22 
The President's Address. 
organisms,, and the movements wliicli have been seen to occur 
in certain forms of living matter (Amoeba^ white blood-cor- 
puscles, young epithelial cells, &c.) will Jead to most valuable 
results bearing upon the much-debated question of vital 
actions. 
" The most delicate constituent nerve-fibres of the plexus 
in the summit of the papillae (see ' Phil. Trans./ for 1884), 
can be readily traced by the aid of this power. The finest 
nerve- fibres thus rendered visible are so thin that in a drawing 
they would be represented by fine single lines. Near the 
summit of the papilla there is a very intricate interlacement 
of nerve-fibres, which, although scarcely brought out by the 
-^Vth, is very clearly demonstrated by this power. In this 
object the separation of the fibres, as they ramify in various 
places one behind another, is remarkable ; and the flat ap- 
pearance of the specimen as seen by the irVth, gives place 
to that of considerable depth of tissue and perspective. The 
finest nerve-fibres, ramifying in the cornea, and in certain 
forms of connective tissue, are beautifully brought out by 
this power ; and their relation to the delicate processes from 
the connective-tissue corpuscles can be more satisfactorily 
demonstrated than by the -^Vt^' The advantage of the -Vth 
in such investigations seems mainly due to its remarkable 
power of penetration/^ 
In my last yearns address I stated the results of some com- 
parative observations on the capabilities of the -Vth and -cr-ih. 
inch objectives; whether a comparison of the -nr^h and 
-ji^th may lead me to the same result I am not at present 
able to state. I also then stated that the best results in illu- 
minating the ^th had been obtained with a Kelner eyepiece 
used as a condenser. The results then obtained have since 
been unqnestionably surpassed by an achromatic condenser 
made by Mr. Hoss, the optical part of which is identical 
with his -Toths inch objective. This was shown to the 
Society at a recent discussion on the illumination of objects 
under high powers, in which it may be remembered that 
much useful information was elicited. 
The last subject to which I shall now feel it my duty to 
call the attention of the Society is the competition for the 
medals ofi^ered by the Society in the spring of last year. With 
a view to stimulate the inventive genius of opticians to some 
improvements in the economical production of good working 
instruments, the Society offered three Quekett medals for 
the best microscope in each of three classes : 
1. A binocular at ten guineas. 
2. A student's microscope at five guineas. 
