An Abstract of a Letter from Mr. Anthony Leewenhoeck Writ to Sir C. W. Jan. 22. 1682/3 from Delft

ther it was for the Husband or Wife, for it may be read Antonia. The Points also betwixt the words are here very singular, but this was the caprice of the Stone-cutter, who sometimes also use a Leaf, hanging or erect, a Hand, a Feather, or such odd fancy for Points. An Abstract of a Letter from Mr. Anthony Leewen hoeck writ to Sir C. W. Jan. 22. 1684. from Delft. Having lately met with a Book published by a Physician of our Country, which treats of Humane Generation, and the Egg-branch as it is found in Women-kinds and not doubting but what is there said, is also applicable to Four-footed Beasts, I examin'd (in the presence of a Physician and other learned Persons as well as alone) the Egg-branches of several Lambs of a year old, that had been several Months in the Winter kept in a Stall for fatting, separated from the Rams. From what I have hitherto found I cannot but wonder why it should be generally believed, That the Tuba Fallopiana does draw, or suck down an Egg from the Egg-branch, thro so narrow a passage, as I knew'd the Tuba Fallopiana to have. Considering therewithal that some of the Eggs were as big as Pease, and others as large as the whole Egg-branch: That they were made up of Glandulous parts interwoven with Blood-Vessels, and were shut up so fast in their Skins or Membranes that I could not with my Nails tear one of them from the Egg-branch: That some of them consisted of very irregular and unlike parts, which were in some places inclosed in particular Skins, and had not at all the shape of an Egg: That some of them which stood out beyond the rest were burst open; and yet when I went to pull them off off, they stick so fast, that the whole Egg-branch came along with them. The smallest Eggs, and of a lesser size, were also firmly rooted and fixt in their skins, and had often a Waterish substance in them. That besides the supposed Eggs of the Egg-branch, there were others lying at a distance from it of an Inch and more, on each side of the Womb, and were included in particular Skins. My Opinion therefore of these Eggs is, that they are Emunctorys, or the Emptyings of some Vessels lying near, such as are often found among the Membranes, or adhering to the Bowels of Animals. But as to Generation tho I have formerly been very reserv'd in declaring my thoughts thereof, yet being now further instructed by manifold Experience, I dare venture to affirm it rather to come from an Animalcule, (such as I find not only in Human seed, but that of all Birds, Beasts, Fishes, and Insects) than an Egg. And the rather for that I find in the Seed of a Man, as also of a Dog, two different sorts of Animalcules, answering the different Sexes of Male and Female. I know some men will even swear that they have found the aforesaid Eggs in the Tuba Fallopiana of Beasts. But I need not believe that these round Bodies they have seen in it, should be drawn down from the imagined Egg-branch, thro the long and very narrow passage of the Tuba Fallopiana. Because some of the Bodies are as big as a Pease (nay as the whole Egg-branch); and of a very firme and compacted Substance. But the way thro which they should pass is no wider than the Compass of a small Pin. Again if it were so as is said, these bodies would be found, not by Chance, but always when searched for immediately after Copulation; but that is so far from being true, that it is hardly to be imagined, if we consider how little time is taken up in the Copulation of several Animals, as a Cow, Rabbet &c. In which so short time nevertheless ought to be drawn down, thro a long and narrow Passage, a great number of Bodies; in some Cases two or three, in others Six Six or Eight, and more, according to the number of Fætus's to be produced. But supposing such Bodies there to be found, why may they not be formed ex residuo Seminis Masculi, gathered together into a Ball or Globule; as we see several other Substances in Animals that are neither of too thick nor too thin a Consistence, as Fat, Sarcous &c., which how they are made, I have formerly given an account. Or Secondly there being no part of the Body which is not nourished, and which does not cast off somethings that are superfluous, why may there not in the Womb or Tuba be several Excretions made which by Compression on all sides may be brought into a round figure? This supposal being true, it will follow that Egg-like Bodies are also in the Womb or Tuba of Females that have not accompanied with the Male. It may be queried, If one Animalcule of Seed be sufficient to produce a Fætus, why are there so many Thousands in one drop of it? I answer that in an Apple-Tree (enduring an Hundred years and bearing every year a great many Thousand Blossoms, which may a great part of them be Apples, having each of them Six or Eight Seeds) each Seed being placed in a proper Soil, and carefully cultivated, is capable of becoming a Tree; yet it may happen that nothing