refractive bodies, that contain smaller cells of the same nature. Fig. 42 s, are highly refractive, transparent, spherical spores, form a beautiful species of pencillium, that is, the yeast plant of the decaying quince fruit. Fig. 42, t, fertile threads attached to the mycelium.

The mycelium, during the early stages of decay, is transparent; in more advanced stages it becomes a dirty, greenish brown, and in still more advanced conditions a brownish black, at which stage the decayed flesh of the fruit becomes either dark brown or black. Very often there can be no connection traced between the masses and lines of spores, figs. 40, 41, 43, and d, e, g, k, i and l, fig. 42, and the fertile threads or mycelium. They are often found attached to the hairs of the fruit branches.

The sporidia begin to vegetate in the cambium (new wood and bark) of the more recent, tender, and smaller limbs early in June. This takes place often some distance from the extremity, but more often at or near the extremity. At first a dead patch on the side of the limb, of an oblong shape, or a dead rim round the limb is noticed. On making a section through the limb, early in the disease, the newly formed layers of wood and bark only are found dead; while the heart wood remains alive, frequently for several weeks, through which the nutrient juices pass to, and preserve vitality in the extremity of the branch. At this stage there are seldom found any fertile or sterile threads upon the surface. If, however, the outside bark be removed, dead lines will be seen running along in the direction of the fibers, in the cambium; and in these dead lines and patches, and even in advance of them, will be found the minute filaments of the mycelium seen at fig. 11, winding about among the cells.

This fungus attacks the quince, pear and apple fruit at all stages of its growth. In the former, the first attack is when it is about the size of a hazel-nut. Much of the fruit decays when it is from one-third to one-half grown, and still more as the fruit is maturing. When the fungus once begins to develop in the mature fruit, it grows luxuriantly, and decay follows close the advance of the mycelium. In the early stages of development, and also when excluded from the air, the sporidia and fertile threads are white and transparent. As they advance toward maturity, they become darker and darker; till they appear a dark brownish black. they appear a dark yellowish brown. lation. The spores 40, 41, 43 and k, l and d, fig. 42, are produced on the fertile threads that rise above the surface, whilst the spores, 48, 49, 50, 51, 52, 55, and 58, are produced from fertile threads arising from discs or périthaecia.

finally, in mass, by reflected light, Singly, and by transmitted light, The fertile threads grow by pullu

Fig. 20, Lignograph F., represents one form of the fertile threads of the fungus that attacks the apple-fruit. It resembles that which attacks

peach leaves and the peach fruit. Wherever it attacks the apple, it produces decay as fast as the mycelium advances. It is not usual for the fertile threads to appear. Generally, the plants in the apple-fruit consist only of mycelia; especially while the apple hangs on the tree. The applefruit, like the peach, is attacked and injured most by this fungus, just previous, and at the period of ripening. In 1862, it destroyed in Ohio a large portion of the apple crop, many of them decaying and falling before they were fully matured. Fig. 23, Lign. B, represents a body which often occurs in the flesh of the fruit.

Fig. 22, Lignograph B, represents the mycelium, when it occurs in the fruit. It is very rugged and luxuriant in appearance, and extends through all parts of the fruit affected. The decay advances as rapidly as progresses this mycelium. Where the trees are affected with blight, the fruit on such trees is sure to be affected, more or less, with this fungus; either when green, or just before and at its maturity. The apple-fruit is liable to be attacked with this fungus at all stages of its development. Often from a half to three-quarters of the crop, and sometimes a greater proportion, is destroyed during the month of June and the early part of July. When the fruit survives this period, it seldom decays much till it is approaching maturity, when it again is attacked and often decays rapidly and prematurely, in large quantities. The next period of attack is after it is picked and laid away for fall and winter use. At this period, the fungus is particularly luxuriant and destructive. The appearance of the mycelium in the fruit is seen in fig. 22, Lign. B. It is peculiarly rugged and rapid in growth, decay keeping pace with its advance.

