tuberculin and proper methods of disinfection of stables and other localities which have been infected by diseased animals it will be possible in a comparatively short time to greatly reduce the number of cases of this disease. Dr. Pearson's report to the Pennsylvania board of health indicates a reduction of 33 per cent in cases of tuberculosis in that State.

As tuberculosis in animals is reduced so will the disease in man be proportionately decreased. There is every evidence to prove conclusively that man may be infected with tuberculosis by drinking the milk from tuberculous animals. Recent work, combined with many experiments that have been conducted in past years, has shown that the tubercle germ of human origin or the tubercle germ of animal origin can adapt itself very readily to its surroundings and grow upon different varieties of media and at different temperatures without its pathogenic or disease-producing properties being destroyed.

It was claimed for a long time that the human tubercle bacillus was not pathogenic for birds. Very recently, however, Nocard has shown that if a culture of the human bacillus be placed in a collodion sack and this sack introduced into the peritoneal cavity of a chicken, after four weeks or more the germ will have assumed the appearance of the avian bacillus and will have become pathogenic for chickens. Again, the tubercle germ has been recently isolated from carp. It was demonstrated very conclusively that these carp were infected from the sputum of a badly tuberculous individual, which sputum was thrown regularly into the pond occupied by the carp. The germ isolated from the carp grew at a very much lower temperature than the human germ, but its origin was undoubtedly human. All this work has proven very conclusively that the tubercle bacillus found in different animals may adapt itself very readily to different surroundings, may be accustomed to grow at lower or higher temperatures, and may eventually grow under conditions that would have been originally entirely destructive to it. This latter point has been very practically demonstrated in this laboratory, the experiments showing that the tubercle bacillus can be gradually accustomed to a nutrient liquid containing glycerin, sodium and potassium phosphate, and ammonium phosphate. When obtained directly from the animal the germ will not grow on this solution, but by cultivating it first upon a medium which more nearly produces the conditions that the germ finds in the animal body it can then be transferred to the solution of mineral salts and caused to grow rapidly and in great abundance. If such conditions can be produced artificially outside of the body there is certainly every reason to believe that the germ can very readily adapt itself to changes in temperature and nutrient conditions that are found in the bodies of different animals and still cause tuberculosis.

During the seven years that tuberculin has been prepared in this laboratory for distribution by the Bureau of Animal Industry to

various State officials and experiment stations, the results have been very generally satisfactory. Thousands of reports have been received, from nearly every State in the Union, from Canada and the West Indies, and from many different sources, and with one or two exceptions (exceptions arising very probably from the fact that the users of the material were not experienced in handling it) all have realized the importance and usefulness of tuberculin.

There have been one or two cases in which it was claimed that the tuberculin gave misleading results. One may be noted especially. A supply of tuberculin had been sent from this laboratory in the spring of the year to a certain State veterinarian who distributed it to some of his assistants. One of these assistants kept the bottles standing in his office for several months in the hot sun. He then used some of their contents to test an animal, which, according to report, passed the test, and was sold. Subsequently, with another lot of tuberculin, the animal showed the tuberculin reaction, which diagnosis was proved upon post-mortem examination. The doctor to whom this tuberculin had been sent was requested to forward the bottle from which the material had been used to this laboratory. He said that he could not get this, but sent another bottle from the same lot which had not been opened but kept under the same conditions. This latter bottle was kept for some six or eight months, until an opportunity occurred to have the veterinarian of the District of Columbia use some of it. He was told that it was old tuberculin, and that nothing was known about its reliability, but that he could use it upon animals which showed signs of tuberculosis. This he did, and reported a very characteristic reaction. The writer feels sure that the failure reported in the first instance was due to a personal error and not to the tuberculin.

Contrary to the generally accepted statement, the diluted bottled tuberculin has often been kept in this laboratory for two or three years or more without its losing its active properties. In order, however, to avoid all trouble, the usual recommendation is that the tuberculin sent out shall not be used more than six weeks after the date upon the bottle, which indicates the time when it was diluted in the laboratory. This may be an unnecessary precaution, but one which seems advisable when the material is placed with such a large number of people.

CONCLUSIONS.

In conclusion, it would seem that the preparation of tuberculin should always be conducted under experienced direction. It should be distributed through some central authority, so that the results from its use can be collected and tabulated and serve as a source of general information. It is an invaluable test, and by its use, as has been demonstrated by several of the States, especially Vermont, it is certainly possible to reduce very materially tuberculosis among cattle, and it may be possible to eventually exterminate it.

THE PRINCIPAL INSECTS AFFECTING THE TOBACCO

PLANT.

By L. O. HOWARD, Ph. D.,

Entomologist.

INTRODUCTION.

The tobacco plant, although indigenous to America, does not suffer so greatly from the attacks of insects in the United States as do others of our crop plants. It has no insect enemies peculiar to itself, but every season a certain amount of damage is done by insects, and in some years favorable to insect increase this damage may mean a serious loss to the planter.

The most comprehensive work upon tobacco insects which has been published is in the Italian language, and includes a consideration of all species which affect this crop, both in the field and in the factory. But this work treats largely of European insects, being a special report of the entomological agricultural experiment station at Florence, entitled "Animals and insects of growing and dried tobacco," by Prof. A. Targioni-Tozzetti. In this country there have been occasional accounts of specific insects in the different agricultural reports and in the bulletins of the State experiment stations. Prof. H. Garman, of the Kentucky experiment station, in particular, has given the subject much attention, and has done admirable work in the important direction of proving the possibility of the practical use of arsenical mixtures on the tobacco plant. The most comprehensive article which has yet been prepared in this country is, at the time of this writing, being printed by the Florida Agricultural Experiment Station as Bulletin No. 48, with the title "A preliminary report upon the insect enemies of tobacco in Florida," by A. L. Quaintance.

