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in the East. Recently I also noticed it in Northern Texas. In Missouri it is common in the streets of cities, along railroads, and even growing in woods.

The field Sow-Thistle (Sonchus Arvensis, L.), which in one of our adjoining States, Wisconsin, has been recognized in the weed law, is found in considerable quantity along one of the great trunk lines entering Chicago. This is a pest somewhat to be dreaded if it should appear in Iowa, as it is a perennial and is much harder to stamp out than the common Sow-Thistle (Sonchus olearaceus, L.) In Chicago and near St. Louis I have seen one of the Pigweeds (Atriplex patula, L. var. hastata) in large numbers. Mr. Hitchcock has recently reported it from Iowa City.

A great many more troublesome weeds could be added to this list, especially such as are found in the streets, and along public highways; but those may be considered at some other time. It would be a great aid to the Botanical Department if the farmers of the State would send in weeds of various kinds, giving their common names, and stating how troublesome they are.

PLANT DISEASES.

During the past summer some of the cherry and pear trees in the orchard were seriously affected with fungous parasites. These diseases were especially troublesome in the new orchard set out by Captain Speer, of the experiment station, and some of the seedlings in the nursery of the horticultural department.

These diseases were chosen as thesis work by some of the special students in the laboratory, and as some of the facts may be of interest I give abstracts of their papers below.* The first paper was prepared by J. A. Kelsey.

LEAF BLIGHT AND CRACKING OF THE PEAR. (Entomosponium maculatum, L.)

That pear trees were attacked by some destructive agent other than the common fire-blight has been a well known fact to botanists of Europe and America for almost a century. The loss from this disease must amount to a great many thousand dollars annually. Every year large numbers of seedlings are completely destroyed by this fungus, while older trees are frequently defoliated by the 4th of July. This not only prevents the development of the fruit during the same year, but often destroys the prospect of a crop the succeeding year, since it not unfrequently happens that a second set of leaves and blossoms is put forth the same autumn. The value of the fruit is greatly deteriorated if not completely destroyed by the unsightly appearance or cracking which the malady produces. The bark is also attacked, so that all parts of the tree except the roots are subject to more or less injury. The disease makes itself manifest in early spring. Many of the leaves instead of retaining a uniformly green appearance are dotted with small carmine-red spots, first appearing on the upper and later on the lower surface of the leaf. The carmine-red color soon changes to a dull brown. During the early stages the fungus remains hidden beneath the cuticle of the leaf, but later it is ruptured and exposes to the surface a countless number

*In these abstracts it is not intended to give references to the valuable papers which have been published on the subjects treated, but rather to some facts about a few common and troublesome diseases.

of spores. On the leaves of a few of the Russian pears on the College grounds, particularly on those of the Bessmanka pear, I found this eruption had taken place without producing the brown spot. I believe that most of the Russian varieties, on account of having thicker leaves than those originating in southwestern Europe, will prove to be much less affected by this disease.

Other species of the genus Pyrus are also infested by a fungus, that to all appearances is the same thing. Many of the quinces brought into our market this fall from the East were almost completely covered with this destructive parasite. This fungus seems to be identical with that on the pear. Some apple seedlings on the ground, growing pear seedlings, were found to be quite seriously attacked by it.

The fungus is carried over winter not only by the winter spores which are produced late in the fall and winter, but also by summer spores, if they succeed in finding lodgement in the buds of next year's growth. Concerning its prevention and destruction nothing very definite can as yet be said, since practical experiments have only been begun.

A number of the leading nurserymen of this country claim that seedlings are much less liable to be attacked if planted in a new soil, or at least soil which has not been occupied by trees.

Barry recommends that the ground be prepared by sub-soil plowing to a depth of two feet the preceding autumn, and also by a liberal application of a compost of lime and leaf mold to be well plowed the following spring, the object being to secure a vigorous growth as early as possible in the season, in order that the young trees may be better able to stand attack. All diseased leaves should be raked up as soon as they fall, and burned.

Prof. Galloway has been highly successful during the past season in preventing the disease, by the application of a mixture of copper, lime and water, in the following proportions: Copper sulphate, six pounds; lime, six pounds; water, twenty-two gallons. A block of five thousand pear trees, treated at intervals of ten days, beginning June 5th, were reported August 11th as being nearly free from the fungus. At the same time another block of young pear trees adjoining these were very severely injured by the fungus.

THE SEED COATS OF CROTALARIA SAGITTALIS AND ASTRAGALUS MOLLISSIMUS.

