294. A. FRANKLIN SHULL 
TABLE 3 
Showing number of male- and female-producers in three lines of Hydatina senta, the 
line in the second column being inbred from that in the first column, and the line in 
the third column from that in the second (see text) 
ORIGINAL LINE INBRED LINE | TWICE INBRED LINE 
| o OF OF ea Oo OF 
% em il D oa || % Or 
Date of first = = || Date of first 6 ig | Date of first | © Ss 
young 5 & young 38 1 young B & 
3 g 5 g g 
Z Z | Z Z Zi | Z 
November | November | November | | 
28 5 23 || 28 9 25 28 i; @ 15 
30 4 4 | 30 0; 41] 30 ee) 20 
December | December | December 
2 | 0 27 || 2 2 ile 33a 2 7 39 
4 | a || 2 a) 4 1 43 || 4 2 18 
1. | 3 23 || 6 20 20 || 6 2 31 
9 11 4 | 9 11 10 8 26 
12 1 22 | if | 2 || 9 1 23 
13 0 | 5 11 2 13 || 11 | 5 8 
0 29*| 13 0 17 | 13 vara 16 
115) | 0 15%) 15 By alae] 15 0 3 
| | 9 3% 
Motal.>......| 27 | 199% 65 | 218 | 50 | 202 
i“ | 
Per cent of & Q| 12.3 22.9 
* Remainder of family not recorded. 
ment, there were 18.2 per cent of male-producers; and in the 
inbred line, including 19 earlier generations, 16.7 per cent. In 
the ‘twice inbred’ line, which is given in full in table 3, there were 
19.8 per cent of male-producers. 
It may be pointed out incidentally that in the original line as 
a whole, not including the last two generations which were incom- 
pletely recorded, the average size of family was 34.5, in the inbred 
line as a whole 30.7, and in the ‘twice inbred’ line 24.0. This 
seems to indicate a loss of vigor, perhaps due to inbreeding. 
Experiment 3. Inbreeding in another line. In this experiment 
the comparative ages of the inbred line and the line from which it 
was derived are not known. The line designated A in table 