grows from all the Apples that fall down; whether thro want of Sun, Rankness of Grass, Weeds, or other Accidents. So in the Womb each Animalcule might suffice for a Generation, if the place where it comes to be nursed be fit for it; But the Womb being so large in Comparison of so small a Creature, and there being so few Vessels and places fit to feed it, and bring it up to a Fætus; there cannot be too great a number of Adventurers, when there is so great a likely-hood to miscarry. It may be asked again, why a Woman bringeth forth but one or two Children, since if there were but two proper pla- places in a uterus, several of the Animalcules might there be fed. I answer, it may happen to these Animalcules, as it does to Seven or Eight Seeds put into a small hole of the ground; that Seed which puts out the biggest and strongest Root, starves all the rest, and becomes a Tree. It may be asked me again, why I make the Animalcules found in the Seed of several Animals to be of such different Sizes, comparatively to the Animals they belong to viz. in the space of a Small Sand in the Seed of a Cock 50000, in the Row of a Cod-fish 10000, in the Row of a Ruff (which fish is a 1000 times less than a Cod-fish) the Animalcules as big as the others. Whereas it seems reasonable that the Animalcules ought to be in bigness to one another, as the Creatures in which they are found; from whence it would follow, that those Animalcules which are in insects, would never be capable of being discovered, because of their exceeding smallness. I answer that we must satisfy ourselves in these things as well as we can, for (not to speak of a Coco Nut) a great Wall-nut with his green shell weighs down a 1000 Apple Tree Seeds, and yet the proportion between the Trees is not so great. In my Letter of the Third of March 1682 I described the texture of a Flesh and Fish-muscle; But have since examined that of a Flea, as judging that if I could find the same Filament, I might be positive that the Muscles of Animals are all of the same make; having therefore several times separated and exposed to View that Muscle of the Breast, whereof the Leg is partly fastened; I observed the same Ring-like Indentings in the Filaments, that I had seen in other places. Some appeared to me thicker in the middle then at the ends as Tub. 2. Fig. 1. $A B C D E F G H$ is the Description of the Filament of a Flea broken out of the Breast, from which I perceived the Filaments of this Insect to grow Tapering towards the ends, and lose themselves in in a Membrane or Tendon, like the Filaments of the Muscle of an Ox. Some of the Indentings were as C F, but most throughout were as A B G H. Several times I had an appearance as if a Filament were constituted of several lesser threads joined together, and lying by the sides of one another. In pursuing my Observations, I took some of the Flesh of the Legs of the Flea, and found it like that of the Breast; here I counted 12. of these before named Filaments, and some threads without indentings which I conceived might be Vessels. I also with much trouble took out the Testicles of a Flea, and placed them before my Microscope, and drew out the Figure as well as I could, as Fig. 2. A B C D is the Testicle, A F and D E are the Vasa Deferentia, when the Testicles were first taken out they were of a dark Colour, but in less than 1/6 of a minute their moisture was evaporated, and then they became crumpled, which I have here represented as well as I could. I also searched for the Vessels having as it were Rings about them (of which I have formerly spoke) and am satisfied they cannot be Air Vessels, but rather Arteries; for I saw them not only encompass the Guts but spread over and among the Eggs. The Sting or Snout of the Flea, or rather the Sheath of it in which it is kept, had Teeth on each side like a Saw, and may not unfitly be compared to a Quill that is split ragged. When the Sting is enclosed in the Sheath the Teeth on each side go between one another. The length of this Sheath is about Three Diameters of the thickness of a Hair. I have made many Attempts the last Autumn, to find out in what time the Worm coming from the Egg of a Flea, would become a full grown Flea. The Eggs of a Flea kept in a warm place were hatched in four days, and became Worms, which I endeavored to bring up, but notwithstanding ding all my endeavours I could keep them no longer alive than Twelve days. When I placed about the half of a small Flye in the glass by the Worms for their Food; the part of the Flye caused such a Steam on the glass that the Worms being hairy were intangled in the moisture, and remained immoveable till they died. When the Worms were Twelve daies old, they were about the length of Four Eggs and the thickness of One. Since I could bring up no Worms, I took some which I thought had attained their full growth, and observed the same to spend Eight or Ten daies in Spinning their Web, and then they stript of their skin and became a Nympha. These Nymphas I saw move