The Catholic bulletin. [volume] (St. Paul, Minn.) 1911-1995, 1915-07-17
Continued from page ID
LIFE AND WORK OF GREGORY
MENDEL.

GIT FNINS WYNN ShINShI
MENDEL.
den, guarding against all possible in
terference of factors which might
vitiate the entire work In spite of
all precautions failures have been met
with, but they could be explained and
later on corrected by still more
stringent control of experiments. 1t
was owing to this occasional unex-
pected and at first glance inexplicable
results, that Mendel waited for eight
weary years to venture upon the field
of speculation in regard to the nature
of INTERPOLATION of generations in
plants.
The typical case of Mendelian study
of heredity is found in the results of
intercrossing the giant and the dwarf
plant: the former attains the height
of to Z feet, the latter is only n to
Ia feet high. The product of this
inter-crossing is in his language
called a hybrid, although the term
was at that time reserved to the
offspring of two distinct species; he
justifies the appellation by maintain
ing that this constitutes a difference
of degree and not of the nature of
the process. In comparing the hybrid
character to the parental forms he no
longer speaks of the transmission of
characteristics from ancestors to the
offspring, but of the resemblance of
the two generations. He found that
the first filial generation bears a
striking similarity to one of the par
entail forms, while the other apparent
ly finds no representation in the first
generation. This observation, found
to be true after repeated experiments,
led to the conclusions that parental
characteristics do not blend, but that
they remain segregated. The offspring
does not visibly contain, and is de-
void of the features noticeable in one
of the ancestors. This is probably the
first clear and systematic statement,
based on accurately ascertained facts,
of the doctrine that somatic modifica-
tions do not determine the character
of the offspring, but that this is con-
ditioned and controlled by the germ
cell. The opinion prevails in biology
today that the germ or preparatory
cell and the somatic. cells are
segregated early in the life-history of
the individual; descendants of the
same stock resemble one another, not
on account of parental acquisitions
and somadic notifications, but be-
cause they are all derived from the
same stock. Germinal continuity in
this conception involves the doctrine
of it's discontinuity from the body
plasm. All variations in succeeding
generations are the product, not of
the blending and intermingling of
ancestral characters, to which doc
trine Darwinism is necessarily COM
mitted, but are the result of germ-cell
characteristics. The doctrine of the
inheritance of acquired characters and
the transmission to the descendants
of ancestral acquisitions, recently re
affirmed by as great an authority as
James Ward of the University of Cam
bridge, is now rejected by the great
majority of biologists and biologists.
The subsequent development of Men
dels doctrine of heredity and evolu-
ton shows that the Austrian cleric
rejected the generally accepted
theory of gradual variations upon the
individual, and formulated the theory
of mutation or sudden transition from
one form to another. Menders theory
of heredity, the scientific study of
which subject he originated, combines
the predetermination as we'll as the
epigenesis theories. The characteris-
tics of the organism are predeter-
mined, to some extent at least, by the
initial structure of the zygote; at
the same time the various organs of
the adult arise from apparently undif-
ferentiated material.
The disappearance in the hybrid
of one Of the differentiating charac-
tiers of the ancestors is only tempo
rary; it comes to view in the offspring
of the hybrid. Those characters
which are transmitted quite, or al
most unchanged in the hybridization,
and, therefore, in themselves consti-
tute the characters of the hybrid, are
termed dominant and those which be-
come latent in the process, recessive. =
(Mendel's Papers Bateson p. 342).
The character termed recessive or
latent is only held in allegiance in the
hybrid, but appears without the
slightest modification in succeeding
generations. In the experiment under
consideration, the character, tallness,
appears to the exclusion of the oppo-
site character, dwarfness;; the former
is, therefore, dominant, the latter re
cessiye. Transitional forms do not
appear in any experiment.
The tall cross-bred were then al
lowed to produce offspring through
Standardization. There was noted in
this second filial generation the ap-
pearance. together with the dominant,
also the characteristics Of the other
grandparents, l. e. the recessiva. The
phenomena of atavism were n1ted by
Investigators before Mendel He is,
however, the first to determine the
exact ratio Of the dominants and re-
cessiVes: the former were more nu-
merous than the latter. Upon inYesti-