CRANIAL GANGLIA IN AMPHIOXUS. 115 



Although I have had them stained in a large number of animals 

 they have appeared only in specimens ^vhich had remained a long 

 time in a relatively strong stain or had been exposed to the air 

 for a long time after staining, or both. In all cases the animals, 

 although alive and reflexly irritable, were in an extreme state of 

 weakness. I have never seen in these bodies stained with methyl- 

 ene-blue such a structure as would indicate that they are normal 

 nervous organs. They always appear as pale, granular or struc- 

 tureless pear-shaped or balloon-shaped bodies attached by the 

 small end to the nerve ratnus. I do not see that any fact regard- 

 ing these bodies suggests comparison with the spinal ganglia of 

 vertebrates. Their form, their position, the fact that they appear 

 stained with methylene-blue only when the animals are subjected 

 to physiological salt solution or are kept in stain in sea water 

 until they have reached a state of extreme weakness, all indicate 

 that they are probably artifacts. From my own observations I 

 should conclude that they are formed by the exudation of fluid 

 from the nerve through a rupture in its sheath. The exuded 

 fluid takes the form of a balloon, remaining attached by a stalk. 

 The most favorable place for the formation of such exudation is 

 in the angle between the dorsal and ventral rami and between two 

 myotomes. They are formed also, but less often, far along the 

 ventral ramus and even relatively far out along the dorsal ramus. 

 If by physiological salt solution in which Dogiel stained his ani- 

 mals, he means a solution of sodium chloride of 0.75 per cent., 

 more or less, this would be very favorable to the formation of 

 such artifacts, since a physiological salt solution for Amphioxus 

 must contain upwards of three per cent, of sodium chloride. The 

 animals soon die in salt solutions of less strength. Dogiel states 

 indeed that his animals died quickly in the physiological salt 

 solution and that the structures described were brought to view 

 by the stain only after three or four hours ! Maceration must 

 have been going on rapidly during all that time. 



Finally, I have been unable to find these bodies in sections of 

 animals well fixed and stained by various methods, or in speci- 

 mens treated with osmic acid. The resemblance which Dogiel 

 notes between these bodies and certain structures connected with 

 the rostral nerves is not at all close. On the proximal portion 



