KUTCHIN. — PERIPHERAL NERVOUS SYSTEM OF AMPHIOXUS. 575 



used the silver-impregnation method of Bielschowsky, by means of 

 which Edinger demonstrated the nerve fibers which he describes. 



IMy observations with regard to the commonly accepted nerve I 

 agree in the main with those of Dogiel. This nerve and its branches, 

 as well as nerve II, exhibit peculiarities during the process of intra- 

 vitam impregnation with methylene blue. Ner^'es I and II usually 

 become colored in the com-se of 20 to 30 minutes, before the sensory 

 nerves of the thicker parts of the body do. If the immersion in methy- 

 lene blue is continued, these anterior nerves shortly lose their color, 

 but if examined after a considerably longer immersion (^ to 3 hours), 

 nerves I and II again appear impregnated, frequently with great 

 brilliancy. This indicates that there is more than one epoch in the 

 course of immersion in methylene blue when a successful impregnation 

 of the anterior sensory nerves may be obtained. Another possibly 

 significant fact with regard to the physiological character of the first 

 two sensory nerves is that the methods of Golgi repeatedly produced 

 no impregnation in these nerves in specimens whose sensory nerves 

 were otherwise well impregnated. 



Figures 1 to 5 are drawn to show the distribution of nerve I in 

 Branchiostoma caribaeum. These furnish a basis for comparison with 

 the previously published figures of Branchiostoma lanceolatum. 

 Figure 6 (PI. 2) shows the exit of nerve I from the neural tube in B. 

 caribaeum, and Figure 11 (PI. 3) presents its exit in B. lanceolatum. 

 A comparison of the two species shows no striking differences in the 

 manner of branching of this nerve, nor in the territory which it in- 

 nervates. I find, as does Dogiel, that some variations occur in the 

 size of this nerve, and in its area of distribution. In the same speci- 

 mens complementary variations are to be noted in the manner of 

 distribution of the branches of nerve II. 



In Figures 11 and 12 particular care has been taken to illustrate 

 the relation of the first two nerves to the most anterior myomere. 

 These figures represent the rostrum without its epithelial covering, 

 this having sloughed off in the course of treatment following immersion 

 in methylene blue. The fact that the main trunk of the first nerve 

 usually gives off no branches for a considerable distance after its exit 

 from the neural tube is of interest as distinguishing it from all other 

 dorsal nerves. The cells of Quatrefages have no definite arrangement 

 with relation to the nerves of the rostrum, as ma\- be readily noted by 

 comparison of Figures 1 to 5. 



The main stem of nerve I, as well as the anterior end of the nerve 

 cord, does not bear a constant relation to the chorda dorsalis nor to 



