MarcH 21, 1912] NATURE 59 
page 12 the sesamoid bones are described as being | membranous ossification; and whether bone is 
Their shape is more correctly 
“pyramidal.”’ In connection with the description 
of the stomach of the ruminant, it would be an 
advantage if it were dealt with a little more fully. 
At present the description is far too meagre to be 
of any service. On p. 92 a list of hereditary 
diseases is given as scheduled by the Minnesota 
Stallion Law. Navicular disease is not included, 
although there is ample evidence of its hereditary 
nature. Laminitis is probably debatable as a 
hereditary disease, but it might be included in 
such a list of undesirable points with advantage, 
for the conformation so commonly associated with 
it is undoubtedly hereditary. The make-up of 
chapter xx. seems to to have got rather 
mixed, for the two first paragraphs of p. 92 re- 
ferring to heredity would be more appropriately 
placed to follow the paragraph on in-and-in breed- 
ing on p. 90, instead cf being sandwiched between 
paragraphs referring to air. 
The chapter on Actinomycosis is very good 
indeed, although we should be very sorry to see 
anybody, farmer or veterinary surgeon, resort to 
the caustic line of treatment as outlined on p. 149, 
especially as better results can be obtained by 
internal medication without pice the same 
amount of pain and suffering. 
The illustrations throughout the book are excel- 
lent on the whole, though we fail to see any point 
in the inclusion of Figs. 74 and 75. In neither 
case is there anything shown at all diagnostic of 
milk fever. 
We have no hesitation in recommending this 
book to agricultural students, for it should be of 
great service to them in the pursuit of their 
veterinary studies. 
“triangular.” 
us 
THE NATURE OF BONE. 
Der Aufbau der Skeletteile in den freien Glied- 
massen der VWirbeltiere. Untersuchungen in 
urodelen Amphibien. Von Prof. H. von 
Eggeling. Pp. vi+324+4 plates. (Jena: 
Gustav Fischer, 1911.) Mk. 16. 
T the present time the problems relating to 
the precise nature and mode of development 
of osseous tissue are being submitted to a search- 
ing scrutiny, and of the most cherished 
beliefs of the majority of anatomists concerning 
the process of evolution and the real structure of 
bone are being threatened. Great activity is being 
displayed in investigating such problems as the 
mode of deposition of the calcium salts in the 
‘scleroblastema; the precise relationship of this 
process of calcification to the cells which in a 
sense determine it; whether there is any funda- 
mental distinction between enchondral and intra- 
NO. 2212, VOL. 89] 
many 
| inquiry. 
really the inert, unchanging tissue one is apt to 
think essential in a skeletal support. 
These problems and others of a similar nature 
are forcing themselves upon the attention of 
workers in widely separated fields of biological 
Surgeons like Sir William Macewen, 
the result of clinical experience, have been led to 
question the current accounts of the development 
of bone; radiographers have been amazed to find 
how rapidly an acutely-inflamed bone reacts to the 
inflammatory process and becomes transparent to 
the X-rays; paleontologists have been puzzled to 
explain why obviously homologous bones in two 
as 
/amniotes may ossify in different ways, being 
enchondrous in one and intramembranous in 
| another; anatomists find a difficulty in drawing 
a sharp line of distinction between enchondrous 
and intramembranous bone in certain parts of the 
skeleton; and embryologists and bio-chemists meet 
| with many difficulties when they attempt to ex- 
plain the precise mode of deposition of the calcium 
salts and the nature of the tissues in which they 
are laid down in the process of bone-formation. 
Most of the work which hitherto has been done 
| with the object of elucidating these and allied 
problems has been based mainly upon the investi- 
gation of the more highly organised and specialised 
Amniota. But Prof. von Eggeling has wisely 
| selected for his research the simplest and least 
modified material he could obtain: he has devoted 
his whole attention to the investigation of certain 
specific features of the process of ossification in 
the limb-bones of the Urodeie Amphibia, the most 
primitive vertebrates possessing limb-bones pre- 
cisely comparable to those of the Amniota. 
His results are presented in the form of this 
large monograph, packed with a mass of detailed 
information relating to the ossification of the limb- 
bones in twenty-four species, representing every 
family of the Urodela. 
He gives a long and minute analysis of the 
voluminous literature relating to the structure and 
histogenesis of so-called coarse-fibred and fine- 
fibred bone; and then sets forth his own observa- 
tions. 
The most primitive osseous tissue is a product 
of the periosteum, but the dental cement and part 
of the placoid-organs of Selachians are of the 
same nature. It assumes its distinctive form by 
reason of the fact that the scleroblasts develop 
first amidst a coarse-fibred matrix of connective 
tissue. 
At a later stage, both in phylogeny 
ontogeny, buds of vascularised tissue eat their 
way through the sheath of coarse-fibred bone into 
the cartilaginous core; and in this loose delicate 
and 