Figs. 20, 12, 14, Lign. E and F, and figs. 40, 41 and 43, Lign. Q, represent the appearance of the fertile moniliform, threads and chains of sporidia, containing in their course masses of spores. The moniliform threads, figs. 14 and 20, are the most abundant during the early and rapid decay of the fruit. In more advanced stages of decay, the rigid fertile threads and masses of spores are developed. Sometimes the fertile moniliform chains of spores are simple, and at others, compound. The simple and compound threads arise from the same source.

A beautiful species of Pencillium is developed abundantly in decaying apples (and other fruit). This fungus is the yeast plant of decaying apples. It produces the numerous small spherical and highly transparent spores that are scattered over the field; in examining the apple fungus, fig. 14, &c, this species of Pencillium is white and transparent, producing beautiful, clear, highly refractive spherical spores, fig. 15, Lign. E. The productive heads are terminal, and often are beautifully triply trichotamous, (fig. 18, Lign. T); that is, the fertile thread is first symmetrically

divided into three equal branches; then each of these three branches is again divided into three branchlets, and each of these branchlets subdivided into three pedicles-upon the extremity of each is developed a beautiful monilliform line of highly transparent spherical spores. Figs. 16 and 17, Lign. T, are imperfect heads of the same species. This fungus, while it probably hastens decay, after once being started by the blight fungus, (S. Pyrus), does not, of itself, start the rot, unless the fruit has arrived at that period of maturity when fermentation and decay becomes a natural process, or the fruit is so unnaturally situated-as regards the conditions of moisture and temperature-that this yeast Pencillium is excited to vegetate and act as a ferment.

This species of fungus is morally, then, rather the consequence than the cause of decay in fruit.

Fig. 37, Lign. U, represents vegetating sporidia. These sporidia were placed into a watch glass, in a solution of sugar, at 10 A. M., and set aside at a temperature of 70 deg. F. At 4 P. M., six hours after, they presented the appearance seen at 37. These sporidia were taken from the apple leaf. Fig. 36, Lign. U, represents the sporidia of the plant-Fig. 35, Lign. G, vegetating. These vegetating filaments are less marked and not as rigid in appearance as the filaments of the plants, 24 and 25. Fig. 59, Lign. H, represents zoospores organizing cylindrical cells. The sporidia and fertile threads of the plants 24, 25 and 35, were placed in a solution of sugar, August 25th. August 27th, numerous zoosporoid cells were moving about actively. Fig. 59, a, b, c, d, e, and f, Lig. H, represent their different shapes. Celia were noticed on the larger ones. The zoospore a, was carefully watched. In it, near the posterior end, are two organized cylindrical cells. These cells, in a short time, were being voided, as seen at b. During the voiding, the zoospore became nearly spherical. c represents these cells void s. d represents the zoospore after voiding the cells. While it was voiding the cells, it had a slow, pulsating, revolving motion. After they were voided, it resumed its former zigzag, progressive, rotary

movement.

The pear trees and pear fruit are affected in the same manner, and by the same cause as the apple and quince. Persimmon fruit is invaded, also, by the Spyaerotheca Pyrus, but it produces in them no signs of decay. The reason of this is, probably, the large amount of sugar and tannic and gallic acids they contain, and the small percentage of water.

MUCER-NIGRICOUS-SALISB.

This is a peculiar mould, of large size, which sometimes produces decay in pear-fruit. It is more apt to attack the early juicy pears, than those

which ripen later. The fertile threads on the surface of the pear occur in masses; are grizzly black by reflected light, and have a curled appearance and a crispy feel like the hair of the negro; hence its specific name. It belongs to the group Physomycetes, the order mucorini, and the genus mucor. Not finding it anywhere described, we have named it from the appearance of the aerial threads.

