522 MARY B. STARK 



7. Development of tumor is initiated by excessive production 

 of melanin. 



8. Melanin occurs normally in ganglion cells, and these cells 

 are related to some of the embryonic rudiments by ganglionated 

 fibres. 



9. Metastases occur normally in many of the larvae with 

 tumors. 



10. A mutation occurred in certain flies of such a kind that 

 pigment appeared in the hypodermal cells of the ventral surface 

 of the last segment forming a pigmented bar. It occurred only 

 in larvae that had tumors. So far the character has not been 

 separated from the stock with hereditary tumor. 



