420 F. H. Krecker, 



indem ich auf jene Einwanderung ectodermaler Elemente Berufung 

 einlege, von der ich früher berichtet habe und die den beiden eben 

 genannten Autoren offenbar entgangen ist. « He is of the opinion that 

 the musculature is derived from the ectoderm but he says nothing 

 conceniing the septa. In his summary he writes, »Das Vorkommen 

 von Neoblasten sowie deren event. Bedeutung für die Reparation bei 

 den limicolen Oligochäten erscheint noch sehr strittig, doch dürften 

 die Neoblasten, wo sie vorhanden sind, auch eine Rolle bei der Repa- 

 ration spielen. « From this brief review of the literature it is seen that 

 quite contradictory opinions are held regarding the origin of the meso- 

 derm. Semper (76), Makarofp (99), Hepke (97), Abel (02) and 

 Michel (98) think the mesoderm comes from the ectoderm. Ran- 

 DOLPH (92), Iwanow (03) and Janda (02) maintain that it is derived 

 from the neoblasts and the most recent worker, v. Wagner (06), com- 

 plicates matters somewhat more by deriving at least the musculature 

 from the ectoderm. 



So far as observed none of the authors who oppose the view that 

 the neoblasts form the mesoderm has offered any Suggestion as to what 

 function the neoblasts perform. Their distribution through the body 

 and their early appearance in the neighborhood of the wound sug- 

 gested that they might be phagocytes. To test this several worms 

 {Limnodrilus and Tuhifex) were injected with foreign substances; some 

 with yeast and others with india ink. Six hours later the individuals 

 were killed. The somites which had been injected with the yeast were 

 swarming with leucocytes most of which were gorged with yeast. The ink 

 had been taken up to a certain extent by the chlorogogue but most 

 of it probably escaped through the nephridia. In not a single instance 

 was there anything to be seen in the neoblasts. They were undisturbed 

 and had not migrated nor were they dividing. It is therefore certain 

 that they are not phagocytes. 



My chief attention has not been given to phenomena of normal 

 regeneration but, since in the absence of the intestine neoblasts are 

 present at the posterior end of the body and since there is also a marked 

 activity of the ectoderm at this point, I have studied both neoblosts 

 and ectoderm in the septa forming zone under normal conditions and 

 it seems certain that no cells from the ectoderm enter the coelom ex- 

 cept those that form the nerve cord. It is true that there is a great 

 similarity between the ectoderm ceUs of this region and the neoblasts 

 and this is an important point since it seems liighly probably that 

 those who have derived the mesoderm from the ectoderm cells have 



