DEC 8 1924 
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[Reprinted from the Cincinnati Lancet-Clinic, May 9, 1903. | 
THE GERM CELL AND THE RESULTS OF MENDEL. 
Discussion before the Academy of Medicine of Cincinnati, April IS, 190S. 
Dr. Michael F. Guyer : Mendel and 
other investigators have found that when 
two pure forms are crossed, a given char¬ 
acter of one parent as a rule predominates 
in the hybrid offspring, and masks the 
corresponding character of the other pa¬ 
rent. For example, if in plants the seed 
of one parent is round and that of the 
other long, then the seed of the hybrid will 
be all round or all long, depending upon 
which parental character predominates. 
Furthermore, in respect to a given charac¬ 
ter, as, for example, the shape of the seed, 
if the hybrids are fertilized among them¬ 
selves, one-fourth of the resulting offspring 
will show again the particular ancestral 
character which was masked (“reces¬ 
sive”), one-fourth the ascendent charac¬ 
ter (“dominant”), which obscured its 
fellow, and the remaining half, though 
apparently of this same ascendent type, 
will really continue to be hybrid or mixed. 
Both the particular isolated dominant 
character in question and its complemen¬ 
tary recessive persist and remain pure in 
succeeding generations, provided the re¬ 
spective forms which bear them are not 
again cross-bred, but the mixed type will 
break up each time into three groups simi¬ 
lar in proportion and kind to those derived 
from the original hybrids. 
To account for the behavior of the two 
sets of parental characters it was supposed 
that any particular quality from one line 
of ancestry does not occur in the same 
germ-cell with a corresponding quality 
from the other line of ancestry. In such 
an event, since there are two parents and 
consequently two sets of qualities or char¬ 
acters, half of the germ cells will contain 
a given quality from one line of ancestry 
and the other half will contain the corre¬ 
sponding character from the opposite line. 
If we designate these parallel qualities as 
A and B respectively, then half the germ 
cells of both the male and the female 
hybrid will contain the A character and 
half the B character. Consequently, when 
two germ-cells unite in fertilization, ac¬ 
cording to the laws of chance, the quali¬ 
ties may be brought together as AA,AB, 
BA or BB. AB and BA are of the mixed 
type, and will occur in one-half of the 
offspring; A A will be represented exclu¬ 
sively in one-fourth and BB in the remain¬ 
ing fourth. That is, with respect to this 
quality, one-fourth have reverted to one 
grandparent, one-fourth to the other, and 
half continue hybrid. 
The above conclusions were derived from 
the study of the characters of hybrids, 
and not from a study of the germ cells. 
The question naturally arises as to whether 
there is any evidence from the study of 
the germ cells themselves to bear out this 
theory of the separation and isolation of 
the corresponding qualities of each parent. 
In studying the germ cells of hybrid pig¬ 
eons some years ago (1897-1900) the 
writer observed certain phenomena which 
led him to much the same opinion regard¬ 
ing the separation of qualities in germ 
cels as that expressed by Mendel, although 
at the time the results of Mendel were 
wholly unknown to him. In the light of 
the Mendelian law, the facts discovered at 
that time become doubly significant, and 
seem to point precisely to such a state of 
affairs in the germ cells as the law would 
necessitate, although the general conclu¬ 
sions originally drawn from the facts by 
the present writer will have to be qualified 
1 Guyer, M. F. “Spermatogenesis of Nor¬ 
mal and of Hybrid Pigeons.” Dissertation, 
University of Chicago, 1900; also, Bulletin 22, 
University of Cincinnati. 
