26 E. W. SEXTON AND M. B. WING. 
EXPERIMENTAL WORK, 
The first question to be decided was whether the red eye-colour was 
a sex-limited character or not—the only adult specimens previously 
observed having been females. 
In order to settle this point the 8 red-eyed young found on November 5 
(p. 22) were placed in a bowl by themselves to come to maturity. It is 
impossible to distinguish males from females until the animals reach 
sexual maturity, which occurs when they are about half-grown, the males 
being then easily distinguishable by the fine coiled hairs of the lower 
antennze, and by the larger gnathopods. The 4 red-eyed young of August 7 
were kept in the Laboratory, only two coming to maturity, both female. 
The 8 red-eyed young of November 5 were kept in another room, not 
heated, with a temperature ranging from 4°—10° C., and were in conse- 
quence much slower in maturing ; but in three months’ time both males 
and females were seen—thus settling the question of the red eye-colour 
being a sex-limited character. In February three pairs mated. These 
were kept separate, each pair in a finger-bowl to itself, and the others, 
which were females, with the two August 7 females, were paired with 
males from the ‘“‘ Pure Black ” stock. Males and females paired were also 
taken from this stock, and thus we had Recessive mated with Recessive 
(R.x R.), Pure Black mated with Recessive (P.xR.), and Pure Black 
mated with Pure Black (P.xP.). We started daily observations and 
records on this generation, calling it the Parent Generation, and counting 
from it the F,, F,, etc. 
Our aim now was to discover if the Mendelian laws of inheritance of 
characters were applicable to the results of these crosses, and the ex- 
periments to this end will be given in detail under the different divisions 
—I Recessives and IIT Dominants. 
I. THE RECESSIVES. 
We commenced work in February, 1914, with the three pairs just 
referred to, adding in May seven pairs taken from the 42 red-eyed animals 
hatched since November 5, 1913, in the Hybrid Stock (see p. 22). Hach 
pair and its offspring have been kept separate, the broods on hatching 
removed from the parents’ finger-bowl and examined for eye-colour, 
each brood being numbered and set aside to come to maturity. In every 
case in which both parents were red-eyed all the offspring have been 
red-eyed. 
The red-eyed animals appear to be more delicate than the black-eyed, 
shorter-lived, and less fertile. They are quite as large and as active, and 
