In order to study the linkage of lemon, the following experiment was carried out. Since it was impracticable to breed directly from the lemon flies, virgin females were taken from stock throwing lemon, and were mated singly to cherry vermilion males. Only a few of the females showed themselves heterozygous for lemon by producing lemon as well as gray sons. Half the daughters of such a pair are expected to be heterozygous for lemon and also for cherry and vermilion, which went in from the father. These daughters were mated singly to cherry vermilion males, and those that gave some lemon sons were continued, {49} and are recorded in table 24. The four classes of females were not separated from each other, but the total of females is given in the table. TABLE 24.--_P_1 lemon (het.) [female] x cherry vermilion [male] [male]. F_1 wild-type [female] x cherry vermilion [male] [male]._ +-------+--------------+-------------+-------------+-------------+------+ | | W^c V | W^c l_m | W^c | W^c l_m V | | | | ---------- | ---+------ | ------+--- | ---+----+---| | | | l_m | V | l_m V | | | |Females+-------+------+------+------+------+------+-------+-----+ Total| | |Cherry | |Cherry| Ver- |Cherry|Lemon |Cherry |Wild |[male]| | | ver- |Lemon.|lemon.|milion| | ver- |lemon |type.|[male]| | |milion.| | | | |milion| ver- | | | | | | | | | | |milion.| | | +-------+-------+------+------+------+------+------+-------+-----+------+ | 71 | 42 | 19 | 2 | 6 | 3 | 6 | 0 | 0 | 78 | | 88 | 26 | 19 | 2 | 8 | 8 | 4 | 0 | 0 | 67 | | 36 | 28 | 7 | 0 | 2 | 1 | 0 | 0 | 0 | 38 | | 51 | 12 | 22 | 0 | 4 | 4 | 4 | 0 | 0 | 46 | | 98 | 29 | 35 | 0 | 8 | 5 | 1 | 0 | 0 | 78 | | 47 | 17 | 11 | 0 | 1 | 3 | 2 | 0 | 0 | 34 | | 46 | 23 | 20 | 1 | 6 | 5 | 2 | 0 | 0 | 57 | +-------+-------+------+------+------+------+------+-------+-----+------+ | 437 | 177 | 133 | 5 | 35 | 29 | 19 | 0 | 0 | 398 | +-------+-------+------+------+------+------+------+-------+-----+------+