AN HEREDITARY TUMOR 521 



be one of these regions and the smaller tumors are merely sec- 

 ondary tumors developed from cells derived from the primary 

 tumor and carried by the blood to another region of the body. 

 The so-called i-econdary tumors are made up of cells similar 

 in character to thore of the primary tumor. When the primary 

 tumor is large and irregular in shape, portions of it can easily be 

 broken off by pressing and manipulating the tumor in the body 

 cavity and can be pushed through the body cavity, away from 

 the large tumor. Metastases, thus artificially produced, have, 

 after an interval of a day or two, shown increase in size. It is 

 not improbable that the metastases are normally formed by 

 pressure against the tumor as the larva bores through the food 

 and thus breaks away small portions of the tumor which are 

 carried by the blood to other regions of the body for lodgment 

 and further development. 



■ Irregularities in the' mitotic figures of rapidly growing tumors 

 have been noted. Investigation of these is being continued 

 and a report on them will be reserved for another paper. 



SUMMARY 



1. Cell suspension from an hereditary tumor in the fly Dro- 

 sophila was injected into adult flies. Abnormal growths oc- 

 curred in some of the flies and caused their death. 



2. Tumors were kept alive and showed further development in 

 hanging drops of Locke's solution. 



3. Tumor-cell suspension was injected into meal worms, but 

 the resistance of some of them was too great to allow the de- 

 velopment of many tumors. Only a small percentage died and 

 only two of these had tumors visible to the naked eye. 



4. All ordinary laboratory media were inoculated with tumor- 

 cell suspension and incubated under aerobic and anaerobic con- 

 ditions. No growths occurred. 



5. The flies were bred on sterile media under absolutely 

 sterile conditions, but the tumor continued to develop as before 

 and is evidently not due to a microorganism. 



6. The tumor develops in embryonic rudiments, destined to 

 develop the adult organs during the pupa stage. 



