706 
Proceedings of the Roycd Society 
and anomalous expansion. There is at that point a knot of great 
complexity and significance. When it is unravelled, there may fie 
something decisive hearing on the present discussion. 
Monday, hth July 1880. 
Mr ROBERT GRAY in the Chair. 
The following Communications were read : — 
1. On Peroxides of Zinc, Cadmium, Magnesium, and Alu- 
minium. By J. Gibson, Ph.D., and R. M. Morison, D.Sc. 
2. On the Processes in Subepiphysal Bone Growth and some 
points in Bone Resorption. By De Burgh Birch, M.B., 
Demonstrator of Physiology in the University of Edin- 
burgh. 
(Abstract.) 
Subepiphysal Bone Grovith . — Two processes must be noticed in 
this connection. 
1st, The replacement of the neck of the cartilaginous head or 
epiphysis by cancellous tissue as an accompaniment to the rise of 
the epiphysis caused by the growth of the cartilage forming its neck. 
The cartilage is channelled by the advancing marrow, the rows of 
cartilage capsules being opened up. 
The opening up of the rows of cartilage capsules results from the 
presence of a capillary blood-vessel forming the head of the column 
of marrow which lies in immediate contact with the next unopened 
capsule (Ranvier). The close proximity into which the pabulum is 
thus brought with the cartilage corpuscle in the unopened capsule 
nearest it causes it to grow rapidly and absorb the surrounding 
cartilage, this occurring, quickest in the direction of least resistance 
that is, towards the marrow. 
The cartilage capsules communicate with each other by means of 
fine channels, a fact already hinted at by Budge. 
The osseous tissue which is deposited upon the cartilage spicules, 
or septa which result from the channelling of the cartilage, forms 
the cancellous tissue ; this forms a stable base off which the epiphysis 
