days as requisite for a closely-allied species, Gardeners' Chronicle, 28th October 1882.

The experiments were varied in many ways, and if Professor Farlow's full reports of the carefully conducted experiments are examined, it will be seen that heterocism, as regards the American species of Podisoma and Ræstelia, completely breaks down at every point. Out of nineteen experiments no less than fourteen were without result; when results followed they were contradictory, and sometimes, as Professor Farlow remarks, "desperate.” In 1879 Professor Farlow was absent, but in 1880 he returned and made further experiments: these were invariably without result.

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We have shown in this work that Puccinia (mildew) and Acidium (blight) are potentially perennial, hereditary, and always either in an active or passive state in the juices of the plants invaded. Professor Farlow adverts to the same fact as regards the American fungi, and suggests that the appearance of the spermogonia was in consequence of the presence beforehand, in the leaves, of the mycelium of some Rastelia which was made to develop by the moist condition in which it was placed. “I am strongly inclined," writes Professor Farlow, "to favour this view." He further states that, unless he is mistaken, he has seen the Rastelia state earlier in the season than the Podisoma; and so, instead of following, as stated by Oersted, it has preceded, the Podisoma. He concludes by saying: Another important fact is to ascertain how many of our Ræsteliæ are perennial. This at least appears to be the case with R. aurantiaca, Pk. If it should be shown that several of our Rastelic are perennial, a fact true of our Gymnosporangia (Podisoma), and to grow in regions remote from Juniperus and Cupressus, then one could not help feeling that any connection between the two genera was probably accidental rather than genetic."

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The amount of confusion that exists in books as to the host plants, and second conditions of the so-called hetero

cismal or metacious fungi is now almost beyond conception. The literature is bewildering and contradictory in the highest degree. The following instance is one of the simplest; many others are involved almost beyond the power of unravelling.

In 1872 we observed an Acidium invading quinces in Mr. Alfred Smee's garden at Hackbridge. At that time no such plant on quinces had been noticed as British; but the fungus was published by us in Mr. Smee's My Garden under the name of E. cydoniæ, Lenz. We afterwards learned that this fungus was considered to be a mere form of Rastelia cornuta, Tul., a parasite of mountain ash, and proved (?) by experiments with spores to be a second condition of Gymnosporangium Juniperi, Lk. Professor W. G. Farlow mentions a distinct Rastelia frequent on quinces in the United States, under the name of R. aurantiaca, Pk., and this is probably our plant. Professor Farlow considers it a true species; but other botanists look upon it as a variety,—not, however, of the R. cornuta, Tul., just mentioned, but of the totally different R. lacerata, Tul., whose alternate condition is said to exist in Podisoma Juniperi, Fr., a second parasite of Juniperus communis, L. In the United States, strange to say, R. aurantiaca, Pk., and R. lacerata, Tul., grow in company on the same host plants.

If the statements just given as to the quince fungus are correct, we have two confessedly very different species of fungi, both frequent on Juniper, and both able to invade quinces, and produce specifically different fungi on the leaves and fruit,—the characters of the two quince fungi being in turn so much disputed by botanists, that their names are sometimes transposed, and one made to do duty for the other; each Rastelia being supposed to answer to the characters peculiar to the other one.

Note.-On page 175 we have stated that the initial experiment of producing an Ecidium from germinating Puccinia

spores was made by Professor De Bary with Puccinia tragopogonis, Corda, the assumed result being Ecidium tragopogonis, Pers. The latter is abundant in this country, but the former, illustrated from a continental example in the left-hand figure of Fig. 90, has never yet been found in Britain. A second species of Puccinia, however, named P. sparsa, Ck., is found both in Britain and on the Continent on Tragopogon. This has rough or slightly echinulate spores, and is illustrated in the righthand figure of Fig. 90. Dr. M. C. Cooke maintains the dis

Teleutospores of Puccinia tragopogonis, Corda, and P. sparsa, Ck.
Enlarged 500 diameters.

tinctness of the two fungi, and P. sparsa, Ck., is retained as a species in the Mycologia Scotica. Many botanists, both British and Continental; look on the two parasites as quite distinct, but the advanced advocates of heterocism now say they are the same, and term both P. tragopogi, Pers., although Persoon never gave this name.

We have not heard whether Ecidium tragopogonis, Pers., follows the germinating spores of Puccinia sparsa, Ck., on goats-beard, —if it does, and the two species of Puccinia are distinct, the case is similar with the one mentioned by Professor W. G. Farlow, where spermogones appeared on pear leaves after the application of the germinating spores of two species of Gymnosporangium and one of Podisoma.

CHAPTER XXVI.

NEW DISEASES OF WHEAT, BARLEY, AND RYE-GRASS, CAUSED BY

Fusisporium culmorum, hordei, and Lolii, W.Sm. THERE can be no doubt that the injury caused to food plants by various species of Fusisporium is much greater than is generally supposed. We have already stated that a form of the potato disease is caused by one or more pests belonging to this genus. Perhaps one reason why some species of Fusisporium have been overlooked is because they are almost invisible without careful attention, combined with a knowledge of their habits of growth. Some species only resemble to the unaided eye a small gelatinous patch, and when this patch is exactly the same colour as the matrix on which it grows (which is often the case), the difficulty of detecting the fungus is increased.

A description of Fusisporium was given under Fusisporium Solani, Mart., Chapter V., one of two species found on potatoes. We will now briefly advert to three species which at present have found no place in the text-books of this country.

There is a Fusisporium found on wheat generally tinted with cream-colour or yellow, and possibly varying in colour from white to pink. It attacks the ears, chiefly perhaps of those plants which have been more or less invaded by corn mildew or other cereal fungi. This Fusisporium forms a pale yellow-orange gelatinous stratum over the ears or some portions of the ears. It glues the spikelets together and stops the growth of the grain. Although this pest has apparently been hitherto unrecognised by

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botanists, we have heard of it from agriculturists at various places. The upper portion of an infected ear, as sent to us by Mr. Chas. B. Plowright from West Lynn, Norfolk, is illustrated, natural size, at Fig. 91. The dwindled portion at the apex from A to B is the part overrun by the Fusisporium. The fungus, owing to its orange colour, gives the ear a spurious appearance of ripeness. When the plant is magnified 400 diameters, it is seen, as at A, Fig. 92, where the crescent shaped fusiform septate spores, so characteristic of the fungus, are illustrated. One of the spores at B is seen breaking up into four portions. After a short rest each portion will burst and produce new mycelium. A single spore is farther enlarged to 1000 diameters at C. The long cells at D belong to one of the outer glumes of the wheat spikelet. This plant may be named Fusisporium culmorum, W.Sm., and described as follows: Mycelium effused, gelatinous, yellow or orange, sparingly septate, torulose; spores large, fusiform, 3.5 septate, orange. the pales, glumes, and spikelets together.

On wheat, fixing

Another Fusisporium, belonging to barley, has recently attracted attention, and this was described and illustrated with two plates in the Jour. Roy. Micro. Soc. for June 1883, p. 321, under, as we think, the incorrect name, as furnished by Dr. Chr. Hansen of Copenhagen, of Fusarium graminearum, Schwb.; this is the F. graminum of Corda. Unfortunately no scale of magnification was given with the plates. The author of the article, Mr. Chas. Geo. Matthews, was good enough to send us some of the infected

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