ELECTROPLAX OF ASTROSCOPUS 105 
Fig. 3 Oblique section through an electroplax treated with 73 per cent 
hydrochloric acid. The portion of the electric layer shows the electric nuclei, 
and also the spaces which were occupied by the rods before they were dissolved. 
The spaces have a greater diameter than that of the rods because the rods swelled 
before being dissolved. 1200. 
fore this indicates clearly that the rods are not composed of 
chitin or keratin, for these substances are not attacked by 
hydrochloric acid of the above strength. To strengthen this 
statement we have only to quote the results from the pepsin 
treatment noted above, in which the rods were digested in 3 
minutes. They could not therefore have been composed of 
chitin or keratin, for according to Encycl. mikr. Technik, these 
substances are not attacked at all by pepsin. From the above 
facts therefore we may with a good degree of certainty con- 
clude that the rods are not composed of any kind of chitinous 
or keratinous substance. Having found that the rods do not 
consist of any kind of connective tissue or of chitin or keratin 
the only reasonable hypothesis left was that they were some form 
of muscle fiber, not having however the same chemical com- 
