374 
other features of development were exaggerations of what oc- 
cured in the Frog. 
From the Selachian to the Bird the author pointed out that 
there was a wide gap which he could not satisfactorily fill up. 
The author, in conclusion, drew attention to the food-yolk 
in the eggs of most vertebrates, which he said was to be looked 
upon as the most important agent in producing the modifica- 
tions which he had described. 
(2) On the Physiological Action of Jaborandi. By 
J. N. Layetzy, St John’s College. 
May 3, 1875, 
The PRESIDENT (PROFESSOR BABINGTON) in the Chair, 
On a method of introducing a Current into a Galvano- 
meter Circuit. By Mr Pririz, Queens’ College. 
Mr Pirre said that electricians had often to work with 
currents far too strong for their galvanometer. He mentioned 
various methods in use for checking the swing of the needle; 
but contended that an easily made and easily used controller 
for rough work was a desideratum. He described an instru- 
ment in the form of a continuously varying shunt, in which a 
moving connection was obtained by a tube filled with mercury 
sliding on a wire of suitable resistance. This form of connection 
was first used by Mr Barrett of Dublin. 
With the aid of Mr Garnett, the Demonstrator of Physics, 
Mr Pirie shewed that a very good connection was obtained by 
this means; and subsequently, that the instrument described 
gave a control over the movements of the needle in a galvano- 
meter whose resistance was not too different from its own. 
