200 STAN I SLAW SKOWRON. 



discharged only on mechanical, chemical or electrical stimulation. 

 It may be mentioned here that all the specimens of Microscolex 

 phosphoreus examined by me were found to be luminescent. In 

 free living animals the small hard particles of the soil may pro- 

 duce, by irritating the skin, the necessary stimulus for the 

 secretion of the slime, which glows brightly with a yellow- 

 greenish tinge. The slime is usually ejaculated from the anal 

 aperture, and only in some specimens kept previously for a 

 longer time undisturbed, did the slime flow also from the mouth 

 opening. The posterior and the anterior end of the alimentary 

 canal were the only two points at which the production of 

 luminous slime was observed. As all these observations were 

 carried out under the binocular microscope it is quite certain 

 that the glands of the skin and the excretory system do not take 

 part in the secretion of luminous slime. If the animal be 

 wounded, however, on any point of the body, the luminescent 

 slime flows from this part, the clitellum not being an exception. 

 Nevertheless the luminous material does not arise from the 

 alimentary canal, because in such cases the luminescence appears 

 when the wound has not reached the intestinum. An injury 

 of the body cavity is sufficient in itself for a production of 

 luminous slime, which does originate, therefore, from the coelomic 

 fluid. This fact was corroborated by microscopical observations. 

 A freshly discharged slime is composed chiefly of round cells with 

 many, strongly light-refracting granules, scattered inside the 

 protoplasm. Cells of this kind are found abundantly in the 

 body cavity. Besides the uninjured cells, a certain amount of 

 free granules, liberated by breaking of the cells, is always sus- 

 pended in the fluid. I wish to call attention to the fact that 

 both the size of those cells, and the structure of the intestinum, 

 excludes the possibility of any other way of reaching the alimen- 

 tary canal by the cells, except by preformed openings at its 

 posterior and anterior end. That the communication with 

 the body cavity is possible in Oligochxta was also shown by Gil- 

 christ in Chilota, though in Microscolex the posterior rather than 

 the anterior part of the intestine is the chief point at which 

 ejaculation of the luminous slime occurs. Benham ('99) found 

 that in the New Zealand earthworm, Octochcstus mitltiponis, the 



