50 HARGITT. [VOL. I. 



Summary and Conclusions. 



1. Tubularian Hydroids readily react to experiments di- 

 rected toward regeneration or grafting. 



2. They exhibit in most cases striking illustrations of 

 heteromorphosis. 



3. They show no marked polarity, readily coalescing in 

 either oral or aboral relations. 



4. They show no sex differentiation of tissues limiting the 

 process of grafting. 



5. Closely allied species may be intergrafted. 



6. Different genera have not been successfully grafted. 



7. Hydromedusae respond to regenerative and grafting 

 experiments with almost equal readiness. 



8. No definite aboral grafting of Medusae has been success- 

 fully made. 



9. Medusae show throughout a sharp polar orientation. 



10. No heteromorphic results have been shown among 

 Medusae. 



SYRACUSE UNIVERSITY, June, 1899. 



LITERATURE CITED. 



1. 1896. BORN. Ueber Verwachsungsversuche mit Amphibienlarven. 



Archiv f. Entwick. Bd. iv, p. 349. 



2. 1897. CRAMPTON. Biological Lectures. 



3. 1894. DAVENPORT. Regeneration in Obelia and its Bearing on Dif- 



ferentiation in the Germ-Plasma. Anat. Anzeiger. Bd. ix, 

 p. 283. 



4. 1897. DRIESCH. Studien u'ber das Regulationsvermogen der Organ- 



ismen. Archiv f. Entwick. Bd. v, p. 389. 



5. 1878. ENGELMANN. Ueber Trembley's Umkehrungsversuch an 



Hydra. Zool. Anzeiger. Jahrg. i, p. 77- 



6. 1897. HARGITT. Recent Experiment on Regeneration. Zool. Bull. 



Vol. i, p. 27. 



7. 1898. HARRISON. Growth and Regeneration of Tail of the Frog 



Larvae. Archiv f. Entwick. Bd. viii, p. 430. 



