4 
Proceedings of the Royal Society of Edinburgh. [Sess. 
in some instances there is a slight irregularity in the size and arrangement 
of the cartilage cells at the bone-forming margin. The minute structure of 
the epiphyses of the long bones may be normal, even in animals in which 
pronounced rachitic-like changes are present in the skeleton. The bone 
marrow of the meat-fed rats set. six weeks and onwards shows, in some 
subjects, a great excess of fat. 
( b ) Cranial Bones . — In the meat-fed rats, ossification, both intra-mem - 
branous and intra- cartilaginous, is less advanced than in the control 
animals, the bony trabeculae in the former being less numerous and enclos- 
ing a marrow excessively rich in red blood corpuscles. While intra- 
membranous and intra- cartilaginous ossification are both affected, the defect 
is in some cases more pronounced in the periosteal bone-formation. 
There is a striking difference in the degree of development of the 
frontal, malar, and maxillary bones in the bones of the meat-fed animals 
at birth, the contrast becoming accentuated as age advances. The bones 
of the jaws in the meat-fed subjects are of a different shape from the 
controls, the former being wider and more square-shaped. This condition 
is associated with an extreme thinness of the bones and a great increase in 
the number of cells — red blood corpuscles and leucocytes — in the medullary 
cavity in the meat-fed rats (see figs. 1 and 2). In a very few animals set. 
three weeks, the difference between the development of the bones in meat-fed 
and bread-and-milk-fed animals is very slight. The average state of bone 
development in the two series is further illustrated in figs. 4 and 6 for 
animals set. three weeks and three months. The bony trabeculse in the 
meat-fed rats are extremely thin, and the medullary spaces show a 
great increase in the number of thin-walled vessels, which are distended 
with red blood corpuscles. This increase in the number of red blood cor- 
puscles in the medulla of meat -fed rats is, in the great majority of subjects, 
a very striking feature (see fig. 2). 
(c) The Structure of the White Nodules in the Bony Ribs . — These 
nodules present a striking histological picture. They are composed mainly 
of cartilage cells, which are derived from the periosteum ; at the periphery 
of these nodules the nodules are undergoing transformation into bones (see 
fig. 7). It is of interest to note that I have recently observed a similar 
histological appearance in the bones of an infant set. fifteen months, whose 
mother — a tuberculous subject — was fed during gestation, and for some 
time prior to it, on a diet containing a great excess of meat (see fig. 8). 
To sum up : — The results show that the bones of animals fed on an 
excessive meat diet present an appearance of delayed and imperfect 
ossification, with increased vascularity, and an increase in the number of 
