Lake, which is 
inhabited by both fish and mollusks, and also that of 
Ruby and Franklin lakes, situated still farther east- 
ward, which abound in molluscan life. That the 
freshness of lakes, and consequently their inhabita- 
bility by fishes and mollusks, do not depend on their 
relation to mountains, or even on the existence of an 
outlet, can be shown by numerous examples in the 
Great Basin. The only explanation of the apparent 
anomaly of an enclosed lake of comparative freshness 
(with less than one per cent of saline matter in solu- 
tion) in the nearly desiccated basin of a far larger 
lake, which never overflowed, has been suggested by 
Mr. Gilbert.2. His hypothesis is, that such lakes owe 
their freshness to complete desiccation and the burial 
of the precipitated salts beneath plaza deposits. 
When water re-occupies such a basin, the imprisoned 
salts may not be redissolved. It is evident that this 
process might take place in any part of an arid region 
like the Great Basin, whether it be near or remote 
from mountain ranges. 
The locality mentioned on p. 137 as having fur- 
nished fossil remains is included within the still dis- 
tinct beach-lines of an ancient lake which once filled 
the Christmas Lake and Silver Lake valleys. The 
shells collected at this locality by myself have been 
1 Wheeler survey, vol. iii. pp. 88, 89. ; 
2 Second ann. rep. of U.S. geol. surv., p. 177. 
