THE POTATO DISEASE.

Daily Southern Cross, Volume XVII, Issue 1435, 13 September 1861, Page 5

THE POTATO DISEASE.

After all that has been wntton about the Potato disease and the paiasite to winch it owes its origin, and the extremely small quantity of new mattei which has been bi ought forwaid, amidst the multitude of lepetitions which have oveiloaded the pages of scientific journals,, it is qxute lefreshiug to have something new to recoid upon the subject. It has been long known that vauous Fungi have moie than one mode of lepioduction. Very many of them, and perhaps all, have two distinct kinds of repioductive bodies, while the Hop mildew has been ascertained to have five In the Potato mould two only had been hitherto described, the one arising from the tips of the branchlets, and the othei in the substance of the Potato leaf amongst the creeping rootlets. It appeals however fiom the observations of De Baiy, an imperfect account only of which has at piesent appeared without figures, that a third mode of fructification take 3 place by that is by repioductive cells, which move about fieely by means of two or moie long lash-like threads, or a multitude of short piocesses, like many of the moie minute animals. Deßary's observations were not, however, confined to the Potato mould, but he ascertained the same fact in the white rust of Cabbages (Cystopus candidus), or rather in that form of it which is so common on Salsafy, especially on our own wild species, Tiagopogon pratense. On placing the spores of these two Fungi m a drop of watei imdei a thin plate of glass, he found that they imbibed the fluid lapidly, swelling very much, and soon indicating changes in the chaiacter of the granular matter with -which they aie filled. This matter, which was at fiist tolerably uniform, became divided into distinct portions, which gradually assumed a definite form, and were ejected by means of a little apertuie at one end of the spore, furnished with two long thread-like appendages, by means of which they moved about with great rapidity in every direction, exactly like the spores of many Alga which are propagated by precisely similai bodies. The motion ceased after a few hours, and the cells germinated, and in the case of the Potato mould, De Bary saw the thieads sent out from the spores penetiating the tissues of a small slice of a Potato tuber i>laced with them in the water. In the case of the Fungus on Goat's Beard, a plant which often retains water for a time in the axils of the leaves, he found the water teemiug with the zoospores of the white rust, which moved about with immense rapidity. It is very probable that that especial form of reproduction in the Hop mildew which consists of germination m every duection, from the granular contents of the terminal necklace-like spores, is a case in point, the zoospores being detained either normally or accidentally within the common coat of the original spore. De Baiy's discovery has a veiy important bearing on the question of the true nature of such Fungi as the yellow, slimy, and at length dusty Fungus which is so common in hothouses, running over the tan, especially amongst Pine Apples, and soiling everythiDg around with its sooty spores No one will deny that moulds are vegetables, though, as Deßary has now shown, their spores in some cases so closely resemble animals ; and by the same leasouing it will be plain enough that these slimy plants are true Fungi, though their spores occasionally, as also the gelatinous mattei of which they aie pimcipally composed, resemble so closely what is found in undoubted animals. The discovery moreover throws light on a set of curious plants, whose nature has been much contested, namely the mould-like -productions which are so common on fish in ponds, and on various animals in the aquaria which are now so much m favour. It was supposed that as these are strictly .aquatic, and as their spores are zoospores like those of many Algre, that they belonged to that class of plants. We now however see that zoospores are found m Fungi, and in consequence these false puff balls may now be referred to Fungi without doing violence to preconceived notions. We ourselves have always entertained the view, believing that they were merely a peculiar form of mould induced by their aquatic mode of growth. It was long since shown that the body of the same salamander when divided, half being kept in the air gently moistened, and the other immersed

in water, produced two distinct plants, /the former half giving rise to a true mould, and the latter to a Leptomitui. This, like many other ill-understood matters, was brought forward as a pioof of spontaneous generation, or the tiansmutation of species, with how little justice will appear fioin the present statement. It is a cuiious fact that those salts of soda which are destructive to moulds in the human stomach leheved the sick fish when administered in small doses ; and this, fact, amongst others, tends to prove tho leal nature of the fis,h mould. Tho bearing of the subject on the Potato disease itself is not at present apparent ; but it is quite clear that in order to understand diseases thoroughly, we must first undeistand the nature of the parasites by which they aie caused. We do not, therefore, think these observations, though of a scientific rather than piactical nature, are out of placo in this Journal, especi°' 1 v us they aie stated in language as little technical ..i , bhe subject admits. — M. J. 8., in Gardeners' Chronicle.