845 
and 3. a posterior cortical layer. The latter consists, like the anterior 
layer, of a single layer of cells, but this layer is folded in so many ways, 
that in sections the impression is excited as if the posterior cortical layer 
is provided with fringe-like prolongations. The entire platelet is enveloped 
by a very thin homogeneous membrane (the electrolemma). A very 
fine network of non-medullated nerve-fibres lies against the anterior 
cortical layer. Where the fibres reach the cells of this layer, those 
cells present peculiar rods. The inner layer is the most complicated. 
To realize its structure we should bear in mind that each electric 
platelet must be considered as a modified muscular fibre. 
The lamellae of the inner layer are derived from the anisotropous- 
and isotropous-dises of the striated muscle-fibre (see also ENGELMANN’S 
researches in “Onderzoekingen Physiol. Lab. Utrecht 4e Reeks 
III, p. 307). 
The doubly refracting layers become thicker, they lose their 
faculty of double refraction, while the isotropous discs remain visi- 
ble as finer, dark stripes. The layers are sinuously disposed and 
thus originates the complicate structure of the inner layer of the 
electric platelet. 
BaBvcHiN could distinguish in young living rays the gradual trans- 
formation of the muscular fibres into electric platelets and was able 
to demonstrate that electric stimulation still elicited contractions in 
fibres which had not yet undergone a complete transformation. The 
electric plate once being formed, contractility is lost, but the generation 
of electricity, which is also a property of the muscular fibre, has 
far more become a principal function. So the electric organ may 
justly be looked upon as a highly interesting object with a view 
to potassium-researches. 
Let it be finally observed that all electric platelets are located in 
a jelly-like connective tissue. 
In successful preparations, treated after MacarLum, I was now 
enabled to establish that the electric platelets contain a great many 
potassium compounds, whereas the jelly in which they are lying is 
almost destitute of potassium (see fig. 2). Whereas in the medullary 
sheath of the medullated nerves a distinct reaction is found, by 
which the neurokeratin-reticulum is disclosed, the non-medullated 
fibres appeared to be entirely potassium-free. It follows that in 
most preparations nothing is to be seen of the nerve-network which 
lies against the anterior cortical layer. This confirms MAcALLUM’s 
finding that no potassium-reaction occurs in the axis-cylinders of the 
nervefibres. The electrolemma is colourless and therefore apparently 
potassium-free. In the electric platelet itself the reaction reveals itself 
