are shed from the summit of the threads, as they mature. They are very prolific on the tender leaves of the peach tree and poa pratense, from the 10th of May to the 15th of June, in this climate (in New York and the Eastern States the range is from about the 15th to 20th of May to the 20th and 30th of June), covering the leaves with piles of pearl white sporidia. During this period they are furnished with abundant nourishment from the young, tender and vigorously growing leaves, to which they are mainly confined; and the threads are mostly fertile, producing enormous numbers of sporidia.

From the 15th of June to the middle of August or first of September, the fertile threads are constantly decreasing, and the sterile threads (figs. 2, fand 4) begin to appear among the fertile ones. These sterile threads are longer and much more slender than the fertile threads, and are not moniliform. During this period, these sterile threads appear abundantly on the young, tender twigs (fig. 4). They occur also, to some extent, on the leaves, mingled with the fertile threads (fig. 2, f). These sterile or inarticulate threads are abortive asci, usually simple, and are called paraphyses. They constitute one of the peculiarities of the Ascomycetous group.

From the 15th of June to the 1st of September may be denominated the period (in this fungus on peach leaves and sprouts) of sterile development. This sterile growth exhausts the peach plant very much less than the fertile or period of reproductive growth which precedes it. The result is, those peach trees which have not become too much exhausted, revive and constantly assume a more and more healthy appearance, as they advance into this stage of sterile growth, and the fungus plants grow more and more sickly, and there is less and less of the sterile threads. By the first of August they have entirely disappeared from the leaves of the poa pratense.

The period then of the greatest ravages of the S. Persica, in any locality, is from the moment the young leaves make their appearance till the tissues of the leaves become firm; at which time the trees that survive begin to assume a more healthy aspect. In instances where the leaves are killed early in the season, and the trees not killed, another crop of leaves often make their appearance; which second crop-although presenting generally a feeble appearance-are not usually much affected with this fungus. The mycelium is greatly disproportionate to the fertile threads. Often leaves become curled and killed, before any signs of either fertile or sterile threads appear above the surface. When, however, the fertile threads do appear, they are prolific. They consist of very large, oblong, prolate, spheroidal sporidia; occasionally single; but generally consisting of more or less erect simple or compound moniliform chains (threads) of

sporidia (fig. 1). Sporidia simple, whether single or arranged in necklaces; sporidia armed with processes at each end, by which they are united to each other. In the advanced stages of the fertile plants, pyenidia are not infrequent; sporidia deciduous falling from the summit of the moniliform threads as they mature.

Fig. 1, Lignograph Y, represents the appearance, in Central Ohio, of the fertile plants on the peach leaf, on the 20th of May. At this date they were very prolific-killing the leaves on most of the older and weaker trees. The leaves on the young vigorous trees were twisted, curled, blistered, overgrown and yellowish.

Fig, 2, d, e, f, represents the appearance of the plants on the leaves, on the 5th of July. The sterile plants (f) and maturer threads, with pyenidia (EE), had begun to show themselves among the fertile threads (d). On the older leaves, at this date, the plants had the appearance seen in fig. 6, a, b, c.

Fig. 3 represents the plants as they appeared on the leaves of the poa pratense on the 20th of June. They were very prolific, covering the whole surface of the leaves with their white sporidia.

Fig. 4, Lignograph Aa, represents the appearance of the sterile plants on the young shoots of the peach tree, July 21st. The numerous sporidia attached to them and lying at their base, probably have fallen from the fertile plants, off the young leaves. The paraphases are, however, said, in some instances, to provide sporidia from their summits.

Fig. 2, E, E, are mature plants with enlarged joints, called pyenidia. These pyenidia are of a light-yellow color, and are filled with stylospores. Figs. 1, 2 and 3, Lignographs Y and Z, represent fertile plants, during their reproductive stage-from May 10th to June 15th. After June 15th these fertile plants rapidly disappear, except on such new leaves as make their appearance thereafter-on which they are often found, but present generally a sickly, feeble appearance, when compared with the vigorous growth on the leaves from the 10th of May to the 15th of June. After the 20th of July, there can scarcely be found a plant on the leaves in this stage of development; they nearly all have the appearance as seen at fig. 6, a, b and c, Lignograph Y. Occasionally may be found a new leaf where the appearance is presented as seen at fig. 2, d, e and ƒ.

