442 BROOKLYN BOTANIC GARDEN MEMOIRS 
at Bremen and Berlin, Germany, and perhaps at Peking, China, while 
monomeric B lobes (Table 1) have been demonstrated in strains from 
all these places except Tucson, Arizona. Besides these places in 
which the two types have been found associated together, the mono- 
meric condition has been found at Chicago, Illinois, at New Carlisle, 
Ohio, at Landau, Germany, and probably at Vicenza, Italy, in which 
places duplicated factors for this character have not yet been dis- 
covered. Excepting only Landau, Germany, these localities in which 
duplication of the B factor has not yet been found, have been repre- 
sented in my cultures by only one wild B-lobed plant from each 
locality. It may be merely a matter of chance that the first plant 
from each of these localities had but one of the B factors. It should 
also be noted that from the only region in which monomeric B lobes 
have not been found, namely at Tucson, Arizona, only two wild 
plants have yet been tested, a number quite too small to give any 
confidence in the suggested inference that no biotypes with monomeric 
B lobes occur at that place. It is obviously necessary to make the 
study of geographical distribution of these B factors much more 
extensive before safe conclusions may be drawn as to the primitive 
or derivative condition of the B lobe with respect to duplication. 
This is a work in which many students might lend assistance by 
crossing together the several wild biotypes from their own localities. 
SUMMARY 
The leaf lobes of shepherd’s-purse are controlled by Mendelian 
factors A, producing elongated sharp lobes, and B which divides the 
leaf to the midrib and brings to light certain characteristic secondary 
lobing. The action of these factors is easily suppressed or obscured 
by unfavorable environmental conditions, and the inheritance ratios 
are usually more or less defective on this account. In previous papers 
both of these characters have been reported to be monomeric, 7. @., 
each was found to be controlled by a single factor. 
It is shown in the present paper that two factors, B and B’, exist 
in certain strains and that these two factors produce the same char- 
acteristic lobing of the leaves, but are inherited independently of each 
other and of the factor A. 
The biotypes having the B factor duplicated appear to be less 
widely distributed than those which are monomeric with respect to 
the B lobes. More extensive data are needed on this point, but if 
the present indications are confirmed, the relatively less frequency of 
the dimeric condition is taken to mean that the duplication of this 
factor has taken place at a relatively recent date. 
