The genus Melanocharis comprises four species, all from New Guinea and its islands. These are not very dissimilar in size or coloration. The best known, well named M. nigra, is a glossy black above of a bluish cast. Beneath the principal tint is olivaceous, passing into pale yellow on the abdomen. The under wing-coverts are white. Total length, nearly five inches. Another genus of the same family, consisting of but a single species, is Pristorhamphus veroteri. A larger bird this by an inch, with rich, velvety black plumage above, emanating pale green. Underneath a bluish tint. Besides, some spots of white on the tail, apparent when the bird is flying, but concealed at other times; there are white plumes, very soft and delicate, waving on either flank. The female is equipped with these same adornments, but is of dimmer coloring, mainly olivaceous. Habitat, the Arfak Mountains.

Less by more than an inch is Rhamphocharis crassirostris, the sole member of its genus. An olive-green bird above with dusky brown wing- and tail-coverts, and blackish tail. Below the body is a pearl-gray with a yellow wash. The female is of larger size, olive-brown above, but differing from the male in being rather more varied in neutral colors, yellow and white spots or dots appearing on the dull surface of wings, tail and back. The under parts are of a soiled white, specked with yellow and brown. The bill is not noticeably larger than that of other species.

THE BACTERIAL DISEASES OF PLANTS:

A CRITICAL REVIEW OF THE PRESENT STATE OF OUR KNOWLEDGE.

BY ERWIN F. SMITH.

II.

I. THE BEET (BETA VULGARIS L.).

1. THE BACTERIOSIS OF FODDER BEETS (1891).

(I) THE DISEASE.

(1) Author, Title of Paper, Place of Publication, etc.-This disease was first described by Dr. Ernst Kramer, Privat Docent

in the technical high school in Graz. His paper entitled (23) Die Bacteriosis der Runkelrübe (Beta vulgaris L.), eine neue Krankheit derselben, was published in Oesterreichisches Landwirtschaftliches Centralblatt, Jahrg. I, Heft 2, pp. 30 to 36, and Heft 3, pp. 40 to 41. Graz, 1891.

(2) Geographical Distribution.-The disease prevailed extensively in 1890 in the Eltzischen earldom in Vukovar, Slavonia. (3) Symptoms.-The beet roots were said to be shrivelled and to contain comparatively little sap. The whole of the affected roots began to change to dark brown soon after harvest. On cutting them open dark brown spots were visible. During the winter the disease spread in the beet cellars to apparently sound beets, in spite of the fact that all roots showing any signs of disease were thrown out and destroyed at the time of storage. Roots in which the disease was well advanced showed a gummy ooze which appeared to be infectious to sound beets. Cattle fed with slightly infected roots were attacked with severe bloating and obstinate constipation, and in one case death ensued. Such was the account forwarded to Dr. Kramer along with samples of the diseased beets. There is no record of the symptoms of this disease as it occurs in the field. The diseased beets received by Dr. Kramer were shrunken and in some places were soft under the epidermis. From these soft places there oozed a slimy brownish fluid, which stuck to the fingers, but was without characteristic smell or taste. Brown or dark brown spots more or less softened, and of various sizes, were visible on cross-sections of roots not too badly infected. The inside of those specimens which were badly attacked was, however, almost entirely brown, and in parts the parenchyma was wholly destroyed, giving place to a slimy, sticky, gum-like, brown-colored, strongly acid, odorless fluid. The destruction of the tissues proceeded so far in some parts of the root that, finally, only the vascular bundles remained. The beets attacked by this disease yielded no characteristic odor, and they only began to smell bad in the last stages of the disease after rotting had set in.

(4) Pathological Histology.-An examination of thin sections, made through a brown spot, showed that the cells of this

parenchyma contained tiny roundish or ellipsoidal shining bodies, which were of various sizes, and either scattered about in the cells or united into groups. The individual particles showed not rarely a tremulous motion. When such a thin section was fixed to a cover glass by passing it three times through the flame, and was then stained with gentian violet, these bodies became a beautiful blue, and their bacterium-like form could be made out more clearly. In the parts of the root which had already become slimy great numbers of bacteria were to be seen in the gum-like fluid, together with loosened cells, plasma, and fragments of cell membranes.

