Note 438 — Chapter XII · (continued 4)

I am inclined to give up the view I formerly expressed with reference to the head-kidney and segmental duct, viz. that they were to be regarded as the most anterior segmental tube, the peritoneal opening of which had become divided, and which had become prolonged backwards so as to serve as the duct for the posterior segmental tubes, and provisionally to accept the Gegenbaur-Fürbringer view which has been fully worked out and ably argued for by Fürbringer (loc. cit. p. 96). According to this view the head-kidney and its duct are to be looked on as the primitive and unsegmented part of the excretory system, more or less similar to the excretory system of many Trematodes and unsegmented Vermes. The segmental tubes I regard as a truly segmental part of the excretory system acquired subsequently.—F. M. B.