Life Sciences Commons^™

Size And Structure Of Leaves Of Cereals In Relation To Climate, William Edward Bruner, John E. Weaver

Papers from the University Studies series (University of Nebraska)

Although a very large amount of work has been done on the variation in form, size, and anatomical structure of native plants grown under different conditions, relatively little attention has been given to similar studies of crop plants. As far as we are able to ascertain, no investigations have been made of variation in the leaves of cereal crops grown under widely different, measured environments.

During the past few years (1920-23), in connection with studies on the development and activities of the roots of crop plants (Weaver, Jean, and Crist, 1922), plant production as a measure of environment (Weaver, 1924), …

Pericarp Studies In Maize. I. The Inheritance Of Pericarp Colors, E. G. Anderson, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Introduction ... 466

Nomenclature ... 467

Pigments present in colored pericarp ... 467

Factor relations of pericarp colors ... 468

Factor relations of red pericarp, P ... 468

Factor relations of cherry pericarp ... 471

Discussion and Summary ... 474

Literature Cited ... 475

The Flat-Headed Apple-Tree Borer, Fred E. Brooks

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The flat-headed apple-tree borer, a serious orchard pest throughout the greater part of United States, is found from the Atlantic to Pacific and from Florida and Texas to Canada.

The larva, or grub, of this insect (which in the adult stage is a medium-sized beetle) bores in the bark and wood of a great variety of trees, but is best known as an enemy of apple, pear, peach, and other cultivated fruit trees. Its depredations are felt in almost every locality where orchards have been planted.

Fortunately, this borer almost invariably confines its attacks to the sunny sides of trees …

Genetic Interrelations Of Two Andromonoecious Types Of Maize, Dwarf And Anther Ear, R. A. Emerson, Sterling H. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Attention was called by Montgomery (1906)to the occasional appearance

of perfect flowers in the staminate inflorescence of maize and similar

cases were reported by Kempton (1913). Montgomery (1911) described

with illustrations a true-breeding type of semi-dwarf dent maize, the ears

of which were perfect-flowered. Perfect-flowered maize was described

and illustrated also by Blaringhem (1908, pp. 180-183). East and

Hayes (1911, pp. 13, 14) noted and illustrated a perfect-flowered sweet

corn. Weatherwax (1916, 1917) showed that typically pistillate

flowers of maize exhibit in microscopic sections the rudiments of stamens

and that staminate flowers show rudiments of pistils.

The Apple-Tree Tent Caterpillar, A. L. Quaintance

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The Apple-Tree Tent Caterpillar makes the unsightly nests or tents to be seen in the spring in trees along roadways, fences, and streams, and' in orchards. It varies greatly in abundance from year to year or over longer periods. Wild cherry is the favorite food plant, but many other plants are attacked, including several orchard fruits, especially the apple. During years when caterpillars are abundant the trees may be so completely stripped of their foliage that larvae are forced to hunt other food plants and hence are to be seen in numbers crawling over the ground and fences and elsewhere. …

The Relative Frequency Of Crossing Over In Microspore And In Megaspore Development In Maize, R. A. Emerson, C. B. Hutchison

Department of Agronomy and Horticulture: Faculty Publications

One of the early developments in the study of linkage in Drosophila was the discovery that the phenomenon of crossing over is confined to the female sex (Morgan 1912). The fact that no crossing over occurs in the male Drosophila holds true not only for sex-linked genes but for factors in the autosomes as well and is so well established that it affords a most convenient method of determining to which of the different linkage groups a new factor belongs.

The same phenomenon, but with the sexes reversed, obtains in the silkworm moth. Tanaka (1914, 1915) has found from back-cross …

Heritable Characters Of Maize: Ix. Crinkly Leaf, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

In 1910 a strain of dent corn obtained at the National Corn Exposition held at Omaha was crossed with a strain of flint corn obtained from the Department of Agronomy of the University of Nebraska. The F₁ plants of this cross were normal and no abnormalities had been observed in the parent strains. But since the latter had not been subjected to self-pollination, there is no assurance that one or other of them did not have in it the character to be described here. In the F₂ generation of this cross there occurred a tpe of plant that …

Heritable Characters Of Maize Ii.-Pistillate Flowered Maize Plants, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

In the "freak"

class at the Annual

Corn Show held at Lincoln, Nebraska,

in the winter of 1913-14,

there was exhibited a corn tassel

with a heavy setting of seeds. A few

seeds are not infrequently found in the

staminate inflorescence of maize, particularly

in pod com, and tillers of various

corn varieties often end in ears instead

of in tassels or have tassels, the central

spikes of which are ear like. The freak

exhibited at the com show, however,

was a large. much branched affair.

wholly tassel-like in form except for the

fact that it bore a heavy crop …

The Roundheaded Apple-Tree Borer, Fred E. Brooks

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The Apple Tree has no more destructive insect enemy than the roundheaded apple-tree borer. It is the grub of a rather large white and brown striped beetle, which usually requires from two to three years to complete its life cycle.

It is found throughout the eastern half of the United States and southeastern Canada, attacks trees of all ages, but is most destructive to young trees up to 10 years old.

Besides the apple, it attacks the quince and pear among cultivated fruits, and the wild crab, service, mountain ash, chokeberry, seedling apple, and some other wild or native trees. …

Genetical Studies Of Variegated Pericarp In Maize, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Two years ago there were presented some results of a study of the inheritance of self pattern in the pericarp of maize seeds, occurring as a sporophytic2 variation in variegated ears (EMERSON1 914). Further results, in entire accord with those previously reported, have now been obtained. In addition, data bearing upon new phases of the problem are also available.

