Oct. 2, 1873] 
health, and had no tendency to fever, although the temperature 
was remarkably high for the month of June. 
* I have not seen a similar accident during my fifteen years’ 
residence in France, but I presume they are not unfrequent 
here, or there would be no reason for the vulgar French ex- 
pression ‘* Mauvaise comme une chenille.” A, GILLANDER 
7, Rue St. Claire, Passy, Paris 
The Glacial Period 
Pror. TYNDALL has several times called attention to a point 
in regard to the height of the snow-line, which seems to be 
steadily overlooked by those who speculate on the causes of the 
great prevalence of snow. during the glacial epoch. It is of 
course well known that the height of the snow-line at any place 
is determined mainly by two things, viz., the depth of annual 
snow-fall, and the temperature of the place. If the amount of 
snow falling over the whole earth is to be increased, the evapora- 
tion must also be increased. (‘‘ Heat asa Mode of Motion,” 
pp. 206-7. New York, 1866.) This would also raise the tem- 
perature, but the snow-line might nevertheless descend. We 
have a case of exactly this kind in the Himalayas. On the warm 
southern side of these mountains the snow-line is, nevertheless, 
3,000 ft. lower than on the northern side, where the temperature 
is very much colder. This is evidently due to a difference in the 
amount of annual precipitation. Assume that the sun was 
at one time much warmer than now, and that since then it has 
been steadily cooling ; and I believe you have the key to the 
solution of the questions asked by J. H. Rohrs, as well as to 
such questions as the widespread occurrence of tropical vegeta- 
tion during the past ages. 
Towa City, U.S. FRANK E, NIPHER 
RECENT RESEARCHES ON THE LOCALISA- 
TION OF THE CEREBRAL FUNCTIONS 
‘THE fifth part of Dr. Brown-Séquard’s new “ Archives 
of Scientific and Practical Medicine” contains an 
excellent report by Dr. Neftel, “on some of the recent 
researches in neuropathology” embracing a digest of 
several important modern methods, recently introduced, 
for the purpose of analysing the functions of the different 
parts of the cerebral hemispheres, together with a suc- 
cinct account of the results arrived at by their employ- 
ment, An abstract of this report forms the substance of 
the present notice. 
The researches of Longet, Magendie, Matteucci, and 
others have led to the assumption by most physiologists, 
that the cerebral hemispheres, especially their cortical 
substance, are destitute of sensibility, being the seats of 
origin of higher mental phenomena only. The experi- 
ments from which these conclusions were arrived at, con- 
sisted in the irritation of the hemispheres in living 
animals by mechanical, chemical, and electrical means ; 
and in none were they succeeded by muscular contrac- 
tions. As if to put the question beyond a doubt, Flourens 
removed the entire hemispheres without disturbing the 
muscular mechanism. 
But the tendency of modern observation is in a diffe- 
rent direction ; the new researches have been made inde- 
pendently by several investigators, with entirely different 
methods, nevertheless the results are the same, contrary 
to that of the earlier workers ; the evidence going to prove 
that the cortical substance of the cerebral hemispheres is 
in close relation with certain muscular groups, forming 
‘the “ psychomotor centres ” of Gudden. 
Fritsch and Hitzig commenced these researches, the 
latter having observed that galvanic excitation of the 
hemispheres in the living man produced contraction of 
the eye-muscles. This aberrant result suggested further 
experiments. They irritated the cerebral hemispheres in 
a dog with an extremely weak current, and found that 
movements of certain groups of muscles followed the ex- 
citation of definite spots on the anterior convex portion of 
the brain, always upon the side opposite to that which was 
acted on; whilst the same excitation of portions of the 
NATURE 
467 
hemispheres situated more posteriorily, produced no 
effect. Thus they found the centre for the extensor and 
adductor muscles of the anterior extremity at the external 
end of the pre-frontal convolution; and somewhat be- 
hind it the centre for the flexor and rotating muscles of the 
same extremity. The irritation of these centres by 
metallic closing of a very weak galvanic current produces 
a single contraction, whilst the interrupted current pro- 
duces tonic and gradually disappearing contractions of 
these muscles, followed by epileptiform movements. The 
anode has much more influence in producing these results 
than the cathode, so much so, that with a current of 
minimal intensity contractions can only be produced by 
the anode. 
When Fritz and Hitzig removed in dogs the centre for 
the anterior extremity, this latter did not become entirely 
paralysed, the animal could use it, but imperfectly, and 
seemed quite unconscious of the condition of the limb, 
which could be placed into any position without attracting 
its attention. 
Nothnagel employs a new method for the determina- 
tion of the functions of the brain. His observations are 
made mostly on rabbits. An incision is made in the 
scalp, the skull is perforated with a needle. Through the 
canal thus formed in the bone a very small drop of a con- 
centrated solution of chromic acid is injected by means of 
a hypodermic syringe with avery slender nozzle. The 
scalp wound is then united by suture, and the animal does 
not seem to be affected, except with regard to the func- 
tional derangement incidental to the lesion. Generally 
they survive the operation two or three weeks, and die 
from causes which Nothnagel cannot explain, no consti- 
tutional symptoms being developed. However, when the 
chromic acid is injected into the lateral cerebral ventricles 
death is the immediate result. On post-mortem exami- 
nation, where the chromic acid was injected a minute cir- 
cumscribed place appears, of a green colour, resistant and 
hard. 
In methods employed previous to this, many causes 
acted to impair the value of the results arrived at ; there 
was considerable hzemorrhage, refrigeration of the brain 
surface, and modification of the intra-cranial pressure, in 
addition to which the animal died very shortly. These 
are obviated by the new means just described ; many fresh 
facts have therefore been brought to light. In one of his 
experiments Nothnagel madea chromic acid lesion on the 
surface of the cerebral cortex, which penetrated very 
slightly into its substance, in a spot corresponding exactly 
to the outer end of the post-frontal convolution. The 
animal appeared healthy, but it was found on careful ob- 
servation that it had lost the muscular sense in the an- 
terior extremity, on the opposite side to the cerebral lesion, 
it being possible to put, and retain for some time, the 
affected paw in strained positions. This condition passed 
off before death, which seems to indicate that the terminal 
station or the real centre for the muscular sense exists 
elsewhere, and that after a time other ways to it become 
developed. 
Nothnagel found, further, a circumscribed locality in 
the cerebral cortex, the lesion of which produces a partial 
and transient hemiplegia of the opposite extremity. 
This spot is in front of that for the muscular sense, and 
deeper than it. In no other portions of the cerebral cor- 
tex, except those above mentioned, have the chromic acid 
lesions been followed by paralytic symptoms. 
Gudden has introduced another method by which the 
function of the different parts of the cerebrum may be 
studied. He finds that newly-born animals, as rabbits, 
will undergo a very great amount of mutilation without 
interfering seriously with the nutritive functions, so that 
portions of the brain may be removed, and the animal 
will grow to full size, with no peculiarities excepting those 
resulting from the absence of the parts removed. The 
slight sensibility, rapid coagulation of the blood, and the 
