566 MONTGOMERY— MORPHOLOGY OF THE [April 24, 



mentally, to which the conclusions of Roule (1889) alone are 

 opposed, and that their first beginning is the preseptal funnel cell. 

 But there is considerable conflict of opinion as to what germ layer 

 produces these cells and the cords that arise behind them. They 

 arise in that cell row of the germ band formed by proliferation of 

 the posterior nephroblasts. The germ band is covered by a thin 

 ectoblast, and the funnel cells lie at points where the mesoblastic 

 dissepiments meet the ectoblast; they are blastoccelic in position. 

 Bergh is positive that funnel cells and nephridial cords are meso- 

 blastic, derived from what he terms the " innere Muskelplatten," 

 and Lehmann and Roule express the same opinion. Wilson hesi- 

 tates to decide whether the nephridial cords are ectoblastic, though 

 he ascribes this origin to the funnel cells. Vejdovsky considers 

 that at this early stage of the embryo, when these parts are first 

 definable, there is no mesoblast but only the two primary germ 

 layers and that the funnel cells may have emigrated from the 

 ectoblast. It is to be noted in this connection that the funnel cells 

 when they are first distinguishable have never been seen actually 

 in the ectoblast, but always beneath it. And the nephridial develop- 

 ment is so correspondent with that of the Hirudinea, for which 

 Burger shows so convincingly that the nephridia are mesoblastic, 

 that the view of Bergh would seem to be correct. Consequently 

 Goodrich (1895) in his summary of the literature on this subject 

 would seem to have misunderstood the facts of the case. We may 

 at least conclude, that in light of the evidence at hand all the inner 

 portion of the nephridium is mesoblastic, and only its distal outer 

 termination comes from the ectoblast. 



Remarkable postembryonic changes have been described by Rosa 

 (1903a) for Lumbricus. In a newly hatched individual two canals 

 extend through the whole trunk and join posteriorly into an ampulla 

 that opens dorsally into the intestine ( for which reason the describer 

 compares it with the nephridia of Rotatoria). From each of these 

 canals tubes branch off segmentally and connect with the nephridia 

 of the corresponding segments, while the nephridia still lack 

 nephridiopores ; later in each segment a diverticulum grows out 

 from each canal and opens on the surface in the position wherein 

 the adult the nephridiopore lies, while in each segment the main 