The chief results reported in the earlier paper were the following: ( I ) The more nearly self-colored the pericarp of any seed of a variegated ear, the more likely is the progeny of that seed to produce a self-colored ear …

The Inheritance Of A Recurring Somatic Variation In Variegated Ears Of Maize, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

The inheritance of variegation has special interest and importance in genetics. It is with forms of variegation that the only two certainly known cases of non-Mendelian inheritance have had to do. I refer to Baur's experiments with Pelargonium, in which crosses of green-leaved and white-leaved forms exhibited somatic segregations in F₁ that bred true in later generations, and to Correns 's work with Mirabilis, which showed green and white leaf color, to be inherited through the mother only. De Vries's con- ception of "ever-sporting" varieties was apparently founded largely upon the behavior of variegated flowers in pedigree …

Multiple Factors Vs. "Golden Mean" In Size Inheritance, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Groth's preliminary note on the "golden mean" in the inheritance of sizes in SCIENCE of April 17, 1914, pp. 581-584, deserves the attention of geneticists. Its publication is of such recent date that I need only call attention to one or two points that seem to me of particular moment.

In brief, Groth's hypothesis is that the mode

of inheritance in F_l not only of surfaces and

volumes, but also of linear dimensions is to be

expressed by √ab rather than by a + b /2

where a and b are parent sizes. The hypothesis

is based upon …

Shorter Articles And Reports: The Simultaneous Modification Of Distinct Mendelian Factors, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

In another paper on the inheritance of a recurring somatic variation in variegated ears of maize, it was shown that the amount of red color developed in the pericarp of variegated seeds bears a definite relation to the development of color in the progeny of such seeds. The relation is such that the more color there is in the pericarp of the seeds planted the more likely are they to produce plants with wholly self-red ears and correspondingly the less likely to produce plants with variegated ears. Self-red ears thus produced behave just as if they were hybrids between self-red …

Shorter Articles And Discussion Simplified Mendelian Formulae, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

I was somewhat surprised by 'Morgan's and Castle's suggestions for a simplification of Mendelian formulae. My surprise was not occasioned so much by the forms these suggestions took as by the fact that any pronounced changes were deemed necessary. I had not only employed the usual formula in my own work but had found no difficulty worth mentioning in understanding the formula used by most other workers in Mendelian fields. My experience with students in elementary courses in genetics had not prepared me for the idea that such formula were particularly difficult. Nevertheless I believe in simplifying the formulae if …

The Possible Origin Of Mutations In Somatic Cells, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

That mutations are accompanied by some change in the germ-plasm is, I take it, indisputable. Have we, however, any reason to suppose that the change takes place within the germ cells? I am not sure, as a matter of fact, that genetists in general regard the gametes as the place of origin of mutations. It is true, however, that experiments in the artificial production of mutations in plants have been limited largely to treatments of the ovaries from about the time of the reduction division to about the time of fertilization. This suggests a belief on the part of investigators …

The Unexpected Occurrence Of Aleurone Colors In F2 Of A Cross Between Non-Colored Varieties Of Maize, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Before the Mendelian methods of analysis became available, considerable wonder would doubtless have been excited by the "mysterious" appearance in F₂ of one colored grain-purple or red-to every five or six white ones in case of a maize cross, both parents and F, of which had only white grains. An occurrence of this sort has recently been noted in one of my maize cultures and the F2 numbers are explained here as a trihybrid or tetrahybrid ratio. The crosses in question were made primarily for a study of size inheritance and fairly large numbers have been grown. The varieties …

Discussion And Correspondence Coupling Vs. Random Segregation, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

To the editor of science: The suggestion offered by Morgan, in SCIENCE of September 22, to account for the coupling and repulsion of factors for various characters in inheritance in such forms as Abraxas, Drosophila, fowls, sweet peas, etc., incites this note.

Briefly Morgan's hypothesis is (1) that the materials representing factors that couple are "near together in a linear series" in the chromosomes; (2) that, when pairs of parental chromosomes conjugate, "like regions stand opposed "; (3) that "homologous chromosomes twist around each other," but that the separation of chromosomes is in a single "plane"; (4) that, thereby the …

The Inheritance Of Sizes And Shapes In Plants, R. A. Emerson

Department of Agronomy and Horticulture: Faculty Publications

Some years ago Lock reported a cross of a tall race of maize with a shorter race which produced an intermediate height in F₁ and exhibited no segregation in F₂ when crossed back with one of the parents. Castle's results with rabbits are very similar to those of Lock with maize. Castle summarizes his results in part as follows:

A cross between rabbits differing in ear-length produces offspring with ears of intermediate length, varying about the mean of the parental ear-lengths. . . . A study of the offspring of the primary cross-breds shows the blend of the …

The Earliest Name For Steller's Sea Cow And Dugong, Theodore S. Palmer

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

In 1811, Illiger published a number of new genera, proposing among others, Rytina for the sea cow of Bering Island and Halicore for the dugong of the Indian Ocean. Nearly all recent writers on mammals have adopted these genera, apparently overlook ing the fact that both animals had been named before 1811. As early as 1794 Retzius described the sea cow in the 'Handlingar' of the Stockholm Academy of Science, placing it in a new genus which he called Hydrodamalis, and the species, based on the Vacca marina of Steller, Hydrodamalis stelleri. The generic description is sufficient to …