The subject of Crotalism and Loco-poisoning has attracted considerable attention in late years. It is sufficiently important to demand a short place in this report. One of the veterinary students, Mr. Ashworth, has studied the seed coats of Crotalaria sagittalis and Astragalus mollissimus for the purpose of obtaining some characters to aid in the diagnosis of these diseases, especially after parts of the seed have passed through the alimentary canal. Crotalaria sagittalis, L., or Rattle-box, is an annual common in the western part of the State, along the Missouri river. It has a rather wide distribution in the United States, occurring in sandy soil from Massachusetts to Illinois, Missouri, Iowa, Nebraska, and south to Texas. Astragalus mollissimus, one of the Loco plants, is a perennial and occurs on high sandy soil, distributed throughout the plains and table-lands of Colorado, New Mexico, Utah, Wyoming, Texas, Indian Territory and Arkansas. In Astragalus

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mollissimus, the outer or palisade layer, is thick and dark, the cells are elongated, like the palisade cells in leaves. They are marked in the upper one third by a light line. The cell cavity is larger at the base, and gradually tapers upwards until it is quite narrow. The palisade cells show four rather distinct folds, the middle one refracting light strongly; the second layer is composed of thick walled cells; the cavity resembles a dumb-bell in outline. The third layer is composed of several rows of thin walled-really differentiated-cells, in two parts; the cells of the lower part of the third layer are more irregular than the first. The fourth layer is made up of four rows of cells, which are elliptical in outline, with a small cell-cavity. The fifth layer is composed of elongated cells similar to those of the fourth. The cells of the sixth layer are very small; some of these occasionally contain an oil globule. The testa of Crotalaria sagittalis is made up of four differentiated layers. The outer is fully one third larger than in Astragalus mollissimus. The light line runs horizontally one fourth the way down from the cuticle. The remaining layers are much like those of Astragalus, excepting the third, which contains three rows of thin walled cells. The aleurone layer and the starch cells of the embryo join the inner layer of seed coats.

DEPARTMENT OF ZOOLOGY, ENTOMOLOGY, AND
GEOLOGY.

HERBERT OSBORN, PROFESSOR.

Work with the general students in this department begins in the fall term of the freshman year, when a course of lectures and class exercises with field studies in economic entomology is given. This is intended not only to acquaint the student with the more important injurious insects and the methods of treating them, but also to give him an elementary knowledge of insect structure, metamorphosis, and the methods of observing and studying animal life. Zoology begins in the fall term of the sophomore year, with laboratory studies of typical forms of animal life, and deals mainly with morphology. Class work embraces recitations from text book, occasional lectures, and quiz on laboratory work, etc. This term is preparatory to, and is followed by, a full term's work in spring of junior year on a study of the different groups of the animal kingdom. Laboratory and class work are associated, and the student acquires familiarity with the animals of different groups by actual study with microscope, or by dissection.

In the fall term of the junior year students prepared for the work may elect a full term's work in entomology, embracing a systematic study of insects, and furnishing also additional drill in methods of study in histology, life histories of insects, etc. Advanced, or special work, may be elected in the senior year, which may consist of vertebrate dissection or elements of embryology, and special studies on selected forms or groups with preparation of thesis. Candidates for the second degree may continue such work with opportunities to pursue original investigations.

Geology is taught to the seniors in the spring term, and embraces a study of the principles as presented in LeConte's "Elements," the preparation of rock sections, essays on economic geology, geological maps, a study of typical fossils, and a review of the geology of Iowa.

Students in the veterinary course are given two exercises per week, second term of first year, and three exercises per week in the first term of the second year, in zoology, and two exercises per week, second term of second year, on animal parasites.

The laboratory is supplied with twenty-five microscopes, various microtomes, including a Thoma, and other apparatus for microscopical study and

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gross dissections. A supply of marine animals properly preserved for laboratory work furnishes means for study of forms otherwise inaccessible to inland students.

The museum contains typical examples in all the principal groups of animals, and in some departments is especially useful for students who wish to make special studies of our State fauna or of certain groups of animals.

Several important additions to the equipment of the laboratory have been made during the past two years, and the collections have been increased by numerous specimens collected in the State by students and myself, and also by some fine series of insects from the Pacific region. Dr. T. W. Shearer, of Wallisville, Texas, a graduate of the class of '81, presented us last year with a magnificent alligator and two alligator gars, and has shown his continued interest in our collection by the donation the present year of a logger-head turtle.

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The most urgent need of the department is for more room where museum, laboratory, and class-rooms can be connected. At present the use of the museum as a means of illustration in the classes of geology and zoology, attended with much inconvenience and loss of time, and is often practically impossible; and the collections are unavailable for the purposes for which they are designed.

The museum is in an inconvenient position for visitors, too small for the collections already on hand, and not well adapted in plan for further improvement. Moreover, it should at the earliest possible day be put in a fireproof building. The presence of quantities of alcohol, essential in the preservation of specimens, is a constant source of danger in a building so largely occupied by students, and where all the materials surrounding it are of such an inflammable nature. The fact that museums, in case of fire, are almost invariably a total loss, is due in large part to the presence of this very combustible material. Not only for the sake of our museum, which is becoming too valuable to be so exposed, but for the safety of the many people living in the building, I would urge that you give this matter the consideration it demands.

The plans which were secured in accordance with your authority, six years ago, call for a building that would cost $18,000 to $20,000; but these plans could be modified or the rooms included in a building to provide for other purposes if deemed best. The essential feature of freedom from danger by fire should, however, be carefully considered in determining such connection.

The rooms essential at the present time are a large, well lighted and conveniently arranged room for general museum, and connected with this, room for storage of alcoholic specimens, geological material, preparation of museum specimens, breeding rooms for insects, etc., which could very properly be placed on a ground or basement floor; also, laboratory room sufficient for at least twenty students, and a lecture room and office.

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