The pears affected with rot caused by this fungus are filled, in the decaying part, with mycelium, fig. 61, Lign. V. The mycelium is luxuriant, and the rot keeps pace with its progress, which is often so rapid that a whole pear will decay in from 48 to 72 hours. The fertile threads do not appear often on the surface till after the fruit is entirely decayed; making it appear as if it were the consequence, instead of the cause of the decay. The microscope, however, discovers the mycelium in advance of the decay. Fig. 60, Lign. W, represents the fertile threads of the mucor nigricous, in various stages of development. a is a mature sporangium. The spores are within a thin, transparent, membranous sack, until mature, when they burst forth upon the surface. b are immature sporangia. The spores show faintly through the sporangic membranes. They are inclosed in large sacs, which are themselves inclosed in the sporangic envelope. c, fig. 64, Lign. V, represents the shape of the majority of the spores, which are spherical. d represents the shape of those spores that are double and those that are oval. These are generally larger than the spherical spores. e, fig. 64, represents germinating spores. It is quite seldom that the fertile threads of this fungus appear on the surface of the fruit. When they do, they are very thrifty and rank in growth, and harsh, crisp and curled, and grizzly black, like the hair of a negro that has begun to turn gray. They often rise half an inch above the surface and appear like a curled compact mass of grizzly black hair.

The sporangia are large, bladder-shaped sacks (fig. 60, ƒ and b, Lign 3,) terminating the fertile threads. f is the columella and m the vesicle that becomes filled with spores. They are filled with a sort of protoplasm at first, contained in sacks. This endochrome is formed into spores. These secondary sacks disappear, and the spores, when mature, make their way to the surface, as seen at a, fig. 60. The bladder-like sporangia, if not kept moist, in a few minutes after they are separated from the mycelium, or fertile threads, shrink and collapse. The spores also shrink and shrivel if not kept moist. If, after they have shrunk and shriveled, moisture be applied, they immediately assume their former plumpness In this respect they differ from most fungi and their spores. This fungus produces a rapid wet rot. The pears decayed by this mould will hardly hold together Aug. 23, 9 A. M-Placed some mature spores of the m. nigricous in a

solution of sugar, between two watch glasses, and exposed to light, at a temperature of 70° F. At three P. M., six hours after, many of the spores had vegetated and presented the appearance seen at fig. 62, a, Lign. V. Others presented no signs of vegetating. It will be seen, by referring to the figure, that three spores have been joined together by their filaments. This system of anostomosis always occurs where spores are arranged near each other in the matrix.

Aug. 24, 6 A. M-21 hours after being placed in the saccharine solution, many of the spores had vegetated so as to present the appearance seen at figs. 63 and 65, Ligns. X and V. The growth was luxuriant and rugged. This fungus only attacks the mature, mellow pear.

PROPHYLACTICS.

In combatting the invasion of this fungus, we necessarily have to rely more upon "preventives" than "curatives." The preventives must be bodies which have an influence in controling mucedinous growth, and still are not injurious to the trees. Among these—that can be cheaply and readily obtained, and which, while they retard the growth of the fungus, act as manures to the trees-may be placed Sulphur, Sulphurous Acid, Sulphites, and Sulphuric Acid. These bodies are all, more or less, destructive to fungus development, and have the power of stopping fermentation. The wine-grower controls the vegetation of yeast plants (fermentation) by burning sulphur in his casks. The sugar manufacturer checks mucedinous cellular development in the juice of the cane, (preventing the formation of glucose, which would interfere with granulation) by adding a few drops of Sulphuric or Sulphurous Acid, or a small quantity of some soluble Sulphite to the freshly expressed juice.

The sporidia are mostly in the circulating juices of the tree, and in their passage become fixed, and vegetate in the tender developing leaf tissues, which afford them a matrix, with abundant nutrient supplies. The preventives should therefore be applied so as to enter the sap of the tree in its early circulation in spring, as soon as the flower and leaf-buds begin to swell or open, that they may reach the sporidia before they begin to vegetate. To this end, I would suggest the digging away of the sod or surface earth from around the trees, and the application of a compost, containing either Sulphur, Sulphurous Acid, Sulphites, or Sulphuric Acid. The refuse gas lime from the purifying vats of gas establishments, either alone or mixed with coal ashes, cinders from foundries, iron furnaces and blacksmith shops; or the pitch from coal oil refineries, boiled down to asphalt and pulverized, furnish cheap and appropriate materials for the purpose, containing the desired bodies for checking mucedinous growths. These