34 E. W. SEXTON AND M. B. WING. 
the bowl, and over the food, and even clings to the amphipods themselves. 
With a lens it is easy to see long streamers of this slime trailing behind 
the little creatures as they swim. 
Proportions of Pure Black to Hybrid Black in the F, generation, 
The experiments to find the proportions of Pure Black and Hybrid 
Black were made with the surviving F, progeny of the first F, brood, 
Brood A, that came to maturity. The following table shows the parentage 
with the number of young hatched, 210 in all, 153 black-eyed and 57 red- 
eyed. 
P.3 x R.2 Parent generation. 
(From Pure Black stock.) | (One of the 8 Reds, p. 26.) 
First Brood—Brood A =22 young. Hybrid. F', generation. 
extruded 16.3.1914. 
A.F, pair. B.F, pair. | C.F, pair. | D.F, pair. | E.F, pair. | F.F, pair. | G.F,. 
4 broods. | 4broods. | Ibrood. | 2 broods. | 3 broods, 2 broods. 1 brood. 
55 young. 48 young. 7 young. 20 young. 43 young. 27 young. 10 young. 
EF, generation. 
Hatched :— 
38 Black. 37 Black. 6 Black. 15 Black. 30 Black. 21 Black. 6 Black. 
17 Red. 11 Red. 1 Red. 5 Red. 13 Red. 6 Red. 4 Red. 
Survived :— 
23 Black. 15 Black. 4 Black. 13 Black. 18 Black. 15 Black. 5 Black. 
10 Red. 7 Red. 0 Red. 3 Red. 7 Red. 4 Red. 3 Red. 
Only 127 reached maturity, 93 black-eyed and 34 red. Of the Black 44 
were males and 49 females ; of the Red 20 were males and 14 females. 
The testing was done with red-eyed mates, the Blacks being separated 
into finger-bowls and each given a Red mate. The resulting broods 
would at once show the P. or H. character, for if the black-eyed animal 
were a Pure Black the offspring would be all black-eyed ; if a Hybrid 
-Black, half the young would be black-eyed and half red-eyed. Later, 
when the constitution of each had been determined, the survivors were 
mated together: “P.X(P = Seige he x ie Sand! dese 
It sometimes happens that the individuals of the first brood of Hybrid 
x Recessive, if few in number, are all of one eye-colour, not the normal 
proportions, half red and half black. This occurred six times in the course 
of these experiments ; in four broods the young were all black-eyed ; in 
two, all red; the highest number in any of these broods was four. To 
avoid error each pair was kept for at least three broods to make quite 
sure of the constitution ; in some cases the black-eyed were mated with 
two or three different red-eyed mates. 
In all 141 experiments were made with the 93 Black-eyed animals. 
Thirteen, 7 males and 6 females, died without proof, probably through 