Fig. 5, Lignograph Y, represents the appearance of the mycelium in the parenchyma of leaves. The mycelium is often largely developed before there is any appearance of fertile threads on the surface. The indi. cation of its presence-where there are no external threads-is the blistering and curling of the leaves.

The young twigs and sprouts are also attacked with this fungus. It

generally appears on them during the last half of June. They produce, mostly, only sterile threads.

The peach fruit is often attacked, about the time it is from one-third to two-thirds grown; but the fungus is usually neither thrifty nor prolific, till the peaches approach maturity. It however often destroys the entire crop before the fruit matures. If the fungus is in the trees, and the peaches escape till they begin to ripen, it then usually makes great ravages. At this stage of the fruit, the mycelium grows with great luxuriance in its tender, rich flesh, and decay keeps progress with the advance of the mycelium. An entire peach will often decay in from 24 to 72 hours the length of time required varying with the temperature and hygrometic condition of the atmosphere. Often on the decayed surfaces may be discovered the fertile, moniliform threads, both simple and compound (fig. 7 a, Lignograph Bb). The sporidia are smaller in size on the fruit, than in plants on the leaves. Fig. 7 shows the mycelium, and the fertile threads on the fruit.; figs. 1, 2, 4, 5, and 6 show the fertile and sterile threads and mycelium of the leaves and twigs. The mycelium of the leaves is more filamentous and less fleshy than that of the fruit, and the sporidia of the concatenated, fertile threads larger.

OBSERVATIONS CONNECTED WITH THE DECAY OF THE FRUIT AND WITH FUNGOID DEVELOPMENT.

A young, vigorous tree, the leaves of which had been severely attacked with the peach fungus in the early part of the season, but which had by the middle of August quite recovered, was loaded with fruit. The fruit had escaped the fungus during the early part of the season. About the 16th of August the peaches began to get mellow. About the same time they began to decay rapidly. Soon after the decay commenced, a white, almost invisible mould (soon turning to a brownish yellow) appeared in spots on the surface of the affected parts. On examining this under the microscope, the appearance was presented as seen at fig. 7, a and b.* The line cd in the figure, represents the line described by the surface of the peach; all above this line belongs to the aerial portion of the plant; these are the fertile threads that bear the sporidia. All below the line cd, represents the mycelium or roots, inside the surface of the peach.

The mycelium is large, rugged, and of luxuriant growth. It advanced with great rapidity through the soft tissues. As fast as the mycelium

The peaches on this tree were nearly all destroyed in a few days by the S. isica. The fruit of many other trees in the same orchard decayed in the same way. I mention this case as a sample of what often occurs when the trees are filled with this fungus.

advanced in the flesh, decay followed. One-fourth of an inch beyond the line of decay, in the sound part of the peach, no mycelium could be traced. The cells, however-seen at figs. 8, 9, 10 and 11, Lignographs Cc and Ywere noticed scattered through the sound, fleshy tissues; and also the peculiar forms seen at fig. 12, Lignograph Dd, were occasionally met with. Fig. 8 a, Lignograph Cc, represents sporidia, and new filaments of mycelium, just beginning to vegetate. These sporidia are often met with lying in masses in the flesh, as seen in the figure. Fig. 10, Lignograph Y, represents cells of the yeast plant; e, fig. 7, Lignograph Bb, represents a budding and branching filament, emanating from a sporidium.

