GENETICS: M. B. STARK 
579 
The tumor may appear in the head, see figure 6. Many flies with 
head-tumors seemed to have no power of coordination and Hved only 
a few days, while other flies did not seem to be disturbed in any way 
whatever. 
When the tumor developed in the abdomen or in the thorax (figs. 1, 
7 and 8) and did not interfere with the development of the appendages 
the length of Hfe of the fly seemed to be normal. Table 3, part ^a,' 
gives the length of hfe of the females of five pairs of flies, also the 
number of offspring from each pair. The length of life of the female 
and the number of offspring correspond closely with same of control as 
indicated in part 'b' of table 3. 
TABLE 3 
NUMBER OF PAIRS 
LENGTH OF LIFE OF 9 
NUMBER OF DAUGHTERS 
NUMBER OF SONS 
a. Pairs of flies having tumors {February 30, 1919) 
1 
18 days 
296 
257 
2 
18 days 
264 
271 
3 
19 days 
198 
110 
4 
36 days 
154 
139 
5 
16 days 
154 
163 
h. Control pairs of normal flies 
1 
20 
304 
264 
2 
35 
263 
232 
3 
22 
198 
207 
It is evident that the presence of the tumor in the abdomen and in 
the thorax of the body is not sufficiently injurious to decrease seriously 
the length of Hfe of the fly. 
4. Inoculation of tumors, — Under aseptic conditions young tumors 
were removed from larvae and inserted into larvae of a different strain 
normally free from tumors. Forty larvae were thus inoculated. Only 
five percent (two) survived the operation, but these continued to five, 
completed metamorphosis and carried the inserted tumor into the adult 
fly. Both these flies were females and were sterile. Matings were at- 
tempted with several males but without success. The tumor was found 
to resemble exactly the tumor that occurs normally in the adult fly in 
the stock from which it was originally removed. 
A few of the larvae from which the tumors were removed recovered 
from the operation. Some of these completed metamorphosis. All of 
;the offspring from these had tumors showing that the tumor is due to 
something in the germ-plasm which is handed over from one generation 
