210 HENRY LESLIE OSBORN 



inwardly aiiioiio- the inner organs. The origins of l)oth kinds 

 can be seen in fig. 15; they arise at close intervals from the col- 

 lecting vessel on both sides. Some of the vessels of the super- 

 ficial system run directly to the surface (one of these is shown in 

 fig. 4 G) where they become circular vessels immediately under 

 the cuticle. Since these tubes encircle the body they are readily 

 seen in sections passing tangentially in the plane of the surface. 

 The tubes frequently anastomose and all communicate directly 

 with the collecting vessel. They are cut across in longitudinal 

 sections and produce the appearance seen in figs. 3 and 5. 



Looss ('85, p. 49) expressed a suspicion that these subcuticular 

 vessels communicate directly with the exterior: ''so halte ich 

 es doch ftir hochst wahrscheinlich, dass^ — der Excretionsporus 

 nicht die einzige Stelle ist von welcher dieses Maschenwerk von 

 Kanalen mit der Aussenwelt in Verbindung tritt und zwar sind 

 es die subcuticularen Maschen des Gefassnetzes welche diese 

 Kommunikationen vermitteln." And later he says "Ich halte 

 es nun nicht fiir unmoglich dass sie (i.e., subcuticular vessels) 

 auch nach aussen miinden," etc. But he closes his account with 

 an admission to the effect that he has not succeeded in demon- 

 strating the presence of openings from them to the exterior. The 

 observations of the movements of the fluids in these passages 

 described above render it very certain that outlets from them 

 directly to the exterior do not exist; were such outlets present we 

 should undoubtedly have seen stuff from within issuing through 

 them. 



Turning now from these superficial vessels to the deep ones we 

 find that they pass inward, permeating the parenchyma every- 

 where. The vessels of one side tend to remain entirely confinrd 

 to that side, they anastomose with one another but do not often 

 become continuous with those of the opposite half of the body. 



Allusion has been made to the flow of the contents of the ex- 

 cretory vessels in life. Pulsations were seen in bass specimens 

 in the wall of the collecting vessel, forcing a stream out into the 

 dependent vessels. Later these streams reversed their direction 

 and the droplets course back again into the larger vessel. As 

 already noted there is no escape distally; the movement is an 

 ebb and flow. 



