Let us pause for a moment in our examination of the individual cups, to ascertain their manner of distribution over the leaves. In this instance they are scattered without any apparent order over the under surface, but generally thickest towards the summit of the leaves; occasionally a few are met with on the upper surface. Sometimes two or three touch at the margins, but we have never met with them truly confluent; generally there is a space greater than the width of the cups around each, the stratum or subiculum from whence they arise is scarcely thickened, and there are no spots or indications on the opposite surface. If a leaf be taken fresh and the cuticle stripped off, which it will sometimes do very readily, the orifices through which the Æcidium has burst will appear in irregular holes. If a section be made of one or two of the fungi in situ, they will be seen to spring from beneath the cuticle, the peridium to be simple, and rounded at the base, the spores clustered at the bottom, and the fringe to be a continuation of its cellular substance.
The spores in this species are orange, subglobose, sometimes angular, and indeed very variable both in size and form, though the majority are comparatively large. Each of these bodies is, doubtless, capable of reproducing its species, and if we compute 2,000 cluster-cups as occurring on each leaf, and we have found half as many more on an ordinary-sized leaf, and suppose each cup to contain 250,000 spores, which again is below the actual number, then we shall have not less than five hundred millions of reproductive bodies on one leaf of the goatsbeard to furnish a crop of parasites for the plants of the succeeding year. We must reckon by millions, and our figures and faculties fail in appreciating the myriads of spores which compose the orange dust produced upon one infected cluster of plants of Tragopogon. Nor is this all, for our number represents only the actual protospores which are contained within the peridia; each of these on germination may produce not only one but many vegetative spores, which are exceedingly minute, and, individually, may be regarded as embryos of a fresh crop of cluster-cups. And this is not the only enemy of the kind to which this unfortunate plant is subject, for another fungus equally prolific often takes possession of the interior of the involucre wherein the young florets are hid, and converts the whole into a mass of purplish black spores even more minute than those of the Æcidium, and both these parasites will be occasionally found flourishing on the same plant at the same time ([Plate V.] figs. 92-94).
Naturally enough, our reader will be debating within himself how these spores, which we have seen, are shed in such profusion, can enter the tissues of the plants which give subsequent evidence of infection; in fact, how the yellow dust with which the goatsbeard of to-day is covered will inoculate the young plants of next year. If one or two of these spores are sprinkled upon the piece of the cuticle which we have recommended to be removed from the leaf for examination, it will be seen that they are very much larger than the stomata or breathing-pores which stud the cuticle: hence it is clear that they cannot gain admittance there. There remains but one other portal to the interior of the plant—namely, the spongioles, or extremities of the roots. Here another difficulty arises; for the spores are as large as the cells through which they have to pass. This difficulty may be lessened when we remember that what are termed the spores which are discharged from the cups are not the true spores, but bodies from which smaller seed-like vesicles are produced; yet, even then there will be much need of an active imagination to invent hypotheses to cover the innumerable difficulties which would encounter their passage through the vessels of the infected plants. The Rev. M. J. Berkeley proved many years ago that the spores of bunt, for example, may be caused to infect all the plants the seeds of which had been placed in contact with them; but this affection did not necessarily accrue from the absorption of the spores, or the ultimate sporidia produced after three or four generations. It is possible that the granular or fluid contents of the spores may be absorbed by the plant, and as a result of this absorption, become inoculated with the virus, which at length breaks out in fungoid growths. Much has been done to elucidate this mystery of inoculation, but much also remains a mystery still. There is no doubt that the inoculation takes place at an early age,[[2]] probably in the seeds of many plants; in others it may be conveyed with the moisture to the roots; but the spores themselves have certainly not yet been traced traversing the tissues of growing plants.
[2]. Dr. de Bary has lately shown that in many similar instances the seed-leaves are inoculated. It will be necessary to refer more particularly to his experiments hereafter.
If, instead of going in search of goatsbeard and its attendant fungus, we turn our steps northward and enter one of the Highgate or Hampstead woods, where the pretty little wood-anemone (Anemone nemorosa) flourishes abundantly, and turn up the radical leaves, one by one, and examine their under-surfaces, we shall at length be rewarded by finding one covered with similar cluster-cups to those we have been describing as occurring on the goatsbeard, but far less commonly. Leaf after leaf will be found covered with the brown spots of another fungus called Puccinia anemones, with which nearly every plant will be more or less infected in the spring of the year; and at length, if we persevere, the anemone cluster-cup (Æcidium leucospermum) will be our reward ([Plate I.] figs. 4-6). The specific name will suggest one point of difference between the two fungi, as in this instance the spores are white, and somewhat elliptic. Probably this species is not common, as we have found it but seldom, though often in search of it. A nearly allied species has been found on Anemones in gardens, having but few large teeth about the orifice, though not constantly four, as the name would indicate (Æ. quadrifidum).
A walk through almost any wood, in the spring of the year, will reward the mycologist with another cluster-cup (Æcidium), in which the peridia are scattered over the whole surface of the leaf. This will be found on the wood spurge, giving a sickly yellowish appearance to the leaves, on the under surface of which it is found. By experience one may soon learn to suspect the occurrence of parasites of this nature on leaves, from the peculiar exhausted and unhealthy appearance which they assume as the spores ripen, and which will spare the labour of turning over the leaves when there are no distinct spots on the upper surface. Æ. Euphorbiæ is found on several species of Euphorbium or spurge, but we have always found it most abundantly on the wood spurge in the Kentish woods between Dartford and Gravesend. The spores in this species are orange, and externally it bears considerable resemblance to the goatsbeard cluster-cup, but the spores are rather smaller and paler, the teeth are less distinct and persistent, the subiculum is more thickened, and the peridia are more densely crowded.
There is another group of species belonging to the same genus of fungi in which the arrangement of the peridia is different. One of the first of our native wild flowers, in making its appearance after the departure of frost and snow, is the little yellow celandine (Ranunculus ficaria).
“Ere a leaf is on the bush,
In the time before the thrush
Has a thought about her nest,