391 



a) The organ consists in a single row of cells, — contra Bourne 

 who gives in his drawings a special cellular wall to the duct, distinct 

 from the cells of the solid lobes. 



b) This row of cells is perforated by three different ducts, — 

 contra Bourne who contends that there is but one duct with a re- 

 current portion. 



c) The cells are united either by two or by three separate com- 

 missures, containing one, two, or three ducts passing from one cell 

 to another, — contra Bourne who has not seen these very distinct 

 commissures. 



d) One of these commissures, Ic, figg. 6, 7, with two ducts, seems 

 to be generally very long and was very likely taken by Schultze and 

 Bourne for one of the free portion of their supposed single duct. 



This very curious commissure seems to have been the principal 

 cause of the mistake these two authors have fallen into by regarding 

 the whole organ as almost identically structured like that of Hi- 

 rudo — a view that neither micro tomic sections nor teased prepa- 

 rations allow me to approve in any way. 



4. Finally I complain of Mr. Bourne's way of discussion. 

 College-Oudenbosch (Holland) 

 31. July 1893. 



Nachdruck verboten. 



Nachtrag zu dem Aufsätze von C. B. Datenport (No. 9, p. 283). 



Vorbemerkung des Herausgebers: 



Der Herr Verfasser wünschte bei der Correctur — welche erst 

 14 Tage nach Erscheinen der Nummer eintraf — die Tabellen IV, V 

 und VI in eine, die unten folgende IV zu vereinigen und die Fig. 5 

 durch die neue (s. u.) zu ersetzen. Statt dessen erscheint nun dieser 

 Nachtrag : 



Table IV. 



Regeneration in Obelia, combining results of cuts at all levels. 



The numbers in the second column, opposite the different cases 

 under "nos. of rings regenerated", have been obtained by adding 

 together the percentages in the tables I, II and III opposite the cor- 

 responding numbers of the first columns and dividing the sums by 3. 