(5) Direct Infection Experiments.-When a little of the soft, slimy mass was lifted on a sterile platinum needle and spread on a sterile [steamed?] section taken from an apparently sound beet, the surface of the latter was covered within forty-eight hours with a slimy, brown, gum-like, acid layer, which consisted of a mass of those bacteria previously found in the diseased beets. Sections cut out of diseased beets with sterile knives and placed on fresh, unsterilized sections from sound beets, and kept in a moist chamber at 24° C., caused the latter to become affected. The infected spots browned and softened, and in the tissues bacteria appeared, which were just like those occurring in the diseased beets. A slimy layer also formed on the sterile cut surface of carrots when a slight quantity of the slimy ooze from the beets was spread over it.

"This preliminary investigation indicated that most likely in this case we have to do with a disease caused by bacteria. Positive proof, however, is not thereby afforded. To accomplish this experimentally it is absolutely necessary to isolate the bacteria occurring in the diseased beets, to cultivate them pure, and then to inoculate the pure cultures into sound living beets. If then as a result of the infection the previously healthy beet should become diseased with the before-mentioned symptoms, and the originally inoculated bacteria should appear once more in the tissues, then there would be no doubt about this being a bacteriosis of the beet."

Clearly this man knew exactly what he had to do.

(II) THE ORGANISM.-This is described as a bacillus, but not named.

(1.) Pathogenesis.

(A) Yes.

(B) Yes. Rather easy.

(C) No. These inoculations led to no satisfactory result, and had to be abandoned, because no suitable beet material was at the experimenter's disposal.

(D) No.

Conclusion.-Pathogenic nature rendered probable. The reason for this judgment in opposition to the above statements will be found in the following paragraph.

While Dr. Kramer was not able to secure infections, owing probably to the unfavorable conditions under which he worked, he hit upon an ingenious method of indirect proof, viz., the development in pure cultures of the same gum which is formed naturally in the diseased beets. His method was as follows: The softened or liquefied parts of the diseased beets were cut out, crushed and heated on a water bath, with the addition of a small quantity of milk of lime. The fluid was then decanted, and the remaining mass of beet squeezed as dry as possible and the two fluids mixed, filtered, and carbon dioxid passed into the filtrate for the removal of the somewhat superfluous lime. The fluid was again filtered and concentrated on the water bath. The fluid was now rendered acid by the addition of some drops of acetic acid, and a white, tough, gum-like substance was precipitated out of it by the addition of 96 per cent. alcohol. To obtain it in a pure condition this substance was repeatedly dissolved in water and reprecipitated by alcohol. The same substance was obtained directly from the gummy ooze of the diseased beets by dissolving it in water, heating, filtering, concentrating on the water bath, and precipitating with alcohol. In this case also the precipitate was a white, tough, gum-like substance. Both of these precipitates were tested chemically with the following results. Mixed with soda-lime and heated in a test tube there was no formation of ammonia, a proof that the substance was free from nitrogen. Boiled with orcin and hydrochloric acid it gave the well-known gum reaction, men

tioned by Reichl and Wiesner. Boiled with sulfuric acid it was converted into dextrose. A watery solution gave a bluish flocculent precipitate with Fehling's solution, and on boiling the latter was reduced. On the addition to a watery solution of ferric chlorid and calcium carbonate the well-known precipitate of gum solutions resulted. No red coloration appeared on treatment with iodin. The formation of oxalic acid could not be detected on long boiling with nitric acid. All these reactions indicated a gum. In the beet this could be derived only from carbohydrates, and most likely from dextrose. Working on this hypothesis, a fluid culture medium was prepared containing 3-4 per cent. of dextrose, a slight quantity of peptone, and the necessary mineral ingredients. In this solution pure cultures of the organism were grown 8 to 14 days at a temperature of 24° C., and from the resulting products of growth a gum-like substance was obtained which proved to be identical with that secured directly from the diseased beets. These cultures were protected from contamination by cotton plugs, and at the close of the experiment cultures therefrom showed them to have remained pure, consequently this bacillus must have converted the dextrose into gum.

2. Morphology.

(1) Shape, size, etc.-The organism as isolated and grown in pure cultures is a thick rod with rounded ends, or often narrowed at the ends (zugespitzt), of variable length, so that not rarely coccus or ellipsoidal forms appear. These rods are about 1.30-2.00 x 0.7-1.0. In cultures they occur singly or in pairs, which latter are more or less biscuit-shaped. Chains

are rarer.

(2) Capsule.-No mention of any capsule.

(3) Flagella.--No statement as to motility, except mention of the trembling motion inside the cells of the beet, which can scarcely be taken as a proof of motility.

(4) Spores.-"Apparently spores are formed." This matter is left in considerable doubt. Rods in the stage of spore formation are said to be 1.35 x 2.00 μ.

(5) Zooglea.-No mention of zooglœa.

(6) Involution forms.-No mention of any distorted forms.