1896 - 97 .] 
Chairmans Opening Address. 
137 
those of the long pseudopodia found in many of the lower inverte- 
brates. hfo one has seen such movement, and the only movement 
that has been followed is that of growth. Cajal is of opinion that 
both the dendron processes and the terminal arborization processes 
actually grow outwards, like the rootlets of a tree, in correspondence 
with the advancing development of the individual in foetal and 
early life. A more likely supposition is that neuron may act on 
neuron by an electrical excitatory process. It is well known that 
such processes occur in contractile muscular fibres, and that one 
muscular fibre set in action by a nervous impulse reaching its end 
plate may generate excitatory electrical changes which stimulate 
adjacent fibres that do not possess end plates. Such a process may 
exist in neurons, but it has not yet been demonstrated. 
The most remarkable example of the branching arrangement of 
a neuron with which I am acquainted occurs in Malapterurus 
eleetrieus , the Raash or the Thunderer-fish of the Arabs, a live 
specimen of which was shown to this Society by Professor Goodsir 
in 1855. 
In this animal the electric organ forms a layer beneath the skin, 
enveloping the body with the exception of the head and fins. Its 
structure, as worked out chiefly by the laborious researches of 
Fritsch of Berlin, is that of a honeycomb-like tissue, in which, 
however, the spaces are not hexagonal, but lozenge-shaped. Each 
lozenge has, of course, four sides, and on two of these, adjacent to 
each other, we find an electric tissue consisting of granular proto- 
plasm, and not unlike that of the electric disks in other electrical 
fishes. Fritsch regards this electric tissue as a layer of modified 
epithelial cells. The electric organ, therefore, is an altered con- 
dition of the skin glands. In the epidermis of the thunderer there 
are peculiar club-shaped cells, which are forms transitional into 
true electric cells, and, towards the tail, lozenge-shaped spaces 
occur in which there is no electric tissue. The number of these 
electric cells is enormous. After counting the number in one 
cubic centimetre of the organ (a cube, each side of which measures 
two-fifths of an inch), Fritsch computes the total number in the 
organ of a full-sized fish, and brings up the total to two millions. 
Each electric cell is supplied with an individual nerve filament 
which enters the lozenge at one angle and loses itself in the electric 
