6So GREENE. [Vol. XV. 



obtained showing the distribution of nerves to the skin and 

 to the epidermis, but in only two sections were nerves shown 

 to have direct relation to the phosphorescent organ. The 

 better one of these sections (PI. XXXIXf Fig. 8) showed 

 nerves branching over the surface of the lens. Whole mounts 

 of the skin were made by the methylen-blue method of Bethe. 

 These showed the most detailed network of nerve fibers lying 

 in the connective tissue of the skin. Preparations containing 

 both phosphorescent organs and lateral-line sense organs 

 showed branches of the lateral-line nerve coming off the main 

 stem and ending in the sense organs with almost diagrammatic 

 regularity. Nerve fibers or bundles of nerve fibers were found 

 in the skin above or below the phosphorescent organs, but no 

 nerve bundles penetrated the phosphorescent organs and ended 

 there. Two organs out of a very large number prepared con- 

 tained each a single nerve fiber which entered the organ and 

 terminated there. In one or two others single fibers seemed 

 to terminate in the organ, but the fact could not be determined 

 with certainty. 



The facts set forth above, based on very favorable prepara- 

 tions, justify the conclusion that the phosphorescent organs of 

 Poriclitliys possess no specific ncri'e supply. The few individual 

 nerve fibers demonstrated to enter the organ may be considered 

 as branches from the general nerve supply of the skin. 



V. Orientation of the Organs with Reference to 

 THE Surface of the Body. 



A line passing through the middle of the three parts of the 

 phosphorescent organ may be taken as its axis, and the position 

 of this axis with reference to the body surface as the direction 

 or position of the organ. In the ventral rows of the body the 

 organs are directed downward, that is, the axes of the organs 

 are almost or quite vertical with the surface of the body of the 

 fish. The organs on the sides of the body and the lower part 

 of the head are directed downward and slightly outward, and 

 the axis of each organ thus makes quite a wide angle with the 

 vertical to the surface. In the pleural row this angle is from 



