« ForrigeFortsett »
ceedingly full : they are all of the same thickness, but their lengths various, and at a medium I judge the proportion of their length to their breadth at least as 50 to one. Even to the greatest magnifiers they look like shreds of horse-hair to a naked eye; from a quarter to three quarters of an inch long; on a moderate estimate, their thickness is not the 100th part of a hair's breadth, and, consequently, if you imagine a hair of your head split into above 7800 equal fibres, each fibre would be as thick as one of these animalcules. Their motion is equable and slow, and they wave their bodies but little, though sometimes they make greater undulations. They swim with the same facility both backward and forward ; so that I cannot distinguish at which end the head is, and I have seen the same worm go forward with one end, and back again with the other end foremost, above 20 times together. Sometimes they will, like leeches, fix one end on the glass plate, on which the water is laid, and move the loose part of their body round about very oddly. These I take leave to call capillary eels, and they are represented in the several postures in which I have seen them swim.
I find the dust of the fungus pulverulentus, or puff-ball, to be the minutest powder that I ever saw: to the naked eye, when crushed, it appears alike a smoke or vapour, and with a common microscope the particles cannot be distinguished: but when viewed with the greatest magnifiers, each grain is visible, and exactly alike, appearing a perfect spherule, of an orange colour, something transparent, whose axis is not above the 50th part of the diameter of a hair; so that a cubical vessel of a hair's breadth of a side, would hold 125,000 of them.
I have seen in some water, fishes as small as cheese-mites, of different sorts, and very curiously made: they are of the crustaceous kind; with many joints, and very long horns ; fringed tails; and have many legs like shrimps ; some of these carry their eggs or spawn under their tails in one bag, another sort in two distinct bags, and some kinds on the fringes of their legs, like lobsters.
The animalcula in pepper-water, represented in fig. e, are very common. The tails of some of these are nine or
ten times as long as their body (which is about one third of a hair's breadth) but generally they are four or five times as long. As they move they will often curl up the tail in the posture marked at b, and this spring is so strong, that when the tail is entangled (as commonly it is) by the end,
they bring back their whole body by the jerk and convolu.
These animalcula also abound in all waters, and are the largest of all; for I can see them in a good
light and position with the bare eye, their length being about the breadth of a hair. These have a very quick motion, and are perpetually beating about like a spaniel in a field, and by their frequent turns and returns, sudden stops, and casting off, seem to be always hunting for prey.
Among these are commonly another sort, but not above one third of their size, whose feet are also
visible ; some of them are shaped almost like a flounder, and others are rounder behind; for by their motions and actions I judge them the same animals. These also will stand and run on a hair, or any thing in the water.
I thought those which I called capillary eels had been peculiar to pepper-water ; but I have since observed the same, though but few, in some stagnant water which drained from a horse dunghill. This liquor was mum-coloured, and the most pregnant of all that I had ever seen; and it would seem incredible to say what a prodigious number of all sorts I estimated to be in a quantity of it of the size of a pepper-corn ; for they appeared as thick as bees in a swarm, or ants on a hillock; so that I was obliged to dilute the water, to observe the particular sorts. I found in this not only almost all the animalcula, seen in the other infusions, but many sorts which I had never met with before.
I found a curious mechanism in a small diving insect, found in standing waters. It is like a small fly, with a head like a house-cricket; but, instead of wings, it has two paddles on the shoulders, and on the end of the hinder legs, which are longer than the other four, instead of feet and claws are perfect oars. I have also observed in two or three sorts of flies, that behind the eyes, on the top of the head, are placed three protuberances, with a black shining globe in each, like a ball in a socket, and are so disposed, as if made to look directly backwards. They are perfectly smooth, and without those hemispherical divisions visible in the cornea of the eyes of the fly and beetle kind, but appear more like those of a spider.
