to these questions were published,* and from them the following evidence bearing upon the question we are considering are selected.

Isaac King, Esq., Wycombe, Bucks, in answer to the question about the barberry, says, "In 1795, a field of about 20 acres had two large barberry bushes growing within 20 yards of it. These appeared to be the focus of destruction to several acres; in front, close to the hedge, the wheat was as black as ink, and further off it was affected to a less degree . . In short, I had 15 acres very good, and 5 of very little value. You may conclude the barberries were destroyed."

Mr. S. Johnson,† Thurning, Norfolk, says,-"My observations on the barberry have been for several years. I have seen the blast from a small stem blown on the wheat in one direction upwards of 2 furlongs like smoke from a chimney."

Mr. W. Maxey,‡ Knotting, Bucks, says,-" When passing a wheat field a few years ago on the eve of harvest, I noticed some streaks of a different and darker hue across a furlong of wheat from the hedge directly opposite; at the end of each streak was a barberry bush."

Mr. James Sheppard, § Chippendale, Newmarket, says, "I have never seen an instance of wheat growing near a barberry not being injured more or less." It is quite unnecessary to quote any further from Mr. Young's correspondents upon this point.

Sir Joseph Banks in his paper on "Wheat Mildew," alluding to the subject before us, mentions the belief as being prevalent amongst farmers, but scarcely credited by botanists, and points out the resemblance the yellow fungus on barberry has to rust, although it is larger. He says:-"Is it not more than possible that the parasitic fungus of the barberry and that of wheat are one and the same species, and that the seed is transferred from the barberry to the corn?"

This is precisely what Professor De Bary did sixty years afterwards, when he actually produced the wheat mildew from the barberry fungus. It must be remembered that, although these statements were made half a century ago, this in no way affects their veracity; but it may be well to quote a more recent instance in which the deleterious influence of the barberry is shown. M. Gabriel Rivet,¶ writing in 1869, alluded to the fact that the Paris and Lyons Railway Company planted a barberry hedge beside their line. The neighbouring proprietors drew up petitions, and asked the company to remove the hedge. The company made trials by cutting a part of it down to see if it were really as hurtful as was alleged, and found the mildew so much diminished thereby that they had the whole hedge removed.

On July 17th, 1882, I examined a field of wheat at Flitcham, Norfolk, in the hedge of which were three barberry bushes. Although they had been cut down a fortnight previously, there was no difficulty in finding the place where each had

* A. Young, Annals of Agriculture, vol. xliii., 1805, p. 457.

+ Loc. cit., p. 469.

t Loc. cit., p. 505.

§ Loc. cit., p. 510.

Banks, in Annals of Agriculture, vol. xliii., p. 521,

Rivet, in Bulletin de la Société Botanique, vol. xvi., p. 331-334. Influence de plantations d'epine-vinette sur la developpement de la rouille des céréale.

been, from the extent to which the corn was destroyed by mildew in a semicircle, about ten yards in diameter, opposite each bush. The rest of the field was free from the disease. As a matter of fact the three barberry bushes, or rather the places where they had been, were found by looking for the mildewed places in the wheat. It was felt at the time that had any disbeliever in the heterocism of the wheat mildew been present, he would have been then and there convinced by the logic of facts.

LIFE-HISTORY OF THE FUNGUS.

Since Persoon gave to the fungus which causes the wheat mildew the name of Puccinia graminis, in the year 1797, our knowledge of its life-history has progressively increased, owing to the researches of Tulasne and De Bary, who have shown, first, its connection with rust; then its mode of germination; and, lastly, its heterocismal character. The genus Puccinia is purely a parasitic one. Up to the present time some eighty species have been met with in Great Britain. A perfect Puccinia has no less than five kinds of reproductive forms, to which the following names have been applied, viz. :-Æcidium, Spermogonia, Uredo, Puccinia, and Promycelium. Since these various forms of fructification constitute a cycle, it matters but little which we commence with, for if they be only taken consecutively, we shall come round to the one with which we started. Perhaps it will be most convenient to begin with the Uredo.

FIRST STAGE: RUST-OR UREDO SPORES (FIG. 1).

Uredo linearis.-The well-known rust of wheat consists, as its names imply, of elongated masses of orange spores, which, during the summer months, occur abundantly upon the living leaves of various grasses and cereals. It is not confined to

the leaves, for it frequently is found upon their sheaths, upon the stem, and also upon the glumes. If a speck of rust be examined through a common lens, it will be seen to consist of a mass of golden dust, around which can be seen the torn edges of the epidermis. This yellow powder consists of oval spores, measuring from 25 to 35 mk. long, by from 15 to 20 mk. wide. They are not uniform in shape, some being more globose than others, but they are all studded with minute protuberances, so as to present a warted appearance. They were originally formed beneath the cuticle of the plant, which, as they increased in size and number, they ruptured. When mature, these spores readily fall apart, and are scattered and carried away by the faintest breath of air. Examined more attentively, the majority will be found to possess, at one end, an appendage marking the point of their attachment to the leaf from which they sprang. If a young pustule of rust be examined in section, it will be found that each spore springs separately from a single transparent thread or tube, a portion of the mycelium or spawn of the fungus. This mycelium consists of an entanglement of hyaline tubes, ramifying between the cells of the plant that bears it; at certain points these accumulate together and give off a mass of branches parallel to each other, all pointing towards the cuticle of the leaf. These branches become enlarged at their superficial extremities, where, eventually, each one produces a single spore. These spores are

at first like the mycelium-colourless, but soon become filled with yellow endo

a, cluster of Uredo-spores springing from mycelium in a Wheat-plant surrounded by the ruptured epidermis; b, c, d, e, f, g, h, i, Uredo-spores of various ages: k, Uredo-spore germinating in water, the first change; l, m, n, further stages of germination in water as explained in the text; o, Three spores of Uredo germinating upon the cuticle of Wheat, the germ-tubes of which are entering the stomata, 8-10 hrs. ; P, Germ-tube from a Uredo-spore squeezing itself into a stomate (7 hrs.).

From an electrotype supplied by "The Gardeners' Chronicle "

k