The present paper contains accounts of several tobacco insects not included in the bulletin by the Florida author, who, as the title indicates, treats only of the species occurring in Florida, but the writer defers to Professor Quaintance in matters of actual field experience concerning several of the species, and wishes here to express his thanks for advance proof sheets of the bulletin in question, which have enabled him to make this paper more complete than it would otherwise have been.

From the time when the seed is sown in the seed bed to the time when the tobacco field is plowed under to some late fall crop, the

tobacco plant is subject to the attacks of several species of insects. Throughout the tobacco-growing regions of the United States there is probably no one insect which does more damage to the marketed product than the tobacco flea-beetle, or "flea bug," as it is commonly known to growers (Epitrix parvula). The large horn worms or " hornblowers," also insects of wide distribution, tobacco growers must always fight. The bud worm, which may be either the larva of Heliothis rhexia or of the cotton boll worm or tomato fruit worm or cornear worm, as it is called according as it affects different plants (larva of Heliothis armiger), attacks and bores into the central leaf roll or "bud" early in the summer, or later in the season into the seed pods or into the terminal flower stalk, and even feeds to a certain extent upon the leaves. Several species of cutworms are liable to occasion replanting in soil which has not been properly treated, and one or two of them rag the leaves late in the season. Certain wireworms also are liable to affect the young plant shortly after it is set out. Two or more species of plant bugs occasionally damage the leaves by inserting their beaks and sucking the juices, causing a drying and shriveling of the leaf in much the same way as the harlequin cabbage bug injures the leaves of cabbage. One of these plant bugs, a small species, insignificant in appearance, has recently proved to be a serious enemy to tobacco culture in Florida. Another new insect, and one which may prove to be a very important factor in tobacco culture, is the so-called tobacco leaf-miner, or "split worm," an insect which although first found in North Carolina only two years ago has since made its appearance in Florida, South Carolina, and southern Virginia. These comprise the principal species damaging growing tobacco at the present time. There is always a chance, however, that new insect enemies may make their appearance just as two of those above mentioned have done in very recent times, and it is safe to say that many of the species which affect solanaceous plants, and especially the tomato, are liable to transfer their attentions to the tobacco crop under favorable conditions.

After the tobacco has reached the factory, an insect enemy of importance, and which is always to be feared, is the cigarette beetle (Lasioderma serricorne), a species which riddles the tobacco leaf, which bores into or out of manufactured cigarettes and cigars, and which, when once introduced into a not over cleanly factory, is very difficult to eradicate. Two or three other little beetles have been found in dried tobacco, namely, the drug-store beetle (Sitodrepa panicea) and the rice weevil (Calandra oryza), but they are not as important as the cigarette beetle..

It is proposed to give in this paper a short account of these insects and other species of less importance, with some indication of the proper remedies under each, and a concluding paragraph on remedial work as a whole.

THE TOBACCO FLEA-BEETLE.

(Epitrix parvula Fabr.)

This active little insect (fig. 7) may be found in almost any tobacco field from Arkansas to Florida and north to Connecticut. It is a minute, oval, reddish-brown species, which occurs upon many solanaceous plants, feeding upon tomato, potato, horse nettle, and jimson weed (Datura stramonium). The beetles make their appearance in July, attacking first the lower and then the upper leaves. After they have fed for awhile the leaf becomes full of small, dry spots and then of holes about the size of a pin point, which later may become considerably enlarged (fig. 8). When

the crop is cured it is poor and thin, and frequently full of small holes. While the main damage is done in the beetle condition, the insect feeds also, in its early stages, upon the tobacco. Its eggs being laid at the roots, hatch into minute, whitish larvæ, which feed upon the roots, and, in the course of about a month, as ascertained by Mr. Chittenden, reach full growth, transform to pupæ, and again to adult beetles. The damage done to the roots in this way must affect the health of the plant to a certain extent, but it is not appreciable in comparison with the damage which the adult beetles do to the leaves.

d

FIG. 7.-Epitrix parvula: a, adult beetle; b, larva, lateral view; c, head of larva; d, posterior leg of same; e, anal segment, dorsal view; f, pupa-a, b, f enlarged about fifteen times, c, d, e more enlarged (after Chittenden).

The insect, in its early stages, is not confined to tobacco, but feeds also upon the nightshade and the jimson weed, as also ascertained by Mr. Chittenden.

It is not alone in the actual damage to the leaves done by the jaws of the beetle that this insect is injurious to the foliage of tobacco, but through the further fact that these little holes, even when the puncture is not through the entire thickness of the leaf, become the entrance points of fungous spores or bacteria, which start a disease of the leaf which frequently damages it much more than the insects. themselves. In moist weather this disease, started by the flea-beetles, may do considerable damage when the flea-beetles themselves are comparatively scarce.

By some writers the round white spots in the leaves, which are illustrated in fig. 9, have been considered to result from the initial work of the tobacco flea-beetle; but, as reported by several workers upon fungous diseases, these spots have been shown to be invaded by