On the Seeds of Oranges, &c. By Mr. ANTHONY VAN
LEUWENHOEK. — [1703.] In November, I received a present of some Surinam oranges; and in the first I opened were 38 complete kernels. I opened several. After stripping one of these kernels of the outer membrane, I discovered that there lay a string under it, that caused a little protuberance in the first skin ; from which string, not only the seed but the plant within it receives its increase and nourishment. Now we may certainly conclude, that the said string does actually comprehend in itself as many distinct vessels as are to be found in the orange-tree when arrived to full maturity; for if all these vessels were not in the young plant, while it lies involved in its mother, the kernel's matrix, whence can they afterwards proceed? Though the said string was very small, yet I was resolved to try if I could have a sight of the vessels within it, and I succeeded several times, but not without a great deal of trouble. Having split the seed into two parts, one of which is repre
sented by CDEF, together with part of
the plant, which would have become a H tree sticking close to it, the plant itself
may be seen at C, no larger than a grain
of sand to the naked eye. The counG
terpart of the said kernel is represented by GHI K, and G the little pit or bed of the plant; and in the said figure between H and K, the cavity in which the second seed also lay, as likewise at D F.
This sight was wholly new to me, though I had dissected many sorts of seeds before ; viz. to see in the middle of one
seed or kernel another complete and perfect seed; especially when I considered that from the vessels arising out of the string, and dispersing themselves through the membranes, both the kernel and plant are produced ; and yet these same vessels must insinuate themselves into the very heart of the first seed, before they can produce a second seed and plant within it.
Placing the plant represented at C in the preceding' fig. before a microscope, I had it dili
0 neated LMNOPQ; where QLM is partly that which nature intends
P for the body and root of the tree;'N NOP the leaves with which the young plant is already provided ; and O P that part of the leaf which is next the sight, and somewhat protuberant, by reason of the in
R closed smaller leaves. MN and PQ show the two sides of the plant torn off from the kernel, to which M it was united, and from which it received its nourishment. I also turned the young plant a little about, as it stood before the microscope, to show the two largest leaves ; whereas in the former position, I could see only one of them. Between the two great leaves, according to all appearance, a great many small ones are shut up; but when I came to cut the leaves across, as they lay involved in the bed of the plant, I imagined that I saw the said small leaves ; and when I cut, after the same manner, that part of the plant which is to be the body and root of the tree, I discovered within the small particle that which was designed for the pith, and even the wood itself, and all as plainly as if I had been observing with my naked
eye a young plant of an inch thick. WX Y Z represent the texture of the pith, as it appeared; where
be observed a great many small particles, which at first sight one would be apt to take for irregular globules, but placed in a right line, and all of them of
greater length than breadth; these I take to W
be nothing else but small tubes or vessels, by which the future plant receives its nourishment, and perhaps every one of them is covered with a distinct membrane.
I put one of these kernels into a glass tube, and on the 10th day I observed that the seed was come to such maturity,
that the part which nature in-
H FG shows that part which is to be the tree; DE the seed or kernel, which being surrounded with its membranes I took them off, the better to expose to view those parts that serve for the nourishment, not only
of the root, but of the upper parts of the plant
particle, no larger than a coarse sand (as the plant is represented at C above), is increased in bulk, within the space of 11 days; and all this is effected by heat and moisture in a close vessel ; a plain demonstration that the plant, and all that belonged to it, was actually in the seed; that is, not only the young plant, its body, root, and fruit, but even its seeds also, to perpetuate the species.
After one of these seeds had lain near six weeks shut up in the glass tube, and grown
in proportion to that time, I observed that one of its leaves was withered or corrupted; on which I opened both the corks, and poured out the sand, which being very dry came away easily, but a small branch of the root had so insinuated itself into the cork, that it could not be separated without violence. IKLMN represents the said whole plant, of which LMN shows the body, and M the three leaves at the top, it had put forth ; IKL is the root, with its twigs and branches; L NO the seed, or kernel,still surrounded with its membranes; and,
lastly, I P shows the cork that stopped the botP tom of the tube, with the root sticking to it.