190 
EDWIN S. GOODKICH. 
focussed to the lower surface ; the nuclei of the wall are again 
visible. There is no opening. 
Innumerable figures could be given of series of sections all 
telling the same story. But the critic will say : it the diver- 
ticula are really closed, sections taken at right angles through 
their tip should show the tubes cut across embedded in the 
thickness of the wall. Such sections are not difficult to find, 
and I figure several on Plates 12 and 13. 
Figs. 10 and 12 represent two consecutive sections across 
the tip of a brancli. In the first are seen the tubes entering 
the wall, while the next (fig. 12) strikes the lumen. A small 
})art of this figure is shown slightly diagrammatised (fig. 11) 
on a larger scale. Again three consecutive sections are 
di'awn in figs. 15, IG, and 17. Here two sections cut through 
the solid wall before the lumen is reached. Lastly, fig. 18 
represents a section through two adjacent processes, one of 
which has been cut so as to expose the lumen, while the other 
shows very clearly the soleuocyte tubes piercing the wall and 
embedded in its cytoplasm. 
The evidence of all these sections is quite unequivocal ; it 
would serve no good purpose to multiply instances ; there is 
no opening, the wall is continuous, and is traversed by the 
tubes of the solenocytes. 
But there is other evidence of a different nature leading to 
the same conclusion. I have observed in a living nephridium 
the fluid inside the nepliridial canal so compressed, perhaps 
by the overlying cover-glass, that it dilated the tip of the 
diverticulum so as to give rise to a bulging vesicle at its 
extremity. Now, such a swelling could obviously not be 
formed if the tip were open. 
We may now turn to injections to corroborate our view. 1 
have recently injected the dorsal hypei’branchial coelom with 
Indian ink. The minute black particles were held in sus- 
pension in sea-water. Such a fluid, if introduced with a 
hypodermic syringe, can be made to fill the coelom. It is 
clear that if the nephridium communicated with the coelom 
the ink would jienetrate into the canal ; this would happen 