on the Fourth day, tho they were Clear and White: on the Sixth they were Red about the Head: on the Tenth they broke their Case, which was a very thin Skin, and leapt into the Glass, living there without Food for the space of Seven daies. I also took some flesh from the Breast of a Louse, and found the flesh Threads of the same make as those of the Flye. I took also the flesh from the feet of a Gnat, and found that of the same make with the former. But perceiving the Legs and Body of the Gnat to be furnished with very fine Feathers, I have caused them to be drawn as Fig. 3. The Wing also of the Gnat being adorned with Feathers, I have drawn that too as Fig. 4, which is a Wing as it appears to the naked Eye. Fig. 5. A B C is the same represented in a larger proportion, to show that not only the whole Circumference of the Wing, as here 5. A B C is beset with great and small Feathers as Fig. 6. But also the Nerves that stiffen the Wing, as DDDD. The Film of the Wing which is between the Nerves DD, seemeth by the Microscope to be full of a great many small Risings; but upon a stricter Examination, they are really small hairs, as Fig. 7, where a beginning was made to represent the whole Wing: A B C are the Feathers, and ADEC are the hairs on the Film. A certain Phisitian having told me that several people afflicted with Agues, had been cured thereof by the use of Sal volatile Oleofum, which had attenuated and rarified their blood. I resolved to make what observations I could, of the mixture of that Salt with Blood. And therefore pricking my finger with a needle, I put the first time two parts of Blood to one of Salt; a second time equal parts of each. The blood turned immediately of a more lively red color, as blood usually does when mixed with fair Water (for I am of the Opinion that when blood running from a Vein is of a dark-red or blackish colour, the reason of the blackness is, that the Globules which make the blood red are not sufficiently diluted with that liquor which Phisitians call the Whey of the blood). Upon viewing my Blood one day, I found it somewhat blacker than ordinary, but not reflecting thereon, and the next day working till I swear, I was seized with an Ague; which I then thought might be caused by the thickness of my Blood; and therefore bethought myself of such things as would attenuate it, drinking a great deal of Warm Tee, and finding myself pretty well therewith, I continued it, unless sometimes that I took a little small bear, eating little but a Sallet or Endive. Upon the Fourth day my urine came again to its Natural Color. But to come more particularly to the alterations made in the blood by Sal Volatile Oleofum. The parts of that blood that lay nearest the Salt, changed colour first, and by degrees those further distant. But taking my Microscope to observe it, I found the Blood Globules each to be dissolved into Six distinct Globules. I then took Four parts of Salt &c. and one of Blood, and viewing it as quick as I could with my glass I found some of the Blood Globules much diminished in $\frac{1}{4}$ of a minute, but in $\frac{1}{2}$ of a minute they were wholly dissolved. I saw once 20 Blood Globules at a distance from the rest, but in continuing to tell them they came first to 18, then 16, after to 3, or 2, which also were dissolving. There There was also here and there a Globule that would not dissolve; nor with a very little Salt would any. What may be the Cause of these Effects, I cannot say, but as to the Effects themselves, I imagine that the Sal Oleosum being taken inwardly, and conveyed into the Lattes, and Veins, may have the force to hinder the Compounding the blood Globules, by which means the blood may become more thin, and perform its circulation more easily. An effect not altogether unlike this, we have from the Brimstone-Match, with which the Wine-Coopers smock their Casks, thereby to hinder the wine from thickening and working. But Brimstone hath not the force of making Wine that is already thick, grow thin. I lately read a Physician of our Country, who affirms there is a fermentation and rising in the Blood, caused by the Intercourse it has with the Air in the Lungs, as we see a Rising in Dough caused by Yeast. That there is a great deal of Air swallowed down into the Stomack with our meats (and some made out of the meat itself) which afterwards enters the Blood, I do not deny, nor that there may be Air contained in the blood, in the same manner as there is in warm Water, or Wine that does not work. But I can't conceive there should be such large bubbles in the blood, as are caused in Dough by Yeast, for these Bubbles moving in a liquid body, whenever their Superficies came to touch, would unite together; whence it would follow, that a great part of the Blood-Vessels, would be full of nothing but Air. Again if there were Air bubbles in the blood, they a thousand times less than a Sand, I should have discovered them, in my many Observations made about the blood for 11. or 12. years last past.