ignated BG Fy, hybrids; GB Fy designates the recip- 
rocal hybrids. 
In the experiments reported here, two methods were 
employed in an attempt to produce each of the six pos- 
sible Fy hybrids between bluegill, green sunfish, and 
each species were kept separated. Eggs from one or 
more ripe females of one species were stripped into a 
damp petri dish, fig. 3A, and milt from one or more 
males of another species was stripped onto the eggs. 
The petri dish was then shaken vigorously in order to 
Table 1. — Intrageneric Lepomis P] crosses attempted experimentally by various biologists and the results of these 
attempts. 
Pj Cross 
(Male x Female) 
Bluegill x green 
Green x bluegill 
Bluegill x red-ear 
Red-ear x bluegill 
Green x pumpkinseed 
Pumpkinseed x green 
Pumpkinseed x orangespottedt 
Orangespotted x pumpkinseed 
Green x orangespotted 
Pumpkinseed x bluegill 
Bluegill x pumpkinseed 
Longeart x green 
Green x longear 
Pumpkinseed x longear 
Longear x pumpkinseed 
Longear x bluegill 
Bluegill x longear 
Reference 
Hubbs & Hubbs (1932) 
Luce (1937) 
Ricker (1948) 
Krumholz (1950) 
Krumholz (1950) 
Hubbs & Hubbs (1932) 
Hubbs & Hubbs (1932) 
Luce (1937) 
Luce (1937) 
Luce (1937) 
Hubbs & Hubbs (1932) 
Luce (1937) 
Lagler & Steinmetz (1957) 
Hubbs & Hubbs (1932) 
Luce (1937) 
Lagler & Steinmetz (1957) 
Hubbs & Hubbs (1932) 
Hubbs & Hubbs (1932) 
Hubbs & Hubbs (1932) 
Hubbs & Hubbs (1932) 
Hubbs & Hubbs (1932) 
Hubbs & Hubbs (1932) 
Result 
61 raised to sexual maturity 
Many raised to free-swimming stage* 
Many raised to sexual maturity 
Many raised to sexual maturity 
No hybrids produced 
11 raised to sexual maturity 
41 raised to sexual maturity 
Some raised to sexual maturity 
Some raised to sexual maturity 
Some raised to sexual maturity 
No spawning occurred 
Many raised to free-swimming stage 
Many raised to sexual maturity 
No spawning occurred 
Many raised to free-swimming stage* 
Many raised to sexual maturity 
Spawning occurred, but all eggs fungused 
No spawning occurred 
No spawning occurred 
No spawning occurred 
No spawning occurred 
No spawning occurred 
*Information from author. 
Orangespotted sunfish, L. humilis (Girard). 
Longear sunfish, L. megalotis (Raf.) 
red-ear sunfish. Each P] cross was made in the lab- 
oratory by using Luce’s method (referred to hereafter 
as laboratory cross) and each was arranged for in out- 
door ponds by placing males of one species with fe- 
males of another species (referred to hereafter as 
field cross), 
Adults used in making the Pj crosses were obtained 
from several lakes and ponds in central Illinois, fig. 2. 
Bluegills were obtained from Lake Italy, Fairmount 
Quarry, Fairmount; from Farmer City Country Club 
Pond, Farmer City; and from Big Pond, Utterback’s 
Farm, 5 miles southeast of Gibson City. Green sunfish 
were obtained from Allerton Lake, 4-H Memorial Camp 
of the University of Illinois at Robert Allerton Park 
near Monticello, and from Pond E2, Fairmount Quarry, 
Fairmount. Red-ear sunfish were obtained from Taylor’s 
Pond, Taylor’s Farm, 3 miles southwest of Fairmount; 
from Lake Italy; and from Big Pond. 
Laboratory Crosses. — Ripe males and females of 
the bluegill, green sunfish, and red-ear sunfish in the 
lakes and ponds named above were trapped and moved 
into aquaria in the laboratory. Males and females of 
mix milt and eggs. Two minutes were allowed for fer- 
tilization to take place, and then 200 to 300 fertilized 
eggs, fig. 3B, were poured into each of a number of 
clean petri dishes filled with aged tap water. As soon 
as the egg fluid, which had prevented the eggs from 
sticking, became diluted, the eggs adhered to the bot- 
toms of the petri dishes. The fertilized eggs or zygotes 
were left undisturbed for approximately 15 minutes to 
allow them to become water hardened. The zygotes 
were then washed by lowering and raising the petri 
dishes four or five times in a large beaker filled with 
aged tap water. After the zygotes had been washed, 
enough water was added to each petri dish to cover 
the zygotes. This water was poured off and replaced 
approximately six times each day during the incubation 
period. After the embryos hatched, the larvae were 
placed in 10-gallon aquaria. The water in these aquaria 
was kept in constant gentle motion by releasing air 
from air stones placed close to the bottom. As soon 
as the larvae became free-swimming fry, they were 
placed in ponds containing no other fish and held for 
one or more growing seasons. 
