Be 
distance or thickness is about 50 u. The nerve and blood-supply of 
the tissue is found running in this electric connective tissue. 
The form of the electroplaxes is not to be made out from this 
vertical section. All that can be determined is that they are flat and 
that they do not extend all the way across the organ. The line of 
the layer is interrupted frequently at somewhat irregular intervals by 
channels or spaces which separate it into from eight to thirty different 
portions (Fig. 1, 5). If no further study of the structure were per- 
mitted we might conclude that the same number of electroplaxes were 
represented. { 
The next step in the study of the form of the electroplax was 
performed by macerating small portions of the organ in nitric acid of 
15 per cent for a number of days. The connective tissue was so 
Ties hina In) Inn 
* hone In 
TI * A 
Iu 4 Pn rn 
Tn) Im 
Fig. 1. Diagram of a portion of a vertical section of the electric organ of A. 
guttatus. 7 an electroplax, 3 sections through incisions, 4 sections through the spaces 
that separate the different electroplaxes. 
loosened or dissolved that, with careful manipulation, whole electro- 
plaxes as well as portions of others were gotten out and the form 
and size was satisfactorily determined. It was then seen that, as a 
rule, only four electroplaxes would be cut by a section across the 
central part of the organ in one of its layers, and that the larger 
number of the spaces in the vertical section of the layer were only 
sections of numerous indentations in the edge of the electroplax, 
which I shall speak of as the incisions (Fig. 1, 2 and 3, 3). This 
can be readily understood by referring to the figures (2 and 3) which 
are camera sketches of two individual electroplaxes. 
A second pecularity of the electroplaxes, as seen in the vertical 
section, is only to be fully explained by a study of the teased prepa- 
rations. In this section (Fig. 1) the line of the electroplax is fre- 
quently seen to leave the line of the layer in which it is running and, 
turning sharply upward or downward, to enter into the line of the 
