developed in the autumn, they will not, as a rule, germinate till the following spring; they then burst in the manner illustrated at Fig. 69, enlarged 1000 diameters, upon old decaying grass and straw upon the ground. In the warm damp weather of April and May one or both segments of a teleutospore will burst and produce a transparent thread of mycelium, termed by botanists pro-mycelium, because it is the first mycelium of a cycle of phenomena belonging to Puccinia. The compound teleutospore is shown at AA, with its short stalk B still attached. As the pro-mycelial threads, CC,

X-200
Fig. 68.

Transverse section through a pustule or Sorus of Puccinia Rubigo-vera, D.C. Enlarged 200 diameters.

increase in length, the protoplasm pours from the spores into the tubes. A series of septa then appear, two of which are seen at DD, and these septa enclose the protoplasm in the growing end of the tube; from this end two or three minute transparent or pale yellowish spores, termed pro-mycelium spores, as at EEE, are borne these speedily fall from their slender supports, and germinate very readily on damp surfaces, as shown at F.

It might be considered reasonable to suppose that these little pro-mycelium spores, as produced in the spring, would, if placed on the leaves of grasses, reproduce the Uredo first described; but many botanists believe it to be proved that they do not and cannot at once reproduce the Uredo; but when placed on the leaves of certain plants

belonging to the Borage family, as Lycopsis arvensis, L., Anchusa officinalis, L., Symphytum tuberosum, L., etc., they produce an apparently totally different fungus,

Teleutospore of Puccinia Rubigo-vera, D.C., germinating in spring.

Enlarged 1000 diameters.

termed Æcidium asperifolii, Pers.

When the Ecidium

in due course produces its spores it is said that the

Ecidium spores give rise to the Uredo if placed on certain grass leaves. In the next chapter will be found a description and illustration of the Æcidium.

Before dismissing Puccinia Rubigo-vera, D.C., we may say that Uredo and Puccinia spores often, though not in this species, grow together in the same pustules, and that P. Rubigo-vera, D.C., and P. graminis, Pers., often grow in company on the same leaves and stems. These parasites divert the material which should go to the production of good ears of grain for their own support; they therefore cause the general growth of corn to be weak and the ears to be small in proportion to the virulence of the attack: the straw, too, is not only damaged, but is made the means of carrying the disease over the winter for the following season. A variety of P. Rubigo-vera, D.C., termed P. simplex, Kör., also occurs. The teleutospores

in this plant consist chiefly of a single cell, similar to the single-celled examples of P. mixta, Fl., illustrated in the left-hand spore in Fig. 14. P. simplex, Kör., has also been described as a species under the name of P. Hordei, Fl., and P. anomala, Rost.

Puccinia Rubigo-vera, D. C., occurs in Europe on Calamagrostis Epigejos, Roth.; Arrhenatherum elatior, L.; Holcus mollis, L.; H. lanatus, L.; Avena flavescens, L.; Festuca elatior, L.; Serrafalcus secalinus, Bab.; Bromus mollis, L.; Secale cereale, Walld.; B. arvensis, L.; B. asper, L.; Triticum vulgare, Vill.; Lolium temulentum, L.; Hordeum vulgare, L.; H. distichum, L.; H. murinum, L.; and H. secalinum, Trin.

Suggestions for preventing and destroying the mildews of corn are adverted to in the chapter where the evidence for the connection of Puccinia and Æcidium is reviewed.

Puccinia Rubigo-vera, D.C., is the same with P. straminis, Fl., and P. striæformis, West.

CHAPTER XXII.

BORAGE BLIGHT.

Ecidium asperifolii, Pers.

As the disease of barberries, believed by many botanists to be one condition of the fungus of summer rust and mildew of wheat, is popularly known as "barberry blight," it may be well to term the closely allied fungus of the Borage family, which is similarly associated by many with the spring mildew of corn, borage blight.

The name of the fungus blight found on various plants belonging to the Borage family, and considered by many observers to be one form of the spring rust of corn, is Ecidium asperifolii, Pers. The name Æcidium is derived from the Greek, and should properly be written Ecidium; the word means a little chamber, in reference to the form of the fungus in an infant state, as shown at C in our illustration of the Ecidium of summer mildew of corn, Fig. 83;-asperifolii, refers to the nature of the coarse hairy leaves of several of the Boraginaceous plants on which the Ecidium grows.

The fungus of spring rust and mildew, already described, is generally common in Britain,—so common that persons walking through wheat fields have sometimes had their boots and clothes covered with the orange spores. The Ecidium, on the other hand, said to be one condition of the Uredo and Puccinia, is one of the rarest of British plants. Ecidia grow within the tissues of plants, and in these positions they form minute spherical balls, filled with chains of whitish or yellowish, semi-transparent, generally spherical, spores. In the process of growth the immersed

spheres burst through the cuticle of the host plant-generally from the under side of the leaves, and often through the stem. As the Ecidium cups mature they burst at the exposed apex, and the fractured part turns back so as to give the little fungus growths the form of minute cups filled with spores.

The under side of a leaf of Tuberous Comfrey, Symphytum tuberosum, L., is illustrated, natural size, at Fig. 70. Two groups of the cups belonging to Ecidium

asperifolii, Pers., natural size.

Acidium cups at B enlarged 10 diameters.

asperifolii, Pers., are shown at AA. Each cluster of cups is surrounded by a large pallid disease patch, which has been caused by the exhaustion of the vital material of the leaf by the spawn of the fungus which at first grew within. The fungus growth has also caused the leaf to become torn. Five of the little Ecidium cups are shown, enlarged to ten diameters, at B.

At A, Fig. 71, one of the mature Ecdium cups is farther enlarged to fifty diameters; the cup has burst, and