446 l*'- H. Krccker. 



i. e. the longitudüial luuscles of the body wall, tlie septa etc., is re- 

 generated from the neoblasts. {Tubifex and Limnodrilus.) 



18) Tlie circular inuscles of the body wall are regenerated from 

 the ectoderm cells in situ. 



19) Wlien the regeneration of the body wall does not occur in 

 the absence of the intestine the neoblasts do not form mesoderm but 

 collect in an unorganized mass at the posterior end of the body. 



20) Wlien, during the absence of the intestine, the regeneration 

 of the body wall at the j)osterior end of the body does not take place 

 the ectoderm cells that have been metamorphosed into neoblast like 

 cells enter the coelom and together with the neoblasts form a mass 

 of cells in the ventral half of the coelom. 



21) Neither the position of the neoblasts nor the area over which 

 the ectoderm cells are metamorphosed is influenccd by inverting the 

 position of the worm's body. 



22) The neoblasts are always fouiid about the metamorphosed 

 ectoderm cells at the posterior end of the body and it seems probable 

 that the neoblasts have some influence in causing the ectoderm cells 

 in their immediate vicinity to assume a neoblast like character. 



23) The neoblasts can migratc toward the anterior end of the 

 body but they do not come in contact with the ectoderm at this point 

 and do not form mesoderm. They are not present at the anterior 

 end of Tubifex or Limnodrilus at levels from which anterior regene- 

 ration occurs. They were not found anterior to the lOth somite under 

 any conditions. 



24) The secondary mesoderm at the anterior end of the body is 

 fiinned from the old mesoderm. 



October 30. 1909. Princeton, N. J. 



Literature List. 



1902. Max Ahki., Beiträge zur Kenntnis der Regenerationsvorgänge bei den 

 linücolen üligocliäten. Diese Zeit«clir. Vol. LXXIII. 1903. 



1901. C. R. Bardeen, On the Physiology of Planaria maculata with especial 

 Refercncp to the Phenomena of Regeneration. Am. Journ. of Physio- 

 logy. Vol. V. 



189."). F. E. Beddard, A Monogvaph of the Order ÜHgochaeta. London. 



1890. R. S. Bergh, Neue Beiträge zur Embryologie der Anneliden. I. Zur Ent- 

 wicklung und Differenzierung des Keimstreifens von Lumbricus. Diese 

 Zeitschr. Vol. L. 