August 9th, 4 P.M., peeled a number of ripe peaches and placed them in an earthen dish, mashing them to a jelly and adding about one half their bulk of water, and set them aside, at a temperature of about 75° Fah. Six hours after, examined them under the microscope. Found the surface portions completely alive with minute, tremulous, vibrating cells, either single or arranged in lines (fig. 13, Lignograph Ee). These belong to the so-called vibriones. The following morning-16 hours after the mixture was made-examined again. Found many of the minute bodies (fig. 13) moving actively about some in curved lines, and others in zig-zag, progressive ones. There was also noticed large oval and spherical cells (vitalized cell), having a tremulous and vibrating motion (fig. 14, Lignograph Ee). The larger of them could be seen to contain minute cells.

Aug. 11, 8 A.M.-The vitalized cells (fig. 14) have assumed the appear ance seen in fig. 15. They are quite numerous, and appear to be zoospores. A white mould began to appear on the surface. The surface layer was filled with organized cells (fig. 16) and the mycelium, represented at fig 17, Lignograph Ff. The zoospores perform the office of organizing these cells (fig. 16). At first the cells in the zoospores are spherical. Their progressive movement, and rotary motion on their progressive line as an axis, rolls the spherical cells into cylinders (fig. 16), when they are voided from the posterior end of the cell. This is a process in the multiplication and organization of cells which, so far as I know, has not before been noticed.*

Fig. 18, Lignograph Dd, represents the spores of the peach fungus vegetating in the flesh of the peach.

Aug. 20th. Placed a broken, ripe peach, about one-fourth decayed (fresh picked from the tree, on the decayed part of which was growing the

• This mode of the organization and multiplication of cells will be more fully described in another paper, "On cell organization in the various processes of the fermentation of organic matter, vegetable and animal."

fungus, fig. 7 a, Lignograph Bb, and all through the decayed tissues ran the mycelium, fig. 7 b), in a loosely-covered glass jar, with about one-sixth its bulk of water, and set aside, at a temperature of 75° Fah.

Twenty-four hours after, examined the peach. It was entirely decayed, and covered, over the whole surface, with a luxuriant growth of the fungus, fig. 7 a, and through the entire flesh ran the mycelium, fig. 7 b. In the newly decayed portion there were many vegetating sporidia and zoospores (fig. 19, Lignograph Dd). At a, are seen two sporidia, the filaments from which anostomoze with each other and are thickly budded.

Fig. 20, Lignograph Dd, represents vitalized cells (so-called vibriones), which posses animalcular motion and are very active, moving rapidly in all directions. There are grounds for believing these bodies to be spermatozoid in character.* They occur in great numbers in all fermenting and decaying bodies.

August 21st, 10 A. M., placed some sporidia of the peach fungus (S. persica) in a solution of sugar in a watch-glass, at 75° F. At 3 P. M.-five hours after they had vegetated as seen in fig. 21 (Lig. Gg). August 22, 6 A. M., twenty hours after, they had vegetated as seen in fig. 22, (Lig. Dd). Wherever two or more sporidia were near each other, germinating filaments had passed from one to the other, joining them all; and the larger filaments, wherever they had come in contact, had united, producing a system of anostomoses, as seen in Fig. 22.

August 23, 8 A. M., forty-six hours after the sporidia of the peach fungus were placed in the saccharine solution, they had begun to branch, and presented the appearance seen in fig. 23, (Lig. Hh).

Progress of the disease in Ohio in 1862.-The young leaves of the peach trees were attacked with the peach fungus (sphasaotheca persica) about the 10th of May, soon after the blossoms had fallen. The attack was general throughout the State, killing nearly all the leaves on the older trees, and on the younger ones where they were not vigorous and healthy. On the young, thrifty trees the leaves became thickened, curled, twisted, blistered, overgrown, and yellowish. The more vigorous trees were attacked less than the weaker ones. This parasite spread rapidly in and on the leaves till about June 15th, when it began to decline, and the peach trees began to recover and assume a more healthy appearance. On the 25th of June. the trees had very much improved; the leaves had a more healthy green and were less curled. By the 21st of July the fertile plants had almost entirely disappeared, except now and then a few on the new leaves, where they were still developed, but in an enfeebled condition. The pear leaves

* In a paper on which I have been for some time engaged, connected with decay, gangrene, fermentation, &c., I shall have more to offer in relation to these interesting little bodies.