172 I'd ix'i-x from the Department of Marine Biology. 



VI. Electroplaxes. Continued. 



Fig. 3. Adult. Longitudinal section of portion of electroplax. Dorsal vacuole? 

 have entirely disappeared. Striations broken and curved. 



Ch. R Chromatic roil. C Connective tissue. 



Ne Nerve-fiber. C. V Vacuole in connective tissue. 



B Blood-vessel. 



VII. Photomicrographs. 



Fig. 1. 20 mm. embryo, XSO. Electric area to show relation of electric to mus- 

 cle tissue. 



R. Ex Rectus externus muscle. R. Inf Rectus inferior muscle 



R. Su Rectus superior muscle. A Artery. 



Fig. 2. 33 mm. embryo, X35. Electric area to show four separate electric organs 



in position. 

 Fig. 3. 80 mm. embryo, X35. Portion of electric area. Fibers of rectus 



superior muscle separated by electric nerve. Overlapping of electroplaxes 



shown. 

 Fig. 4. 33 mm. embryo, X85. Electric nerve passing through rectus superior 



muscle. Oculomotor nerve. Three branches of oculomotor to right. 

 Fig. 5. 45 mm. embryo, X85. Electric and oculomotor branches of III nerve. 



immediately after leaving brain. Ganglion of V nerve below. 

 Fig. 6. 45 mm. embryo, X85. Electric and oculomotor branches of III nerve 



passing through the foramen in the cranial wall. 

 Fig. 7. 45 mm. embryo, X85. Electric nerve in rectus superior muscle. Branches 



of oculomotor to right of muscle. 

 Fig. 8. 45 mm. embryo, X85. Large branch of electric nerve entering electric 



organ. Oculomotor to right. 

 Fig. 9. 45 mm. embryo, XS5. View from opposite side of embryo. Fibers of 



rectus superior muscle entirely separated by electric nerve. Nerve breaking 



up in muscle to form branches. Oculomotor to left. 

 Fig. 10. 45 mm. embryo, X85. Branches of electric nerve after leaving rectus 



superior muscle, going to various parts of the electric organ. Branches of 



oculomotor separating to go to muscles. 



Fig. 11. 80 mm. embryo, X85. Fibers of rectus superior muscle almost oblit- 

 erated by the electric nerve. 



