276 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
b. Histology. 
Sharpey’s Fibres. — E. Grynfeltt ( Comptes Rendus Acad. Sci ., 
1922, 174, 966-8, 1 fig.). According to Kolliker and Ranvier the 
perforating fibres or Sharpey’s fibres belong exclusively to the periosteal 
bone. There are connective bundles, more or less calcified, enclosed in 
the new formed matrix in process of ossification. But it seems that 
there are other perforating fibres which may be distinguished as medul- 
lary. They are much finer than the others ; they are continuous with 
delicate collagenous fibres in the connective framework of the medulla. 
They are found on the surface of all the osseous lamellae in contact with 
the medulla. Thus, taking the two kinds of perforating fibres, there is 
a penetration of the whole matrix from the periosteum to the medulla. 
J. A. T. 
Ciliary Movement. — J. Gray ( Proc . Roy. Soc., Series B, 1922, 
93, 104-31). The cilium is capable of expending potential energy in 
the form of work as long as it is in organic connexion with the cell 
protoplasm. Each ciliated cell of Mytilus is capable of independent 
movement when isolated. The cilia of the Ctenophore Pleurobrachia 
require a definite stimulus to induce their beat. The cilium is an 
clastic fibre or bundle of fibres, usually in communication with the cell 
protoplasm by intracellular fibrillae. The beat consists of a rapid 
effective stroke and a slower recovery stroke. In an acid solution there 
is gradual slowing and then rest. The effect is reversible by alkalies. 
The rate of the beat is most simply controlled by controlling the 
hydrogen ion concentration within the cell. Under normal circum- 
stances the activity of the lateral cilia depends on the presence of 
potassium ions. The cilia come to rest if the osmotic pressure of the 
external medium exceeds a certain value. A hypothesis is put forward 
that the mechanism of ciliary movement is essentially the same as 
that of muscular movement. The effect of ions on the cell-membrane 
has been studied. J. A. T. 
Reaction of Frog’s Melanophores to Pituitary Extracts. — L. T. 
Hogben and F. R. Winton {Proc. Roy. Soc., Series B, 1922, 93, 
318-29). Extracts of the posterior lobe of the pituitary gland have a 
specific effect on the melanophores of the frog, causing them to undergo 
extreme expansion. An injection, equivalent to less than yo^th of the 
ordinary clinical dose, is adequate to produce a conspicuous darkening 
of the skin visible to the naked eye. The effect is the reverse of that 
which followed administration of adrenalin. The melanophore stimulant 
is only slowly destroyed by boiling with 0 * 5 p.c. hydrochloric acid : it 
is therefore different from the pressor principle, and in its slow destruc- 
tion by acid hydrolysis agrees with oxytocic or uterine principle. It 
acts directly on the dermal melanophores rather than on the nerve 
endings. J. A. T. 
Spiral Valve of Larval Lamprey. — J. Mawas ( Comptes Rendus 
Acad. Sci., 1922, 174, 1041-3). The lymphoid organ of the spiral 
valve of the Ammocoete larva shows lymphoid tissue, a system of vessels 
and blood sinuses, and a partitioning connective tissue system — the 
