LINKAGE 67 
ees vms aaa 
YWAB, VMS RFB 
A number of females of this type have been made 
up by Muller. The next formula shows the kinds of 
eggs that were produced by one of these females and 
the numbers of each kind that were produced. 
Non-crossovers: 
ywab, vms rf b’-6. 
YWAB VMS RFEB-8 
Single crossovers: 
YWabi vms rf b’-2. 
YWAB; vms rf b’-2. 
ywab VMS RFB-2. 
YWAB,; Vms rf b’-l. 
YWAB; VMS rf b’-l. 
ywab vms RFB-1. 
Double crossover: 
ywah VMS RFb’‘-1. 
Counts of over 600 offspring from females of the 
same type have given similar results. The character- 
istic method of interchange here demonstrated may 
perhaps be better realized by contrasting the com- 
binations just given with the following, which illus- 
trate types of eggs found not to be produced by such 
females: - 
y WaB, Vm8 rf B’ 
YWab, Vms Rf B’ 
It is not supposed, however, that the per cent. of 
