June 7 ,1924 A Genetic ami Cytological Study of Wheat Hybrids 1029 
In the cross Amby X Kubanka several F 3 segregates were classed as the durum 
or intermediate type but had more than 14 chromosomes. Number 6 , for instance, 
was classed as a durum type in F 3 and had 14 bivalent and 5 or 6 single chro¬ 
mosomes (S), a total of about 20 haploid chromosomes. When these various 
segregates were carried to F 4 it was found that all of them had 14 chromosomes 
and were all of the durum type. The fertility varied greatly, ranging from 0 
grains per spikelet to individuals as fertile as the parent. Number 7 , which was 
classed as intermediate in F 3 and also had an intermediate number of chromo¬ 
somes, was intermediate and had an intermediate chromosome number in F 4 . 
This individual was relatively sterile in F 4 . One vulgare type recorded as having 
18 chromosomes in F 3 was found to have 21 chromosomes in F 4 , but had the 
typical durum awns and the hard grain typical of Kubanka. It was also as 
fertile as the parent. This case is unusually interesting because apparently two 
characters peculiar to the durum group are found in a 21 chromosome segregate. 
Whether or not this individual will be found homozygous and completely fertile 
in later generations is, of course, questionable. Two F 3 segregates classed as 
intermediate and with 21 chromosomes were found to segregate vulgare types of 
spikes in F 4 and had approximately 21 chromosomes each. Pictures of these F 4 
segregates are shown in Plate 2 and are arranged in the same order as they are 
in the Table. 
In the cross Marquis X Alaska a number of F 3 segregates were selected which 
appeared to be intermediate and which possessed combinations of durum and 
vulgare characters. In F 4 certain of these segregates maintained the combina¬ 
tion of parental characters and in most cases had an intermediate number of 
chromosomes, usually with several single lagging chromosomes at the time of 
the reduction division. One segregate in F 4 had a durum type of head but with 
the small vulgare type of keel (Plate 1 ). This individual had 14 chromosomes, 
but was relatively sterile, as indicated by the number of grains per spikelet. An 
unusual combination was found with a durum head type but with soft grain. 
This individual had 14 chromosomes and was practically as fertile as the parent. 
The other F 4 segregates for which chromosome counts were made were found to 
have an intermediate chromosome number and ranged in fertility from 0.5 grains 
per spikelet to 2 grains per spikelet. Number 7, in F 4 , had wrinkled grain, 
indicating its heterozygous condition and undoubtedly its progeny in F 5 would 
show various degrees of sterility. It will be of interest to follow these inter¬ 
mediate types into future generations and determine the relation of morphological 
characters and chromosome numbers. 
There are several cases where the characteristics of the two parents are com¬ 
bined in a single individual and this individual may possess the parental chromo¬ 
some numbers of 14 or 21 . These results may indicate that in rare cases segre¬ 
gates can be recovered combining certain of the parental characters. Practical 
breeding experiments made in an attempt to combine the desirable characters of 
the emmer wheats with the bread-making qualities and yield of the vulgare 
wheats indicate, however, that the possibilities of recovering such intermediate 
types are rare and that the best results can be obtained by selecting the parental 
varieties within the vulgare group (2, 9 , 12, 4> 5,6). 
CONCLUSIONS 
Crosses between wheat species of the emmer group with 14 chromosomes, 
with members of the vulgare group with 21 chromosomes, result in partially 
sterile F x hybrids, and all degrees of sterility in F 2 . Previous cytological studies 
of chromosome number and behavior in Fj and F 2 indicate that gametes and 
segregates with an intermediate chromosome number tend to be eliminated 
