66 
dict the growth habits from an observation of the flower form and 
coloring, but few cases have been observed of close linkage, to 
form definite races. 
According to the chromosome theory of inheritance, most if 
not all of the inherited traits of a plant are transmitted by the 
chromosomes—tiny, dark-staining bodies evident in the cell nu- 
cleus during cell division. Usually the number of these formed 
in each cell by any kind of plant is constant, and each one seems 
to carry its own burden of the total inheritance of the plant. De- 
tailed studies of Drosophila flies, daturas, and other organisms go 
to prove the soundness of this theory. Accordingly, chromosome 
studies of the gladiolus were undertaken, with the hope of learn- 
ing more about its mode of inheritance, and of possibly finding an 
explanation of certain sterilities observed in some interspecific 
crosses. 
For this study, pollen mother cells from the anthers of flower 
buds were used. Each mother cell nucleus divides into four nu- 
clei, each of which then develops into the nucleus of a pollen 
grain. In the gladiolus this nuclear division takes place when the 
flower stalk is just emerging from the leaves, and there are really 
two steps in the process; first a division into two, then into four 
nuclei. During this process, the number of chromosomes in each 
nucleus is reduced from the number in the usual vegetative cells, 
to half that number in each pollen grain. The pollen mother cells 
at this stage are free in the cavity of the anther sac, and are easily 
squeezed out on a microscopic slide, stained and studied. The 
chromosomes stain black with aceto-carmine, but are very small 
and in the early part of the telophase, after they are drawn away 
from the equatorial plate, they are short and bent nearly double, 
so that they are rather hard to count accurately. Counts were 
made after the first, and after the second division, when the 
chromosomes were in two or in four groups, and in each case the 
resulting count was the same, indicating that reduction division 
took place at the first division within the pollen mother cell. The 
results of these counts are as shown in table 1, page 67. ih 
“Priority” is a hybrid derived from G. primulinus crossed wi 
a garden variety of hybrid gladiolus. “Halloween” is a seedling ° 
a cross of G. quartinianus with a Primulinus hybrid, and the re 
maining two are botanical species. The chromosome numbers peo 
uniformly the same in all of these forms belonging to widely dit- 
a 
