380 Analysis of Scientific Books. 
quantity of serum was found in it, which was removed with a sponge, and 
the incisions made were closed by sutures. At the énd of twenty-four 
hours the sutures were divided, and the pericardium was again examined. 
Not a single drop of fluid had collected in it, in any instance, though in 
two of the trials the right auricle and ventricle were considerably dis- 
tended with blood. 
The author applies these results to man, and remarks that 
no inference can be drawn from serous effusions having pro- 
duced no observed effects during life, since large portions of fluid 
have been found in the pericardium, and even in the ventricles 
of the brain, without a single symptom to indicate the fact. 
4, On the Mechanism of the Spine. By Heary Earle, Esq. F.R.S. 
This paper describes the peculiar mechanism of the spine 
and spinal canal in birds, by which a remarkable extent of 
motion is obtained in the neck without pressure on the medul- 
lary column. It is curious, that the cervical vertebre in birds 
are not only numerous, but that they vary in number from nine 
to twenty-four; whereas, in the class mammalia, their number, 
with one exception (the three-toed sloth), is constantly seven. 
The mole, whose head appears buried between the shoulders, 
has precisely the same number as the horse, and as the pre- 
posterously long-necked giraffe. 
Mr. Earle’s is a curious paper, but as a great part of it con- 
sists of explanations and descriptions of complicated processes 
and tuberosities not intelligible without his accompanying plate, 
we must refer our anatomical readers to the original for these 
details of structure. His observations upon the mechanism and 
uses of the human spine are well put together, and deserve the 
attention of those who are fond of detecting what they call 
contrivance in the works of nature; that is, of comparing the 
works of Infinite Wisdom, whence all our contrivances have 
originated, with what they blindly refer to the effort of human 
sagacity and invention. Our author’s pathological hints at the 
conclusion of his paper also merit notice : 
That a certain degree of freedom of motion between the membranes is 
essential to the due performance of the functions of the spinal marrow, is 
poate by the effect of accidents and disease. It would be out of place 
nere, to bring forward a detail of particular cases, but I may mention 
briefly, that I have ascertained, by dissection, that the most distressing 
train of nervous symptoms, and even complete paraplegia, may be pro- 
duced by adhesions taking place between the membranes, and by effusion 
into the canal or theca. 
In conclusion I may observe, that this view of the subject tends to throw 
considerable light on the pathology of the spine, and assists in explaining 
a circumstance which I have repeatedly noticed in diseases affecting the 
vertebra, namely, that the symptoms of irritation and inflammation of the 
spinal marrow are much more early manifested, and are generally far 
more serious in their consequences when the dorsal vertebre are affected, 
than when either the cervical or lumbar are the seat of disease. In the 
former case, the slightest congestion or effusion is often productive of 
serious symptoms, from the canal being smaller and more completely filled 
with the marrow and its membranes ; whilst, in the latter description of 
