903 



the lips of the neural tube, and for a long time after that period. It 

 forms a very beautiful conical structure at the base of the tube. I 

 only know of one good figure of it as yet published; it is contained 

 in one of Prof. His' recent papers. For a long time it is the only 

 part of the primitive (as opposed to the permanent) central canal 

 which is ciliated. Later by its lateral growth and extension a little 

 distance up the sides of the canal it forms the whole or a greater 

 portion of the permanent central canal. — I am as yet not quite cer- 

 tain that it forms the whole canal. As it Annelids it gives rise to 

 no nervous elements. In the embryo this highly important ciliated 

 groove extends throughout the whole central nervous system. The 

 extension and discussion of the bearings on general morphological 

 questions of the facts contained in this section I defer for a subsequent 

 occasion. 



Appendix. 



It is with regret that I feel bound to reply to some remarks of 

 Prof. Froeiep's contained in a note on pp. 820—821 of his „Be- 

 merkungen zur Frage nach der Wirbeltheorie des Kopfskelettes" (Anat. 

 Anz. Bd. II, No. 27, 1887). Prof. Froriep is quite correct in resent- 

 ing Prof. Gegenbaue's statement that „die BEARo'schen Aufstellungen 

 von suprabranchialen Sinnesorganen haben in A. Froriep einen Ver- 

 treter gefunden". — It goes without saying that this statement is 

 untrue, simply because in point of time Prof. Feoriep's paper „Über 

 Anlagen von Sinnesorganen etc." appeared, before either of my com- 

 munications on the subject. My „Vorläufige Mitteilung" was written 

 before Prof. Froriep's work appeared and printed before I saw Prof. 

 Feoriep's paper, to which in point of fact Prof. Wiedersheim drew 

 my attention by letter after my note had appeared in the Zool. An- 

 zeiger, and immediately after that I received the copy which Prof. 

 Froriep kindly sent me. Prof. Froriep complains that in my „Vor- 

 läufige Mitteilung" there „(1) findet sich keine Andeutung über die 

 typische Beziehung der in Rede stehenden Organenanlagen zu den 

 Kiemenspalten, im Gegenteil, (2) bei der Diskussion der Frage, ob auch 

 die Riechgrube mit Olfactorius-Ganglion als ein Seitenorgan oder von 

 Beaed sogen, „segmentales Sinnesorgan" betrachtet werden dürfe, sieht 

 sich der Verfasser genötigt, die MARSHALL'sche Aufi"assung der Riech- 

 grube als modifizierter Kiemenspalte durch eine besondere Erörterung 

 doch in Einklang mit seiner eigenen Auffassung zu bringen". 



I have numbered the two accusations in this passage — neither 

 of them is true. To take the last first I could hardly support an 

 hypothesis of the nature of the nose which I did not believe in, and 



