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NATURE 
| Oct. 23, 1873 
tration of his subject. They should be important, as 
they respect the science they are applied to, yet clear, and 
such as may easily and generally be understood. They 
should rather approach to simplicity, and explain the 
established principles of the subject, than be elaborate 
and apply to minute phenomena only. I speak here (be 
it understood) of those lectures which are delivered 
before a mixed audience, and the nature of which will not 
admit of their being applied to the explanation of any but 
the principal parts of a science. If to a_ particular 
audience you dwell on a particular subject, still adhere to 
the same principle, though perhaps not exactly to the 
same rule, Let your experiments apply to the subject 
you elucidate, do not introduce those which are not to the 
oint. 
Pe Though this last part of my letter may appear super- 
fluous, seeing that the principle is so evident to every 
capacity, yet I assure you, dear A., I have seen it broken 
through in the most violent manner—a mere alehouse 
trick has more than once been introduced in a lecture, 
delivered not far from Pall Mall, as an elucidation of the 
laws of motion. 
“Neither should too much stress be laid upon what I 
would call small experiments, or rather illustrations. It 
pleases me well to observe a neat idea enter the head of a 
lecturer, the which he will immediately and aptly illus- 
trate or explain by a few motions of his hand—a card, a 
lamp, a glass of water, or any other thing that may be by 
him ; but when he calls your attention in a particular way 
to a decisive experiment that has entered his mind, clear 
and important in its application to the subject, and then 
lets fall a card, I turn with disgust from the lecturer and 
his experiments. 
ready wit and the presence of mind to turn any casual 
circumstance to an illustration of his subject. Any par- 
ticular circumstance that has become table-talk for the 
town, any local advantages or disadvantages, any trivial 
circumstance that may arise in company, give great force 
to illustrations aptly drawn from them, and please the 
audience highly, as they conceive they perfectly under- 
stand them. 
“ Apt experiments (to which I have before referred) 
ought to be explained by satisfactory theory, or otherwise 
we merely patch an old coat with new cloth, and the 
whole (hole) becomes worse. If a satisfactory theory can 
be given, it ought to be given. If we doubt a received 
opinion, let us not leave the doubt unnoticed, and affirm 
our own ideas, but state it clearly, and lay down also our 
objections. If the scientific world is divided in opinion, 
state both sides of the question, and let each one judge 
for himself, by noticing the most striking and forcible 
circumstances on each side. Then, and then only, shall 
we do justice to the subject, please the audience, and 
satisfy our honour, the honour of a philosopher.” 
We trust that during the ensuing session, these 
opinions of Faraday may be in the minds of every 
lecturer on Science. 
ECKER’S “CONVOLUTIONS OF THEB RAIN” 
On the Convolutions of the Human Brain. By Dr. 
Alexander Ecker, Professor of Anatomy and Compara- 
tive Anatomy in the University of Freiburg, Baden. 
Translated, by permission of the author, by John C, 
Galton, M.A., Oxon., M.R.C.S., F.LS., &c., &c. 
Translator of Prof. Roser’s “Manual of Surgical 
Anatomy,” &c, (London: Smith, Elder, & Co., 1873.) 
©* late years the topographical anatomy of the surface 
of the brain has deservedly attracted considerable 
attention ; and the recent able investigations of Hughlings 
’Tis well, too, when the lecturer has the: 
Jackson and Ferrier have shown the importance, in fact 
the absolute necessity of a correct and generally recog- 
nised description and enumeration of the cerebral con- 
volutions. Mr. Galton therefore deserves the thanks of 
all interested in the subject, forshaving introduced to us 
in English dress this valuable monograph by Prof, Ecker 
of Freiburg. 
There are two methods by which the complex human 
brain may be analysed and reduced to its simpler 
elements, two paths that lead to the same goal; the one 
is by a careful examination and comparison of the brains 
of the lower animals, and especially of apes, which latter 
in their higher groups present a “ sketch map ” as it were, 
which is filled in and completed in man only. This has 
been carried out with great success by Gratiolet primarily, 
and in England it has been followed amongst others by 
Huxley, Marshall, Flower and Rolleston. The other 
method is by tracing the development of the fcetal brain, 
and observing which fissures, and therefore which convo- 
lutions, are the first to make their appearance, and so are 
of primary importance, and how these subsequently under- 
go farther evolution and complication. Tiedemann and 
Reichert have hitherto been our authorities on this point, 
and it is by this method chiefly that Prof. Ecker arrives 
at his conclusions, 
In this country the admirable little treatise of Prof. 
Turner has been welcomed and the classification therein 
adopted is now generally accepted, and taught in several 
of our anatomical schools. Prof. Ecker in the main 
follows Prof. Turner, although the nomenclature, of 
course, is that of the German school, and so differs 
occasionally from ours, which follows rather Gratiolet and 
the French school. The synonyms are, however, in all 
cases faithfully given. 
The author insists upon the essential difference between 
the Sylvian fissure and the other sulci, these being mere 
indentations of the cortex, whilst that is formed by the 
folding of the temporo-sphenoidal lobe on the fore part of 
the brain during its development. The anterior or as- 
cending branch of this fissure! is here correctly described 
as being short and arrested by the hinder end of the lower 
frontal convolution, whilst that described as such by Prof. 
Turner is a distinct sulcus (pracentral) terminating close — 
behind the ascending ramus. The gyrus connecting the 
inferior and ascending frontal (anterior central) convolu- 
tions is always present, although it is not always super- 
ficial, being occasionally concealed by the over-lapping of 
those convolutions. Instead of the orbital lobule usually ~ 
described on the under surface of the frontal lobe, the 
three frontal convolutions are traced round the apex to 
the orbital surface. The narrow ridge internal to the 
olfactory sulcus (gyrus rectus) is regarded as the con- 
tinuation of the first, the gyrus between that and the 
orbital sulcus as the second, and outside the last as the 
third. We should rather consider all internal to the 
orbital sulcus as first frontal, whichis grooved by a special 
olfactory sulcus, and the second as ending posteriorly 
between the anterior branches of the triradiate orbital 
sulcus. The marginal convolution is regarded as simply 
the inner surface of the superior frontal, 
In the parietal lobe the supra-marginal and angular 
convolutions are amongst the most difficult in the brain 
to indicate and circumscribe. Prof. Ecker describes the 
