No. I.] GERM-LAYERS T!^ CLEPSINE. 153 



" In ihren wesentlichen Grundlagen halte ich aber meine 

 Ansichten von der Entstehung des Bauchmarkes, wie sie 1878 

 fur Lumbricus und 1881 fiir Lopadorhynchus entwickelt wurden, 

 aufrecht, da sie durch fortgesetzte Beobachtungen an anderen 

 Anneliden nicht bloss bestatigt sondern auch weiter ausgebildet 

 werden konnten. Uberall entsteht der Bauchstrang tmabh'djigig 

 vom Kopfganglion aiis zwei seitlichen Anlagen, o/me Betheili- 

 gung einer soliden oder rohrenformigen medianen Einstiilpung 

 des Ektoderms." 



It is remarkable that so careful an investigator as Kleinenberg 

 should have entirely overlooked the relation of these " seitlichen 

 Anlagen " to the terminal neuroblasts. 



The " neural canal " of Branchiobdella, which Salensky (No. 

 15) homologizes with the medullary canal of vertebrates, has 

 also been effectually disposed of by Kleinenberg (No. 26, 

 p. 127), It has just as little morphological significance as the 

 "neural groove" which Nusbaum describes in Clepsine. 

 Salensky discovered eight teloblasts in Branchiobdella, but 

 missed their special relations and significance. 



Kleinenberg's studies on Nephelis (No. 26, p. 129), which 

 were begun some time ago, and not carried to completion, failed 

 to give him the clue to the precise origin of the nerve-chain 

 and its relation to the epidermal layer. The loss of the original 

 epidermis, as stated by Rathke, and more fully described by 

 Bergh, was also observed by Kleinenberg. 



Goette (No. 27, p. 91), adheres to the belief that the germ- 

 bands are wholly mesoblastic, and discredits the testimony of 

 those who derive from them the ventral chain, which, as every 

 one will now admit, is ectodermic in origin.^ 



(26.) Kleinenberg, N. Die Entstehung des Annelids aus der Larve von 

 Lopadorhynchus. 



Zeitschr. f. wiss. Zoo/. XLIV. i and 2. 1886. 



(27.) Goette. A. Abhandl. z. Entwicklungsgesch. der Thiere. Heft. 2. Ver- 

 gleichender Theil. 1884. 



* So strong is Goette's faith on this point that he feels inspired to prepare for his 

 heterodox brethren a very edifying homily in the form of a lengthy foot-note, warn- 

 ing them of the unpleasant consequences of an " einseitige Beurtheilung," and admon- 

 ishing them of the saving efficacy of the " vergleichende Methode." The counter 

 homily needs no quill from the wing of the angel Gabriel. When facts conflict with 

 theory we know on which side the error lies; and we have little respect for a (not 

 tAe) " comparative method," which begins by denying well-authenticated facts. 



