No. I.] GERM-LAYERS TN CLEPSTNE. n^ 



plasmas, wie die grline der Dotterkornchen ist zu charakteris- 

 tisch, als dass man dieselbe ubersehen konnte." (p. 53). 



" Die Muskelfaserschicht und das Epithelium des Chylus- 

 darmes entstehen beide aus urspriinglich von dem Keimstreifen 

 herriihrenden zelligen Elementen " (p. 51). The same origin 

 is claimed for the intestine (Enddarni) and the oesophagus 

 (Schlunddarm). 



Metschnikoff (No. 7, p. 672) expresses no decided opinion 

 on the origin of the mesenteron, but throws out the following 

 suggestion. Speaking of the inner stratum (mesoderm) of the 

 germ-bands, he says: " Man kann sehr leicht die Uberzeugung 

 gewinnen, dass das sich spaltende Blatt die aussere {yielleicht 

 audi die innere) Wand des Mitteldarmes, den sog. Fettkorper, 

 und die Segmentalorgane liefert." 



The latest authority on this subject is Joseph Nusbaum (No. 

 8). In the introduction to his paper, Nusbaum states at some 

 length Hoffmann's erroneous views concerning the nature of the 

 " entoplasts," and then announces, as a discovery of his own, 

 the fact that these entoplasts (" Hots protoplasmiqjies ") represent 

 the entoderm. Why so much attention should be lavished on 

 Hoffmann's ideas, which had already been refuted by Bergh, 

 and why the fact should be suppressed that the origin of the en- 

 toderm had been ascertained eight years before, I will leave 

 Nusbaum to explain. To discover what has already been dis- 

 covered, and refute what has already been refuted, is a double- 

 headed offence, inexcusable if the result of ignorance, unpar- 

 donable if done deliberately, Nusbaum very narrowly escapes 

 from this charge, for later on he feels constrained to drop the 

 following saving remark: " Selon Whitman, I'epithelium intes- 

 tinal se forme aux depens de grands globes entodermiques, a la 

 surface desquels se montrent les noyaux libres et ensuite une 

 couche de cellules epitheliales qui limite de tous les c6tes le 

 vitellus nutritif. En un mot, d'apres Whitman, I'entoderme 

 secondaire se forme de I'entoderme primitif." 



Nusbaum carefully refrains from any direct acknowledgment 



(7.) Metschnikoff, Elias. Beitriige zur Entwickelungesgeschichte einiger 

 neideren Thiere. Vorlaufige Mittheilung. Alelanges Biologiques VII., p. 671. 1871. 



(8.) Nusbaum, Joseph. Recherches sur I'organogenfese des Hirudinees (Clepsine 

 eomplanata Sav.). Archives slaves de Biologie, I. Fasc. 2, pp. 310-340, and Fasc, 

 3, pp. 539-556. 1886. Published separate. 



