324 DIVERGENT EVOLUTION THROUGH SEGREGATION. 
When M = 5, m = 4, then if 
c= 4, half-breeds = pure-breeds X ?, 
c=}, half-breeds = pure-breeds X #, 
c=, half-breeds = pure breeds x 4, 
o— half-breeds = pure-breeds X #, 
e=1,  half-breeds = pure-breeds X §, 
c= 1, half-breeds = pure-breeds X ‘5, 
Css, half-breeds = pure-breeds X 74, 
Cia half-breeds = pure-breeds X 14, 
c= 5, haif-breeds = pure-breeds X 1%, 
c= 4,, half-breeds = pure-breeds X yé3, 
¢ = qlyo, half-breeds = pure-breeds X yo4s3 
TABLE Y. 
When M10, and— 
m=9;| m=8; | m=T; | m=6; | m=—5; | m=4; | m=3; | m=2; | m=). 
= | a SS | = : 
If c=4, then Half-breeds— 2 ; Ain agp 2 ! 
Pure-breeds * Si egeae af 0 a 10 ro ag i6 a0 
16? (ae 10S Sooo seonee | 11 iz | 13 ti is 16 ri ee it 
TP @ 3s, Wel 12 ce sasase | a Ti | i is #5 35 or ai as 
iW? Gat Bl ee ceeeoee 13 16 15 fs | so] os 31 34 37 
IGE fe see, bss We eso seaocoe 1a os | 2 2 | 30 34 38 a2 a6 
TOP assy 1301 Co peepore ae 15 ay |) ess 30 a5 | aig WN 25 BO 3s 
JP Mosc [ele 1PM oo sesdebe gear oa | 3 Fae | biatch arene ales $6 73 
OY Ga tiy be IE SSa5soens4| 15 zr | si ae 35 66 7£ BE 
The GS stig, lS ee csanesae 108 sic 46| «Cex «| «Coe «| on | és 636 7134 Boz 
16? WS sainoy Jeb 1S boboooos | doe | dos | soor | aor B0o0 | sive | sobs 790E 5992 
| | | 
OBSERVATIONS ON TABLE V. 
This mathematical analysis of the effects of positive segregation and 
segregate fecundity when codperating brings distinctly into view Sev- 
eral important relations 
First. Incomplete forms of segregation, that avail little or nothing in 
preventing a form from being absorbed in the course of time, become 
very efficient when strengthened by moderate degrees of mutual steril- 
ity. Take, for instance, the line of the table in which ¢— 745. If i in 
every 100 unions is a cross with some other form, the form will in time 
be overwhelmed, unless other causes come in to counteract; but here 
we see that, if segregate fecundity occurs in the ratio of 10 to 9, the 
pure form becomes 12 times as numerous as the half-breeds; and if in 
the ratio of 10 to 5, it becomes 100 times as numerous. 
Second. Again, if we take the proportional differences between the 
different terms of the top line opposite ¢— 4, we shall find them very 
unlike the differences that appear in the bottom line opposite ¢ = y9'o0- 
In the former the first term is 9 times as large as the last; while in the 
latter the first term is more than 80 times as large as the last. This 
shows that when segregation is intense, differences in the degree of segre- 
gate fecundity produce greater contrasts than the same differences do 
when the segregation is slight. 
