770 



RUDOLF CUMIN 



SUMMARY 



1. This paper présents a standard-table which is divided in 10 phases. The 

 standard terr.perature of the development is 25' C. The standard-table gives the 

 organogenese froni the late gastrula-state (E2) to hatching and represents a 

 supplément to the early development described by Raven {\946a, 1946/)). The 

 tem.poral appearance of the organs is presented on the tab. I ( (p. 751). 



2. The very discussible opinion of Bloch (1938) concerning the genèse of the 

 digestive gland has been refuted. Against Bloch the nutritive sac isn't absorbed 

 by the two epitheliums of the digestive gland which are formed by the stomach. 

 The cells of the nutritive sac rather pass a textural transformation to the adult 

 digestive gland. Against Bloch the nutritive sac présents no real larval organ 

 but a partial larval organ. 



3. There must be shown off three new observations. The larval nephridia 

 of Limnaea sîaguaUs are pure mesodermal built. Only one third of the nuchal- 

 cells treads out near the head vesicle in the second half of the embryonic period. 

 The muscle-epithelium of the stomach has no mesodermal origin; the little-celled 

 gut-plate formes in the same time the cylindrical and the muscle-epithelium of 

 the stomach. 



4. In the moment of hatching the gastropods are only adult-like on the face 

 of it. Ail the complex of the nervous System shows the intense positive allometry 

 which is typical for the invertebrates. The process which formics the nutritive sac 

 to the adult structure of the digestive gland goes on and is finished eight days 

 after hatching. The degeneracy of the nuchal-cells extends to the third week after 

 hatching. In the moment of hatching exist only three parts of the sexual apparatus 

 (pénis, oviduct, hermaphrodite gland). The puberty of Limnaea stagiialis mani- 

 fests one month and a half after hatching. 



H. LITERATURVERZEICHNIS 



Baldwin, E. 1935. The energy sources in ontogenesis. VIII. The respiraîory quotient of 



dexeloping gastropod eggs. J. exp. Biol. 12, 27-35. 

 Bloch, S. 1938. Beitrag zu Kenntnis der Ontogenèse von Siisswasserpulmonaten mit 



besonderer Beriicksichtigung der Mitteldarmdriise. Rev. suisse Zool. 45: 



157-220. 



Bluemink, J. g. 1967. The subceUular structure of the blastula of Limnaea stagnalis L. 



(MoUusca) and the mobilisation of the nutrient reserve. Diss. Utrecht 



(„Bronder-Offsef, Rotterdam). 

 BoBRETZKY, M. 1877. Studien iiber die embryonale Entwickhmg der Gastropoden. Arch. 



mikrosk. Anat. 13: 95-169. 

 BoETTGER, c. R. 1944. Basommatophora. Die Tierwelt der Nord- und Ostsee. IX b2, Leipzig. 



