Nachdruck verboten, 

 üebersetzungsrecht vorbehalten. 



Intracellular Canals in the Skin of Phascolosoma. 



By 

 Margaret Lewis Nickerson, Minneapolis, 



With Plate 12. 



A paper containing a description of the various organs found in 

 the skin of Phascolosoma gouldi, including those discussed in this 

 paper, will appear in a forthcoming number of the Journal of Morpho- 

 logy. After the plates for that article had been sent to the litho- 

 grapher, further observations upon new material gave a number of 

 new details which are here presented. 



In the skin of this Gephyrean are found several well-marked forms 

 of epidermal organs, one of which, the largest and most conspicuous, 

 is characterized by the presence of a system of intracellular sacks or 

 ampullae leading into communicating canals. Such organs are found 

 abundantly in all parts of the body of the worm, with the exception 

 of the anterior portion of the proboscis. They show no plan of 

 arrangement or distribution. Each is ovoidal in shape and is sur- 

 rounded by a delicate membrane which is probably to be regarded 

 as an invagination of the membrana propria. 



Each organ contains, besides certain sensory cells which will not 

 be discussed here, a large number, often as many as twenty or thirty 

 large gland cells, each of which is broadened at the base and nar- 

 rowed somewhat toward the peripheral end. The nucleus is situated 

 near the base of the cell and above the nucleus is an intracellular 

 ampulla opening into a canal which unites with similar canals coming 

 from adjacent cells. By the union of several such canals, a duct is 

 formed which communicates with the exterior through a pore in the 

 cuticula at the summit of the organ (PI. 12, Fig. 1). 



